DENVER — Colorado has reported 884 human cases of West Nile virus this year as of Friday, several times the number in any other state and the same number for all last year in Illinois when it was the hardest-hit state.
Trailing Colorado were South Dakota with 206 reported human cases, Nebraska with 194 and Texas with 125. Total cases nationwide last week reached 1,602, with 28 resulting in death, according to the Centers for Disease Control and Prevention.
The Colorado Department of Public Health and Environment confirmed its 11th West Nile death this year, a 73-year-old Boulder County man. On Thursday the department announced the death of the 10th victim, an 85-year-old Adams County woman.
Both counties share a border with Denver County, indicating the mosquito-borne virus is spreading from Colorado’s hard-hit rural communities to the heavily populated Denver suburbs.
“Most of the people currently infected were not exposed to mosquitoes while hunting or fishing in the backwoods. They were doing everyday activities around the house like gardening, getting mail, walking the dog and sitting in their own back yard,” said Dr. Richard L. Vogt, executive director of the Tri-County Health Department.
“This is proof that illnesses from West Nile can occur in the Denver metropolitan area as well as in rural parts of Colorado,” he said.
Last year Illinois led the nation in West Nile human infections, but Colorado has already matched its number of cases with four months left in the year. Illinois also has almost three times the population, with 12.4 million to Colorado’s 4.3 million.
First detected in the United States in 1999, the virus can cause encephalitis, meningitis, paralysis and death, especially among the elderly. Those over age 60 are warned to stay inside from dusk to midnight, the peak mosquito feeding times.
Of course, there are exceptions.
“We’ve had at least four people in their 20s who got meningitis,” said Dr. Adrienne LeBailly, director of the Larimer County (Colo.) Department of Health and Environment. “But the good thing about people in their 20s is that they tend to recover fully.”
In 80 percent of cases, however, the victim shows no symptoms. Most of those who do show symptoms contract the milder West Nile fever, a three-day illness that results in headache and fever.
The hardest-hit Colorado counties, notably Larimer and Weld, are now spraying insecticide by truck around the perimeters of their largest communities. Larimer County is planning to launch an aerial-spraying campaign today to reach its more-remote agricultural areas.
Health officials have warned residents to spray themselves with an insect repellant containing DEET whenever they go outside.
Pets can also contract West Nile, but DEET can be harmful to dogs and cats.