Weld County’s first human case of West Nile virus in 2024 identified

DENVER (KDVR) — A fifth Coloradan has tested positive for West Nile viru s, this time in Weld County, according to local health officials.

On July 11, the county’s health department noted that three mosquito pools in two areas of the county tested positive for the virus. The mosquitos were near Johnstown, Milliken, Platteville, Firestone, Dacono and Fort Lupton.

On July 8, Weld County investigators identified five pools, including one in each testing zone. Traps are monitored weekly. In the announcement of mosquitos positive for West Nile virus, Weld County Health Department’s Executive Director Jason Chessher said the virus “has a permanent summer presence in Colorado.”

In 2023, Weld County reported 52 cases of West Nile virus in humans, and 35 the year before.

However, fewer mosquitos are being reported in traps this year than compared to the five-year average. According to the Colorado Department of Public Health and Environment, five human cases of West Nile virus have been reported so far this year across the state in Arapahoe, Delta, Mesa and now Weld County. The cases have resulted in three hospitalizations and one person exhibited neurologic symptoms.

Historically, Colorado sees a few hundred cases each year, although last year’s cases were higher than they have been since 2003.

What to know about West Nile virus, how to stay safe

West Nile virus symptoms can take three to 14 days to appear after an infection, according to the Weld County Health Department. The symptoms can include fever, headache, nausea, vomiting, muscle aches, weakness and rash, but the health department said most infected people do not show any symptoms.

If the symptoms do develop, the infected individual should immediately seek a healthcare professional. There are no medications to treat the virus, nor any vaccines for prevention. While fewer than 1% of infected people develop a serious and sometimes fatal neuroinvasive illness from the virus, about 1 in 5 people infected develop a fever and other symptoms.

Health officials recommend that anyone who may be exposed to mosquitoes prevent getting bit by remembering the four Ds:

• Drain standing water around your house regularly — this can include overturned toys, flowerpots, clogged gutters, rain barrels, tires and anything else that holds water
• Dusk and dawn are mosquitoes’ peak activity times. Limit outdoor activities during those hours and take preventative measures for bites
• DEET is the effective ingredient in insect repellant for consumers to look out for. Other effective repellents contain picaridin, IR3535, lemon eucalyptus oil and para-menthane-diol
• Dress to cover your skin: Long sleeves, pants and a hat can help keep bugs from biting

According to the Centers for Disease Control and Prevention, individuals over the age of 60 and individuals with pre-existing conditions are more at risk for severe infection from West Nile virus.

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