L — Lassa Fever Virus
Lassa fever is an acute viral haemorrhagic illness caused by the Lassa virus, which is endemic in West Africa, particularly in countries such as Nigeria, Sierra Leone, Liberia, and Guinea. The clinical significance of Lassa fever lies in its high morbidity and potential mortality, especially in hospitalized patients where case fatality rates can reach 15–20%. The disease is transmitted primarily through contact with food or household items contaminated with urine or faeces of infected Mastomys rats, although person-to-person transmission can occur in healthcare settings.
Clinically, Lassa fever presents with a wide range of symptoms, making diagnosis difficult. Early symptoms include fever, malaise, sore throat, and headache, which can progress to vomiting, chest pain, haemorrhage, and in severe cases, multi-organ failure. One of the most significant complications is sensorineural hearing loss, which occurs in a substantial proportion of survivors and can be permanent. Early treatment with ribavirin has been shown to reduce mortality if administered in the early stages of infection, highlighting the importance of rapid diagnosis and clinical awareness.
Lassa virus is an enveloped, single-stranded, negative-sense RNA virus belonging to the Arenaviridae family. Its genome is bi-segmented, consisting of a small (S) segment and a large (L) segment, which encode viral proteins through an ambisense coding strategy. The S segment encodes the nucleoprotein (NP) and glycoprotein precursor (GPC), while the L segment encodes the RNA-dependent RNA polymerase and matrix protein (Z). The nucleoprotein plays a key role in immune evasion by suppressing the host interferon response, allowing the virus to replicate efficiently within host cells. Viral entry occurs via receptor-mediated endocytosis, commonly using alpha-dystroglycan as a cellular receptor.
Lassa fever is an acute viral haemorrhagic illness caused by the Lassa virus, which is endemic in West Africa, particularly in countries such as Nigeria, Sierra Leone, Liberia, and Guinea. The clinical significance of Lassa fever lies in its high morbidity and potential mortality, especially in hospitalized patients where case fatality rates can reach 15–20%. The disease is transmitted primarily through contact with food or household items contaminated with urine or faeces of infected Mastomys rats, although person-to-person transmission can occur in healthcare settings.
Clinically, Lassa fever presents with a wide range of symptoms, making diagnosis difficult. Early symptoms include fever, malaise, sore throat, and headache, which can progress to vomiting, chest pain, haemorrhage, and in severe cases, multi-organ failure. One of the most significant complications is sensorineural hearing loss, which occurs in a substantial proportion of survivors and can be permanent. Early treatment with ribavirin has been shown to reduce mortality if administered in the early stages of infection, highlighting the importance of rapid diagnosis and clinical awareness.
Lassa virus is an enveloped, single-stranded, negative-sense RNA virus belonging to the Arenaviridae family. Its genome is bi-segmented, consisting of a small (S) segment and a large (L) segment, which encode viral proteins through an ambisense coding strategy. The S segment encodes the nucleoprotein (NP) and glycoprotein precursor (GPC), while the L segment encodes the RNA-dependent RNA polymerase and matrix protein (Z). The nucleoprotein plays a key role in immune evasion by suppressing the host interferon response, allowing the virus to replicate efficiently within host cells. Viral entry occurs via receptor-mediated endocytosis, commonly using alpha-dystroglycan as a cellular receptor.