1975 — St. Louis Encephalitis outbreak, IL (47), also MS (13) — 60

Illinois:
–47 IL Department of Public Health. 27 Years Ago In IDPH History. Accessed 9-14-2016.

Mississippi:
–13 CDC Wonder. Compressed Mortality, 1968-1975. St. Louis Encephalitis search (ICD-8 062.3)

CDC: “St. Louis encephalitis (SLE) virus is spread to people by the bite of an infected mosquito. Most people infected with SLE virus do not have symptoms. Those people who do become ill may experience fever, headache, nausea, vomiting, and tiredness. Some people may develop neuro-invasive 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. There are no vaccines to prevent or medicines to treat SLE. You can reduce your risk of infection with SLE virus by using insect repellent, wearing long-sleeved shirts and long pants, and taking steps to control mosquitoes indoors and outdoors.”

“Transmission: St. Louis encephalitis (SLE) virus is spread to people through the bite of an infected mosquito. Mosquitoes become infected when they feed on birds that have the virus in their blood.

“Birds that live in urban-suburban areas, such as the house sparrow, pigeon, blue jay, and robin, are common SLE virus hosts. The principal vectors are Culex species mosquitoes, including Cx. pipiens and Cx. quinquefasciatus in Eastern states, Cx. nigripalpus in Florida, and Cx. tarsalis and members of the Cx. pipiens complex in Western states.

“People do not develop high enough levels of the virus in their blood to infect mosquitoes. As a result, people are considered “dead-end” hosts for SLE virus. However, the levels of SLE virus in people’s blood is enough to spread the infection through blood transfusions, though this very rarely occurs.

Illinois Dept. of PH: “Illinois suffered the nation’s worst epidemic of St. Louis encephalitis in 1975, resulting in 578 cases and 47 deaths. It was the first major outbreak of a mosquito-borne disease in the state since 1930, when malaria sickened more than 300 Illinoisans.”

Source

Illinois Department of Public Health. 27 Years Ago In IDPH History. Accessed 9-14-2016 at: http://www.idph.state.il.us/webhistory14.htm

Centers for Disease Control and Prevention, National Center for Health Statistics. Compressed Mortality File 1968-1978. CDC WONDER Online Database. Accessed at http://wonder.cdc.gov/cmf-icd8.html on Dec 15, 2021 8:50:41 PM

Centers for Disease Control and Prevention. “St. Louis Encephalitis.” (Webpage). Accessed 12-15-2021 at: https://www.cdc.gov/sle/index.html