LASSA HEMORRHAGIC FEVER - A severe form of epidemic fever first identified in Lassa, Nigeria. It is caused by the Lassa virus, a member of Arenaviridae. The illness is characterized by high fever, sore throat, muscle aches, skin rash (with hemorrhages), headache, abdominal pain, vomiting, and diarrhea. A rat serves as a reservoir for the illness, but person to person transmission is also reported.