Mosquito surveillance is the primary method used throughout the province to detect, prevent and control West Nile Virus. It is used to determine the risk of contracting WNV in a particular region. There are 74 different species of mosquitoes found across Canada. The WNV infection has been found in 10 of these species. The Huron County Health Unit performs two methods of mosquito surveillance - mosquito larval sampling and adult mosquito trapping.
Mosquito Larval Sampling
Larval sampling is used to collect mosquito larvae from catch basins throughout Huron County. Working with municipal staff in each community, the Health Unit is able dip for larvae in catch basins using a device called a larval dipper. The dipper is a long plastic rod with a container fixed to the bottom end for collecting water and larvae. Once the dipper is filled with larvae, they are transferred into a small container. The larvae are then allowed to mature into adult mosquitoes, at which point they are identified "in house" by mosquito identifiers.
Adult Mosquito Trapping
The Huron County Health Unit traps adult mosquitoes from spring until fall so that they can be sent for identification and viral testing. CDC 'light' traps which use both dry ice (gaseous carbon dioxide or CO2) and light are used to attract mosquitoes. Twice weekly these traps are set out in different locations throughout Huron County; they are collected the following day and the mosquitoes are sent for testing.
How do the traps work?
The CDC 'light traps' release carbon dioxide and use an ultra-violet light to attract mosquitoes; a fan pulls the mosquitoes into a net where they cannot escape. The light and fan are powered by a battery, programmed to come on at dusk and go off at dawn.
Mosquito traps are not a form of mosquito control. They do not eliminate or reduce the mosquito population in an area. They are only used to capture a sample of the mosquitoes in an area to determine what species are residing there, and if they carry WNV.
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