infectious diseases
Lassa Fever
Introduction
Lassa fever is an often fatal Overview of Arbovirus, Arenavirus, and Filovirus Infections that occurs mostly in West Africa. It may involve multiple organ systems. Diagnosis is with serologic tests and polymerase chain reaction (PCR). Treatment includes IV Lassa virus is a single-stranded RNA virus in the Arenaviridae family. Lassa fever outbreaks have occurred in Nigeria, Liberia, Guinea, Togo, Benin, Ghana, and Sierra Leone. Cases have been imported to the United States, Germany, Sweden, and the United Kingdom. Although cases can occur at any time of the year in endemic countries, there is a seasonal peak during February to late March. Health care professionals should be prepared for an increased patient load in hospitals, and surveillance should be intensified during that time. The reservoir is the ratsMastomys natalensis,M. erythroleucus, andHylomyscus pamfi.The pygmy mouse (Mus baoulei)has recently been implicated as a reservoir species in West Africa, all of which commonly inhabit houses in Africa. Most human cases result from contamination of food with rodent urine, saliva, or feces, but human-to-human transmission can occur via exposure to the urine, feces, saliva, vomitus, or blood of infected people. Nosocomial human-to-human transmission is common when personal protective equipment is not available or not used. Based on serologic data, indigenous people in endemic areas have a very high rate of infection—much higher than their rate of hospitalization for Lassa fever—suggesting that many infections are mild and self-limited. However, some observational studies of missionaries sent to endemic areas show they have a much higher rate of severe illness and mortality. The Centers for Disease Control and Prevention estimates that about 80% of infected people have mild disease and about 20% have severe, multisystem disease ( Reference ). 