Lassa fever

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Type: Viral

Geography: West Africa

Cases Per Year: 400,000

Fatality Rate: 1%

First Discovered: 1969 in Lassa, Nigeria by Jordi Casals

Lassa fever is an animal-borne illness that is transmitted to humans via contact with food or household items contaminated with urine of feces of the multimammate rat.

Signs and symptoms typically occur 1 to 3 weeks after the patient is infected. Only about 20% of infected individuals experience symptoms, which include hemorrhaging, respiratory distress, vomiting, facial swelling, pain in the chest and abdomen, tremors, and temporary or permanent hearing loss. Death may occur within two weeks after symptom onset due to multi-organ failure.

Photo: Lassa fever virus – Electron micrograph

Pregnant women in the third trimester who become infected see particularly high death rates, and spontaneous miscarriage is a serious complication of infection, at about 95%.