Lassa fever is a recently discovered viral infection found in the tropical regions of the world, especially West Africa. This fever is a major public health concern because it is highly contagious and can cause a severe or fatal illness. The rapid spread of the infection has been clearly identified in the case of hospital outbreaks. Treatment is symptomatic (treating the symptoms of high fever, etc.); there is no special 'cure'.
Native rats are the reservoir of the disease but the exact mode of transmission to humans is uncertain. The virus is present in all body fluids of an infected person and persists in the urine for several weeks after recovery.
Epidemics have been recognized in Nigeria, Sierra Leone and Zaire.