The California Department of Public Health (CDPH) announced today three confirmed deaths in California due to West Nile virus (WNV). The deceased persons were residents of Kern, Los Angeles and San Bernardino counties. CDPH is unable to provide additional patient details including demographic information and name of hospital providing care to protect confidentiality.

“West Nile virus can cause a deadly infection in humans, and the elderly are particularly susceptible,” said CDPH Director and State Health Officer Dr. Karen Smith. “August and September are peak periods of West Nile virus transmission in the state so we urge everyone to take every possible precaution to protect themselves against mosquito bites.”

As of September 1, CDPH has reported 87 human cases of WNV from 13 California counties this year. Additionally, 239 dead birds from 30 counties have tested positive for WNV in 2017, and 2,284 mosquito samples from 24 counties have also tested positive for WNV this year.

The numbers of WNV positive dead birds and mosquito samples are below those at this same time last year, but the number of positive mosquito samples exceeds the state’s most recent five year average.

West Nile virus is influenced by many factors, including climate, the number and types of birds and mosquitoes in an area, and the level of WNV immunity in birds. 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 serious neurologic illnesses such as encephalitis or meningitis.

People 50 years of age and older and individuals with diabetes or hypertension have a higher chance of getting sick, and are more likely to develop complications.

CDPH recommends that individuals protect against mosquito bites and WNV by practicing the “Three Ds”:
1. DEET – Apply insect repellent containing DEET, picaridin, oil of lemon eucalyptus or IR3535 according to label instructions. Repellents keep the mosquitoes from biting you. Insect repellents should not be used on children under two months of age.

2. DAWN AND DUSK – Mosquitoes that transmit West Nile Virus usually bite in the early morning and evening so it is important to wear proper clothing and repellent if outside during these times. Make sure your doors and windows have tight-fitting screens to keep out mosquitoes. Repair or replace screens that have tears or holes.

3. DRAIN – Mosquitoes lay their eggs on standing water. Eliminate all sources of standing water on your property by emptying flower pots, old car tires, buckets, and other containers. If you know of a swimming pool that is not being properly maintained, please contact your local mosquito and vector control agency.

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