First human cases of West Nile virus detected in Denver, Jefferson County this season

The Denver Department of Public Health and Environment announced Monday that the city's first human case of West Nile virus this season has been confirmed. Officials in Jefferson County have also confirmed their first human cases of the virus, with three people infected.

There have been over one dozen cases of West Nile in Colorado this year, which has resulted in one death.

According to the Colorado Department of Public Health and Environment, West Nile virus has been found in mosquitoes in eight of the 16 counties that have tested mosquitoes this year, including Adams, Arapahoe, Boulder, Broomfield, Denver, Jefferson, Larimer and Weld counties. In Fort Collins, the West Nile infection rate in mosquitoes is currently 11 times higher than the historical average, and four times higher than it was in 2023.

The DDPHE is urging residents to take precautions to avoid being bitten by an infected mosquito. Eliminating standing water where mosquitoes breed can help prevent an increase in mosquitoes. Officials said it's important to empty and scrub, turn over, cover or throw out items like tires, buckets, planters, toys, pools, birdbaths and trash containers once a week. Cleaning out street and home gutters that may hold water can also help control the mosquito population.

Wearing repellents with DEET, limiting outdoor activity at dawn and dusk and wearing long sleeves and pants outside can all help reduce the risk of being bitten. The city also advised residents to make sure windows and doors have intact screens to keep mosquitoes out and to avoid watering cement or streets, which can create puddles.

Those infected with West Nile virus may feel fatigued and experience fever, headaches, body aches and rashes or swollen lymph nodes. Symptoms usually appear within 3-14 days. Officials warned that, while anyone can be infected, those over 50 or with weakened immune systems are at higher risk of developing serious symptoms. Authorities urged anyone experiencing symptoms to consult their healthcare provider immediately.