Will West Nile Virus Arrive in 2003?

(Santa Ana) – The rapid progression of West Nile Virus (WNV) across the United States has Orange County health and vector control officials anticipating the first locally acquired case of WNV to occur this year.

“Based on the spread of WNV last year, it is very possible that the virus will become a public health threat in Orange County this year,” said Mark Horton, M.D., Orange County Health Officer. “WNV is another reason that we should all take a few simple precautions to reduce our chance of being bitten by mosquitoes.”

WNV has now been confirmed in 44 states, with over 4,000 human WNV cases in the United States during 2002. The majority of WNV cases are contracted through the bite of an infected mosquito. Most people infected with WNV have no symptoms or only mild ones like fever, headache and body aches, but the elderly and those with weakened immune systems face a higher risk from WNV.

“The chance of contracting WNV infection is very small, so there is no reason to seek medical treatment or testing for a mosquito bite,” said Dr. Horton. “People with the severe form of WNV infection have symptoms like severe headache, high fever, muscle weakness, confusion, stiff neck and nausea. These symptoms of serious illness require immediate medical attention.”

The key to reducing the risk of WNV infection is controlling the mosquito population. This can be accomplished by eliminating standing water from around your home and property.   Out of service pools and backyard ponds, for example, are capable of producing thousands of mosquitoes daily.  Mosquitoes can develop in anything that holds water for more than a week.   Eliminating mosquito-breeding areas also helps prevent the other mosquito-borne diseases that occur locally, such as Western Equine encephalitis and St. Louis encephalitis.   Mosquito control information is available from the Orange County Vector Control District at www.ocvcd.org or by calling (714) 971-2421.

To deter mosquitoes from biting, use insect repellents containing DEET, always following label directions. When using insect repellents on children, the American Academy of Pediatrics has recommended a cautious approach using products with a low concentration of DEET, 10% or less, on children aged 2 - 12. Other ways to avoid mosquito bites include limiting outside activity at dusk and dawn when mosquitoes are most active, wearing long sleeved shirts and long pants when outside, and making sure that doors and windows have tight fitting screens.

As part of their WNV surveillance efforts, the Orange County Vector Control District is testing birds that have been dead for less than 24 hours.  For more information regarding dead bird testing, visit www.ocvcd.org or call (714) 971-2421. The State of California has also established a toll-free telephone number for the public to report dead birds. That number is 1-877-WNV-BIRD.

A WNV vaccine for horses has been licensed by the US Department of Agriculture. Horse owners are advised to consult their veterinarian when considering vaccination. WNV information for horse owners can be found on the Orange County Animal Care Services Web site at www.ocpetinfo.com/nile.htm. 

The Centers for Disease Control and Prevention (CDC) has WNV information posted at www.cdc.gov/ncidod/dvbid/westnile/index.htm.

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