An overview of Lassa fever

Lassa fever is a viral hemorrhagic fever caused by Lassa virus (Lassa mammarenavirus), a negative-sense singlestranded RNA virus of the Arenaviridae family.[1][2] In most cases Lassa virus infection is asymptomatic (presenting no symptom).[1] When symptomatic it is characterized by mild acute febrile disease to a chronic fatal disease with severe toxaemia, capillary leak, hemorrhagic situations, shock and multiple organ failure.[3] Early diagnosis of Lassa fever is very important because of the transmissibility of infection, the need for potent isolation of infected persons and for containing potentially infectious specimens during laboratory testing.[4][5] Lassa fever was first elucidated in the 1950s, but the virus was not recognized until 1969 when it infected two missionary nurses in Lassa Village, Borno State, Northeastern Nigeria.[1] Natal multimammate rat or common African rat of Mastomys genus are the reservoir of Lassa virus.[1] When the rodents become infected with Lassa virus, they infect humans through their urine and faeces, but remain unharmed.[6] Because of its similarities with other febrile diseases such as malaria, typhoid, Ebola hemorrhagic fever, early detection is difficult. Thus when persons have persistent fever not responding to normal conventional therapies, they should be screened for other possible causes (especially in endemic regions). When the presence of Lassa fever is established in a community, immediate isolation of infected individuals, screening, standard infection prevention and control practices and meticulous contact tracing can halt outbreaks.[1] Treatment involves supportive measures and early use of the antiviral drug ribavirin. Note: This article has been updated since its initial publication on 15 Jun 2019 (summary of changes). The previous version is archived at this link as a record.