Question 1

What is Lassa fever?

Accepted Answer

Lassa fever is an acute viral haemorrhagic illness caused by Lassa virus — an arenavirus transmitted from infected Mastomys rodents to humans, endemic in West Africa. Approximately 80% of Lassa infections are mild or asymptomatic; approximately 20% progress to severe disease with haemorrhagic manifestations, multi-organ failure and — without treatment — 15-25% case fatality in hospitalised patients. Nigeria reports the highest burden — thousands of cases annually.

Question 2

How is Lassa transmitted?

Accepted Answer

From rodents to humans: through direct contact with infected Mastomys urine or faeces (contaminating food, household surfaces); inhalation of aerosols from rodent excreta; and eating infected rodents (common in West Africa). Person-to-person: through direct contact with blood, bodily secretions or organs of infected individuals — primarily in healthcare settings without adequate PPE and in households caring for sick family members. Sexual transmission has been reported (virus persists in semen for up to 3 months after recovery).

Question 3

What are the symptoms?

Accepted Answer

Onset is gradual: fever, fatigue, headache, myalgia, sore throat — mimicking influenza, malaria, typhoid or dengue (the great mimickers). Approximately 80% remain mild. Severe disease develops in approximately 20%: haemorrhagic manifestations (petechiae, bleeding from mucous membranes, GI bleeding); pleural and pericardial effusions; facial oedema; proteinuria; encephalopathy; and septic shock. A key clinical sign: "white exudate on pharynx" — not typical of viral pharyngitis — suggests Lassa. A characteristic feature: the sudden onset of sensorineural deafness during recovery.

Question 4

Why is Lassa a WHO R&D Blueprint priority?

Accepted Answer

Lassa is on the WHO R&D Blueprint (priority pathogen list for emergency research) because: large burden in West Africa (100,000-300,000 cases/year) severely underestimated; no approved vaccine; limited treatment (ribavirin effective only if given within 6 days); high case fatality in hospitalised patients; healthcare worker risk; pandemic potential (imported cases globally); and its occurrence in a ring of countries experiencing frequent outbreaks. The Blueprint designation drives research investment and emergency use authorisation pathways.

Question 5

How is Lassa treated?

Accepted Answer

Ribavirin (IV — 10-day course): significantly reduces mortality when given within 6 days of symptom onset, reducing CFR from approximately 15-25% to approximately 5%. Beyond day 6, benefit is less clear. Supportive care: IV fluids (careful management — Lassa patients are at risk of pulmonary oedema); treatment of electrolyte imbalances; management of secondary infections. No specific antiviral beyond ribavirin is approved. Strict infection prevention measures are essential for healthcare workers.

Question 6

What makes Lassa so dangerous in pregnancy?

Accepted Answer

Lassa fever in pregnancy carries devastating outcomes: maternal CFR of 20-30% in severe disease; fetal/neonatal mortality approaches 100% in severe maternal disease (from placental virus replication and direct fetal infection). Uterine evacuation (delivery or termination) appears to improve maternal outcome in severe late-stage disease — a recommendation that creates profound ethical challenges. Pregnant women are therefore the highest-priority group for access to early ribavirin treatment and potential future Lassa vaccination.

Question 7

What are vaccines in development?

Accepted Answer

Multiple Lassa vaccine candidates are in clinical development: rVSV-LASV (recombinant vesicular stomatitis virus — similar approach to rVSV-ZEBOV for Ebola); GEO-LM01 (DNA/protein subunit); MVA-LASV (modified vaccinia Ankara vector); and mRNA vaccines (CEPI-funded). The challenge: Lassa has multiple lineages (I-VII) across different West African countries — requiring broad cross-lineage protection. CEPI committed approximately $120M for Lassa vaccine development by 2022. No vaccine has yet completed Phase 3 trials.

Question 8

What is the Lassa hearing loss burden?

Accepted Answer

Sensorineural hearing loss is the most common complication of Lassa fever — occurring in approximately 25-30% of clinical cases (all severity levels, including mild). It is often sudden-onset, bilateral, and permanent — caused by immune-mediated cochlear damage during the immune response to infection. Lassa fever is estimated to be responsible for 30,000-50,000 new cases of profound deafness per year in West Africa, making it the leading infectious cause of acquired hearing loss on the continent.

Question 9

How does GMJ News cover Lassa fever?

Accepted Answer

GMJ News covers WHO Lassa situation reports, Nigeria outbreak data, ribavirin access, vaccine development and the rodent reservoir. Lassa fever is part of the GMJ's global VHF and pandemic preparedness coverage — directly relevant to PHIG's health security surveillance and the Georgian Medical Journal.

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