ABSTRACT
In early 1959, large numbers of people in the Acholi region of northwestern Uganda were noted to be falling ill with disease characterized by fever, severe back and joint pain, lymphadenopathy, and an itchy rash. Locally, the disease was known as o’nyong-nyong, meaning very painful and weak. By the time the epidemic died out more than 3 years later, it is estimated that more than 2 million people had been infected with o’nyong-nyong virus, with evidence of infection being found as far south as Mozambique and as far west as Senegal. A single strain of o’nyong-nyong virus was recovered from a pool of An. funestus collected in 1978 in western Kenya, following a period of several years during which no evidence of virus activity could be detected. The Alphavirus genus of the family Togaviridae, of which o’nyong-nyong virus is a member, consists of 26 serologically related members, all but one of which are transmitted by mosquitoes.
