Larimer County mourns first West Nile virus death of the season


Larimer County has reported its first death due to West Nile virus this season, a 66-year-old resident who had been hospitalized since the end of July with neuroinvasive West Nile virus, according to a news release from the Larimer County Department of Health and Environment. This is the third death in Colorado this year caused by the mosquito-borne disease.

West Nile virus cases surge in Larimer County

The health department said that there have been 29 confirmed cases of West Nile virus in Larimer County this year, including eight hospitalizations. This is a significant increase from the previous years, when there were only two cases in 2022 and six cases in 2021.

“We are saddened to report the passing of one of our residents. Unfortunately, we will likely continue to see cases of West Nile virus for the next month or two. We continue to see positive pools of mosquitoes from the weekly trapping and testing. Therefore, we urge residents to take this disease seriously and take extra precautions to prevent getting bitten by mosquitoes,” said Tom Gonzales, Larimer County public health director, in the news release.

West Nile virus symptoms can appear 3-14 days after being infected. Although 80% of infected people do not develop symptoms, for some, initial symptoms can include fever plus headache, vomiting, diarrhea, muscle aches, joint pain, weakness, and a rash. Less than 1% of individuals infected with West Nile virus develop a serious, sometimes fatal, neuroinvasive illness, however, there are no medications to treat, or vaccines to prevent, West Nile virus infection.

Fort Collins plans to spray for mosquitoes again

On the same day that Larimer County announced the death of a person infected with West Nile virus, the city of Fort Collins announced it will spray for mosquitoes again this weekend. Spraying of a permethrin-based mist will occur from 8 p.m. Sunday, Aug. 27 to 2 a.m. Monday, Aug. 28 within the borders of Taft Hill Road on the west to College Avenue on the east, and from Horsetooth Road on the north to city limits on the south, which includes the Registry Ridge, Ridgewood Hills and Shenandoah neighborhoods.

This will be the sixth time the city has sprayed this season, and it will be the third time some of these neighborhoods have been sprayed this summer. The decision to spray for Culex mosquitoes can be made once the vector index in a five-trap area reaches 0.75, according to city policy. The highest vector index for a five-trap area in southwest Fort Collins was 1.13, according to data posted on the city’s website Tuesday.

Culex mosquitoes are the type that carry West Nile virus. The vector index estimates levels of West Nile virus-infected mosquitoes and potential risk of human transmission.

How to protect yourself from West Nile virus

The Larimer County Department of Health and Environment advises residents to take extra precautions to prevent mosquito bites and practice the 4 D’s:

  • Defend – Use DEET or other effective mosquito repellent – Use an EPA-registered mosquito repellent that has been proven to be effective against West Nile virus-carrying mosquitoes. DEET, Picaridin, Oil of Lemon Eucalyptus (also called p-menthane-3,8-diol or PMD) and IR3535 are effective choices.
  • Dusk to Dawn – Avoid exposure during peak Culex mosquito feeding times, from dusk through dawn.
  • Dress – Wear long sleeves and pants to keep mosquitoes from biting.
  • Drain – Remove standing water in your yard or garden to minimize mosquito breeding areas.

The Larimer County Department of Health and Environment closely monitors West Nile virus prevalence in the community through partnerships with municipalities, a mosquito abatement company (Vector Disease Control International), and Colorado State University to monitor and assess the risk to Larimer County residents.


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