The o’nyong’nyong virus (ONNV) is a togavirus, closely related to chikungunya and Igbo Ora viruses. The name comes from the Nilotic language of Uganda and Sudan and means “weakening of the joints”. The virus can infect humans and may cause disease. ONNV is transmitted by bites from an infected mosquito.
There have been two epidemics of o’nyong’nyong fever. The first occurred from 1959 to 1962, spreading from Uganda to Kenya, Tanzania, Zaire (Democratic Republic of the Congo), Malawi and Mozambique. The second epidemic in 1996–1997 was confined to Uganda. In 2013, ONNV was confirmed as the cause of disease in a 60-year-old German woman who became infected while traveling in East Africa. Frequent minor outbreaks occur.
Common symptoms of infection with the virus are polyarthritis, rash and fever. Other symptoms include eye pain, chest pain, lymphadenitis and lethargy. The disease is self-limiting. No fatalities due to infection are known.