Sacramento, California - The California Department of Public Health (CDPH) is reporting increased West Nile virus activity across the state and is investigating numerous suspect cases in humans. While the first human case has not been confirmed by CDPH, a resident of Los Angeles County has symptoms consistent with West Nile virus disease. Initial tests on that patient indicate a probable West Nile virus diagnosis, requiring further testing for confirmation.

“Californians should take every possible precaution to avoid mosquito bites,” said CDPH Director and State Public Health Officer Dr. Karen Smith. “Simple steps, like applying repellent, wearing long-sleeved shirts and pants in the early morning and evening, and draining standing water near your home can help to prevent bites from infected mosquitoes.”  

To date in 2016, West Nile virus has been detected in mosquitoes and birds in 30 California counties. Approximately 600 dead birds and 896 mosquito pools sampled in California this year have been found to harbor the virus. 

West Nile virus is transmitted to humans and animals by the bite of an infected mosquito. The risk of serious illness to most people is low. However, some individuals – less than one percent – can develop a 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 complications. Recent data also indicate that people with diabetes and/or hypertension are at greatest risk for serious illness.

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 mosquitoes from biting. DEET can be used safely on infants and children two 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 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 or drain all sources of standing water around homes and properties, including buckets, old car tires, rain gutters, birdbaths, and pet bowls. If a swimming pool is not being properly maintained, please contact the local mosquito and vector control agency.

 California’s West Nile virus website includes the latest information on West Nile virus activity in the state. Californians are encouraged to report all dead birds on the website or by calling toll-free 1-877-WNV-BIRD (968-2473).