West Nile Virus detected in mosquito sample in Laramie

Published: Jul. 26, 2021 at 7:16 PM CDT
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CHEYENNE, Wyo. (PRESS RELEASE) - West Nile virus (WNv) has been documented in a mosquito sample collected last week on the western edge of city limits.

The positive sample was isolated in mosquitos collected from surveillances traps monitored by City of Laramie Mosquito Control. The samples were determined to be positive for WNv via PCR testing at the Wyoming State Vet Lab on Monday, July 26, 2021. 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 Mosquito Technicians and the Wyoming State vet lab have tested a total of 34 samples of Culex tarsalis mosquitoes thus far in the 2021 mosquito 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 is reporting one positive mosquito pool (Albany County) and no other positive human or animal cases in Wyoming at this time.

Current surveillance locally shows moderate numbers of vector mosquitoes being collected at trap locations adjacent to the Big Laramie River, agricultural areas on the west side of town, and in some rural locations. Residential surveillance sites within the city limits report low vector numbers. Mosquito control will continue to fog residential neighborhoods where both vector and nuisance mosquitos are being found in adult mosquito surveillance traps. Mosquito Control is also currently performing targeted larval control and adult fogging operations to control vector mosquitoes in areas of higher vector densities and areas where citizens often recreate in the evening hours and in areas on the western edge of town where vector numbers are higher.

Targeted areas include: parks and recreation areas, golf courses, the Laramie River Greenbelt Trail, and agricultural areas adjacent to city limits.

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.

Further Wyoming WNv information can be found on line at: the or the Centers for Disease Control website:

Hotline information regarding chemical applications on City owned properties will be updated daily at 4:00 p.m. Call 721-5056 or click on the Mosquito and Chemical Application hotline tab on the City of Laramie home page (

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