Once the mosquitoes are transported back to the GCMCD lab, the catch bags containing the mosquitoes are set into a dry ice box just before beginning the identification procedure. The carbon dioxide and the cold from the dry ice will put the mosquitoes to sleep so that they are easily identifiable. Dry ice is placed onto metal trays lined with blue laminated paper. As the dry ice sublimates, it releases carbon dioxide keeping the mosquitoes asleep. The mosquitoes are then sorted into piles by genus and species. The blue paper makes it easier to see identifying bands and marks on the mosquitoes' legs, wings, and body. From here they can be separated into samples of ranging from 20 to 50 mosquitoes of the same species and shipped off for testing.
GCMCD currently tests for West Nile virus (WNv), St. Louis Encephalitis (SLE), and Western Equine Encephalitis (WEE). Testing of these mosquito samples is performed at Oregon State University or The University of California, Davis. In a typical mosquito season, GCMCD tests anywhere from 400 to 700 mosquito samples. This testing is performed to provide an early indication of disease presence to protect public health from mosquito-borne disease.
GCMCD disease surveillance program consists of trapping mosquitoes and testing them for disease presence. To capture mosquitoes, we use traps baited with carbon dioxide. These traps consist of a bucket filled with dry ice, battery operated fan and light, and a catch bag on the bottom. The carbon dioxide released from the dry ice will attract the mosquitoes. From there they see the light above the fan and fly toward it. As the mosquitoes reach the light, the fan will pull them down into the catch bag where they cannot escape. Upon collection, the catch bag is separated from the fan, closed, and placed into a container with wet paper towels. These paper towels allow the mosquitoes to drink water and regain moisture which is essential to keeping them alive.