Weld County Culex mosquitoes test positive for West Nile Virus

The Weld County Health Department continues to take proactive measures in monitoring for West Nile Virus (WNV). The number of Culex mosquitoes, which carry WNV, is increasing. Compared to a 5-year average, the 2023 trapped Culex mosquito count is much higher for this season.

“The increasing hot weather after a very wet spring and early summer has created favorable conditions for the Culex mosquito that carries West Nile virus,” said Jason Chessher, Executive Director of the Weld County Health Department. “The public needs to be vigilant, because West Nile Virus has a permanent summer presence in Colorado.”

A health department contractor monitors mosquito traps on a weekly basis in three zones of Weld County: the Greeley, Evans, Kersey, LaSalle area (Zone 1); the Johnstown, Milliken, and Platteville area (Zone 2); and the Firestone, Dacono and Fort Lupton area (Zone 3).  Mosquitoes trapped in Zone 2 and Zone 3 have tested positive for WNV.  

Currently, there are no human cases of WNV in Weld County. However, health officials expect this to change as the Culex mosquito season continues to expand with the hot weather in July and August. 

West Nile Virus symptoms can appear three to 14 days after an infection. Initial symptoms can include fever, headache, nausea and vomiting, muscle aches and weakness, and rash, but most infected people don’t exhibit any symptoms. If a person develops symptoms, they should see a healthcare professional immediately. There are no medications to treat or vaccines to prevent WNV infection. Less than one percent of infected people develop a serious, sometimes fatal, neuro-invasive illness. Health officials recommend following the four “D’s” to prevent mosquito bites:

DRAIN standing water around your house weekly. Remember to drain water from tires, cans, flowerpots, clogged rain gutters, rain barrels, toys and puddles.

DUSK and DAWN are when mosquitoes are most active. Limit outdoor activities and take precautions to prevent mosquito bites during these times.

DEET is an effective ingredient to look for in insect repellents. Other repellents containing picaridin, IR3535, oil of lemon eucalyptus, or para-menthane-diol are also effective against mosquitoes.  Always follow the product label instructions carefully.

DRESS in long sleeves and pants, and a hat, in areas where mosquitoes are active.

For more information about preventing mosquito bites and WNV, visit: www.weldhealth.org.

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