The normal titre range of widal and brucella agglutination tests in a cross section of the human population in Nairobi and Naivasha

Abstract

A survey of the literature revealed that among infectious diseases, typhoid fever and brucellosis are widespread in Kenya; the Widal's and Brucella agglutination tests are still widely used in the diagnosis of these diseases respectively, and that no comprehensive studies had been carried out to establish what constitutes the ''l101"1l1al'' and "abnormal" antibody levels in healthy, unvaccinated persons from different localities in Kenya. A total of 377 samples of blood were taken from a cross-section of the Kenyan populatio~ residing in Nairobi and Naivasha, but of these 364 (97 %) were from healthy, unvaccinated individuals including those in contact with dairy animals, while the rest (13) were from bacteriologically proven typhoid cases diagnosed at the Kenyatta National Hospital. The serum samples were diluted between 1:20 and 1:2560 and then subjected to the Widal's test for antibodies against S.typhi,-the related paratyphi A and C and Brucella abortus .-;and Br.melitensis according to standard (l~a.X procedures (Protell et aI., 1971) using Wellcome reagents. Results showed that a significant percentage (66 %) of the healthy, unvaccinated individuals had low level reactivity to typhoid antigens whereas 30% showed no reactivity. High levels of reactivity were however rare. Overall agglutinin titres obtained for the healthy population showed that 96% of the individuals had titres 1:80 for both Hand 0 antigens of S. typhi and only 4% had titres of 1:160. A higher frequency of reactivity was observed