Arapahoe County reported the first known human case of West Nile virus in Colorado for 2024 on Wednesday, marking an early start to the mosquito-borne disease’s season.
Typically, Colorado doesn’t see its first West Nile cases until July, and they take off in August. Mosquito activity increases when days are hot and nights stay relatively warm.
“While we know that West Nile virus is endemic to Colorado — meaning we expect to see some cases each year — we never quite know how many to expect or just how bad a season will be,” Melissa Adair, communicable disease epidemiology manager at Arapahoe County Public Health, said in a news release. “What this first case confirms for us, however, is that West Nile virus is present in our mosquito population, and as mosquito numbers increase, the risk of West Nile virus will, too,”
Last year, Colorado had 634 known cases in more than half of the state’s counties, which was the highest total since 2003, when the virus arrived in the state. Fifty-one of those people died and 386 spent time as hospital inpatients.
To prevent infection with West Nile virus:
Wear insect repellant with DEET or another ingredient approved by the Environmental Protection Agency during outdoor activities
Avoid spending time outdoors around dawn and dusk, when mosquitoes are most active
Consider using mosquito netting when camping
Avoid stagnant water sources, such as ponds
Wear long-sleeved shirts and long pants for outdoor activities
Drain flowerpots, tires and other items that collect water, which mosquitoes use to breed
Keep window screens in good repair
Maintain your septic tank, if you have one, so mosquitoes can’t breed in it
All Colorado counties have reported at least one human case of West Nile virus since 2003. No one knows how many people have had the virus, because most don’t get sick.
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About one in five people who get West Nile develop mild symptoms, such as fever, body aches, a headache and, less commonly, a rash or swollen lymph nodes. Treatment focuses on relieving discomfort.
One in 150 people develop severe symptoms, such as coma, tremors, neck stiffness, muscle weakness, confusion, or paralysis. People over 60 and those with chronic conditions are at higher risk of a severe infection.
Arapahoe County Public Health urged people who think they might have West Nile to see a doctor and call their local health department.
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