Lassa Fever

Abstract

Abstract This chapter discusses Lassa fever virus in detail. Lassa fever virus was first recognized in West Africa in 1969, but it has likely existed in that region for much longer. Lassa fever virus causes persistent infection in its natural rodent host, that is, a long-term infection that does not directly kill. The rodent host carries these viruses in its blood and passes them in its urine and feces. It is by contact with such excretions from the rodent that humans become infected. The rodent-to-human transmission is augmented by human-to-human transmission, which spreads the viruses via contaminated blood, excreta, or saliva. After the virus enters its host, a 4- to 12-day incubation period passes; then the symptoms of disease suddenly begin. Usually, a flu-like syndrome of fever, chills, and malaise with muscle and headaches is followed by abdominal pain, nausea, and vomiting. The terminal stage adds poor coagulation, increased vascular permeability, hemorrhage, and neurologic symptoms. Those progressing to death have extremely large amounts of virus in their blood. Currently, a very modest amount of research is under way in the West African countries where Lassa fever virus is endemic.