Stanislaus County Public Health has confirmed the first human West Nile virus (WNV) infection in the county. An adult female was diagnosed with West Nile fever (non-neuroinvasive disease). The first pools of mosquitoes in the county tested positive for West Nile virus on June 11, 2021.

West Nile virus spreads to people and animals through the bite of a mosquito infected with the virus. Hot weather, abandoned swimming pools, and standing water create ideal conditions for the development of mosquitoes and the subsequent spread of the virus. About one in five people will develop West Nile fever with symptoms of headache, fever, and fatigue. However, some people (less than one percent) will develop serious neurologic illness, such as encephalitis or meningitis.

People 50 years of age and older have a higher chance of getting sick and are more likely to develop serious illness when infected with WNV. Studies also indicate that those with diabetes and/or hypertension are at greatest risk for serious illness. There is no specific treatment for WNV disease. Public Health recommends community members to prevent exposure to mosquito bites and West Nile virus by following the “Four Ds”:

DEET – Apply insect repellent containing DEET, picaridin, oil of lemon eucalyptus or IR 3535 according to label instructions to keep mosquitoes from biting you. Apply repellents only to exposed skin and/or clothing. DEET can be used safely on infants and children 2 months of age and older.

DAWN & DUSK – Mosquitoes that carry WNV tend to bite in the early morning and evening, so it is important to wear repellent at this time. Make sure that your doors and windows have tight-fitting screens to keep out mosquitoes. Repair or replace screens with tears or holes.

DRESS – Wear clothing that reduces the risk of skin exposure to mosquito bites (i.e., long pants and long-sleeved shirts).

DRAIN – Mosquitoes lay their eggs on standing water. Eliminate all sources of standing water on your property, including flowerpots, old car tires, rain gutters and pet bowls. If you have a pond, use mosquito fish or commercially available products to eliminate mosquito larvae. Neglected swimming pools are also prime place for mosquito breeding.

As of July 30, WNV has been detected in 20 mosquito samples and one dead bird in Stanislaus County. The risk of disease due to WNV usually increases at this time of year and is highest throughout the summer and early fall.

The East Side and Turlock Mosquito Abatement Districts are available to help with neglected pools in the prevention of mosquito development in Stanislaus County. For additional information or to request service, residents should contact their local District Stanislaus County residents:

North of the Tuolumne River contact: Eastside Mosquito Abatement District at (209) 522‐4098 (www.eastsidemosquito.com).

South of the Tuolumne River contact: Turlock Mosquito Abatement District at (209) 634‐1234 (www.turlockmosquito.org).

Additional Information on West Nile Virus can also be found at:

Stanislaus County Public Health - www.schsa.org/publichealth/pages/wnv/

California Department of Public Health - www.westnile.ca.gov

Centers for Disease Control and Prevention - www.cdc.gov/westnile/index.html