West Nile virus detected in mosquito sample

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LARAMIE, Wyo. (RELEASE) - West Nile virus (WNv) has been documented in two separate mosquito samples collected this week in Laramie. The positive samples were isolated in mosquitoes collected from surveillance traps monitored by City of Laramie Mosquito Control. This trap was located within the City limits. The samples were determined to be positive for WNv using the City’s Rapid Analyte Measurement Platform (RAMP) analyzer on August 11th. The samples will be sent to the Wyoming State Veterinary Laboratory for confirmation.

The rating of the Risk of West Nile virus infection continues to be rated at LEVEL 1 (LOW RISK) based on the Centers for Disease Control (CDC) guidelines for a phased response to WNv surveillance data. Currently virus activity is categorized as “Limited to sporadic activity in local mosquitoes and birds”. City of Laramie technicians have tested a total of 76 samples of Culex tarsalis mosquitoes throughout the summer season. Culex tarsalis is the known vector of WNv in the region. No avian, equine, or human cases have been reported at this time in Albany County. Wyoming Department of Health has reported mosquito positive samples from Goshen County and Laramie County. An equine case has been reported in Campbell County. Currently no human cases have been reported in the state.

Although total mosquito numbers are currently low, vector mosquitoes that can effectively transmit WNv make up a greater percentage of the mosquito population in late summer due to the overwintering and reproduction cycles of these species. Current surveillance locally shows low to moderate numbers of vector mosquitoes being collected at trap locations adjacent to the Big Laramie River and in some rural locations. Residential surveillance sites within the city limits report low vector numbers.

Mosquito control will continue to fog perimeter neighborhoods where incidence of Culex tarsalis is greater. This tactic is designed to control any older mosquitoes that have taken up harborage in areas of the City after being displaced from rural agricultural habitat by the haying harvest. A return to full fogging residential fogging will be evaluated after Mosquito Control has completed fogging in each of the 3 zones and trap data and subsequent RAMP testing is evaluated. Mosquito Control is also currently performing targeted fogging operations to control vector mosquitoes in areas of higher vector densities and areas where citizens often recreate in the evening hours. Targeted areas include: Parks and recreation areas, golf courses, and the Laramie River Greenbelt Trail. All “No Spray” zones will continue to be honored at this time.

Citizens are reminded that WNV can infect people of all ages but the elderly may be at the greatest risk for a serious infection. Locally, the mosquitoes that transmit WNV are most active after dusk and citizens should limit activities in areas with high mosquito populations during this time. Repairing screens, especially in sleeping rooms, and using personal protection such as proper clothing and insect repellent containing DEET can also reduce the risk.