(WJET/WFXP/YourErie.com) — Though six groups of mosquitoes have tested positive for West Nile virus in Erie County, that’s well below the levels seen in some past seasons.

On Aug. 24, a group of mosquitoes collected in Millcreek Township became the sixth group to test positive for the virus in Erie County this season. West Nile virus can cause encephalitis, an infection that can cause brain swelling, and it poses a danger of severe illness in older adults and people with weak immune systems.

Due to the potential severity of the illness, the county’s Department of Health nets and tests mosquito groups to determine if the virus is present. If necessary, the department implements “control work.”

While new groups have tested positive throughout the 2022 season, past seasons have seen double digits. In 2002 and then again in 2012, 40 different groups tested positive for the virus. In 2018, 28 groups of mosquitoes tested positive during mosquito season. The seasons, however, do vary greatly. In 2021, only two groups of mosquitoes tested positive.

“One thing to note about this year is that we have not been finding large numbers of mosquitoes in our traps,” said Breanna Adams, the director of Environmental Health Services at the Department of Health.

The department already has been implementing larval control work.

“This control work includes utilizing larvicide to stop larval mosquitoes from becoming the biting, disease-spreading adults,” Adams said. Other larval control work includes dumping any tires and water sources the department might find, and responding to vacant swimming pool complaints. Stagnant water, like in vacant swimming pools and inside tires, serve as a breeding ground for mosquitoes.

“In areas where we have had more than one positive mosquito group, our next action would be a barrier spray that is used on vegetation. That spray would then kill the adult mosquitoes as they land on the vegetation,” Adams said. “We really try to only use the adulticide spray from our truck or ATV as a last resort after multiple positives and high mosquito concentrations in one location.”

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The mosquito season in Erie County typically ends at the end of September.