West Nile Virus detected in mosquitoes on edge of town
City employees responded to three positive WNV samples with localized larvicide and fogging, eliminating the threat before any chance of human infection.
West Nile Virus has been detected in three samples across two of the 77 pools tested across the greater Laramie area this summer.
The presence of WNV-positive pools of mosquitoes can sound scary. But given proper resources and attention from Integrated Pest Management officials, these cases often do not expand into double digits, or affect human health.
Vector mosquitoes typically reach the highest levels of activity in July and August, City of Laramie IPM Manager Tyler Shevling said.
“The two traps that have had positive samples are outside of city limits right on the edge of town so we are taking it very seriously,” he said.
Shevling added that Culex tarsalis, the vector mosquitoes known to Wyoming, are most commonly found where agricultural areas meet city limits.
“We know the location of all the West Nile Virus positives, so we have been able to make targeted larvicide and fogging applications,” Shevling said.
“Fortunately, we have not been getting back-to-back positives,” Shevling said. “We are successfully breaking up that life cycle.”
The city’s IPM employees conduct WNV sample testing every Thursday, testing about 10-20 samples every week.
The last time WNV was detected near Laramie was in 2019, when IPM found four positives. In 2018 and 2020, no WNV vector mosquitoes were observed.
Albany, Goshen, Fremont, Campbell, Crook and Natrona have tended to exhibit the highest likelihood of positive WNV cases in a typical year. However, Albany was the only positive county in the state until more recent positives were detected in Teton and Laramie counties.
The high volumes of mosquitoes detected in Laramie during May and June are of nuisance species. On the other hand, vector mosquitoes — the ones that carry WNV — become prevalent in July, August and September since they prefer hot, dry conditions.
“Everyone notices the large amounts of floodwater mosquitoes that come out in June,” Shevling said. “Vector mosquitoes are not as ferocious — or focused on humans — as floodwater mosquitoes. Now they are active in the evening and people don't realize that they're there.”
To keep safe in the height of mosquito season, Shevling refers individuals to the city’s webpage on Mosquito Bite Prevention.
-