West Nile virus ‘possible’ in Pitkin County after Garfield County detection

Mosquito bites are no longer just a nuisance, but a concern to public health.

In light of Garfield County confirming the presence of West Nile virus and Redstone’s recent complaint of increased mosquito activity, those in this area should be aware of exposure risk.

“We’ve historically considered ourselves to be relatively immune to most mosquito-borne diseases because of the high elevation,” said Carlyn Porter, emergency response and epidemiology program administrator for Pitkin County. “It is possible to get bitten by a (mosquito) that could transmit West Nile Virus (within Pitkin County). It’s unlikely but possible.”

While mosquitoes typically have what Porter called a “fairly limited range,” where they stay close to where they hatch, she did say they are expanding their range due to climate change. However, she said she is less concerned that mosquitoes from Garfield County will directly transmit the disease to Pitkin County; instead, it’s more likely that infected birds will make the journey, as was the case in Garfield County.

“Mosquitoes are acquiring the virus from infected birds,” Garfield County Environmental Health Manager Jannette Whitcomb confirmed in a press release. “Our program collects mosquitoes to identify their type and to test for the presence of West Nile virus. Mosquitoes in last week’s samples came back positive.”

Still, increased mosquito activity in Redstone that was reported via complaint also generated significant concern prompting Pitkin County Environmental Health to conduct surveillance. Superfund Site Manager Tom Dunlop interviewed three local residents during his visit and one over the phone and surveyed the general Redstone area searching for mosquito breeding areas. 

Ultimately, though, the activity was deemed to be an isolated, non-threatening incident, according to Porter. CDC and EPA documents were dropped off at the Redstone Inn in support of using a species-specific larvicide, a type of insecticide specifically designed to kill insect larvae. Residents were also encouraged to contact Environmental Health with future complaints.

Pitkin County has not yet confirmed the presence of West Nile virus. While reports of a camper in the area who developed West Nile virus were released in 2023, Porter said the camper could have gotten it from a mosquito bite either in Pitkin or Delta County, which she said is a hot spot.  

She also previously told The Aspen Times in April that the Aedes aegypti mosquito, a species associated with transmitting several viruses (including dengue, Zika, and yellow fever), was identified in Mesa County last year.

“There’s a possibility it could also migrate over here,” she noted, although there is still no evidence that the species is in Pitkin County.

Residents and visitors to Pitkin County can take precautions against mosquito bites by using insect repellent like DEET or lemon eucalyptus bug spray, covering exposed skin with long-sleeved shirts and pants, avoiding being out at dawn and dusk, and preventing stagnant water with aerators, fountains, or fish.

“Keep in mind the exposure risk,” Porter said. “There are definitely steps you can take prevention-wise.”