A Blog by Maryn McKenna

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.

8 thoughts on “Disorganized Mosquito Control Will Make US Vulnerable to Zika

  1. I am Director of the Chesapeake Health Department, referenced above, and also serve as Chair of the Mosquito Control Commission. Contrary to the above inference, the health department and mosquito control enjoy a strong, collaborative relationship and partnership. We GIS positives or excess numbers of bridge vectors and map vulnerable populations within a 1 mile buffer and warn them to stay indoors. Our abatement program is data driven. We are fortunate that our local officials strongly support mosquito control as a public health necessity and not merely for nuisance control. More localities would benefit from programs modeled after our interagency operations.

  2. Calling all individuals to bare their legs & arms to attract blood sucking mosqutoes. They are visible in daytime and can be smacked with a roll of padded newspaper.

  3. Me and my family leave in Hancock county Mississippi. In the middle of the Zika dangerous area. The mosquitos are reall bad here, and we wonder why no one spraying for mosquito control yet in our area?

  4. I’ve read (don’t recall source) that the Aedes aegypte mosquito prefers small water sources for laying eggs…like bottle caps, plant saucers & accordion style down spout extensions… where each valley could be the source of 500 mosquitoes.
    What I keep seeing to combat the spread of Zika is spraying of vegetation in neighborhoods and larger areas of water.
    If what I’ve read is correct, a different approach should be taken, i.e. a campaign that reaches out first to those populations who can’t afford screens and insect repellent…and making them aware of the importantance of removing standing water in small vessels.

  5. Politicians argue that they “don’t have the money” for mosquito control. But, there’s always enough money for whatever sports stadium, road project, etc. that benefits the politician in charge. The amount of money which will be spent on social services for ONE microcephaly patient over his/her lifetime would pay for an ENTIRE SEASON of aerial spraying in Miami-Dade county. In reality, it boils down to “not in my budget, let’s put it in yours”. So that the cost of controlling zika, chikungunya, dengue, etc. stays out of the county budget and gets put into the healthcare budget. Which is, in turn, paid by insurance companies and healthcare providers or the person(s) who actually become infected. Somebody needs to wake up.

  6. Knowing the risk level in a particular location on a particular day allows jurisdictions to targeted spraying, thereby being more environmentally responsible as well as cost effective.
    Comprehensive mosquito control requires prior monitoring and tracking of where the mosquitos are, which strains are present, number of cases in the vicinity, etc.
    It’s doable, especially with GIS based mobile data entry and cloud hosted analytics.
    That’s what the suite of vector control software developed by VectorAnalytica does!

  7. This articles pretty out of wack… First of all mosquito control is actually very organized. There are many different mosquito districts because they all have their own unique geographical areas with different mosquitoes. Each area or county would take years if not decades learn how to control mosquitoes in that area. Mosquito control is very complex.. handing something like that over to the CDC to oversee would make their head spin.

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