First West Nile Case Confirmed in Larimer County

The Larimer County Department of Health and Environment confirmed the first human case of West Nile virus this year. An adult male residing in Loveland, who was hospitalized, is now recovering at home. Health officials noted he may have contracted the virus during recent travel outside the state.

Although no local mosquito samples have tested positive for the virus this season, it is expected to be circulating, as is common in the summer. In 2025, Larimer County reported 53 confirmed cases, leading to 20 hospitalizations, the highest since 2013. Eight residents have died from the virus since 2021.

Larimer County typically sees more West Nile virus cases than other parts of Colorado. Public Health Director Tom Gonzales emphasized the importance of protection against mosquito bites, as most human cases occur later in the summer. A new surveillance dashboard will provide weekly updates on mosquito activity and case data to help residents assess risk.

West Nile virus is transmitted through infected mosquito bites. Symptoms, appearing three to 14 days after infection, can include fever, fatigue, headache, body aches, rash, and swollen lymph nodes. Individuals aged 55 and older, and those with weakened immune systems or underlying health conditions, face a higher risk of severe illness.