1997 - O'nyong-nyong (ONN) fever in Uganda
12 March 1997
Disease Outbreak Reported
In June 1997, health officials in Rakai district in south western Uganda noticed an increased number of cases of an acute febrile illness with crippling arthritis, skin rash, and lymphadenopathies. The disease spread into the neighbouring Mbarara and Masaka districts of Uganda. No fatal cases were reported. Viruses isolated by the Uganda Virus Research Institute (UVRI) were forwarded to the Centers for Disease Control and Prevention in Fort Collins, Colorado, USA where sequence analysis confirmed ONN virus. One serum sample yielded a virus at CDC, and IgM antibody to ONN was detected in additional samples, indicating recent infection. A joint team from CDC, UVRI, the Ugandan Ministry of Health, the Kenya Medical Research Institute, Makarere University, and WHO conducted an epidemiological survey from January to February 1997 and confirmed continuing transmission of ONN fever in south western Uganda.
An epidemic of ONN fever was last reported in Uganda during 1959-1962. The epidemic started in the northern part of the country and spread south and east into Kenya, Tanzania, and Zambia affecting an estimated 2 million people.