What is the mortality rate of Lassa fever?

The overall case fatality rate (CFR) is approximately 1%, reflecting the high proportion of mild or asymptomatic cases. In hospitalised patients — who represent the severe end of the spectrum — the CFR rises to 15-25%. Lassa fever accounts for an estimated 5,000 deaths per year across West Africa. Pregnant women in the third trimester face especially high risk: foetal mortality approaches 80%, and maternal mortality is also significantly elevated.