Two women in Stanislaus County are the first confirmed human cases of West Nile virus (WNV) infection in California this year. The women were identified after they donated blood and routine testing performed by the blood bank confirmed WNV infection.
"With the first confirmed human illnesses from West Nile virus this year, we are intensifying our surveillance for the virus with the help of all counties,” said California Department of Public Health Director Dr. Mark Horton. “The most important step people can take to prevent West Nile virus infection is to protect themselves from being bitten by a mosquito.”
WNV is most commonly transmitted to humans and animals through a mosquito bite from a mosquito harboring the virus. The risk of serious illness to most people is low. However, some individuals -- less than 1 percent -- will develop serious neurologic illness such as encephalitis or meningitis.
All donated blood is routinely screened for WNV to ensure the safety of the blood supply. The women from Stanislaus County developed symptoms consistent with WNV illness. Neither were hospitalized. Both are recovering.
To date, WNV has been detected in 19 California counties in 52 dead birds, 107 mosquito samples, six sentinel chickens and one squirrel.
Experts refer to the “four Ds” as the most effective ways to prevent WNV:
1. DEET – Apply inspect repellent containing DEET, picaradin, oil of lemon eucalyptus or IR 3535 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. DRESS – Wear clothing that reduces the risk of skin exposure.
3. DAWN AND DUSK – Exposure to mosquitoes is most common during the early morning and evening so it is important to wear repellent at that time. Make sure that your doors and windows have tight-fitting screens to keep out mosquitoes.
4. 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 have a pond, use mosquito fish (available from your local mosquito and vector control agency) or commercially available products to eliminate mosquito larvae.
For more information about WNV, visit www.westnile.ca.gov. Dead birds can be reported on the Web site or by calling toll-free 877-WNV-BIRD (877-968-2473).