Large scale irrigation and arbovirus epidemiology, Kano Plain, Kenya. II. Preliminary serological survey.

Abstract

1,844 of 4,109 sera collected from children in 26 schools on the Kano Plain, Nyanzo Province, Kenya during May and June 1969 were tested for antibodies to a variety of arboviruses. Over 60% of the children had HI antibodies against both Chikungunya and O'nyong-nyong viruses and 45% had antibody levels of 1 : 160 or greater against O'nyong-nyong suggesting recent infection with this virus. 35% of children aged less than 6 years had O'nyong-nyong virus antibodies and O'nyong-nyong was probably the virus responsible for most of the group A virus antibody. The average annual probability of infection with O'nyong-nyong virus was calculated at 9·6% and the virus is probably endemic in the area. Very few sera were found with group B virus antibodies but West Nile and probably Zika virus is thought to be endemic at a low level. Bunyarnwera group viruses are active in the area and Bwamba virus also appears to be endemic. Nyando virus antibodies were found in a considerable number of children aged 10 years or older and an epidemic probably occurred some 10–15 years previously; but there is no evidence that transmission is active at present.