SLE appears in epidemic form at intervals of approximately 10 years. The last outbreak in Memphis occurred in 1975, with 62 reported cases and 12 fatalities. To date, no cases have been reported in Memphis and Shelby County in over 20 years.
Since 1968, the Memphis and Shelby County Health Department's Mosquito Control Program has been actively involved in SLE surveillance by measuring antibodies to the virus in the blood of wild birds and chickens. These animals serve as a reservoir for the St. Louis encephalitis virus. Positive antibody testing serves as an early warning signal.
Although mosquito control is an important means of decreasing transmission of SLE to humans, personal protective measures are also important. Individuals can help by flushing any standing water in birdbaths, small wading pools, and pets' water bowls, and by adding fresh water daily. This will decrease the potential for mosquito breeding sites.
Although the majority of the cases reported during the outbreak were older adults, young children should not be considered low-risk, since they are a target population by being outdoors frequently.