Antibodies against haemorrhagic fever viruses in Kenya populations.

Human sera from Lodwar (77 sera), Nzoia (841 sera), Masinga (251 sera), Laisamis (174 sera) and the Malindi/Kilifi area (556 sera) in Kenya were tested by indirect immunofluorescence for antibodies against Marburg, Ebola (Zaire and Sudan strains), Congo haemorrhagic fever, Rift Valley fever and Lassa viruses. Antibodies against Ebola virus, particularly the Zaire strain, were detected in all regions and were, over-all, more abundant than antibodies against the other antigens. Ebola and Marburg antibody prevalence rates were highest in the samples from Lodwar and Laisamis, both semi-desert areas. Antibodies against Rift Valley fever virus were also highest in the Lodwar sample followed by Malindi/Kilifi and Laisamis. Congo haemorrhagic fever virus antibodies were rare and no antibodies against Lassa virus were detected in the 1899 sera tested.

Outbreak of botulism in Kenyan nomads.

During disease surveillance in Kenya, a series of deaths were investigated among a group of nomadic Gabra in Marsabit. The cause was identified as botulism (Clostridium botulinum Type A), contracted from sour milk prepared traditionally in a gourd. Reported outbreaks of botulism in Africa would appear to be extremely rare.

Investigations into yellow fever virus and other arboviruses in the northern regions of Kenya.

Previous studies having shown an appreciable level of yellow fever immunity to exist in northern Kenya, further epidemiological and serological surveys were carried out there in 1968 in an attempt to define more clearly the distribution of yellow fever and to locate possible vector and reservoir hosts of the disease; these surveys also provided information on a number of other arboviruses.Altogether 436 sera from 5 areas in northern Kenya were screened by haemagglutination-inhibition tests with 8 antigens, and 107 of these sera by neutralization tests for Group-B arboviruses. Small numbers of yellow-fever-immune adults were found in Ileret, Garissa, Loglogo and Mikona. At Marsabit high proportions of immune adults and children were found among the Burgi tribe. As the Burgi are permanent agricultural workers on Marsabit Mountain, an entomological investigation was made, over 15 000 mosquitos being collected. From these, 13 strains of Pongola virus, 1 strain of Semliki Forest virus and an unidentified virus were isolated, but no yellow fever strains. Aedes africanus and Aedes simpsoni were not found at Marsabit; small numbers of Aedes aegypti were collected biting man. The vector potential of other mosquitos collected (particularly Mansonia africana, which is present throughout the year) is discussed.

Yellow fever immunity surveys in northern Uganda and Kenya and eastern Somalia, 1966-67.

Recent epidemics of yellow fever in eastern Africa have stimulated serological surveys in the Karamoja district of Uganda, the northern frontier district of Kenya and the Giohar district of Somalia. All sera collected in the surveys were screened for group B arbovirus antibody using the HI test. Yellow fever immunity was confirmed by the mouse-protection test.No yellow fever immunity was found in sera collected from a residential tribal group at Karamoja but a small number of samples from persons who had previously lived outside the district showed immunity. Immunity was detected in sera from areas of the Northern Frontier district of Kenya. It is thought that this immunity may, in some areas, have resulted from extensions of the Ethiopian epidemic of 1960-62 into the region, but in another area of the district the immunity seems to have arisen from continuing focal transmission within Kenya. Yellow fever immunity was also detected in Somalia.