Aedes Aegypti and Local Vector Control: Mapping out a Plan for Zika Vector Surveillance and Control

Summertime is approaching, which means mosquito season is upon us. As the weather gets warmer, we can expect to see an increase in the population of one of the main mosquito species transmitting the Zika virus throughout the U.S—Aedes aegypti. To help understand the range and areas most likely to be impacted by Zika, NACCHO created several maps depicting the recorded distribution of Aedes aegypti between 1960 and 2014, along with maps showing the distribution of local vector control departments. Used in conjunction with the Centers for Disease Control and Prevention’s (CDC’s) maps, NACCHO’s density maps provide a better understanding of the spread and range of the Aedes aegypti mosquito.

Map 1 - A. Aegypti Distribution

As local health departments (LHDs) are the frontline in protecting their communities in a Zika response, it is important to work with vector control services to prepare for and/or prevent positive cases of local transmission of the virus.

While it is difficult to know where local transmission of Zika will occur among mosquitoes and individuals, the information presented in the map below can help LHDs and their local vector control programs coordinate a response to addressing the population of Aedes aegypti in their areas. The areas with high to moderate densities of Aedes aegypti, such as the East Coast, the South and parts of Arizona and California, should be vigilant in creating plans for monitoring and controlling the mosquito population. This should be done both before and after cases of Zika emerge, whether they are due to local transmission or not.

Map 7 - updated

In addressing the response to Zika, it is important to remember the capacity challenges that both LHDs and vector control services face. The availability of vector control services can vary widely on a state and local basis. And since mosquitoes do not recognize borders, the gaps in vector control services mean that even if vector control is done within one county, those efforts can be undermined if surrounding counties do not conduct vector control as well.

The lack of vector control services are no coincidence. As funding for these programs continues to dwindle, more and more vector control services will be negatively impacted. According to a NACCHO assessment on the Impact of Budget Cuts on Environmental Health Services at Local Health Departments in 2012, the second most common type of service to be affected by budget cuts is vector control. This mirrors a 2014 report from the Council of State and Territorial Epidemiologists (CSTE), which showed that mosquito surveillance programs have faced significant declines in staff working at least half-time between 2004 and 2012. In fact, between those years, the percentage of staff working on those programs declined by 41%.

Map 2 - LHD vector control services

Map 3 - LHD vector control services - New England

Unfortunately, the impacts of budget cuts are affecting health services in other ways, as well. Earlier this year, President Obama requested $1.8 billion in emergency funding to support the Zika response. In March, Congress was unable to come to a consensus on the funding request, which resulted in CDC having to exercise other options for Zika response. In this case, exercising “other options” meant redirecting $44.25 million of Public Health Emergency Preparedness (PHEP) funds away from state and local health departments, which has put many health departments in a bind. As with previous budget cuts, many health departments anticipate the funding shift to have a negative impact on their services and staffing. According to a recent NACCHO survey about the PHEP cuts, 47% of LHDs foresee impacts on staffing and many are concerned about a decreased ability to conduct surveillance activities.

So what can be done?

Let your elected officials know why it is important to support funding for LHDs. These funds are critical to responding to emergencies, including Zika. Your voice can make a difference!

For LHDs and vector control services, below are resources to use for planning, surveillance, and control:

About Nyana Quashie

Nyana Quashie serves as the Senior Program Assistant on NACCHO's Infectious Disease & Informatics team.

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