A mosquito bites a person's hand.

GCPH: Mosquitoes can do more than just bite

Take precautions against contracting West Nile virus

July 9, 2024

Mosquitoes are an annual annoyance and no one loves getting bit. In Colorado, some mosquitoes carry the West Nile virus, a rare but serious illness.

The virus circulates in sick birds in late June to early September. It is transmitted to people when Culex tarsalis mosquitos bite an infected bird and then bite a person.
Areas around the Colorado River Valley have had higher numbers of Culex mosquitos. Garfield County reports weekly trapping and testing results to assess mosquito risk.

Most people show no symptoms, but in rare cases, the virus can cause serious brain infections. There is no vaccine to prevent West Nile virus. The only way to reduce your risk is to take precautions to avoid bites.

The 4-Ds of prevention

Drain standing water – a mosquito can lay up to 300 eggs in a puddle the size of a bottle cap.
Dusk and dawn limit activity – this is when mosquitoes are most active.
DEET or other effective repellents – repellents work by helping to prevent mosquitoes from biting you.
Dress appropriately – wear long sleeves and pants during dusk and dawn when mosquitos are most active.

Groups most at risk

Older and immunocompromised people
Most people who are infected have a minor illness and recover fully. But older people and those with weak immune systems are more likely to get a serious illness from the infection.
Pets occasionally get West Nile virus and very rarely get sick. Horses are more susceptible to serious illness than dogs and cats. A vaccine is available for Equine West Nile virus.