Abstract
Lassa fever is an acute viral hemorrhagic illness; the virus is endemic in West Africa and also of concern with regard to bioterrorism. Transmission of Lassa virus between humans may occur through direct contact with infected blood or bodily secretions. Oral administration of the antiviral drug ribavirin is often considered for postexposure prophylaxis, but no systematically collected data or uniform guidelines exist for this indication. Furthermore, the relatively low secondary attack rates for Lassa fever, the restriction of the area of endemicity to West Africa, and the infrequency of high-risk exposures make it unlikely that controlled prospective efficacy trials will ever be possible. Recommendations for postexposure use of ribavirin can therefore be made only on the basis of a thorough understanding and logical extrapolation of existing data. Here, we review the pertinent issues and propose guidelines based on extensive review of the literature, as well as our experience in this field. We recommend oral ribavirin postexposure prophylaxis for Lassa fever exclusively for definitive high-risk exposures. These guidelines may also serve for exposure to other hemorrhagic fever viruses susceptible to ribavirin.