California is seeing a record number of mosquitoes with West Nile virus, according to officials with the California Department of Public Health.
This year, 37 counties have reported West Nile virus activity, of which 22 reported human infection. A total of 181 human cases have been reported to CDPH, a significant increase compared with the 101 cases reported by this time last year, state health officials said. Eight confirmed deaths have been reported to CDPH.
“The proportion of mosquitoes infected with West Nile virus is at the highest level ever detected in California,” Ron Chapman, director of CDPH, said in a news release. “Last week, 52 new human cases were reported to CDPH. We expect to see more people become infected as this is the time of year when the risk of infection is the highest.”
West Nile virus cases in people have not been reported in Merced County, but according to Allan Inman, manager at the Merced County Mosquito Abatement District, confirmation of human cases in this area is just a matter of time.
“We’ve been expecting a human case for a couple of months now,” Inman said. “We’re in peak transmission period right now. Just take a look at our neighboring counties.”
Fresno, Stanislaus and Tulare counties have all reported West Nile virus cases in people. The first indication of West Nile virus activity in Merced occurred in late July, and as of Monday, two horses, one bird, six chickens and 10 mosquitoes have tested positive. Inman said a West Nile equine vaccine is available and asks that horse owners get their horses vaccinated. Both of the horses that were infected were not vaccinated.
Officials also urge residents to avoid the outdoors during dusk and dawn and to apply insect repellent. “We’re counting on the public to protect themselves,” Inman said. “All it takes is one infected mosquito, and unfortunately we can’t get rid of all of them.”
The Abatement District began aerial treatments over Merced County two weeks ago and will fly over the city of Merced tonight. Inman explained that the district is concentrating on vector-borne disease control and that nuisance mosquitoes are secondary.
Last year, 21 sentinel chickens, eight mosquitoes and 38 birds tested positive for West Nile in Merced County. No cases of infected people were reported last year. In 2012, 13 human cases were reported in Merced County.
According to the Centers for Disease Control and Prevention, most people infected with West Nile virus will have no symptoms. About one in five people who are infected will develop a fever with other symptoms, and about 1 percent of infected people develop serious neurological illnesses.