Chapter 4 - Lassa Fever

Abstract

Lassa virus is one of more than 25 causative viruses of viral hemorrhagic fever. Lassa fever was first recognized in Nigeria in 1969 and subsequently noted across West Africa. Unlike many viral hemorrhagic fevers, Lassa fever is not a rare disease that emerges only in outbreak form. Yearly infections may number in tens or even hundreds of thousands, with thousands of deaths. There is also concern of Lassa and other hemorrhagic fever viruses being used as bioweapons. Humans are infected through exposure to contaminated excreta of the rodent Mastomys natalensis, which is the natural reservoir, sometimes with secondary transmission between humans via contact with infected bodily fluids. In severe cases, patients progress to vascular instability and hemorrhage, with a case fatality in hospitalized cases of ≈25%. Treatment follows the guidelines for septic shock and as well as the administration of the antiviral drug ribavirin. Patients should be isolated under specialized viral hemorrhagic fever precautions and contacts monitored daily for 3 weeks. Prevention in the community is oriented toward limiting contact with rodents.