Arapahoe County identifies mosquitoes carrying West Nile virus

BY NINA JOSS NJOSS@COLORADOCOMMUNITYMEDIA.COM

Environmental health experts have detected West Nile virus in mosquitoes near the Arapahoe County Fairgrounds, marking the rst known presence of the virus in the county this year.

is spring and summer, which have brought record-high levels of rainfall to much of the metro area, have also created prime breeding grounds for mosquitoes.

e Arapahoe County Public Health Department discovered the mosquitoes carrying the virus through their mosquito surveillance program, which uses traps to capture the insects for testing at a state laboratory. ey use this method to identify pools, or groups of mosquitoes, that are carrying the virus.

e department has three collection sites in the county: at the fairgrounds, near Arapahoe and Parker Road and near Heritage High School.

“It’s not uncommon for positive pools (of mosquitoes) to occur every year,” said Vanessa Fiene, environmental health supervisor at the public health department. “Given that we have identi ed a positive pool in the county, it’s not unlikely that we would see other positive pools in the county as well.”

In 2022, Colorado led the nation in West Nile virus, with a con rmed 206 positive cases and 20 related deaths, according to the Colorado Department of Public Health and Environment. In 2021, Colorado ranked second, falling behind Arizona.

As of July 11, the state health department had zero identi ed human cases of West Nile virus so far this year.

What is West Nile virus?

In humans, the virus can range from being asymptomatic to deadly.

“It really is dependent on the person, you know, it depends on essentially their health,” Fiene said.

Most people are asymptomatic when they are infected with the virus. According to the county’s website, one in ve people develop a fever, body aches, a headache, skin rashes and/or swollen lymph nodes.

Less than 1% of people will develop severe symptoms that a ect the nervous system. ese may include a high fever, tremors, neck sti ness, muscle weakness, confusion and disorientation, a coma, paralysis and potentially death.

“ e risk is extremely small, but to some people, it could be extremely dangerous,” Fiene said.

If a person thinks they may have the virus, Fiene said they should seek medical care. ere are no speci c treatments for the illness and no vaccines, but medical support can help relieve symptoms, according to the Centers for Disease Control and Prevention.

Prevention

Experts say the best way to protect oneself from the virus is to prevent situations that could lead to bites.

“(Residents) need to protect themselves, especially at the times of dawn and dusk” Fiene said. “If you have to go outside at that time, making sure you wear long clothing, long pants, long sleeve shirts. And, again, wearing DEET-containing insect repellent.”

Dylan Garrison, environmental health manager at Arapahoe County Public Health, added that it can also be bene cial to eliminate spaces where mosquitoes would like to breed. Some of these areas could include standing water in areas like puddles, gutters, owerpots, tires, pool covers, boats and tarps.

“If you have tall grass or shrub areas or a bunch of bushes, it can be conducive to providing a place for them to hang out -- so keeping that trimmed and clean is always good idea,” he said.

If considering chemical treatment options for these areas, Garrison and Fiene said it is important to do so properly in order to not cause greater harm to other wildlife.

County actions e county is undertaking mitigation e orts where the infected mosquitoes were found, including insecticides and extensive mowing.

Along with its surveillance and mitigation e orts, Garrison said the county is working hard to educate and inform the community of the precautions they should take.

“ is is largely about individual responsibility and what can you do as an individual to help prevent being bitten in the rst place,” he said. “ e more you know, the more you’re able to prevent the bite, and that’s the idea.

Boulder, Delta, Larimer and Weld counties also have mosquitoes con rmed to be carrying the virus, according to Arapahoe County.