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Africa’s Yellow Fever Outbreak is a Glimpse of Our Connected Future

Zika virus has been earning all the headlines, because it is already affecting Americans—including 300 pregnant women, according to a new CDC estimate—and is expected to move into U.S. mosquitoes as the summer bug season starts.

But outside the United States, another mosquito-borne disease is attracting the world’s attention, and it may predict more than Zika does about how epidemics will move around the world in the future. The disease is yellow fever, the epicenter of the outbreak is Angola, and the force that could push it around the globe is Chinese investment in the developing world.

A member of the Angolan military administers a yellow fever vaccine to a child at 'Quilometro 30' market, Luanda, Angola, in February.
A member of the Angolan military administers a yellow fever vaccine to a child at ‘Quilometro 30’ market, Luanda, Angola, in February.

The Angolan outbreak began in December and is large: more than 2,400 cases and 298 deaths, according to the latest report from the World Health Organization. It was originally centered on the capital, Luanda, and has spread through the western half of the country. It has also hopped borders: There are 42 cases in the neighboring Democratic Republic of the Congo and two cases in Kenya (along with an an unrelated outbreak in Uganda, between Kenya and the DRC).

But what has some researchers unusually alarmed is that there are 11 cases in China: workers or families who returned from Angola into an area where yellow fever does not now exist—but the mosquitoes that spread it do.

“Approximately two billion people live in Aedes aegypti-infested countries in Asia,” Sean Wasserman, Paul Anantharajah Tambyah, and Poh Lian Lim, researchers from South Africa and Singapore, say in a paper published online in May in the International Journal of Infectious Diseases. “The prospect of a yellow fever introduction into this unvaccinated population poses a major global health threat,” they write.

Maps of Angola showing month-to-month spread of yellow fever.
Maps of Angola showing month-to-month spread of yellow fever.
Courtesy the World Health Organization.

Yellow fever is a persistent problem in West Africa, where the virus cycles between monkeys and mosquitoes and spills over to humans. That happens first in villages at forest edges, and then in cities as infected people carry the virus to urban mosquitoes. (These happen to be the same kinds of mosquitoes that transmit Zika, and also chikungunya and dengue: voracious day-biters that breed in pools of water as small as a bottle cap, and attack people not only outdoors but inside houses.)

A vaccine prevents yellow fever, but only about 70 percent of Angolans receive it, not enough to create the herd immunity that would prevent an outbreak from taking hold.

That is a serious gap, because unlike the other diseases carried by Aedes mosquitoes—which except for the birth defects of Zika mostly cause mild illnesses—yellow fever can kill. As many as one in four of those who develop symptoms go on to have liver and kidney failure, jaundice (which gives the disease its name) and bleeding, and one in four of those victims die.

Fumigating a Texas town infected with yellow fever, 1873.
Fumigating a Texas town infected with yellow fever, 1873.
Photograph by North Wind Picture Archives, Alamy

Yellow fever has never taken hold in Asia. Lack of familiarity with the disease may explain why the 11 infected people who returned to China were not vaccinated, despite Chinese regulations saying they should have been.

They probably have a lot of company: Angola is one of China’s biggest investment targets in Africa, for cropland and for energy. In 2009, according to the Centre for Chinese Studies in South Africa, China bought almost one-third of Angola’s crude oil. The Chinese expatriate community in Africa is estimated to be 20,000 people, who include not just semi-permanent residents but temporary construction workers who are shipped from job to job.

Because the continents harbor the same mosquito species—Singapore, where Tambyah and Lim work, wages a constant battle against dengue—the researchers suggest that just one unknowing traveler carrying yellow fever virus in their blood could spark a chain of transmission. That could trigger what The Economist warned in an editorial earlier this month would be “a preventable tragedy,” an epidemic as explosive as chikungunya after it arrived in India in 2005, or Zika in the Americas this year.

The authors of the new paper say: “The current scenario of a yellow fever outbreak in Angola, where there is a large community of non-immune foreign nationals, coupled with high volumes of air travel to an environment conducive to transmission in Asia, is unprecedented in history… The growing number of imported cases in China shows how critical it is to recognize this risk now in order to take adequate preventive action so that a global catastrophe can be averted.”

The action that is most needed is vaccination. Monday marked the start of the World Health Assembly, the annual conclave of member states of the World Health Organization. In the opening meeting, director general Dr. Margaret Chan delivered what she called a “stern warning” on failures to vaccinate adequately. (Chan’s term ends in June 2017, so she may have felt safe being blunt—though she did not name names.)

A Rockefeller scientist administers yellow-fever vaccine in Santiago de Guayaquil, Ecuador, in the 1920s.
A Rockefeller scientist administers yellow-fever vaccine in Santiago de Guayaquil, Ecuador, in the 1920s.
Photograph Courtesy of Rockefeller Foundation

“The world failed to use an excellent preventive tool to its full strategic advantage. For more than a decade, WHO has been warning that changes in demography and land use patterns in Africa have created ideal conditions for explosive outbreaks of urban yellow fever,” she said. “Yellow fever vaccines should be and must be used more widely to protect people living in endemic countries.”

Because of the Angolan outbreak, yellow fever vaccines are in short supply worldwide, as Kai Kupferschmidt reported in Science in April. Only four factories, in Russia, Brazil, France and Senegal, make the compounds, and one is about to close. But in May, a WHO emergency committee declined to rank yellow fever as a “public health emergency of international concern.” As global health-law scholars Daniel Lucey and Lawrence Gostin wrote in JAMA two weeks ago, that designation could have given the agency increased leverage to negotiate with vaccine manufacturers. (Following the decision, the committee advised “rapid evaluation” of dividing vaccine doses so that more people can be protected.)

But that may not be enough. In its editorial, The Economist did the vaccine math:

Should yellow fever come to Asia, some experts reckon that over 100m people living in large, well-connected cities would need to be vaccinated. That would rapidly exhaust the world’s supply of vaccine, even if only a fifth of a dose (thought to be enough to confer immunity to adults) were administered to each person who needed it. In the long term, if the disease establishes itself in Asia’s jungles, over 1 billion more people could be at risk…

The world has already failed to thwart yellow fever effectively in Africa. That threatens to put millions more lives at risk.

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Zika Is Likely to Become a Permanent Peril in U.S.

Mosquitos caught for testing in McAllen, Texas, await shipment to a lab. McAllen city workers are catching them in "mosquito traps" and sending them to labs to test for Zika and other mosquito-borne diseases.
Mosquitos caught for testing in McAllen, Texas, await shipment to a lab. Southern states that harbor the species that carries Zika are watching for infected mosquitoes.
Photograph by John Moore/Getty Images

Once Zika virus arrives in the United States, it will be here to stay. Leading experts now predict that the mosquito-borne disease will become a constant low-level threat that Americans will need to be vaccinated against routinely—as we do now for rubella, a virus that, like Zika, causes birth defects.

That is, once there is a vaccine for Zika. The earliest possible deployment of Zika vaccines could be several years away, researchers from around the globe predicted at an Atlanta conference Tuesday, the annual meeting of the Global Virus Network.

Overall, they said, Zika should be understood not as an epidemic wave that will pass over the world and then vanish, but rather as a permanent problem that will wax and wane, as West Nile virus has.

“We don’t know the future course of the epidemic of Zika, but we have to be prepared for the virus to be present for years,” José Esparza of the University of Maryland School of Medicine, current president of the Global Virus Network, said at the conference. “Without a vaccine, we will not be able to control the future course of this epidemic.”

Race for a Vaccine

Everyone reluctantly accepts that vaccines will take some time, while also expecting that infections could reach the United States soon. “The risk of Zika virus beginning to circulate in the United States on the mainland—it’s already in Puerto Rico, of course—is going to be peaking during the next few weeks,” said Scott Weaver, a virologist from the University of Texas Medical Branch.

“The number of travelers coming into the U.S. with Zika is very high, the temperatures are permissive now for mosquito transmission, and populations of mosquitos are growing,” he said.

Delfina Tirado, left, and Chalmers Vasquez of the Miami-Dade County's Mosquito Control Division inspect a pool in Miami, March 17, 2016. The Aedes aegypti mosquito -- the type that is spreading the Zika virus and fear of grave birth defects throughout Latin America and the Caribbean -- is being found in Florida and is expected to soon be buzzing around its usual haunts in the United States.
Workers from the Miami-Dade County’s Mosquito Control Division inspect a pool in Miami. The Aedes aegypti mosquito—the type that is spreading the Zika virus—is being found in Florida and is expected to soon be buzzing around its usual haunts in the United States.
Photograph by Max Reed/The New York Times

A vaccine is most needed to protect women who are pregnant or planning to be, because the virus causes devastating birth defects that seem to appear late in pregnancy, and may also cause more subtle problems as children get older.

“We have no information to believe there are any long-term consequences from infection to healthy adults or healthy children,” Weaver said.

While a small vaccine trial sponsored by the National Institutes of Health could begin as early as next fall, expanding that research into trials with thousands of participants could be complicated by the rapid growth of the epidemic, which is both infecting people and also rendering them immune once they recover.

The first Zika vaccines to be developed probably won’t go to everyone, Weaver predicted. “I think initially there will be some vaccines developed and licensed that are not optimal for vaccinating large populations, that will require multiple doses,” he said. “Those will probably be targeted to girls before they reach childbearing age, or women … if we can determine that they are not immune, if we have the diagnostics to do that.

“And then eventually we should be able to develop a live attenuated vaccine, like the one we have now for yellow fever that has been available for many decades in South America,” Weaver said. Then, he added, doctors can vaccinate children, and the population will develop what we think of as “herd” immunity that protects even the unvaccinated.

MCALLEN, TX - APRIL 14: A health inspector sprays a neighborhood for mosquitos early on April 14, 2016 in McAllen, Texas. Health officials, especially in areas along the Texas-Mexico border, are preparing for the expected arrival of the Zika virus, carried by the aegypti mosquito, which is endemic to the region. The Centers for Disease Control (CDC), announced this week that Zika is the definitive cause of birth defects seen in Brazil and other countries affected by the outbreak. ()
A health inspector sprays a neighborhood for mosquitos in McAllen, Texas. Health officials, especially in areas along the Texas-Mexico border, are preparing for the expected arrival of the Zika virus, which is endemic to the region.
Photograph by John Moore/Getty Images

Introducing a Zika vaccine in that manner would follow the path that rubella vaccine took in the 1960s. Before the vaccine existed, epidemics of rubella (also known as “German measles”) caused only mild illness in adults; but the virus had devastating effects when it infected pregnant women. In 1964-65, the last such epidemic, 11,000 U.S. children were born deaf, 3,500 were born blind, 1,800 were born with developmental abnormalities, and women suffered 2,100 stillbirths—along with more than 11,000 miscarriages and elective abortions.

The vaccine was introduced in 1969 and put on the childhood vaccination schedule that is composed by the Advisory Committee on Immunization Practices, an expert panel that assists the CDC; it is part of the MMR (“measles, mumps, rubella”) shot given at 12-15 months and 4-6 years. Since the vaccine was introduced, there have been only a few cases of rubella in the United States each year.

While the Zika vaccine hunt proceeds, scientists said at the Atlanta conference, it’s imperative to create easy-to-use tests to identify infected people, most of whom show no symptoms. Right now, it is difficult even to ascertain how many people in the Zika zone are already immune, since the current tests for diagnosing Zika infection, which were developed by the Centers for Disease Control and Prevention, are not commercially or widely available.

Zika’s Imminent Arrival

Travelers to the United States, whether visitors or residents returning home, are likely to be the reason that Zika ignites in the U.S. Weaver urged anyone traveling in the Zika zone to be scrupulous with mosquito repellent not just while there, but also for two weeks after they return, to be sure that they do not accidentally transmit the disease to U.S. mosquitos.

“It only takes one infected person to arrive and be bitten and the transmission cycle takes off,” Weaver said.

In the gap before a vaccine can arrive, the researchers said it’s important to achieve antiviral drugs that can work against the virus, and research presented at the conference suggests that combinations of drugs already on the market could be used in the short term.

In Recife, Brazil, Zika virus has been linked to birth defects in babies born to infected mothers. Here, Joao Batista comforts his daughter Alice Vitoria, who has microcephaly.
In Recife, Brazil, Zika virus has been linked to birth defects in babies born to infected mothers. Here, Joao Batista comforts his daughter Alice Vitoria, who has microcephaly.
Photograph by Tomas Munita, National Geographic

“These are drugs that have been used for a long time in people, so the safety issue is not a problem,” said Glaucius Oliva, a structural biologist from the Sao Carlos Institute of Physics at the University of Sao Paulo. “Repurposing drugs could begin in a year or two, whereas new drugs will take longer—10 years, maybe eight.”

Because so much research is needed, scientists sounded especially concerned that funding for Zika work in the U.S. has not yet been authorized. Congress went on recess without approving a White House request for more funds.

“A lot of the scientists in the U.S. are waiting for the floodgates to be opened with funding; a lot of the work that has been done so far has been done with shoestring budgets,” Raymond Schinazi, director of Emory’s Laboratory of Biochemical Pharmacology, said.

“This takes fuel, and the fuel unfortunately is very limited right now.”

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The Entire World is Getting a New Polio Vaccine This Month

In the final push to end polio, global health planners are embarking on an unthinkably ambitious and potentially risky move. They’re switching 155 countries—a good portion of the world—from one polio vaccine to another.

An Afghan health worker administers polio vaccine drops to a child in Kabul. Afghanistan and Pakistan are the last two countries to see polio outbreaks.
An Afghan health worker administers polio vaccine drops to a child in Kabul. Afghanistan and Pakistan are the only countries with polio cases this year.
Photograph by SHAH MARAI, AFP, Getty

This will require moving millions of doses of a new vaccine into place over the course of two weeks in late April, while sequestering the remaining stocks of the old one.

And that’s only one of the many maneuvers necessary to truly end polio, which in the 1980s caused more than 350,000 cases of paralysis a year. So far in 2016, there have been only nine cases in two countries: Afghanistan and Pakistan.

The vaccine switch is part of the final strategy to put a noose around the few remaining cases, by improving the match between the viruses that remain in the wild and the vaccine that suppresses them. If it goes as planned, it will improve children’s immunity to wild-type polio while removing their vulnerability to a variant of the disease that can be accidentally caused by the vaccine itself.

It looks like the goal is in sight. But polio has slipped from control before.

“This is the largest, the fastest, and [a] unique event that is taking place,” Dr. Michel Zaffran, the director of polio eradication at the World Health Organization, said in a phone call with reporters Thursday morning. “This is an unprecedented event that has never been done before in the world.”

After almost 30 years of trying, the move has the potential to finally stop any new cases of polio from occurring. But planners acknowledge that the move carries some risk: It could accidentally ignite an outbreak of the type of polio caused by the vaccine.

“We are anticipating there will be at least one event we will have to respond to,” said Dr. Steven Cochi, who serves as a senior liaison between the eradication campaign and the Centers for Disease Control and Prevention.

Shots or Drops?

To understand the complexity of this, it helps to remember a little history. The start of the effort to control polio, back in the 1950s, was a competition between two scientists: Jonas Salk, who developed an injectible vaccine using killed virus, and Albert Sabin, who formulated a vaccine taken by mouth that relies on living but weakened polio.

Salk’s vaccine ended up ruling in the industrialized world. But Sabin’s became the foundation of the international eradication campaign, not just because it can be administered even by people with no medical training, but because, as the virus gets into the gut and attaches there, it produces copies that pass out of the body in feces and create immunity in anyone else who picks it up.

That strength turned out to be a weakness, because as the live virus reproduces, it can mutate from its weakened form into a virulent disease-causing type, and cause polio in any of those nearby who would otherwise have been protected when the vaccine virus was shed. Last year, when there were only 74 cases of polio in the world, 27, more than a third, were caused by what is called “vaccine-derived” virus.

Polio virus comes in three “types,” or strains—known for simplicity as types 1, 2 and 3—that are different enough from each other that they all must be included in the vaccine. Type 2 is the most efficient at attaching to the gut, and partly because of that, it became the first strain to be eradicated; it has not been seen in the wild since 1999. But for the same reason, it is the strain most likely to cause vaccine-derived cases. So the new vaccine being rolled out on Sunday deletes the Type 2 weakened virus.

Why Change All at Once?

That substitution will only work if everyone in the world who is using oral polio vaccine, or OPV, switches at the same time; if one country continued to use the three-type vaccine, it could put others at risk. So beginning this weekend, thousands of volunteers and monitors will fan out, across the developing world and also in industrialized societies such as the Russian Federation which are still using OPV, to make sure the new vaccine is delivered on schedule and, crucially, kept cold as it goes.

To reduce the vulnerability inherent in the switch, as many countries as possible were supposed to give children one shot of the injectable vaccine, known as IPV, to make sure their immunity was as high as possible. But planners acknowledged Thursday that there is a shortage of IPV, and not all children may have received the protective dose.

Most people stop shedding the vaccine virus in two to four weeks; that, Cochi said, is considered the window of vulnerability post-switch in which an outbreak might spark. There are also rare cases in which people with immune-system disorders hang onto the virus and shed it for years; since they are not made sick by it, they are very hard to spot. (To find them, some countries screen sewage for the presence of polio.)

Will This Cause an Outbreak?

Hypothetically, a long-term shedder carrying mutated type 2 polio virus could ignite an outbreak at any time. But Zaffran said, with unusual frankness, that in the countries that would be most vulnerable, immune-deficient children often do not live long; and in the countries where good medical care sustains their lives, immunization rates are already high enough to make the possibility of an outbreak null.

Nevertheless, Cochi said that to keep any potential outbreaks from spreading, stockpiles of the old oral vaccine will be kept on hand in each country, and million of doses of a new, Type 2-only vaccine are ready for emergency deployment if needed.

Planners hope the giant vaccine switch is the beginning of the endgame of eradication. It is late—they thought they would get to the goal 16 years ago—and each delay has been costly. The next steps will also be expensive and complex: first rolling out IPV across the world, and then scouring laboratories for any forgotten frozen samples that might harbor the polio virus.

But in the end, if they are successful, polio will become the second human disease eradicated from the world.

Earlier on Phenomena:

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As Zika Advances, Can the U.S. Cope?

The Dallas County Mosquito Lab traps and searches through mosquitos looking for any that carry the Zika virus.
The Dallas County Mosquito Lab traps and searches through mosquitoes looking for any that carry the Zika virus.
Photograph by LM Otero, AP Images

The Zika virus that is advancing on the United States is unlike any other outbreak the country has faced, and countering it will require an effort unlike anything the U.S. and its public health infrastructure has done before.

More than 300 delegates to an emergency summit held at the Centers for Disease Control and Prevention in Atlanta—state, local and tribal officials, members of nonprofits and representatives of private companies—heard that message over and over again Friday. Scientists, political appointees, and public health experts urged them to find a way to pull together groups who seldom have a reason to communicate: health departments, academic physicians, community well-baby clinics, birth-defect surveillance programs, mosquito-control workers, even garbagemen and gardeners.

All of that expertise, they said, will be needed to prevent a disease that is carried by mosquitoes that elude spraying, infects most of its victims silently, damages fetuses in ways that are still not understood, and may not be detected until well after it has arrived.

“Nothing about Zika is going to be easy or quick,” Dr. Thomas R. Frieden, the CDC’s director, said at a press conference halfway through the all-day meeting. “The control of this particular mosquito is hard, and though we are learning a lot quickly, there is still a lot we don’t know. There is an urgent need to learn more.”

CDC Director Dr. Thomas R. Frieden addresses media during the Zika Action Plan Summit in Atlanta, April 1, 2016.
CDC Director Dr. Thomas R. Frieden addresses media during the Zika Action Plan Summit in Atlanta, April 1, 2016.
Photograph by Maryn McKenna.

The meeting, which was standing-room-only in its main sessions and watched by 2,000 people online, revealed a simmering anger over Congress refusing to authorize money to combat the disease. The Obama Administration requested an emergency appropriation of $1.9 billion in February, but no funds have been  approved; Congress recommended the White House use money from last year’s Ebola response instead.

“I understand the polarization of politics in this country; I don’t understand why children are being made the center of it,” Dr. Edward McCabe, the chief medical officer of the March of Dimes, who spoke at the summit, said in a side interview. “We know what needs to be done, and it’s not stealing fron Ebola to fix this disorder. Congress needs to do the right thing.”

The financial stress of anticipating Zika is already hitting some jurisdictions. Daniel Kass, New York City’s deputy commissioner for environmental health services, told the meeting the city has already spent $3 million preparing for Zika, without ever having a case, and expects to spend $5-6 million more. Dr. Umair Shah, executive director of public health and environmental services for Harris County, Texas, which encompasses Houston, said his county expects to spend about half that much but added: “The real challenge is a lot of our daily work has been moved to the side.”

Dr. Georges Benjamin, executive director of the American Public Health Association, said during a break that health departments may struggle because financial support for public health has been so erratic: high just after the World Trade Center attacks and the first advent of West Nile virus, then sliding, only to rise during the 2009 H1N1 flu and then fall again until Ebola arrived. “When the money goes away, the jobs go away, and you’re left without the people you need,” he said. “It’s yo-yo funding, when what we need is to build a consistent approach.”

Zika has barely touched the U.S., compared to the devastation it has wrought in South America. (See “Here’s What we Know Now About Zika and Birth Defects.”) So far, according to the CDC’s most recent numbers, 312 U.S. residents have been infected while traveling in the Zika zone, including 27 pregnant women. No one has contracted Zika from a mosquito in the mainland U.S., but 6 people have caught sexually transmitted Zika from travelers, including two pregnant women, and one person has developed Guillain-Barré paralysis. In US territories—Puerto Rico, American Samoa and the U.S. Virgin Islands—349 people have been infected by local mosquitoes and three while traveling, including 37 pregnant women.

Where Zika cases have been diagnosed in the United States as of March 30, 2016.
Where Zika cases have been diagnosed in the United States as of March 30, 2016.
Map courtesy of the CDC; original here.

Puerto Rico “could have hundreds of thousands of infections and tens of thousands of pregnant women infected,” Frieden said, but he declined to provide projections for the U.S. mainland. “We don’t want to  speculate what may happen,” he said. “We want to maximize our preparedness for what we can prevent.”

Without a vaccine, a disease-specific treatment or even a rapid diagnostic test, preventing Zika will fall on the expertise of mosquito control agencies, and summit attendees were clearly worried about the strain. (See “Disorganized Mosquito Control will Make U.S. Vulnerable to Zika.”) In some jurisdictions, mosquito control is a well-funded part of the health department. In others, personnel are so scarce that “it might be a guy who does water sampling during the day, and at night, it’s Chuck in a truck” spraying for nuisance mosquitoes, Stanton E. Cope, PhD, director of entomology and regulatory services for Terminix and president of the American Mosquito Control Association, told me.

A particular challenge, Cope added, is that existing mosquito control programs were built either to banish nuisance mosquitoes that interfere with tourism or to quell the night-biting mosquitoes that spread West Nile virus—but the Aedes species that transmit Zika bite during the day, breed in minuscule pools of water, lurk inside houses, and require different spraying equipment to dispel them and different traps to catch them so they can be tested to see whether they are carrying virus.

In a piece of irony, the CDC originated from a 1940s agency called the “Office of Malaria Control in War Areas,” and during the summit’s opening session, organizers showed a 70-year-old short movie about its work targeting Aedes aegypti, the mosquito that now spreads Zika. In the intervening decades, that insect slipped off the list of public health priorities, said Dr. Lyle Petersen, director of the CDC’s division of vector-borne diseases.

“It’s an important vector worldwide,” he told me. “It spreads dengue; there are several hundred milion cases of dengue every year. It spreads yellow fever, and right now we are having the first large urban yellow fever outbreak we have had in decades. It also spreads chikungunya. So it’s a bad actor.

“But what happened was, there’s a vaccine for yellow fever. And dengue was confined to the tropical world, and Zika wasn’t even on the horizon yet. So it became a very neglected mosquito, and now we are dealing with it again.”

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To Fix Antibiotic Resistance: A Cabinet Post And More Money

Turkeys in a North Carolina intensive farm.
Turkeys in a North Carolina intensive farm.
Photograph by Mercy for Animals via Wikimedia Commons.

A White House panel of experts has made a striking recommendation: the United States needs a champion—perhaps even a new Cabinet member—backed with plenty of funding to fight antibiotic resistance.

This champion, who could also be an assistant secretary, would guarantee the issue does not slip away beneath short-term priorities and agency infighting. And most of all, as the group mentions numerous times, the effort needs money: “The (government) must commit sufficient resources to solving the problem with funding continued over a long period of time… Key elements necessary to achieve the goals of the national action plan are underfunded.”

Eighteen months ago, the Obama White House made a historic commitment—the first by any administration—to combating antibiotic resistance. The administration announced a national strategy against resistance, President Obama signed an executive order launching the effort, and the White House subsequently held a first of its kind Forum on Antibiotic Stewardship.

To figure out what the country should do, the White House named a Presidential Advisory Council on Combating Antibiotic-Resistant Bacteria. Today that panel of experts launches a two-day meeting to start dealing with the practicalities, and has issued a 126-page report out of their first 180 days of research.

Other priorities (which will be familiar from other examinations of resistance such as the reports from the British Review on Antimicrobial Resistance): improve surveillance to detect resistance faster, stimulate the development of new drugs, foster innovation in rapid diagnostic devices to cut down on useless  prescribing, explore international agreements on conserving antibiotics,  try to educate the public on appropriate antibiotic use.

From the launch of the national strategy and the council’s being named, many advocates have criticized its makeup for being long on medical research but short on the kind of public health insight that could push back against the agricultural status quo. So it’s encouraging that the group put at the top of their list a commitment to a “One Health” approach, which is to say, considering human and animal issues to be connected, and not separate realms. Each of the major issues examined by the report contains a “One Health” addendum.

At the same time, the report (which will be voted on Thursday at the meeting’s conclusion) has relatively little to say about the specifics of reducing antibiotic use in agriculture, beyond support for the ongoing Food and Drug Administration policies that are forcing relinquishment of growth promoter antibiotics by next year. Dr. David Wallinga, a senior health officer at the Natural Resources Defense Council, expands on this in a Medium post, saying the US is going down a path that failed in Europe, which found that growth-promoter bans led to sneaky label changes.

“The Advisory Council should take a step back,” he writes. “Evaluate what’s not working for the U.S. to reach its ultimate goal of reducing widespread overuse of antibiotics. And issue a Plan B, one that recommends meaningful targets for reducing of antibiotic use in livestock, or alternatively recommends an end to the use of antibiotics in livestock for both growth promotion and disease prevention.”

The lack of specificity is frustrating, given that recent news has made the connection between agricultural use and human health threats even more clear than scientists have demonstrated previously. The extremely resistant superbug MCR-1, a gene that confers resistance to the last resort drug colistin, has now moved around the world. As I reported last fall, MCR arose because human medicine had dismissed colistin as not-useful,  agriculture took up the drug, and then medicine decided it was needed after all. Since then, MCR has been identified in more than 20 countries, in humans, farm animals, food or the environment. Recently, researchers in Tunisia found MCR in chickens on several large farms there, and traced the birds back to hatcheries in France.

As Laurent Poirel and Patrice Nordmann, two prominent European researchers into antibiotic resistance, wrote Tuesday in the Journal of Antimicrobial Chemotherapy: “MCR-1 is one of the few and clear examples of the animal origin of a resistance trait that may later hit the entire human health system.”

The expansion of that last-ditch resistance is unlikely to slow down without explicit international regulations and targets. As Bloomberg reported Tuesday night in a blockbuster set of stories reported in India, farms there are freely using colistin and other crucial antibiotics (Cipro, Levaquin, doxycycline) including ones banned in Western agriculture (Baytril, gentamicin) in multi-drug cocktails that are likely to encourage multi-resistant organisms.

As the think tank CDDEP has demonstrated, the demand for meat is rising in the developing world—and with it, antibiotic use to support meat production is rising too. The use of antibiotics in agriculture is a crucial part of the fight against resistance. It’s important that the White House effort examine that issue with the detail it gives to other parts of the puzzle.

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To Slow Down Antibiotic Resistance, Focus on the Basics

Washing hands.
Washing hands.
Photograph by Arlington County, Flickr (CC).

A project chartered by the British government, which has been examining everything that can be done to stem the tide of antibiotic resistance, in its next-to-last report has focused on the basics: municipal sanitation and hospital hygiene.

It’s something of a change in tone for the Review on Antimicrobial Resistance, a two-year effort created by Prime Minister David Cameron, supported by the Wellcome Trust and chaired by Lord Jim O’Neill, the former chief economist of Goldman Sachs (who now also serves in an unpaid post in Cameron’s government). The Review’s previous reports have examined what could be changed or created to solve problems that contribute to the rise of resistance: funding drug development, supporting vaccine research, detecting counterfeit drugs, innovating rapid-diagnosis devices and improving vaccine use.

In its new analysis, the group backs away from technological optimism to address seemingly intractable problems: how hospitals continue to cause antibiotic-resistant infections in their most vulnerable patients, and how the lack of clean water and sanitation both create diseases that demand antibiotic use, and also spread antibiotic-resistant bacteria.

Obviously neither of those concerns are new: Ignaz Semelweis  linked unwashed hands to fatal childbed fever in 1847, and John Snow made the connection between contaminated water and a cholera outbreak in 1854. Yet today, just in the United States, more than 1.7 million people contract healthcare-associated infections each year, and worldwide, more than 2 million people die from waterborne diarrheal disease.

So the problems are not solved. “We felt it would be of value to point out that just doing the basics can make a huge amount of difference,” Lord O’Neill said by phone. “It is concerning that not enough has happened, and that’s a reason for a new, independent voice to highlight that.”


The Review commissioned an analysis from postgraduate students at the London School of Economics which found that, just in four countries with emerging economies (India, Indonesia, Nigeria and Brazil), 494 million cases of diarrhea each year are treated with antibiotics, a number that could rise to 622 million cases by 2030. If infrastructure were improved, 60 percent of those courses of antibiotics could be foregone. The report says that contaminated water also allows bacteria to cycle between humans and the environment, spinning up the dissemination of resistance genes. (In fact, in 2011, the team who discovered the resistance supergene NDM identified municipal water supplies and puddles as a major contributor to the spread of that almost untreatable bug.)

If sanitation seems a simple goal, so does hygiene—yet the Review finds that persistent neglect of simple tasks such as washing hands is fueling the spread of resistance. As few as 30 to 40 percent of hospital staff wash their hands as often as they should, it says, and doctors perform worse than nurses or staff who are lower in the hierarchy. Though it is crucial those rates be improved, there group finds there is nowhere near enough research into what actually motivates healthcare workers to change their behavior, and recommends funding studies that could pick apart what works. (Dismayingly, that does not now happen. A few years ago, infection-prevention specialist Dr. Eli Perencevich and several colleagues analyzed funding awarded by the National Institutes of Health to study AIDS, versus funding for research into hospital infections. For every US death from AIDS, they found, the NIH awarded the equivalent of $69,000; for every US death from MRSA, drug-resistant staph, $570.)

In its final comments, the Review calls for something that, for years, researchers deep in the trenches of antibiotic resistance research have been begging for: the creation of a comprehensive, global, rapid surveillance system that could alert the world when something new emerges. Two examples of where that would have made a difference: NDM was first identified in Sweden in 2008, but was subsequently found to have been diagnosed in India, its place of origin, as early as 2006. And MCR-1, the most recent dismaying superbug—which is resistant to the utterly last-resort drug colistin—was found last fall to have spread to more than a dozen countries, but was first identified in China in 2013.

“Even in some of the world’s most developed health systems, AMR surveillance data is often patchy and retrospective—virtually none is ‘real time’,” the Review says. “Without effective monitoring, we will lack early warning of emerging patterns of drug resistance, and lack the insights needed to guide and evaluate our response.”

The Review will conclude its two years of research with a final presentation of big-picture recommendations for health agencies and governments this summer, with presentations to the World Health Assembly and the United Nations.

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Can We Keep Zika Out of the US Blood Supply?

A doctor draw blood from Luana, who was born with microcephaly, at the Oswaldo Cruz Hospital in Recife, Brazil, Thursday, Jan. 28, 2016. Photograph by Felipe Dana, AP
A doctor draw blood from Luana, who was born with microcephaly, at the Oswaldo Cruz Hospital in Recife, Brazil, Thursday, Jan. 28, 2016. Photograph by Felipe Dana, AP

If Zika virus comes to the United States, will the US blood supply be at risk?

Because the disease has demonstrated that it can pass via blood from mother to fetus, and via other bodily fluids between sexual partners, the question lurks in the back of most discussions of Zika’s likely arrival on the US mainland. And because there is not now a test for donated blood, keeping the virus out of the blood supply relies on people adhering to restrictions published by the Food and Drug Administration that ask travelers to defer donating for a period of time—an imprecise deterrent, but currently as good as it gets.

The concern for the blood supply is reasonable. In 2002, when West Nile virus was newly arrived in the United States, transfusions given to a teenage accident victim—who died of her injuries, and became an organ donor—caused that disease to pass to all four recipients of her organs. Dengue, another mosquito-borne illness that is burgeoning in Central and South America and has become established in south Florida, has also passed between blood donors and recipients, though there are only a few cases on record. And Zika virus was identified in 3 percent of donated blood in French Polynesia in late 2013 and early 2014, when the virus first landed in that area.

(See: Pictures Capture Daily Battle Against Zika Mosquitoes)

The concern has been sharpened by a new analysis, published Wednesday in the journal PLoS Currents Outbreaks, that plots the range of the mosquito species known to carry Zika against the numbers of travelers who arrive from the Zika zone. The researchers—from several US government agencies, North Carolina State University and University of Arizona, and Durham University in England—predicted that cities within the mosquito’s range are at highest risk of local transmission of Zika if they have international airports, or airports receiving connecting flights from those hubs. Other cities receiving large numbers of travelers from the Zika transmission zone were at moderate or lower risk if they fell near the edge of the mosquito’s range. So, for instance, Miami, Orlando, Jacksonville, Tallahassee, and New Orleans were at high risk of receiving the disease; New York, Atlanta and Houston were at moderate risk, and Dallas, Denver and Los Angeles at low risk.

A map of cities most at risk for arrival and local transmission of Zika virus.
A map of cities most at risk for arrival and local transmission of Zika virus.
Graphic from Monaghan et al., PLoS Current Outbreaks, March 16, 2016.

What was jaw-dropping in the study, though, were the sheer numbers of people who arrive in US cities from the Zika transmission zone: up to 1 million per month in Miami and New York, 500,000 per month in Atlanta, Houston, New York and Dallas, and millions per month through the ground border crossings of San Diego, El Paso and Laredo.

To prevent Zika contaminating the blood supply, the FDA issued guidelines last month addressing blood donation and this month regarding donated cells and tissues. For blood donation, the agency recommended that blood agencies ask people to defer donation for four weeks after experiencing Zika symptoms, traveling in the Zika transmission zone,  or having sex with a man who either had the symptoms or traveled in the Zika zone. For tissues such as ligaments and corneas, and cells (which include sperm and eggs), the agency extended the deferral to six months. The FDA has not placed any restrictions on donation of solid organs, arguing that because they are both life-saving and in short supply, the benefit outweighs the risk.

Blood donations.
Blood donations.
Photograph by MikeHT, Flickr (CC).

Dr. Matthew Kuehnert, who is director of the office of blood, organ and other tissue safety at the Centers for Disease Control and Prevention, and is serving as the lead for the blood safety team in the CDC’S Zika response, said knowing how far to go to protect the blood supply is challenging because data is so sparse.

“There is little that we know about transfusion transmission of Zika, although I think we should assume it can happen,” he said by phone. “From the data that has been collected on Zika, about 80 percent of people don’t know they are infected. There is a period of viremia”—when virus circulates in the blood—”but we don’t know how long that viremia is. It is thought to be 7-10 days, but as we start to collect more data we may find it is longer than that.”

“It is possible we could get a transfusion or transplant transmission case before we even know local transmission of Zika is occurring.”

A problem, Kuehnert pointed out, is that because symptoms are the signal of an infection, only people who show signs of Zika infection—mostly fever, headache, rash and red eyes—are being interviewed and tested to add to knowledge about the disease. People who do not experience symptoms are not visible to investigators. They also become viremic; but since they are not interviewed or tested, the duration of their viremia, when the virus in their blood could pass into a blood donation, is not being uncovered. And there are early signals that, even after it passes out of the blood, the virus can take shelter in other tissues and fluids. “Zika can be sexually transmitted long after viremia is thought to be gone, so there are likely protected sites where it can hide,” he said. “Thus there might be blips of viremia occurring after symptoms have resolved. So there is a lot of potential for transfusion transmission.”

Those considerations apply in areas where Zika is not yet locally established. Where it is—which in the United States is Puerto Rico (160 cases as of March 9), American Samoa (13 cases) and the Virgin Islands (1 case)—blood is assumed to be a risk, and workarounds are being urgently sought. Because there is no test for Zika in donated blood—an approved test is “weeks to months away,” Kuehnert said—the only alternative is to use what are called “pathogen reduction” treatments, which inactivate viruses. Currently, pathogen reduction can only be used on platelets and plasma; red blood cells can be altered by pathogen reduction, and authorities are urgently searching for better techniques..

In a sign of how quickly an epidemic can upset the balance of blood supplies, Puerto Rico is now receiving outsourced blood from the US mainland, via a joint effort of three blood-collection agencies—the  American Red Cross, Blood Centers of America, and America’s Blood Centers—and the Department of Health and Human Services. The CDC estimates the current need for clean blood and blood products in Puerto Rico is 2,500 units of red blood cells, and an additional 1,000 units of other blood products, every week.

Despite the protections put in place by the FDA, public health authorities are braced for the possibility that transfusion-associated Zika could begin occurring in the United States. “This could happen at any time,” Kuehnert acknowledged.

He added: “It is possible we could get a transfusion or transplant transmission case before we even know local transmission of Zika is occurring,” because the illness that necessitates a transfusion—or the immunosuppressive drugs that transplants recipients take—make them more vulnerable to disease. “We are doing a lot of work to be prepared.”


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Some US Hospital Infections Dropping, But Superbug Risks Are High

Handwashing after exposure to bacteria at a petting zoo.
Handwashing after exposure to bacteria at a petting zoo.
Photograph by Blue Yonder, Flickr (CC)

Fifteen years after a national report exposed how many Americans were being made sick and dying because of medical errors, some infections caused by hospitals are decreasing, according to the Centers for Disease Control and Prevention. But in a report published Thursday, the agency warns that the incidence of other infections remains stubbornly high, despite fixes that are simple in some cases—and the proportion of them that are antibiotic-resistant is, in its director’s words, “chilling.”

Drawing on data from its National Healthcare Safety Network, which compiles reports from 4,000  hospitals, 1,135 rehab facilities and 501 long-term acute care hospitals (which house severely ill patients who need ICU-level care for a long time), the agency reported that in 2011, 722,000 “healthcare-associated infections” occurred, and approximately 75,000 patients died. Between 2011 and 2014, it said:

  • for central line-associated bloodstream infection, which start from a tube threaded near the heart to deliver medications: a 50 percent reduction in hospitals and 9 percent in  long-term acute care hospitals;
  • forurinary-tract infections caused by catheters inserted into the bladder: no change in hospitals, an 11 percent reduction in long-term acute care hospitals, and a 14 percent reduction in inpatient rehab facilities;
  • for infections in surgical incisions, a 17 percent reduction in hospitals;
  • and for Clostridium difficile infections—the devastating antibiotic-associated diarrhea that is a signal for high antibiotic use and insufficient hygiene—an 8 percent reduction in hospitals.
Changes in four healthcare-associated infections in US healthcare facilities.
Changes in four healthcare-associated infections in US healthcare facilities.
Graphic by the CDC; original here.

But while those reductions are good news, the troubling aspect of the report is the percentages of hospital-caused infections that are antibiotic-resistant. In 2014, the CDC said, 14.9 percent of those infections were resistant. Breaking those down:

  • in hospitals, 18 percent of central line-associated bloodstream infections, 15 percent of surgical-site infections and 10 percent of catheter-associated urinary tract infections were resistant;
  • in rehab facilities, 12 percent of urinary-tract infections were resistant;
  • and in long-term acute care hospitals, 28 percent of central line-associated bloodstream infections and 29 percent of cather-associated urinary tract infections were resistant.

In a phone briefing with reporters, Dr. Thomas Frieden, the CDC’s director, called the high levels of resistance in infections in long-term care facilities—more than one in four of each infection— “chilling.” Asked how he would describe the rate in regular hospitals, which exceeds one in seven, he replied: “deeply concerning.”

According to the CDC’s data, 4 percent of patients develop an infection as a result of a hospital stay. Many of those, Frieden said, are the responsibility of healthcare personnel who fail to follow simple, known procedures, from washing hands to neglecting rules for installing catheters to continuing antibiotics beyond when they are needed. “Doctors are the key to stamping out superbugs,” he said. “No one should get sick when they are trying to get well.”

But, Frieden said, forcing down rates of healthcare infections and resistance in hospitals will also require investment in new diagnostics and patient records, beyond what hospitals can currently afford—especially since resistant bacteria can be carried into hospitals from longterm care facilities, which may have fewer staff and less resources for infection control.

Dr. Peter Pronovost, director of the Armstrong Institute for Patient Safety and Quality at Johns Hopkins—an early champion of cockpit-style checklists to prevent healthcare infections, who was also on the call to reporters—added: “We need things to better identify organisms faster, so we could implement appropriate checklists. We  need to better understand when surfaces are clean very much earlier, so we know if our cleaning efforts are effective. And we need to have better regional and networked information systems, so we know what resistance patterns are in community hospitals and longterm care facilities, and be able to link them when patients come to acute-care hospitals and then go back again.”

At the same time as it released its report, the CDC launched an Antibiotic Resistance Patient Safety Atlas, a web-based interactive that creates data visualizations of hotspots of resistant infections, nationally and by state, by drawing from the National Healthcare Safety Network database. Using the atlas, here is what MRSA, drug-resistant staph, looks like in hospital infections from 2011 to 2014:

MRSA (multi-drug resistant staph) in all hospital infections from 2011 to 2014.
MRSA (multi-drug resistant staph) in all hospital infections from 2011 to 2014.

And here is the occurrence of CRE—carbapenem-resistant Enterobacteriaceae—the “nightmare bacteria” that respond to only one or two antibiotic families:

CRE (carbapenem-resistant Enterobacteriaceae), which are resistant to almost all antibiotics, in hospitals between 2011 and 2014.
CRE (carbapenem-resistant Enterobacteriaceae), which are resistant to almost all antibiotics, in hospitals between 2011 and 2014.

The CDC’s report was released Thursday in many pieces: in addition to the atlas, a press release, a scientific paper, a simpler factsheet, and a state-by-state report assessing progress against national benchmarks.

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Disorganized Mosquito Control Will Make US Vulnerable to Zika

As Zika virus advances in Central and South America, and more US residents (almost 150 so far) return from the area with infections, public health officials are braced for the next likely step: the moment when Zika passes from a traveler bearing the virus in his or her blood, to a local mosquito, and then to another person. That viral traffic has the potential to ignite Zika outbreaks in the United States in the areas where the mosquito species which carry it already flourish, across the South, in the Mid-Atlantic states and as far north as Des Moines, Cleveland and New York.

And though no one is yet talking about it publicly, that presents an enormous problem. In the United States, mosquito control — the tracking, spraying and surveillance that, in the absence of a vaccine, provides the best defense — is conducted by a crazy quilt of local districts that are dependent on cities and counties for funding and personnel. Some belong to local health departments, and others to departments of agriculture, transportation, or parks and recreation; almost none of them answer to the Centers for Disease Control and Prevention, the federal agency that directs US response to new disease threats.

When Zika arrives, that unorganized patchwork could leave the United States vulnerable to a rapidly expanding epidemic. The time that it would take to reorganize mosquito control into a coordinated system may already be running out.

CDC maps of the ranges of two mosquito species that could transmit Zika virus.
CDC maps of the ranges of two mosquito species that could transmit Zika virus.
Graphic from CDC.gov, original here.

“There are more than 700 mosquito-abatement districts in the United States, and it can be very difficult to figure out where they fit into public health,” says Joseph Conlon, a former US Navy entomologist who serves as a spokesman for the American Mosquito Control Association. “Chesapeake, Va. has its own taxing district, nothing to do with the health department. Massachusetts has seven mosquito-control districts, run by the state; so does Delaware. Florida has a government body that establishes policy, but mosquito control is done at the county level; I think they’ve got 66 local abatement districts.”

Some of those bodies, he cautioned, are as well-funded as if they were private industry: “Lee County, Fla., where Fort Myers is, has a budget of $24 million. They have 27 aircraft, more mosquito-control capability than anywhere else in the world. But other places don’t have the budget to do aerial spraying, or the capacity to do mosquito surveillance to drive their control programs. There’s not enough lab capacity, no funding for communication, which is critical.”

Al Hoffer, foreground, with Hoffer Pest Solutions, sprays for mosquitoes as homeowner Bryan Ballejo looks on in Boca Raton, Florida, February 2016. Photograph by Wilfredo Lee, AP
Al Hoffer, foreground, with Hoffer Pest Solutions, sprays for mosquitoes as homeowner Bryan Ballejo looks on in Boca Raton, Florida, February 2016. Photograph by Wilfredo Lee, AP

The uneven status of mosquito defenses is no secret among public health workers, who have been trying for several years to get policy-makers’ attention. Last year, the Association of State and Territorial Health Officials presciently wrote in a report, “Before the Swarm,” assessing vector (that is, not just mosquitoes, but ticks and other insects) control efforts:

The unpredictable nature and severity of vector-borne disease outbreaks demonstrates the urgent need for careful preparation and the incorporation of vector-control emergency-management activities into overall public health preparedness efforts. Since climate change is altering temperature and precipitation patterns across the country, it is critical that public health professionals also prepare for a potential increase in the geographic spread of existing vectors, such as Aedes albopictus or Aedes aegypti, and potentially for new vector-borne diseases.

In 2014, the Council of State and Territorial Epidemiologists examined staffing and budgets for mosquito control in state and large city health departments, comparing levels in 2012 and in 2004, the year that West Nile virus spread to all of the lower 48 states. They found dismaying drops:

  • Overall federal funding down 60 percent, from $24 million to $10 million.
  • Number of staff working at least half-time on West Nile surveillance: down  41 percent.
  • Proportion of states conducting mosquito surveillance: down from 96 percent to 80 percent.
  • States that had reduced mosquito trapping: 58 percent; states that had reduced mosquito testing: 68 percent.
  • States that had reduced testing of human patients suspected of having West Nile: 46 percent.

The group warned that lab capacity in the states, crucial for detecting which of many mosquito- and tick-borne diseases have arrived, and where they are going next, had been deprived of enough money and expertise to be unrecoverable.

Although many state public health laboratories have the capability to test for St. Louis encephalitis (79%), Eastern equine encephalitis (59%), Western equine encephalitis (39%) or LaCrosse (42%) viruses, routine testing for these viruses by state laboratories in meningoencephalitis patient specimens actually occurs much less frequently than for West Nile virus (SLE 73%, EEE 27%, WEE 9%, LaCrosse 8%). In part, this disparity results from inadequate laboratory staffing. Further, only nine state laboratories perform testing for dengue, four for Powassan, and two each for Chikungunya and Colorado tick fever viruses.

“There’s a critical gap of efficiency,” says Dr. E. Oscar Alleyne, a senior advisor at the National Association of County and City Health Officials, who at the start of the West Nile epidemic was the director of epidemiology of Rockland County, NY. “Those that do it obviously try to do it as well as they can, but the reality is, the defunding of many of these vector-borne programs for the sake of other programs, or for the sake of something that’s a little bit more sexy, from a Congressional standpoint, has had an impact on the ability for folks to rapidly mobilize.”

Making things worse, he pointed out, is that whatever mosquito-control capacity still exists was built to respond to West Nile. But Zika is spread by different mosquito species that live in different environmental niches and bite at different times of day; existing lab tests and already-owned mosquito-catching equipment do not match those species. Alleyne said: “You have a defunded system, you have a lessened capacity, and now you have a new threat that, with the equipment that you have, doesn’t provide you with adequate mechanisms to know how to detect them and respond.”

An Aedes aegypti mosquito, the chief vector of Zika virus.
An Aedes aegypti mosquito, the chief vector of Zika virus.
Photograph by James Gathany, CDC

Detecting the Aedes mosquitoes that spread Zika is a particular challenge because those species can breed in very small pools of water: puddles in discarded tires, upturned bottle caps. Anywhere with poor garbage collection, reduced municipal services, or low-quality housing represents prime habitat, and wiping out that habitat requires having enough personnel to scour private properties and go door to door. Dr. Peter Jay Hotez, a noted tropical disease expert who is dean of the National School of Tropical Medicine at Baylor College of Medicine in Houston, sees those practically outside his door.

“The Gulf Coast has both species of mosquitoes, and has the second risk factor for Zika, which is extreme poverty,” he told me. “People who live in poverty don’t have access to window screens, don’t have garbage collection;  in many poor neighborhoods, you see plastic containers filled with water, cups discarded, tires lying on the side of the road.”

Without well-funded, well-staffed mosquito surveillance, he said, “We won’t know that Zika’s here until babies start showing up in delivery suites with microcephaly.”

The Obama Administration has asked Congress to authorize a $1.8 billion emergency fund to respond to Zika, with $828 million of that for the CDC. As welcome as that will be, if it is approved, public health experts worry it may not be enough, for two reasons. First, since many mosquito control bodies don’t belong to the public health pyramid—which has the Department of Health and Human Services at the top, then the CDC, then state health departments, then county or city ones—there is no existing mechanism by which money can be funneled to them quickly.

And second, the money—as abundant as it might be—is a one-time emergency appropriation. That means it is likely there will be specific things on which it can and can’t be spent. On the likely list: equipment, assays, physical goods. On the not-likely: ongoing salaries. But those working in the field say that what public health needs most is steady funding to prop up its depleted workforce—and in the past decade, it has been persistently deprived.

“On an annual basis, public health funding continues to be at best fairly flat, and emergency preparedness funding has declined since the bump-up after 9/11,” says Richard Hamburg, interim president and CEO of the nonprofit Trust for America’s Health, which studies public health capacity. “We should be learning that we can’t jump from one emergency funding vehicle to another. We need to maintain a constant higher level of funding to ensure foundational capabilities, no matter what emergency comes through.”

 Update: Via Twitter, Tyler Dukes of WRAL.com in Raleigh, NC points out his colleague Mark Binker’s discovery that North Carolina has already sacrificed its mosquito-control funding to budget cuts.
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As Antibiotics Fail, We Need More Vaccines

The global problem of antibiotic misuse that allows bacteria to become resistant can be solved in part by more use—not of antibiotics, but of vaccines and other compounds, which could reduce the occurrence of diseases that antibiotics are otherwise used to treat.

A patient receives a vaccination injection at Gorkha district hospital in Nepal. Photograph by Alex Treadway, National Geographic Creative
A patient receives a vaccination injection at Gorkha district hospital in Nepal. Photograph by Alex Treadway, National Geographic Creative

That is the latest piece of analysis of the worldwide resistance problem from the Review on AMR, the British project that is conducting a two-year examination of antibiotic resistance at the request of UK Prime Minister David Cameron. The group, which is supported by the Wellcome Trust, is closing in on its deadline of May 2016 for presenting comprehensive recommendations to ameliorate resistance. On the way, it has examined reducing agricultural use of antibiotics, funding drug development, promoting increased use of diagnostic devices, combatting over-the-counter sales and counterfeits, and achieving better data on the occurrence and cost of resistance.

“This year, 2016, is a critical year for action on the wider issue of drug-resistant infections, and both vaccines and alternative therapies have a crucial role to play as part of the strategy to tackle this threat. Internationally there will be focus on this issue at the World Health Assembly, the G7, G20 and UN General Assembly,” the report says. “This is a crucial time for the world to make significant progress – a moment that needs to be seized.”

The project is chaired by Lord Jim O’Neill, the former chief economist for Goldman Sachs, who is also Commercial Secretary to the Treasury in Cameron’s government. “Drug resistant infections could be compared to a slow-motion car crash,” he said. “Antibiotics are important to tackle this threat, but if we can encourage the development and use of vaccines and other alternatives we give the world a better chance of beating drug resistance.”

In the newest report, the Review proposes that better use of vaccines, along with development of new vaccines and other non-antibiotic compounds, could reduce the need for antibiotic use. But what stands in the way, it says, is a lack of funding both for getting existing vaccines to vulnerable populations, and also for developing crucially needed new vaccines.

Vaccines, it says, can reduce the occurrence of bacterial infections for which antibiotics are used; viral infections, for which the drugs are often given in error, increasing resistance; infections that occur in hospitals, a setting in which bacteria often become multi-drug resistant; and infections in farm animals, forestalling the huge use of antibiotics on farms.

Crucially needed vaccines are not being developed.
Crucially needed vaccines are not being developed.
Graphic courtesy the Review on Antimicrobial Resistance.

The report finds that existing vaccines are not being used as much as they might be: globally, pneumococcal and rotavirus vaccines reach only 31 percent, and 18 percent, of children eligible for them. If pneumococcal vaccine were fully deployed, it says, the lives of 800,000 children younger than 5 could be saved every year—and in addition, 11.4 million days of antibiotic consumption, almost half the global usage for that disease, could be prevented.

But there is also a need for new vaccines to address specific diseases which antibiotic resistance makes worse. In 2013, the US Centers for Disease Control and Prevention compiled a long list of the resistant bacteria that it considers the most serious threats to health. There are no vaccines for the problems that it ranked as most urgent: resistant gonorrhea, Clostridium difficile, and bacteria such as E. coli and Klebsiella that have become resistant to the last-resort antibiotic class carbapenems and collectively are known as CRE.

Unlike antibiotics, vaccines can be attractive moneymakers for pharma companies, but the size of the clinical trials needed to get them to market means that many candidates stall in development, the report notes. To improve vaccine’s prospects in the market, it proposes additional funding to buy existing vaccines for low-income countries and to support early-stage research, and the creation of reward commitments (also known as advance market commitments or market entry rewards) for vaccines that make it through the development pipeline and reach the market.

Elizabeth Jungman, director of public health at The Pew Charitable Trusts, said about the proposals:  “This report highlights the need to take a multifaceted approach to addressing antibiotic resistance. Vaccines and some alternatives can play a critical role in the fight against antibiotic resistance by preventing infections, and other alternatives can make antibiotics more effective or even replace them for treatment.”

Vaccine syringes.
Vaccine syringes.
Photograph by Debora Cartagena, CDC.gov.

The new report is being released just after midnight in Britain, and a number of experts gave the Review their comments to release at the time of publication.

Dr. Jeremy Farrar, Director of the Wellcome Trust, said: “Our own analysis on how we might use vaccines and other alternatives to tackle this crisis supports the O’Neill team’s report, and suggests they will be an important way we can reduce – but not replace – our need for antibiotics. Vaccines are also critical for controlling epidemics, like Ebola, and endemic diseases such as TB and dengue fever, and how we incentivise developing news ones must take the whole picture into account.”

Dr. Seth Berkley, CEO of Gavi, the Vaccine Alliance—which is praised in the report for innovative funding strategies that allow vaccines to flow to poor countries—said: “It is exciting to see such a powerful argument on the important roles vaccines play, not just in preventing diseases and therefore reducing antibiotic usage, but also in directly reducing antimicrobial resistance. New incentives are needed to further accelerate their development.”

Previous posts in this series:

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To Prevent Zika Birth Defects, CDC Suggests Abstinence

Joana Dark, eight months pregnant, sits with her husband in their community in Recife, Pernambuco state, Brazil. Residents said several members of the community were currently sick with mosquito-borne illnesses including the Zika virus.
Joana Dark, eight months pregnant, sits with her husband in their community in Recife, Pernambuco state, Brazil. Residents said several members of the community were currently sick with mosquito-borne illnesses including the Zika virus.
Photograph by Mario Tama, Getty

The U.S. Centers for Disease Control and Prevention has responded to the discovery that Zika virus can be transmitted sexually, recommending that if pregnant women’s partners have traveled to areas where the virus is circulating, they either rigorously use condoms, or abstain from sex til the pregnancy has ended.

It is one of several pieces of news that are complicating the debate over how best to protect against Zika infection, which is exploding in South and Central America and is linked to an apparent epidemic of birth defects in Brazil. On Wednesday, the European Centre for Disease Prevention and Control said it had been notified of Zika being passed via blood transfusion. Also on Friday, the United Nations chief of human rights, and subsequently the secretary general, said that countries which restrict access to birth control and abortion—which includes many of the 31 countries where the disease is burgeoning—must repeal those laws in response to Zika. And Brazilian health authorities said they have detected virus in the saliva and urine of infected people, though they could not draw conclusions about whether it is transmitted by those body fluids.

The CDC’s recommendations are a response to the announcement Tuesday by Dallas County Health and Human Services Department that a man in Dallas transmitted the virus to his sexual partner after returning from traveling in Venezuela. (The department did not specify the gender of the man’s partner and said a pregnancy was not involved.) They also come after a woman in Hawaii, who was infected while living in South America in the early stages of pregnancy, gave birth to a baby with the Zika-related birth defect microcephaly. The CDC has recommended that pregnant women not travel to 30 countries and jurisdictions where the virus is circulating, in the Caribbean, Central and South America, and the Pacific Islands, as well as the US territory of Puerto Rico.

In a conference call with reporters Friday, CDC director Dr. Thomas Frieden cautioned that it has been 70 years since an infectious disease has posed a direct threat to fetuses—rubella, in that case. (See “Way Before Zika, Rubella Changed Minds on Abortion” at National Geographic News.)

“We are not aware of any prior mosquito-borne disease associated with such a potentially devastating birth outcome on a  scale anything like what appears to be occurring with Zika,” he said. “Because this phenomenon is so new we are quite literally discovering more about it each and every day.”

The CDC’s new recommendations say:

  • Men who live in or have traveled to places where Zika virus is being transmitted, and whose partner is pregnant, should either abstain from sex as long as the pregnancy lasts, or should use condoms for vaginal, anal or oral sex.
  • Men who live in or travel to places where Zika is being transmitted, and have a sexual partner who is not currently pregnant, may want to consider either using condoms or abstaining from sex.

The CDC earlier recommended that pregnant women who live in areas where Zika is circulating should strictly avoid mosquito bites.

In an odd coincidence, the recommendations come four days after the CDC separately published recommendations for women about alcohol use and possible pregnancy, which were widely criticized for not addressing the role of men.

Countries where Zika is spreading as of Feb. 4 2016 (excludes cases in the United States).
Countries where Zika is spreading as of Feb. 4 2016 (excludes cases in the United States).
Graphic by the European Centre for Disease Control and Prevention; original here.

Asked about sexual transmission to women who are not pregnant or to same-sex partners, Frieden pointed out that Zika is most often a mild illness in adults, though it has been linked to the paralytic syndrome Guillain-Barre. “Our primary concern and priority here is the protection of pregnant women,” he said.

(See: Here’s What We Know Now About Zika and Birth Defects)

In a separate set of recommendations, the CDC updated its advice for pregnant women who may have been exposed to Zika, suggesting that women who have traveled where it is circulating be tested for the virus (from 2 to 12 weeks after returning to the United States) even if they do not show symptoms. The agency cautioned though that the tests can return false results because they cross-react to infection with other mosquito-borne viruses, and Frieden said the tests may be in short supply for a while. “We wish more tests were available; our laboratories are literally working around the clock to get tests kits out,” he said. “Not everyone who wants a test will be able to get it.”

The CDC has made Zika a reportable disease in the United States, meaning that state health authorities should report new diagnoses to the agency. So far, Frieden said, the CDC has been told of 51 cases in the United States, 50 imported and the single sexually associated case, and 21 in Puerto Rico. Of those 72 cases, seven are pregnant women, he said. (The CDC maintains a map, not yet updated with those numbers.)

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Last-Ditch Antibiotic Resistance: What Is The Role Of Food?

A cattle feedlot in California's Imperial Valley. Photograph by Gerd Ludwig, Nat Geo Creative
A cattle feedlot in California’s Imperial Valley. Photograph by Gerd Ludwig, Nat Geo Creative

As concern for Zika virus ramped up in January, the recent and sudden recognition that last-ditch antibiotic resistance is moving across the globe has all but vanished from the news.

But it’s about to become important again. Two letters published in Lancet Infectious Diseases, the journal that has published all the revelations of the newly identified MCR-1 gene that protects bacteria from the last-resort antibiotic colistin, reveal a worrisome new development. In both humans and animals in China, bacteria have been found that harbor both MCR, and also NDM, the last perilous superbug gene, which confers resistance to a crucial class of drugs called carbapenems.

In the last set of publications about MCR several weeks ago, researchers revealed that bacteria with MCR resistance were doing the equivalent of assembling a winning hand at cards, shuffling the DNA for different resistance factors into shared mobile genetic elements that are capable of transferring among bacteria. With the acquisition of NDM, the hand gets stronger—and the bacteria, closer to lethally untreatable.

Hong Du and colleagues report that, once MCR was identified last November, they went back into the sample banks of a hospital in Suzhou, China. They found four bacteria possessing mcr-1, two E. coli and two Klebsiella, that were collected between January 2013 and November last year. The bacteria came from three patients, two inpatients and one outpatient, and two of the samples, the Klebsiellas, also carried ndm-5, which confers resistance to the carbapenems. The researchers say this is is “of great global public health concern.”

Xu Yao and colleagues, from the team that initially identified MCR, separately report a further discovery of a different MCR-NDM combination, from the initial analysis of human, food and animal samples that first yielded MCR. They found:

…one E. coli strain, THSJ02, recovered from a chicken wing sample purchased at a large supermarket in Guangzhou in July, 2014, was resistant to all antimicrobial drugs tested except doxycycline and tigecycline… This strain carried blaNDM-9, fosA3, rmtB, blaCTX-M-65, and floR, accounting for carbapenem, fosfomycin, aminoglycoside, cephalosporin, and florfenicol resistance, respectively, in addition to mcr-1 accounting for colistin resistance.

Here, they say, is why this is mysterious, and critical:

Recovery of an E. coli strain co-producing MCR-1, NDM-9, and FosA3 from chicken … is concerning since carbapenems and fosfomycin are not approved for use in food animals in China. Given that colistin and carbapenem-resistant E. coli can be found in retail meat, and that the resistance genes for crucial antimicrobials are located on conjugative plasmids, such strains might colonise the human intestinal tract and transfer the resistance plasmids to other Gram-negative pathogens, which might result in untreatable infections.

It’s been clear from the first identification of MCR that the use of last-ditch antibiotics in agriculture is driving its emergence—completely legal use in the case of colistin, as I explained in this analysis of European colistin-use statistics. It’s hard to know, at this point, where the resistance in these newest results comes from, since as the authors say those drugs are not used legally in Chinese livestock. Were they used without authorization? Did the resistance migrate from animals or livestock originating in countries with less oversight than China now applies? Or, since the finding came from an animal part that had been handled several times—at slaughter, while being butchered, while being packaged or displayed—does it represent human contamination, and from whom?

If there is any good news to be found in these reports, it is that MCR and NDM are not moving together. Both sets of researchers say that mcr-1 and the two varieties of the ndm gene are housed on separate plasmids, the mobile genetic elements that can move between organisms. So MCR and NDM resistance have not combined in a single mobile element. Nevertheless, as these dire resistance factors combine and move, it’s going to be crucial to try to identify their sources—possibly healthcare, possibly people in the community, very likely food—and to attempt to slow their march toward an invincible combination.

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An Epidemic 14 Years Ago Shows How Zika Could Unfold in the US

An Aedes albopictus mosquito, which health authorities worry may begin to spread Zika.
An Aedes albopictus mosquito, which health authorities worry may begin to spread Zika.
Photograph by James Gathany, CDC.

If the Zika virus comes to the United States, we could face the threat of the same sort of virgin soil epidemic—an infection arriving in a population that has never been exposed to it before—that has caused more than 1 million known infections, and probably several million asymptomatic ones, in Central and South America. It’s nerve-wracking to wonder what that would be like: How many people would fall ill, how serious the effects would be in adults or in babies, and most important, how good a job we would do of protecting ourselves.

But, in fact, we can guess what it would be like. Because we have a good example, not that long ago, of a novel mosquito-borne threat that caused very serious illness arriving in the United States. And the data since its arrival shows that, despite catching on fairly quickly to what was happening, the U.S. didn’t do that good a job.

This possibility became more real Monday when the Pan American Health Organization released a statement that predicts Zika virus, the mosquito-borne disease that is exploding in South and Central America and seems likely to be causing an epidemic of birth defects especially in Brazil, will spread throughout the Americas. PAHO, which is a regional office of the World Health Organization, said:

There are two main reasons for the virus’s rapid spread (to 21 countries and territories): (1) the population of the Americas had not previously been exposed to Zika and therefore lacks immunity, and (2) Aedes mosquitoes—the main vector for Zika transmission—are present in all the region’s countries except Canada and continental Chile.

PAHO anticipates that Zika virus will continue to spread and will likely reach all countries and territories of the region where Aedes mosquitoes are found.

Those “countries and territories where Aedes mosquitoes are found” include a good portion of the United States, as these maps from the Centers for Disease Control and Prevention demonstrate:

CDC maps of the ranges of two mosquito species that could transmit Zika virus.
CDC maps of the ranges of two mosquito species that could transmit Zika virus.
Graphic from CDC.gov, original here.


The recent history is this: In the summer of 1999, the New York City health department put together reports that had come in from several doctors in the city and realized that an outbreak of encephalitis was moving through the area. Eight people who lived in one neighborhood were ill, four of them so seriously that they had to be put on respirators; five had what their doctors described as “profound muscle weakness.”

Within a month, 37 people had been identified with the perplexing syndrome, which seemed be caused by a virus, and four had died. At the same time, veterinarians at the Bronx Zoo discovered an unusual numbers of dead birds: exotics, like flamingos, and city birds, primarily crows. Their alertness provided the crucial piece for the CDC to realize that a novel disease had landed in the United States: West Nile virus, which was well-known in Europe, but had never been seen in this country before.

West Nile is transmitted by mosquitoes in a complex interplay with birds. It began moving with both birds and bugs down the East Coast and then across the Gulf Coast. As it went, the CDC realized that the neurologic illness that marked the disease’s first arrival had not been a one-time event, but its own looming epidemic within the larger one. “Neuroinvasive” West Nile, which in its worst manifestations caused not transient encephalitis but long-lasting floppy paralysis that resembled polio — and sometimes killed — bloomed in the summer of 2002 east of the Mississippi, and then moved west in the years afterward as the disease exhausted the pool of the vulnerable.

The CDC’s maps showing the emergence of “neuroinvasive” West Nile virus disease from 2001 to 2004; areas in black had the highest incidence.
Graphic by Maryn McKenna using maps by the CDC; originals available here.

So far, so normal, for a newly arrived disease. But here’s where the story gets complicated. By the beginning of this decade, West Nile had become endemic in the lower 48 states. It is not a mysterious new arrival; it is a known, life-altering threat. Its risk waxes and wanes with weather and insect populations, but it has one simple preventative: not allowing yourself to be bitten by a mosquito.

And yet: Here are the CDC’s most recent maps of neuroinvasive West Nile—showing that people are still falling to its most dire complication, 14 years after it was identified.

The CDC's maps for 2011-2014 showing the incidence of "neuroinvasive" West Nile virus disease; areas in black had the highest incidence.
The CDC’s maps for 2011-2014 showing the incidence of “neuroinvasive” West Nile virus disease; areas in black had the highest incidence.
Graphic by Maryn McKenna using maps by the CDC; originals available here.

The point here is not that people are careless or unthinking; in the early years of West Nile, two of the victims were the husband of the CDC’s then director, and the chief of its mosquito-borne diseases division, who would have been well aware of the risks. (Both recovered fully.) The point is that always behaving in a manner that protects you from a mosquito bite—conscientiously, persistently, faultlessly emptying pots and puddles, putting on long sleeves and repellent, choosing when not to go outdoors—is very difficult to maintain.

Zika is not West Nile. Among other things, Zika is spread by many fewer species of mosquitoes — one or possibly two, compared to 65 for West Nile. And West Nile’s non-human hosts, birds, live in closer proximity to more of us than Zika’s, which appear to be non-human primates. But though the rare, deadly complications of West Nile virus infection are different from those of Zika, they are just as serious and life-altering — and yet we failed to protect ourselves from them. As Zika spreads, we can hope that is a lesson we learn in time.

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CDC Recommendations for Pregnant Women Exposed to Zika

An Aedes aegypti mosquito, the chief vector of Zika virus.
An Aedes aegypti mosquito, the chief vector of Zika virus.
Photograph by James Gathany, CDC

(This post has been updated twice.)

The Centers for Disease Control and Prevention has responded to growing alarm over the Zika virus epidemic in Central and South America with quickly published guidelines covering health care and tests for pregnant women who may have been exposed to the virus.

The guidelines come on the heels of the CDC’s recommendation last Friday night that US women who are pregnant, or planning to become pregnant, avoid traveling to the 13 countries where transmission of Zika has occurred, and also to the US territory of Puerto Rico.

Zika, which is transmitted by mosquitoes, arrived in South America in 2014 and ignited a pandemic. Most of the adult cases, which number more than 1 million, have been mild. (It is generally accepted that four out of five people infected with Zika do not develop symptoms; so the true number of those infected is likely more than 5 million.) But in Brazil, there has been an epidemic of a birth defect called microcephaly—smaller than usual brains and heads in newborns— that is associated temporally, and by some lab tests, with Zika infection. So far in Brazil there have been more than 3,500 cases of microcephaly. Zika has come to the United States as well, with local transmission in Puerto Rico and an imported case in the county surrounding Houston, and on Friday, a baby born in Hawaii to a woman who lived in Brazil while she was pregnant was diagnosed with Zika microcephaly. Today, the Illinois Department of Public Health disclosed that it is monitoring two pregnant women who traveled to Zika transmission areas.

(Update, Jan. 20: According to Florida media, that state’s department of health has announced three cases in Florida, all travel-related.)

The CDC’s guidelines today offer advice for pregnant women who traveled to a location where Zika is circulating, whether or not the woman reports symptoms of Zika infection: sudden fever, a rash, conjunctivitis, and joint pain. Broadly, women with a travel history and symptoms should have blood drawn to be tested for Zika infection—the test can be performed only by the CDC and some health departments—and if positive, should have regular ultrasounds to track fetal development and should be seen by one of several specialists. Pregnant women who traveled to a Zika area but did not experience symptoms are recommended to undergo ultrasounds first, and to seek a test to confirm infection if there are abnormalities in the imaging.

The CDC's advice for testing and treating pregnant women exposed to Zika virus, expressed as a flow chart.
The CDC’s advice for testing and treating pregnant women exposed to Zika virus, expressed as a flow chart.
Graphic by the CDC; original here.

Within the text of the recommendations, which were published as an early release from the CDC’s weekly journal Morbidity and Mortality Weekly Report, there are hints of how complex this emerging situation has become. There is no vaccine for Zika, so as prevention the agency can recommend only “wearing long-sleeved shirts and long pants, using U.S. Environmental Protection Agency-registered insect repellents, using permethrin-treated clothing and gear, and staying and sleeping in screened-in or air-conditioned rooms.” There is no specific treatment, so it can recommend only “rest, fluids, and use of analgesics and antipyretics. Fever should be treated with acetaminophen.” (The CDC specifically rules out aspirin, because the mosquito-borne diseases chikungunya and dengue are also circulating in the areas where Zika is, and dengue can lead to hemorrhagic fever—so drugs that can increase bleeding are not recommended.)

The limited options for confirming Zika in a fetus are especially difficult, since amniocentesis—which could yield a sample for testing—also carries a risk of miscarriage. The CDC says:

Zika virus RT-PCR testing can be performed on amniotic fluid. Currently, it is unknown how sensitive or specific this test is for congenital infection. Also, it is unknown if a positive result is predictive of a subsequent fetal abnormality, and if so, what proportion of infants born after infection will have abnormalities. Amniocentesis is associated with an overall 0.1% risk of pregnancy loss when performed at less than 24 weeks of gestation…. early amniocentesis (≤14 weeks of gestation) is not recommended. Health care providers should discuss the risks and benefits of amniocentesis with their patients.

The CDC has also published guidance for health care professionals here, and explanations of how to send samples for testing here.

Update, Jan. 22: The CDC has added Barbados, Bolivia, Ecuador, Guadeloupe, Saint Martin, Guyana, Cape Verde, and Samoa to its “don’t travel if pregnant” list.

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For Fear of Zika, CDC Recommends Pregnant Women Not Travel

An Aedes aegypti mosquito, the vector of Zika virus.
An Aedes aegypti mosquito, the vector of Zika virus.
Photograph by James Gathany, CDC.

(This post has been updated with news of the first Zika birth defects case found in the United States.)

In an extraordinary statement likely to launch international controversy, the US Centers for Disease Control and Prevention recommended Friday evening that pregnant women not travel to 14 countries and territories—the commonwealth of Puerto Rico, and Brazil, Colombia, El Salvador, French Guiana, Guatemala, Haiti, Honduras, Martinique, Mexico, Panama, Paraguay, Suriname, and Venezuela—for fear of birth defects associated with infection by mosquito-borne Zika virus.

The recommendation comes in the form of a “Level 2 travel alert,” which in the agency’s lingo represents a warning to “practice enhanced precautions.” In the Zika announcement, the CDC says that pregnant women “should consider postponing travel,” adding, “pregnant women who must travel to one of these areas should talk to their doctor or other healthcare provider first and strictly follow steps to avoid mosquito bites.” Women planning to become pregnant, it says, “should consult with their healthcare provider before traveling to these areas.”

Zika virus has been exploding in South and Central America. In Brazil, where the virus arrived just seven months ago, there have been more than 1 million cases of infection, and more than 3,500 cases of a rare birth defect called microcephaly, babies born with smaller than normal skulls and brains.

The warning follows the CDC’s own analysis of samples from two stillborn children and two who died after birth who suffered microcephaly. The agency said:

“For the two full-term infants, tests showed that Zika virus was present in the brain. Genetic sequence analysis showed that the virus in the four cases was the same as the Zika virus strain currently circulating in Brazil.  All four mothers reported having experienced a fever and rash illness consistent with Zika virus disease during their pregnancies.”

The countries and territories named by the CDC Friday are jurisdictions where Zika virus transmission has been confirmed. (On Friday, one other country not mentioned in the CDC’s list, Guyana, also reported cases, according to Caribbean media.)

The warning not to travel—made, the CDC said, “out of an abundance of caution”— is likely to be controversial. It warns women away from the site of the Olympics, which take place in Rio de Janeiro in August, as well as from most of the beach and tourist economies of Central and South America. In what may be a first, it warns citizens of the United States from entering a part of the United States, the unincorporated territory of Puerto Rico.

Puerto Rico is part of the advisory because Zika infections have occurred there. Zika has also landed in Texas, via a local resident who was infected in Latin America and returned there, but has not been transmitted locally.

How far the risk of imported Zika might be spread by local mosquitoes.
How far the risk of imported Zika might be spread by local mosquitoes.
Graphic from Bogoch et al., The Lancet.

But researchers from several countries said in The Lancet Thursday that infected travelers should also be considered a risk to their home countries, because virus levels in their blood could be high enough to pass Zika back to local mosquitoes when they return.

As a result, they said, some among the 9.9 million travelers who leave from Brazilian airports every year could bring the disease with them and establish it at their destinations. The US receives 2.7 million travelers yearly from Brazil; Italy, 419,000; France, 404,000; and China, 84,000.

The main mosquito species responsible for spreading Zika, Aedes aegypti, flourishes in the far Southern US, and a second species that may transmit the virus, Aedes albopictus, ranges as far north as New York. Thus, the researchers said, if Zika virus came to the United States, 22.7 million people — primarily in Southern California, South Texas and Florida — would be at risk of contracting the disease year-round, and possibly 60 million seasonally if both mosquito species were involved.

Update: Late Friday evening, the CDC also sent out a HAN, a Health Alert Network advisory to health care workers to help them recognize possible cases of Zika. It’s here.

Update 2: Also late Friday, the Hawaii State Department of Health announced that it has identified the first case of Zika-related birth defects in the US, in a baby born on Oahu to a woman who became pregnant while living in Brazil last summer.

“This case further emphasizes the importance of the CDC travel recommendations released today,” state epidemiologist Dr. Sarah Park said in the announcement. “An astute Hawaii physician recognized the possible role of Zika virus infection, immediately notified the Department of Health, and worked with us to confirm the suspected diagnosis.”

So far six Hawaii residents have been found infected with Zika, the announcement said, but all caught the disease outside the state. Hawaii has made Zika a reportable disease, which means physicians who recognize a case are obliged to inform the state department.

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