DENVER—With the mosquito population booming, Colorado health officials warned Friday this could be a bad year for West Nile virus, which has now been detected in three people.
The third case was reported in Boulder County. The earlier victims live in eastern and northeast Colorado.
Counts of the Culex mosquito, which carries the disease, are the same or higher this year than in 2003, when West Nile killed 63 people in Colorado and was diagnosed in nearly 2,900 others.
“Based on the surveillance data from around the state, the indicators are suggesting that we’re heading into a high-risk year,” said John Pape, an epidemiologist with the state Department of Public Heath and Environment.
Infected mosquitoes have been found in Boulder, El Paso, Jefferson, Larimer, Logan, Mesa, Otero, Prowers and Weld counties, the health department said.
A wet spring, a rainy start to the summer and hot weather makes it possible for the mosquitoes and the virus to develop faster, said Melina Hogan, another health department epidemiologist.
Health officials expect more human cases because they began discovering infected mosquitoes earlier than usual. Already, 26 groups of mosquitoes have tested positive, with 18 of those detected since July 1.
Normally, infected mosquitoes would only now be starting to turn up.
“This is the time (for people) to start protecting themselves. This is the time to start using insect repellent with DEET and also try not to be outside at times of dusk and dawn,” Hogan said.
Health officials said the total number of human cases is much higher than what is reported because only a small proportion of people who are infected feel sick.
Symptoms include fever, headache and neck stiffness. In more serious cases, blindness, paralysis and inflammation of the brain have been reported.
This year’s victims include a 51-year-old who lives in Logan County and a resident of Cheyenne County.
State health officials didn’t release any details on the Boulder County case. The Camera newspaper reported on its Web site the victim is a 54-year-old man who lives in the east part of the county.
Nationally, last year was the worst year for West Nile since 2003, with at least 177 deaths reported. The deadliest year for West Nile was 2002, when 284 people died.
