La Crosse Encephalitis Virus Infection: Transmission Dynamics, Neurological Outcomes, and Strategies for Prevention and Treatment

Abstract

La Crosse virus (LACV) is a mosquito-borne orthobunyavirus and a significant cause of pediatric viral encephalitis in North America. First isolated in 1960 from a fatal case of encephalitis in La Crosse, Wisconsin, LACV is maintained in an enzootic cycle between the primary vector, Aedes triseriatus (the eastern treehole mosquito), and small mammal amplifier hosts such as chipmunks and squirrels. The virus possesses a tri-segmented, negative-sense single-stranded RNA genome that encodes structural and non-structural proteins, which facilitate viral replication and potent immune evasion. While the majority of human infections are asymptomatic, LACV can cause severe neuroinvasive disease, primarily in children under 16, presenting as meningoencephalitis with symptoms ranging from fever and headache to seizures, coma, and long-term neurological sequelae. Diagnosis relies on serological assays like IgM ELISA and molecular methods such as RT-PCR. No specific antiviral therapy exists, making management supportive and prevention critical. Preventive strategies focus on public education, personal protection against mosquito bites, and environmental management to reduce mosquito breeding sites. This review provides a detailed examination of LACV's history, virology, replication cycle, pathogenesis, clinical presentation, diagnostic methodologies, and the overarching public health strategies required for its containment. The continued emergence and seasonal recurrence of LACV underscore the necessity for sustained surveillance, vector control, and research into novel therapeutics and vaccines.