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Vector Surveillance Program

By Patti Casey, Vermont Agency of Agriculture, Food & Markets

The Vector Surveillance Program tracks vector (disease-carrying) populations of mosquitoes and ticks statewide through several programs.

Mosquito Surveillance Program

Our flagship program is our Mosquito Surveillance Program. In this program, we trap mosquitos that may carry such diseases as West Nile virus, Eastern Equine Encephalitis, and Zika virus, identify them to species in our lab, and coordinate with the VT Department of Health Laboratory (VDHL) to test the mosquitoes for viruses. We have over 100 trap sites statewide in more than 80 towns and use at least 4 different types of traps to conduct surveillance. We employ a minimum of 6 field and lab technicians from May through November each year. The program’s primary goal is to locate and monitor vector mosquitoes in the interest of protecting public health, not to control nuisance mosquito populations (as opposed to the Mosquito Control Districts, who are charged with and receive financial assistance from the state for controlling nuisance mosquito populations for comfort). We maintain a database of our findings.

Our Mosquito Surveillance Program includes a rapid response arm that micro-locates surveillance to areas of concern, whether stemming from human or veterinary illness or from overwhelming numbers of nuisance mosquitoes that could contain vector populations.

Types of Mosquito Traps

Resting box traps target Culiseta melanura, the main vector of EEE. These boxes are placed at the edges of acidic hardwood swamps. Female mosquitoes that have taken a bloodmeal from birds in the tree canopy above settle to the forest floor to find a dark and quiet place to digest the bloodmeal and make her eggs. The mosquitoes settle into these boxes and are vacuumed out weekly using a handheld aspirator.



CDC Light Traps are used as a sensing tool to determine the mosquito species that are present in the area. Dry ice, which releases carbon dioxide, is used to attract female mosquitoes that are looking for a bloodmeal.





Gravid traps target Culex mosquitoes, the main vector of WNV. This trap uses a tray of cow manure water that attracts female mosquitoes looking for a place to lay her eggs.


Tick Surveillance Program

We have a robust Tick Surveillance Program. We have nearly completed a 5-year statewide survey of all towns and gores in Vermont to gather information on what tick species we have in Vermont, what their preferred habitats are, what the tick density is by town, and what diseases they may be carrying. These ticks are tested for diseases such as Lyme disease, anaplasmosis, babesiosis, Powassan virus, and Borrelia miyamotoi.

We also operate the citizen-driven Passive Tick Surveillance Program, in which Vermonters who find ticks on themselves, their children or pets, or in their environment can send them to our lab for identification. All ticks submitted should have the date and physical location of discovery (“on my arm”), the geographic location from which the tick came as best as can be determined, and contact information for the sender. In return, we provide information as to the species, life stage, sex, and engorgement rate of the tick, so that in the event of illness, the sender can give this information to a care provider to guide treatment. We do not test these ticks for diseases.

We partner with VDH in a separate statewide tick surveillance program that targets geographic areas of concern based on tick densities (as determined by our own internal tick surveillance program) or on geographic areas of increased human illness as reported by VDH.

We also survey for and prepare to respond to emerging tick and mosquito arboviral vectors (but as yet undetected in Vermont), such as the Asian Long-Horned Tick, the Lonestar Tick, and the Asian Tiger Mosquito.

If you see us out there in the field waving a big white flannel flag around looking for ticks or vacuuming mosquitoes out of a bunch of little black boxes, stop over and say hi. Our techs don’t bite, even though the mosquitoes may!

And remember to wear long pants and long sleeves as much as possible when you’re working outdoors, wear your EPA-approved insect repellent, avoid dawn and dusk activities, and get rid of any standing water around your home or farm that you can. Bunk tires present a problem that we’re hoping to address at some point in the future, but for now, if you can use sidewalls on your bunks, it will save a world of hurt in mosquito bites and help protect you from the mosquitoes that can carry West Nile virus.