Baseline antibody titres against Salmonella typhi in apparently asymptomatic HIV positive individuals

BackgroundEnteric fever is common in tropical regions and is caused by Salmonella enterica serotype typhi (S typhi). For diagnosis of enteric fever, the Widal test is the most widely used test after blood culture. In HIV infected individuals false positive and false negative Widal reactions are common. The result is variable titres and baseline titres that are unusual in this patient population. AimsThis study was done to determine the baseline antibody titres for S typhi among HIV infected individuals.MethodAverage baseline antibody titres against O and H antigens of S typhi were measured by standard Widal test in 200 HIV positive asymptomatic individuals, as well as 200 age and sex-matched controls. The results were compiled and statistically analysed.ResultsA total of 84 (42%) of the cases had an H antibody titre of >1:20 and 105 (52.5%) had a titre of >1:20 against O antigen. This implies that positive titre of H and O antigen is significantly associated with HIV positive cases with