Makindo Medical Notes

🦠 Lassa Fever is an acute viral haemorrhagic illness. Most infections are asymptomatic or mild (≈80%), but severe disease can cause haemorrhage, multi-organ failure, and death. An estimated 100,000–300,000 infections occur annually with around 5,000 deaths. Mortality is particularly high in the third trimester of pregnancy.

📍 About

• Zoonotic acute viral illness, spread by the multimammate rat (Mastomys species).
• Endemic in parts of West Africa — Sierra Leone, Liberia, Guinea, Nigeria.
• First described in Lassa, Nigeria (1969).

🧬 Aetiology

• Caused by a single-stranded RNA virus from the Arenaviridae family.
• Reservoir = chronically infected rodents that shed virus in urine/faeces.

🩺 Clinical Features

• Incubation: 1–3 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 (≈1/3 survivors), multi-organ failure.
• Pregnancy: very high mortality, especially in 3rd trimester.

🔬 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 ⚠️ all samples must be processed in high-level containment labs in UK.

🧤 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.

💊 Management

• Ribavirin — 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.

📚 References

• UKHSA: Lassa fever guidance
• CDC: Lassa fever
• WHO: Lassa fever fact sheet