In Shelby County, the public health focus centers on several specific viruses transmitted by local mosquito species. While many infections remain asymptomatic, the risk for severe neurological complications persists for vulnerable populations.
West Nile Virus (WNV): This remains the most prevalent mosquito-borne threat in the Memphis area. Transmitted primarily by Culex mosquitoes, WNV activity is monitored through “mosquito pools” (groups of trapped mosquitoes) and reported human cases. As of April 2026, Shelby County has already recorded its first human case of the year, following a trend of early-season activity linked to milder winters.
St. Louis Encephalitis (SLEV): Historically present in the Mid-South, SLEV often mirrors the transmission patterns of West Nile. While less frequent, health officials monitor for this virus as it shares the same Culex vectors that thrive in urban and suburban drainage systems.
La Crosse Encephalitis (LACV): Though more common in East Tennesseeâs Appalachian region, the Aedes triseriatus (Eastern Treehole Mosquito) carries this risk into wooded suburban pockets of Memphis and Germantown. This virus is of particular concern for pediatric populations, as it is a leading cause of viral encephalitis in children.
Travel-Related Viruses: Due to Memphis being a major transportation hub (FedEx Superhub and Memphis International Airport), there is a consistent secondary risk of “imported” cases of Zika, Dengue, and Chikungunya from travelers returning from tropical climates.
The Mississippi River Basin: The vast network of wetlands and tributaries provides a natural breeding ground for “floodwater” mosquitoes, which, while often just a nuisance, can drive overall population density.
Urban Infrastructure: In older Memphis neighborhoods, aging drainage systems and combined sewers provide stagnant, organic-rich waterâthe preferred breeding environment for the Culex mosquitoes responsible for West Nile Virus.
The Wolf River Greenway: The integration of wooded corridors and walking trails within residential zones increases the “edge effect,” where humans are more likely to come into contact with woodland species like Aedes albopictus (Asian Tiger Mosquito).
