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September - West Nile Virus

Beverly Miller

Beverly Miller, MHA, MBA, Area Director
Indian Health Service California Area Office


With the California Department of Public Heath (CDPH)’s announcement on July 20, 2015 of the first confirmed human death from West Nile Vires in Sacramento County, CA, we would like to remind folks to take precautions when out in the early morning / evening hours.

West Nile Virus is a virus that was first found in the United States in 1999 when it first appeared in New York.  Appearing in California in 2003, this virus is naturally found in the bird population. The virus spreads from bird to humans by the bite of a mosquito.   A female mosquito will bite an infected bird and within just a few short days the virus will appear in its saliva, where it gets injected into humans, horses, and other animals during a bite. 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. There is typically a 3 to 14 day incubation period after being bitten before symptoms appear.

Currently, a vaccination has been developed to protect horses but so far there is no vaccine for humans and only supportive therapy can be given. Therefore, the state has an ongoing active surveillance program.  At this time thirty-five California counties have reported WNV activity so far this year, four more than this time last year and above the five-year average of 22, according to the state “Fight the Bite” website. To date, 1,333 mosquito samples have tested positive for WNV, which significantly exceeds the five-year average of 330.


The best way to protect yourself from mosquito-borne illness is by reducing the number of mosquitoes around your neighborhood, and taking personal precautions to avoid mosquito bites.

  • Mosquitoes lay their eggs on standing water. Eliminate all sources of standing water in your yard by check for items that may collect water, such as cans, bottles, jars, buckets, old tires, drums, pet food/drink bowls, and other containers.
  • Change water in flower vases, birdbaths and animal watering pans at least twice a week. Ensure that your swimming pools are properly maintained.
  • Make sure doors and windows have tight-fitting screens. Repair or replace screens that have tears or holes in them.
  • Wear lightweight clothing that covers the arms and legs if you’re outside, particularly at dawn and dusk when mosquitoes are most active.
  • Use insect repellent to avoid being bitten by mosquitoes anytime you go outside. Apply repellents in accordance with the labeling instructions. Look for ingredients such as DEET, picaradin, oil of lemon eucalyptus or IR3535.  DEET can be used safely on infants and children two months of age and older. Ensuring protection is particularly important for the elderly and small children.

For additional information on West Nile Virus, see

Centers for Disease Control and Prevention (CDC) at Exit Disclaimer: You Are Leaving

Fight the Bite, California West Nile website: Exit Disclaimer: You Are Leaving