West Nile Encephalitis Question & Answer Sheet

Q.What is West Nile encephalitis?
A.West Nile encephalitis is a mosquito-borne viral disease which can cause an inflammation of the brain. The West Nile virus (WNV) is commonly found in Africa, West Asia, the Middle East and Europe. For the first time in North America, WNV was confirmed to be present in the New York metropolitan area during the summer and fall of 1999.
Q.How do people get West Nile encephalitis and what are the symptoms?
A.WNV is transmitted to people by the bite of a mosquito, primarily the northern house mosquito, Culex pipiens. Most infections are asymptomatic or mild. Symptoms may include: fever, headache, and body aches, often with skin rash and swollen lymph glands. In rare cases, more severe infection may result, with symptoms such as high fever, neck stiffness, stupor, disorientation, coma, tremors, convulsions, muscle weakness, paralysis and, rarely, death.
Q.How is West Nile encephalitis treated?
A.There is no specific therapy. Most individuals recover spontaneously without hospitalization. However, those developing more serious symptoms require hospitalization for supportive therapy.
Q.Is there a vaccine against West Nile encephalitis?
A.No.
Q.What is the incubation period in humans?
A.Usually 5 to 15 days.
Q.What proportion of people die when infected with WNV?
A.Since the majority of infected persons are asymptomatic, the overall fatality rate is much less than 1%. However, for hospitalized patients with encephalitis, case fatality rates may range from 3% to 15%, and are highest in the elderly.
Q. What is the transmission cycle for WNV?
A.Mosquitoes become infected after feeding on infected birds with high levels of virus in the blood. After a period of 10 days to 2 weeks, the mosquitoes can then transmit the virus to humans or other birds and animals when taking a second blood meal. Most birds, which serve as the "intermediate host" for the virus, show no signs of illness from the disease. The disease can only be transmitted by mosquito bite, and not from bird or from birds to people or other animals.
Q.What was the evidence of WNV activity in New Jersey in 1999?
A. WNV was confirmed in 73 crows from 16 counties, as well as in 4 other types of birds, 1 cat, and 2 "specimen pools" of mosquitoes. Crows are particularly susceptible to illness from the WNV and, therefore, can serve as a valuable "sentinel" for the presence of the virus. No human or horse cases of West Nile encephalitis were confirmed in New Jersey in 1999.
Q.Does New Jersey have a plan to detect WNV and prevent human cases in 2000?
A.A multi-agency plan for surveillance and mosquito control has been developed to include the following:

  • Mosquito, bird, horse and human surveillance to detect the presence and location of WNV activity.

  • Comprehensive mosquito surveillance and control in all 21 counties.

  • A coordinated system of reporting and laboratory testing of samples.

  • A communications and public education plan.
Q. What can I do to reduce my risk of becoming infected with WNV?

A.Eliminate stagnant water around the home in discarded tires, blocked gutters, unclean birdbaths, poorly maintained pools, and any type of receptacle with decaying organic matter.

Limit outdoor activities at dawn, dusk and the early evening, when possible.

Wear long-sleeved shirts and long pants whenever you are outdoors. weather permitting.

Make sure screen doors and windows are in good condition.

When going outside, use an insect repellent containing DEET on the skin or clothing, or a repellent containing permethrin on clothing. Insect repellents should not be applied to children less than three years old. Always use a repellent according to the directions on the product label.

Q.Where can I get more information about WNV?
A.The following web sites are a source of additional information: New Jersey Department of Health (www.state.nj.us/health/), Centers for Disease Control and Prevention (www.cdc.gov), and New Jersey Mosquito Homepage (www.njmosquito.org). Local mosquito surveillance and control information is also available from your county mosquito control agency, and specific questions regarding WNV may be addressed to your local health department.


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