St. Louis Encephalitis
St. Louis encephalitis virus (SLEV) is a mosquito-borne flavivirus that is
maintained in a cycle between Culex mosquitoes and birds. Prior to
the introduction of West Nile Virus to the United States in 1999, SLE was the
most common mosquito-transmitted pathogen in the U.S. Occasionally,
an infected mosquito will bite a human, causing disease. Symptoms appear 4
to 21 days after the bite of an infected mosquito. Most infections are
unapparent but when symptoms occur they can range from fever with headache to
meningitis, encephalitis, and coma. People over the age of 50 seem to be at
greater risk for severe disease.
Many SLE epidemics have been documented in North America. In 1990,
there were 223 cases in Florida. Since the introduction of WNV, SLEV
activity has decreased dramatically. Research has suggested that WNV
infection may provide some immunity to SLEV.
For mosquito-borne disease prevention tips:
For more information about SLE, see the Centers for Disease Control:
Ottendorfer C, Ambrose J, White G, Unnasch T, Stark L. Isolation of Genotype
V St. Louis Encephalitis Virus in Florida. Emerging Infectious Diseases. 2009;
15(4): 604-606. (158
Fang Y, Reisen W. Previous Infection with West Nile or St. Louis Encephalitis
Viruses provides cross protection during reinfection in house finches. Am
J Trop Med Hyg. 2006; 75(30): 480-485.