Evaluation of the Widal tube agglutination test for the diagnosis of typhoid fever among children admitted to a rural hdospital in Tanzania and a comparison with previous studies
1 International Vaccine Institute, Seoul, Korea
2 National Institute for Medical Research - Amani Centre, Tanga, Tanzania
3 Joint Malaria Program, Tanga, Tanzania
4 Teule Hospital, Muheza, Tanga, Tanzania
5 Mahidol Oxford Research Unit, Bangkok, Thailand
6 Public Health Laboratory (Pemba) - Ivo de Carneri, Chake Chake, Tanzania
7 London School of Hygiene and Tropical Medicine, Keppel St, London, UK
8 University of Vienna, Biocenter, Vienna, Austria
BMC Infectious Diseases 2010, 10:180 doi:10.1186/1471-2334-10-180Published: 22 June 2010
The diagnosis of typhoid fever is confirmed by culture of Salmonella enterica serotype Typhi (S. typhi). However, a more rapid, simpler, and cheaper diagnostic method would be very useful especially in developing countries. The Widal test is widely used in Africa but little information exists about its reliability.
We assessed the performance of the Widal tube agglutination test among febrile hospitalized Tanzanian children. We calculated the sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of various anti-TH and -TO titers using culture-confirmed typhoid fever cases as the "true positives" and all other febrile children with blood culture negative for S. typhi as the "true negatives."
We found that 16 (1%) of 1,680 children had culture-proven typhoid fever. A single anti-TH titer of 1:80 and higher was the optimal indicator of typhoid fever. This had a sensitivity of 75%, specificity of 98%, NPV of 100%, but PPV was only 26%. We compared our main findings with those from previous studies.
Among febrile hospitalized Tanzanian children with a low prevalence of typhoid fever, a Widal titer of ≥ 1:80 performed well in terms of sensitivity, specificity, and NPV. However a test with improved PPV that is similarly easy to apply and cost-efficient is desirable.