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CDPH Confirms First Human West Nile Virus Illness of 2017

Date: 4/28/2017 
Number: 17-043 
Contact: Ali Bay - (916) 440-7259 

SACRAMENTO – The California Department of Public Health (CDPH) announced the first confirmed illness in California due to West Nile virus (WNV). The illness occurred in Kings County.

“West Nile virus activity in the state is increasing, so I urge Californians to take every possible precaution to protect against mosquito bites,” said CDPH Director and State Public Health Officer Dr. Karen Smith.

This year to date, West Nile virus activity has been detected in three dead birds, one each from San Mateo, Orange, and San Diego counties. Heavy rains this winter in California have contributed to an increase in mosquito breeding sites. It is not known what impact the wet weather may have on the actual virus transmission risk in humans. So far this season, West Nile activity is within expected levels.

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 West Nile 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 1 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, picaradin, 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 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 that 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).

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