California counties report West Nile Virus activity much higher than average

State Health Officer Dr. Karen Smith is warning that the level of West Nile virus activity is on the rise throughout the state.

“While there have been no human cases of West Nile virus reported so far this year, it is only a matter of time before we see the first case,” Dr. Smith said. “As people go outdoors to enjoy the warm weather we’ve been experiencing, we’d like them to be safe and know how to protect themselves against West Nile virus.”

31 California counties have reported WNV activity so far this year, 10 more than this time last year and above the five-year average of 18. To date, 240 mosquito samples have tested positive for WNV, six more than last year at this time.

Health managers say that WNV is influenced by many factors such as climate, the number and types of birds and mosquitoes in an area, and the level of immunity in birds to WNV.

It is possible that the drought has contributed to West Nile virus amplification say health experts. They say that with the reduction of sources of water for birds and mosquitoes, they are coming into closer contact with humans and amplifying the transmission of the virus.

CDPH recommends that people prevent exposure to mosquito bites and WNV 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 the mosquitoes from biting you. 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 that your 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 all sources of standing water on your property, by emptying flower pots, old car tires, and buckets. If you know of a swimming pool that is not being properly maintained, please contact your local mosquito and vector control agency.

WNV is transmitted to humans and animals by the bite of an infected mosquito say health managers. The risk of serious illness to most people is low. However, some individuals – less than one percent – can develop a serious neurological 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. Studies also indicate that those with diabetes and/or hypertension are at greatest risk for serious illness.

California’s West Nile virus website includes the latest information on WNV activity in the state.

If you find a dead bird you’re asked to report it on the website or by calling toll-free 1-877-WNV-BIRD (968-2473).