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.
“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.”
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.”
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.”