NEWS

For Immediate Release:
Contact:
Michael Williams, Ph D., Communicable Disease Control, 314- 615-1630
Pager 314-430-5885

West Nile Virus: The Message is Prevention
Possible case of WNV in St. Louis County: test results expected next week

Saint Louis County, Missouri, August 22, 2003 - Public Health officials in St. Louis County are waiting for confirmation of a positive test result on a County resident who may have West Nile virus. If confirmed, this would be the first human case of the virus in St. Louis County this year. The 53-year-old West County man is recovering at home. West Nile encephalitis is diagnosed by testing a blood sample and/or spinal fluid.

The incidence of WNV has been less prevalent in the St. Louis metropolitan area this summer than last year. Health officials attribute this to a number of factors, including weather (a wet spring and a dry summer), fewer birds, and exhaustive public health efforts in mosquito control, including larvaciding and spraying. In addition, a more educated public appears to be taking greater preventive measures.

But, health officials urge, this is no time to become complacent! Prevention is still the key message in avoiding exposure. People can reduce their chance of exposure by taking these steps:

• Stay indoors at dawn, dusk, and in the early evening, when mosquitoes are most active.
  
• When outdoors wear long-sleeved shirts, long pants and light colors.
  
• Spray clothing with repellents containing permethrin or DEET since mosquitoes may bite through thin clothing.
  
• Apply insect repellent sparingly to exposed skin. An effective repellent will contain 35% DEET (N, N-diethyl-meta-tolumide). DEET in high concentrations (greater than 35%) provides no additional protection.
• Repellents may irritate the eyes and mouth, so avoid applying repellent to the hands of children.
  
• Whenever you use an insecticide or inspect repellent, be sure to read and follow the manufacturer's DIRECTIONS FOR USE, as printed on the product.
  
• Eliminate sources of standing water where mosquitoes can breed around homes.
  
• Change the water in birdbaths weekly.
  

There is no specific treatment for West Nile encephalitis in humans. In more severe cases, intensive supportive therapy is indicated, often involving hospitalization, intravenous fluids, airway management, respiratory support (ventilator), prevention of secondary infections (pneumonia, urinary tract, etc.), and good nursing care. No human vaccine has been approved, but several companies are working towards developing a vaccine.

Most human infections are mild. Symptoms usually appear 3 to 15 days after infection, and include fever, headache, body aches, occasional skin rash and swollen lymph glands. More severe infection may be marked by headache, high fever, neck stiffness, stupor, disorientation, coma, tremors, convulsions, muscle weakness, paralysis, and, rarely, death. Persons older than 50 years of age and those with compromised immune systems have the highest risk of severe disease. If you have symptoms, contact your health care provider.

Less than 1% of people who get bitten by an infected mosquito become infected and get severely ill. Case-fatality rates range from 3% to 15% among those with severe illness due to West Nile virus, and are highest among the elderly. Persons over 50 years of age and people with compromised immune systems are more likely to experience significant clinical disease from West Nile virus infection.

Ever since West Nile virus was confirmed in dead birds in the St. Louis metropolitan area in fall 2001, health officials have anticipated the disease would eventually spread to the human population. Local public health agencies joined together to form a Metropolitan West Nile Virus Task Group, to monitor the progress of WNV and coordinate response measures.

The disease infects birds and is spread through mosquitoes. Crows, blue jays, and hawks are particularly vulnerable to the West Nile virus. A diseased bird cannot infect humans - virtually all human cases occur as a result of a bite by an infected mosquito. That is why it is so important to prevent exposure to mosquitoes.

For more information on West Nile virus, log on to www.scchealth.org and proceed to the West Nile virus page. If you don't have access to the Internet, you may call your local health department. In Saint Louis County the phone number is 314-615-1630; in St. Charles County it's 636-949-7404; and in the City of St. Louis it's 314-622-4252. Jefferson County residents may call 636-789-3372. In Franklin County call 636-583-7300.

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