Two people have died of the West Nile virus in El Paso County this year amid an “early and intense” mosquito season, public health officials said.

Since the first human case of the virus was reported in the county on Aug. 1, the number has spiked to 18 as of Monday, including the two deaths, according to the El Paso County Public Health Department.

Not only are the cases the first in two years, they soar above the number of cases reported in the last decade combined. El Paso County saw just nine positive cases between 2013-2021, and no cases were reported last year. According to Colorado Department of Health and Environment data, the last West Nile-related death in the county was in 2003.

The surge follows a spring and summer of heavy precipitation, including historic rains in May and June, that brought about more standing water and, consequently, thriving mosquito breeding grounds. West Nile virus returns “season to season” as mosquitoes feed on infected birds, and then on humans, EPCPH co-medical director Bernadette Albanese told the county Board of Public Health on Wednesday.

Statewide, 11 deaths have been reported across Weld, Pueblo, Boulder, Jefferson, La Plata and, now, El Paso counties, according to Annemarie Harper, communications director for the Colorado Department of Health and Environment’s Disease Control and Public Health Response.

The state’s first death from the virus occurred in Weld County earlier this month.

Of the 122 people confirmed by CDPHE to be infected statewide, 73 have been hospitalized – up from 43 last week, according to previous reporting by the Denver Gazette.

Public health data provided to The Gazette on Monday shows that, of the county’s 18 confirmed cases, which span from Falcon to Northgate to Old Colorado City, 83% contracted the virus locally.

“The message to the public is that infected mosquitos are probably all over the county,” Albanese said.

Not only have cases increased dramatically from recent years, the 2023 season’s peak came weeks earlier than is typical, Albanese said. Most human

cases of West Nile virus are reported in August and early September, but cases peaked by mid-july and early August, officials said.

On average, Colorado as a whole would normally have seen less than 10 cases by this point in the year.

Most people who get infected with West Nile virus via a mosquito bite don’t end up showing symptoms, though some can ultimately develop an illness with deadly potential.

According to Haley Zachary, EPCPH communicable disease program manager, the county breaks down cases by symptom severity to better understand how and why different population groups are affected and better “target them for messaging” on mitigating risk.

Currently, 67% of the county’s confirmed cases exhibit “neuroinvasive” symptoms, where the virus impacts the brain and central nervous system and can cause encephalitis or meningitis.

Zachary said the neuroinvasive symptoms typically affect people over 55. Those with certain health conditions, including cancer, diabetes, hypertension, kidney disease, and people who have received organ transplants are at greater risk of becoming symptomatic in some way.

Zachary encouraged residents to use some kind of insect repellent, especially when mosquitoes are most active around dawn and dusk. People can also wear long sleeves and pants and socks to avoid bites and should drain any standing water near their homes.

“Just a tablespoon of water is enough to become a mosquito breeding habitat,” Zachary said, meaning even the smallest pools – water caught in flowerpots, bird feeders, sidewalk cracks or tree stumps – can boost the mosquito population.