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Health Department EH Mobile Site

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The disease. St. Louis Encephalitis is a viral disease of the brain and spinal cord obtained through a mosquito bite. Symptoms begin with a headache and may progress to a stiff neck and spine, fever, vomiting, sensitivity to light, drowsiness, seizures, coma, and possible death (less than 5% of cases). Infective individuals have such mild symptoms that they do not realize they are sick. Signs of illness may not appear for several weeks after infection. The elderly and young children are the most susceptible to developing a serious illness. The last outbreak in 1990 infected 213 people and caused 11 deaths. There were no human cases in Volusia County.

The mosquito. The mosquito linked to St. Louis Encephalitis, Culex nigripalpus, is a plain brownish insect that lays egg rafts in water including artificial containers, polluted pools, roadside ditches, and rain-diluted salt marshes. It feeds at night, taking blood from birds, mammals and reptiles. If it bites a bird infected with encephalitis, it may pick up the virus and passes it to a human it bites later.


  • Avoid outdoor activities from dusk until dawn, when many mosquitoes are biting.

  • If you must go out, wear long-sleeve shirts, long pants, and insect spray containing DEET.

  • Empty anything in the yard that holds water such as buckets, tires, flower containers, birdbaths, and drains.

  • Empty and refill your pet's water dish daily.

  • Repair screens on doors and windows.

  • Stock ornamental ponds with mosquito-eating fish.

This is a scaled down version
of our main environmental health site. For more detailed information please visit our main site at http://www.doh.state.fl.us/chd/volusia/EH/index.html