Distribution Of Salmonella Typhi Antibodies In The Sera Of Healthy Blood Donors At Kenyatta National Hospital

Abstract

Background A survey of literature revealed that among infectious diseases, typhoid fever is widespread in Kenya. Widal test is still widely used in the diagnosis of this disease. Interpretation of Widal test depends on knowledge of the baseline titres among healthy population. These titres can be used as cut-off value to arrive at diagnostic titres. The level of normal agglutinins for these organisms varies in different countries and communities, and this variation depends on the degree to which the typhoid is endemic in each area, a factor which may change over time. It has been more than a decade since the Widal titres in apparently healthy population have been assessed. Furthermore, no baseline Widal titres have been assessed in blood donors. Objective To determine the distribution of Salmonella typhi antibodies among healthy blood donors. Study Design Cross-sectional descriptive survey. Methodology Participants in this cross-sectional analysis were voluntary but apparently healthy blood donors at the KNH Blood Transfusion Unit. Consecutive sampling was applied. Consented participants’ demographic data and focused medical history was collected by use of structured pre-tested questionnaires and blood samples were taken for assessment of Widal titres. Data was presented in the form of tables, graphs and histograms. Descriptive inferential statistics such as means, medians, proportions and standard deviation was determined where applicable. Results Among the 353 serum specimens which were tested, 75 (21.25%) sera were found to be positive for the Widal test and 278 were negative. The most frequently recorded titre of the reactive sera was 1:40 for both the anti-O antibodies and the anti-H antibodies which occurred in 49% and 44% of the reactive sera respectively. Conclusion In conclusion, it was found out that about 20% of healthy blood donors had a positive Widal screening test. About 50% of this population had a baseline titre of 1:40 for both the O and H antigen with a significant proportion of blood donors having titres ≥ 1:80. Hence, we recommend the cut off titres of ≥ 1:80 for diagnosis of typhoid fever with the appropriate clinical features.