O'nyong-nyong fever: a neglected mosquito-borne viral disease.

O'nyong nyong virus (ONNV), a mosquito-borne Alphavirus, is primarily transmitted through the bite of Anopheles funestus and Anopheles gambiae mosquitoes, which are also malaria parasite vectors in Africa. The virus, first isolated in Uganda in 1959, is endemic in sub-Saharan Africa and has caused several major outbreaks both in West and East Africa. ONNV fever, characterized by severe arthralgia, is similar to chikungunya fever, with the exception of cervical lymphadenitis, which is peculiar to the former. Prevention measures do not differ from those adopted against malaria parasite transmission. Effective vaccines and drugs are not available, but animal models suggest that vaccine candidates against CHIKV may also confer protection against ONNV.