Anti-typhoid agglutinins in school aged African children

Abstract

Objectives: To determine baseline antibody responses to H and O antigens of Salmonella typhi and Salmonella paratyphi (A, B and C) in school aged Nigerian children. Design: Cross-sectional study involving 175 children. Using both rapid slide and tube agglutination techniques in dilutions of sera (1:20 to 1:320), agglutination reactions with various antigens were determined. Setting: Community based study involving primary school pupils in Benin City. Subjects: Apparently healthy school children (5-16 years) selected systematically, using multistage sampling technique. Results: No subject demonstrated agglutination to any of antigens al 1: 320 dilution. Two (1.1%), 26 (14.9%), 85 (33.1%) and 51 (29.1%) pupils respectively had reactions to either antigens of Salmonella typhi at dilutions of 1:160, 1:80, 1:40 and 1:20. At 1:40 dilution 1 (0.6%) and 3 (2.3%) each had reactions to HB, OB and HC respectively. Sixteen per cent had reactions at higher dilutions of ≥1:80 and this occurred more significantly in older children (xy2 = 15.50; p<0.001), those with low maternal socio-economic status (xy2 = 22.06, p<0.001), those from poor apartments (x2 = 4.49; p<0.05) and those who used predominantly none pipe-borne water (x2 = 5.40; p<0.02). Against OD and HD, about 50.0% seroconverted at 1:40 dilution with antibodies against H being more prevalent. Conclusion: Interpretation of single widal reaction in endemic areas must take into cognisance age, clinical and socio-cultural characteristics of the child.