St. Louis encephalitis (SLE) virus is a mosquito-borne flavivirus that is maintained in a cycle between Culex mosquitoes and birds.
Prior to the introduction of West Nile in 1999, SLE was the most common mosquito-transmitted pathogen in the U.S.
Since the introduction of West Nile virus, St. Louis encephalitis activity has decreased dramatically. Research has suggested that West Nile virus infection may provide some immunity to SLE in birds.
Disease Prevention
Learn about steps that can be taken to help prevent mosquito and tick bites and ways to maximize protection against vector-borne illnesses.
Transmission
St. Louis encephalitis virus is spread to people by the bite of an infected mosquito.
Symptoms
Most people infected with St. Louis encephalitis virus do not have symptoms. Those people who do become ill may experience fever, headache, nausea, vomiting, and tiredness.
Some people may develop neuroinvasive disease, such as encephalitis (inflammation of the brain) or meningitis (inflammation of the membranes that surround the brain and spinal cord). In rare cases, long-term disability or death can occur.
Individuals at Increased Risk of Severe Illness
People over the age of 50 seem to be at greater risk for severe disease.
Treatment
There is currently no therapeutic treatment for SLE. Current methods consist primarily of symptom treatment and supportive care.
Surveillance and Data
Information for Health Care Providers
Disease Reporting Requirement
All practitioners, health care facilities, and laboratories in Florida are required to notify the Florida Department of Health of diseases or conditions of public health significance under section 381.0031, Florida Statutes, and Chapter 64D-3, Florida Administrative Code.