Lassa Virus

Lassa virus (LASV), a member of the Arenaviridae family, is a zoonotic pathogen responsible for Lassa fever, a haemorrhagic disease endemic to West Africa. First identified in Nigeria in 1969, LASV has since been classified as an Old-World arenavirus with unique virological and epidemiological characteristics. The virus is maintained in rodent reservoirs, primarily Mastomys natalensis , and spreads to humans through direct contact with contaminated excreta or via human-to-human transmission. Endemic regions, including Nigeria, Sierra Leone, Guinea, and Liberia, report thousands of infections annually, with case fatality rates reaching up to 20% in severe cases. Survivors often suffer long-term complications such as hearing loss. The virology of LASV reveals a bisegmented RNA genome with ambisense coding, encoding essential viral proteins involved in replication, immune evasion, and pathogenicity. Its transmission cycle and replication mechanisms contribute to its high infectivity, particularly in healthcare settings. Diagnosis remains a challenge due to overlapping symptoms with other haemorrhagic fevers, but molecular methods such as reverse transcription polymerase chain reaction have improved detection. Despite advances in antiviral treatments like ribavirin, effective therapy remains limited. Vaccine development efforts are ongoing, with several candidates in clinical trials. Public health measures, including rodent control and community education, play a crucial role in prevention. Given the potential for regional and global spread, Lassa fever remains a significant public health threat. This chapter explores the latest advancements in LASV research, diagnosis, treatment, and prevention, highlighting critical gaps and future directions for improved disease control and eradication efforts.