CDC answers your questions about ST. LOUIS ENCEPHALITIS
Q. How do people get St. Louis encephalitis?
A. By the bite of a mosquito (primarily the Culex
species) that become infected with St. Louis encephalitis virus (a flavivirus
antigenically related to Japanese encephalitis virus).
Q. What is the basic transmission cycle?
A. Mosquitoes become infected by feeding on birds infected
with the St. Louis encephalitis virus. Infected mosquitoes then transmit the
St. Louis encephalitis virus to humans and animacially in the
aged).
Q. How many cases of St. Louis encephalitis occur in the
U.S.?
A. Since 1964 there have been 4,478 reported human cases of
St. Louis encephalitis, with an average of 128 cases reported annually.
Q. How is St. Louis encephalitis treated?
A. There is no specific therapy. Intensive supportive therapy
is indicated.
Q. Is the disease seasonal in its occurrence?
A. In temperate areas of the United States, St. Louis
encephalitis cases occur primarily in the late summer or early fall. In the
southern United States where the climate is milder St. Louis encephalitis can
occur year round.
Q. Who is at risk for getting St. Louis encephalitis?
A. All residents of areas where active cases have been
identified are at risk of getting St. Louis encephalitis.
Q. Where does St. Louis encephalitis occur?
A. See map:
St. Louis encephalitis outbreaks can occur throughout most of the United
States. The last major epidemic of St. Louis encephalitis occurred in
the
Midwest from 1974-1977. During that outbreak, over 2,500
cases in 35 states were reported to the CDC. Currently, outbreaks of St. Louis
encephalitis have been limited in size (usually <30 cases), although the
potential still exists for epidemic St. Louis encephalitis. The most recent
outbreak of St. Louis encephalitis occurred in New Orleans, Louisiana in 1999,
with 20 reported cases.
Q. Is there a vaccine against St. Louis encephalitis?
A. No.
Q. Where can I get more information on St. Louis
encephalitis?
A. Visit the CDC website on St. Louis encephalitis: http://www.cdc.gov/ncidod/dvbid/arbor/arboinfo.htm
