On April 22, 2022, the Ministry of Health and Public Hygiene of Guinea declared a Lassa fever outbreak following the laboratory confirmation of two cases from the Guéckédou prefecture in the southeast of Guinea (WHO).

Lassa fever is an animal-borne, or zoonotic, acute viral haemorrhagic illness. It is endemic in parts of West Africa including Sierra Leone, Liberia, Guinea and Nigeria. Neighboring countries are also at risk, as the animal vector for Lassa virus, the “multimammate rat” (Mastomys natalensis) is distributed throughout the region (CDC).

Signs and symptoms of Lassa fever typically occur 1-3 weeks after the patient comes into contact with the virus. For the majority of Lassa fever virus infections (approximately 80%), symptoms are mild and are undiagnosed. Mild symptoms include slight fever, general malaise and weakness, and headache. In 20% of infected individuals, however, disease may progress to more serious symptoms including hemorrhaging (in gums, eyes, or nose, as examples), respiratory distress, repeated vomiting, facial swelling, pain in the chest, back, and abdomen, and shock. Neurological problems have also been described, including hearing loss, tremors, and encephalitis. Death may occur within two weeks after symptom onset due to multi-organ failure (CDC).

• See the CDC's flyer on "What you need to know about Lassa Fever."
• See the CDC's Lassa Fever Factsheet.
• See the WHO's Disease Outbreak News (DONs) for the latest updates on recent outbreaks of Lassa Fever.

Figure: CDC Outbreak Lassa Distribution Map.

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