Agglutinins for brucellae antigens in blood sera of an urban and rural population in Kenya.

The antibody titres for Brucella arbotus and Br. melitensis in 364 sera from healthy individuals in Nairobi and Naivasha are presented. A majority (96%) had no detectable agglutinins. Reactivity was markedly higher in the Naivasha serum samples, than in those from Nairobi. In Naivasha, seven per cent showed reactivity, whereas in Nairobi a larger majority (98%), showed no reactivity, with antibody titres ranging from 1:20-1:160. Age and sex were found to have no effect on antibody titre distribution in the two populations. The presence of brucellae antibodies in the healthy population screened (with titres upto 1:80) may be due to exposure to brucellae antigens, rather than denoting brucellosis, this titre could therefore be taken as the baseline in the healthy Kenyan population.

Salmonella typhi and Salmonella paratyphi antibodies in Kenya.

The distribution of Salmonella typhi, S. paratyphi A. and S. paratyphi C. agglutinins among 364 sera from a randomly selected group of healthy individuals in Nairobi and Naivasha (Kenya) were analysed in relation to bacteriologically confirmed cases of typhoid fever at the Kenyatta National Hospital (KNH). Out of these, 30% of the healthy individuals had no detectable Widal titres. Overall agglutinin titres obtained for the healthy population showed that 96% of the individuals had low level reactivity with titres < 1:80 for both H and O antigens of S. typhi, while 4% had titres of 1:160 or above. Agglutinins for S. paratyphi A and C were rarely present in the sera tested. Age and sex were found to have no effect on antibody titre distribution in the two populations but differences in the water source may have affected the percentage of positive tests recorded. In this typhoid endemic region titres upto 1:80 are not uncommon but both H and O titres of 1:160 and above found in conjunction with the clinical picture may be taken to be suggestive of typhoid fever.