The Distribution of Anti-salmonella Antibodies in the Sera of Healthy Blood Donors in Baquba city

Abstract

Background: Misuse and interpretation of the Widal test for the laboratory diagnosis of typhoid fever usually result in over diagnosis of the disease particularly in endemic areas which lack standard baseline anti-salmonella antibody titer for healthy individuals.Aim of study: to determine the baseline anti-salmonella antibody titer in healthy individual in Baquba city, and to evaluate the widal tube agglutination test in the diagnosis of clinically suspected typhoid fever.Subjects and methods: one hundred and twenty three apparently healthy blood donors and 127 clinically suspected patients as having typhoid fever were enrolled in this study. The Widal test was done using tube agglutination on serially diluted sera. Data were statistically analyzed.Results: The baseline anti-(O) antibody titer of S. typhi, S. paratyphi A,B, and C in healthy blood donors were 1:160, 1:160, 1:160 and 1:80 respectively. While the baseline anti-(H) antibody titer of S. typhi, S. paratyphi A,B, and C were 1:640, 1:640, 1:320 and 1:80 respectively. The mean anti-(O) and anti-(H) of S. typhi and S.paratyphi A, B was significantly higher in patients compared to healthy controls. According to baseline anti-salmonella antibody titer in healthy blood donors, a total of 89 (70%) of typhoid fever patients were positive by Widal test. 34(26.8%), 15 (11.8%), 26(20.5%) and 14(11%) had S. typhi, S. paratyphi A, B, and C respectively.Conclusion: pre-knowledge of baseline anti-salmonella antibody titer of healthy individuals in a community may improve the efficacy of Widal tube agglutination test in laboratory diagnosis of clinically suspected typhoid fever in an endemic area.Key words: typhoid fever, Widal test, Salmonellosis.