Four Stanislaus County residents have all been confirmed to have contracted West Nile Virus (WNV) and all four have developed the fairly uncommon neurological illness, known as neuroinvasive WNV, the Stanislaus County Health Services Agency reported on August 22.
The four cases are the first human cases of the virus in the county for the year.
As of August 18, California had 31 counties with WNV activity. There were 26 cases, which does not include the four cases recently confirmed in Stanislaus County. Two cases in California have been fatal.
The number of human cases in California this season is higher than the same time period last year, which had 16 cases. It’s also higher than the five-year average of 17.6 cases for the same time frame, according to westnile.gov.
Some of the increased WNV activity is attributable to the increased rainfall this year that lasted longer into spring, which gave mosquitoes increased breeding grounds.
Stanislaus County has reported two dead birds and 155 positive mosquito samples. Of those, 86 have been in the Turlock Mosquito Abatement District’s territory, which includes Ceres. SCHSA and the local mosquito abatement districts announced the first pools of mosquitoes positive for WNV in June of 2023. One case of equine WNV was also recently identified.
Mosquitoes become infected with WNV when they feed on infected birds. Infected mosquitoes can then spread WNV to humans and other animals when they bite, according to the Centers for Disease Control.
Approximately one in five people who are infected with WNV will develop symptoms such as fever, headache, body aches, joint pains, vomiting, diarrhea, or rash. Less than one 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 WNV 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.
There are no medications to treat or vaccines to prevent WNV infection. People with milder illnesses typically recover on their own, although symptoms may last for several weeks or months. In the neuroinvasive forms, patients can suffer severe and sometimes long-term symptoms.
“Because there is no vaccine and no specific treatment for West Nile Virus, it is important for people to take steps to protect themselves and their families from mosquito bites,” said Dr. Thea Papasozomenos, Stanislaus County Public Health officer. “We also urge residents to help control the mosquito population by dumping and draining any standing water around their homes, and reporting neglected swimming pools, as these can serve as mosquito breeding sites.”
Mosquitoes like to breed in stagnant water, preferring weedy areas that provide cover. The lagoons at dairy farms make for perfect breeding grounds, but so do flooded fields, uncared for swimming pools, urban catch basins, overwatered lawns, and pretty much anything that holds water and allows it to stagnate.
The district will continue with their treatment and surveillance programs by identifying mosquito breeding sources and mosquito borne disease activity. They will perform treatments according to their surveillance results. The district reminds residents that they can help by taking the following precautions:
• Dump or drain standing water. These are places mosquitoes like to lay their eggs.
• Defend yourself against mosquitoes by using repellants containing DEET, Picaridin or Oil of Lemon Eucalyptus.
• Avoid being outdoors at dusk and dawn. These are the times when WNV carrying mosquitoes are generally most active.
•Report neglected swimming pools to your local mosquito abatement district.
• Use tight fitting door and window screens to keep mosquitoes from entering your home.
• Contact your veterinarian for information on vaccinating equine against WNV.
For additional information or to request service, Turlock residents should contact the Turlock Mosquito Abatement District at (209) 634-1234 or (www.turlockmosquito.org).
Reporting and testing of dead birds are important steps in preventing WNV. A confirmed case of the virus in dead birds or mosquito samples helps to identify areas that need treatment to reduce mosquito activity. To report a dead bird, call the California State hotline at 1-877-WNV-BIRD or report it online at www.westnile.ca.gov. Birds of particular interest are crows, ravens, magpies, jays and raptors (hawk or eagle).
