LARAMIE -- West Nile virus has been documented in a mosquito sample collected southwest of Laramie.

Tyler Shevling, Mosquito Control Crew Supervisor, said the positive sample was isolated in mosquitoes collected from a surveillance trap monitored by City of Laramie Mosquito Control using the City’s Rapid Analyte Measurement Platform, or RAMP.

“Each Thursday, we run our mosquito samples through the RAMP platform, Last week, we received a positive WNv sample in one of our rural traps located about 6 miles southwest of town on the Laramie River,” said Shevling.

He said 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 guidelines for a phased response to WNv surveillance data.

“Right now, we’ve two positive samples fairly far apart, and we’re still seeing low, and in some places, moderate vector mosquito numbers. That keeps us at low risk for the time being. If we see the continued virus or more vector mosquitoes, then we’ll probably increase the risk if that were to occur.”

Currently, virus activity is categorized as “limited to sporadic activity in local mosquitoes and birds.” City of Laramie Mosquito Technicians have tested a total of 22 samples of Culex tarsalis mosquitoes in 2019 with two samples being positive. 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.

“We actually have had WNv in Wyoming for quite some time. Last year, the Laramie Valley did not test any positives, but previous years, there was one neuro-invasive WNv human case in Campbell County so far. All of the surrounding states have WNv activity as well.”

Current surveillance locally shows low to moderate numbers of vector mosquitoes being collected at trap locations adjacent to the Big Laramie River and in rural locations. Residential surveillance sites within the city limits report low vector numbers. Overall, nuisance mosquito numbers have been decreasing and vector mosquito numbers have been slowly increasing.

“The increased moisture this year, and especially going late into the summer, the vector mosquitoes like the later, warmer, semi-permanent waters. So this is a year where we could certainly see more of them,” Shevling said.

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 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.

“We’ll continue to monitor our adult mosquito numbers. We have 23 traps in and around Laramie, so we keep a really good idea of what’s going on with the mosquito population. Currently, we’re over threshold numbers that will trigger us to continue our adult mosquito fogging in residential areas until we get those numbers down. Overall, we’re seeing a dip in numbers, especially nuisance mosquito numbers. We’ve had better weather for the last 2 weeks and the trucks have been able to get out a little bit more.”

Shevling said that with the water rising on the Greenbelt and the Laramie River, we’ve had more standing water than in previous years.

“Areas around town where people have stagnant water in tires or buckets, things like that if we could remind people to empty those. It’s a possibility that mosquitoes are able to lay eggs and be able to go through their life cycle in those kinds of containers. If you could drain those, it would help also. Even things like dog pools, if you could refresh the water once a week, it would disrupt the mosquito life cycle and help a lot.”

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 online at 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. For further information contact Tyler Shevling, Mosquito Control Crew Supervisor at 721-5258; or Todd Feezer, Assistant City Manager at 721-5226;

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