๐ฆ Lassa Fever is an acute viral haemorrhagic illness. Most infections are asymptomatic or mild (โ80%),
but severe disease can cause haemorrhage, multi-organ failure, and death. An estimated 100,000โ300,000 infections
occur annually with around 5,000 deaths. Mortality is particularly high in the third trimester of pregnancy.
๐ About
- Zoonotic acute viral illness, spread by the multimammate rat (Mastomys species).
- Endemic in parts of West Africa โ Sierra Leone, Liberia, Guinea, Nigeria.
- First described in Lassa, Nigeria (1969).
๐งฌ Aetiology
- Caused by a single-stranded RNA virus from the Arenaviridae family.
- Reservoir = chronically infected rodents that shed virus in urine/faeces.
๐ฉบ Clinical Features
- Incubation: 1โ3 weeks post exposure.
- Mild disease: fever, malaise, weakness, headache.
- Severe disease: haemorrhage (gums, eyes, nose), chest/abdominal pain, facial swelling, shock.
- Complications: encephalitis, tremor, deafness (โ1/3 survivors), multi-organ failure.
- Pregnancy: very high mortality, especially in 3rd trimester.
๐ฌ Investigations
- ELISA for IgM/IgG and Lassa antigen.
- RT-PCR in the early acute phase (diagnostic gold standard).
- Supportive labs: FBC, U&E, LFTs; but โ ๏ธ all samples must be processed in high-level containment labs in UK.
๐งค Infection Control
- Isolate immediately in a negative pressure room if suspected.
- Strict PPE: gowns, gloves, goggles, masks/respirators.
- Decontamination: sterilise equipment, dispose of contaminated materials safely.
๐ Management
- Ribavirin โ effective if given early in disease course.
- Supportive care: fluid/electrolyte balance, oxygenation, BP support, treat coinfections.
- Prevention: rodent control, rodent-proof food storage, hygiene in endemic areas.
๐ References