The number of individuals sickened with the West Nile virus in California continues to climb as the rates of infected mosquitoes reaches previously unseen levels, the California Department of Public Health reported.
“The proportion of mosquitoes infected with West Nile virus is at the highest level ever detected in California,” said Dr. Ron Chapman, director of the CDPH and state health officer. “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.”
The state West Nile virus website is reporting there are 238 confirmed human cases of West Nile virus in 26 counties, as of Wednesday. At this time last year the state had confirmed 117 cases.
West Nile virus is transmitted to humans and animals through a mosquito bite. Mosquitoes become infected when they feed on infected birds.
In the United States, most people are infected from June through September, and the number of these infections usually peaks in mid-August, according to the Centers for Disease Control. Seasonal outbreaks often occur in local areas that can vary from year to year. For example, Stanislaus County had at least one human case reported in October 2011.
Approximately 1 in 5 people who are infected with West Nile virus will develop symptoms such as fever, headache, body aches, joint pains, vomiting, diarrhea, or rash. Less than 1 percent will develop a serious neurologic illness such as encephalitis or meningitis (inflammation of the brain or surrounding tissues). About 10 percent of people who develop neurologic infection due to West Nile virus will die, according to the CDC. People over 50 years of age and those with certain medical conditions, such as cancer, diabetes, hypertension, kidney disease, and organ transplants, are at greater risk for serious illness.
Stanislaus County has confirmed 24 West Nile virus cases, which has the county tied with Fresno County as having the third highest rate of human infections in the state. Of the local cases, 15 have been diagnosed with the neuroinvasive form of the virus, said Stanislaus County Health Services Agency Public Health Officer Dr. John Walker.
The CDPH has confirmed eight West Nile virus-related deaths this year, including two 65-year-old men in Stanislaus County.
“We are very much in the season for West Nile and there is a risk it could last through October,” Walker said.
In Stanislaus County, 89 dead birds and 113 mosquito samples have tested positive for the virus. The county also has seen 12 sentinel chickens test positive for West Nile.
The Turlock Mosquito Abatement District website indicates Turlock has seen five confirmed human cases, as well as 22 dead birds.
The District also reported an increase in mosquito activity in several areas of Turlock and Denair. A particular hotspot of activity has been reported in the area bounded by East Avenue, N. Gratton Road, W. Tuolumne Road and Geer Road.
The CDPH recommends that individuals prevent exposure to mosquito bites and West Nile virus by practicing the “Three Ds:”
1. DEET – Apply insect repellent containing DEET, picaradin, oil of lemon eucalyptus or IR3535 according to label instructions. Repellents keep the mosquitoes from biting you. DEET can be used safely on infants and children 2 months of age and older.
2. DAWN AND DUSK – Mosquitoes bite in the early morning and evening so it is important to wear proper clothing and repellent if outside during these times. Make sure that your doors and windows have tight-fitting screens to keep out mosquitoes. Repair or replace screens with tears or holes.
3. DRAIN – Mosquitoes lay their eggs on standing water. Eliminate all sources of standing water on your property, including flower pots, old car tires, rain gutters and pet bowls. If you know of a swimming pool that is not being properly maintained, please contact your local mosquito and vector control agency.
The East Side and Turlock Mosquito Abatement Districts are treating mosquito habitats using ground and aerial spray equipment and are doing aerial surveillance photography for neglected swimming pools.
The Districts provide mosquito fish, free of charge, to put in ornamental ponds and other backyard locations. To report mosquito-breeding problem areas, residents should contact one of the two mosquito abatement districts that serve the county. For areas north of the Tuolumne River, residents should call the Eastside Mosquito Abatement District at 522-4098 (www.eastsidemosquito.com) all others should contact the Turlock Mosquito Abatement District at 634-1234 (turlockmosquito.org). Reporting and testing of dead birds also helps in locating areas needing treatment for West Nile Virus. To report a dead bird, call the California State hotline at 1-877-WNV-BIRD or online at www.westnile.ca.gov.