Larimer resident hospitalized for West Nile virus

One person has been hospitalized with West Nile virus, and two Fort Collins residents who donated blood were found to have been carrying the disease, Larimer County health officials announced Saturday.

The Larimer County Department of Health and Environment learned this week a Loveland resident had been hospitalized with meningitis from a rare neuro-invasive form of West Nile that accounts for about 1 percent of all infections. The resident, whose identity has not been publicly released, is the first confirmed human case of West Nile in Larimer County this year.

Additionally, two Fort Collins residents who donated blood in July were found to have been infected. Blood tests confirmed West Nile virus was present, and the blood was discarded. The donors did not show any signs or symptoms of West Nile.

Positive tests in blood donations are among the most reliable indicators of very recent West Nile virus in humans, health officials said in a Saturday morning news release.

“These infections in Larimer County residents show that the risk of West Nile disease is increasing, and everyone along the county’s Front Range should be taking personal precautions to prevent mosquito bites,” Health Department Director Adrienne LeBailly said in a statement. “Community measures to keep larvae from growing into biting mosquitoes began in the spring. Spraying to reduce adult mosquitoes has already begun by some of Fort Collins’ homeowner associations, as well as city control efforts in Loveland, Windsor, Timnath and Johnstown.”

CSU:  Mosquito numbers high, West Nile risk fairly low

Spraying in parts of Colorado has grown contentious over the years, and jurisdictions have differing parameters in deciding when to spray.

The vector index that quantifies infected mosquitoes is 0.28 in one of the city’s four zones. Fort Collins officials will not consider spraying until the index reaches 0.75 or higher in any of the sectors. There must also be at least two confirmed human cases before control efforts and spraying will begin in city limits.

The abundance of Culex mosquitoes — the type that can carry the virus — and the rate of infection in those mosquitoes is what determines the vector index.

Timnath, Windsor and other areas of Northern Colorado have begun some fogging operations. Loveland officials can also let residents know the day of spraying — the city has sprayed at least one of the 53 zones it monitors each day this summer, said Broox Boze, operations manager at Colorado Mosquito Control.

Spraying has not started yet in unincorporated Larimer County. Officials there continue to monitor the situation.

The county uses a lower vector index threshold — 0.5 — and may order spraying earlier. The county does not require human cases before making the decision to spray.

“Spraying decisions are based on elevated numbers of infected mosquitoes. By the time human cases are reported, many people will have already been infected and spraying will be much less effective,” according to the health department’s website.

The human cases this week are among the first human cases reported in Colorado this summer. A Mesa County man contracted the disease and reported it July 8. This same time in 2014, four people had become infected, according to the Colorado Department of Public Health and Environment.

THE CITY:  West Nile virus found in Fort Collins

A Loveland man, believed to have been infected in late July, was 2014's first human case of West Nile in Larimer County. In 2013, there were seven deaths in Colorado and 322 reported cases of the virus statewide. There were four deaths reported statewide last year and 115 reported human cases.

West Nile symptoms range from minimal-to-serious flu-like sickness, usually appearing three to 14 days after being bitten by an infected mosquito. About 75 percent of people who are infected are asymptomatic, and about 25 percent will develop West Nile fever. Less than 1 percent develop the severe neuro-invasive form that can lead to hospitalization, critical illness, chronic disability or even death, the health department said.

Residents are reminded to drain standing water, wear long-sleeved shirts and pants while outside, use DEET-infused insect repellent and limit time outside in the early morning and evening hours.

For information about West Nile virus, mosquito counts and trap information, visit www.fcgov.com/westnile or http://www.co.larimer.co.us/health/cd/westnile.cfm.

Reporter Jason Pohl covers breaking news for the Coloradoan. Follow him on Twitter: @pohl_jason.