Widal test case study in Togo: Proposition for a rational use

摘要

The Widal test is still being used in Togo and the results are labelled “positive” even for only one agglutinin without titration. As a result of that, more and more people claim to have typhoid fever while the clinical state is not suggestive and no bacteriological test is performed. We discuss here the results of 200 patients seen in routine laboratories from November 2005 to April 2006. The agglutinin TO, TH, AO, AH, BO, BH, CO, CH were tested in tube and the titre determined for any positive agglutination. We have put together the result of all the agglutinins to have a complete serological profile toward the pathologic?Salmonella?. Malaria test was performed and the clinical status of the patient checked. Only 3 patients (1.5%) had the serological profile of an infection toSalmonella typhi, 154 patients had a clear negative profile and 42 patients had an intermediate profile. The 42 intermediate profiles are subjects to interpretation. The various hypotheses to explore were a serological scar of an old infection, a headed infection due to an early antibiotherapy, a cross reaction to?Salmonella?with another germ having a common antigen O. When the patient was positive to malaria test, the most probable disease was malaria in endemic area because of the cross reactivity. The rate of positive malaria was 100% among the 3 patients with positive profile in Widal test versus 3.9% among the 154 patients negative in Widal test and 26.2% among the 42 patients with intermediate serological profiles. The number of positive results is small, pointing out the weakness of clinical diagnosis preceeding the Widal test. The number of intermediate results is high, raising the need of adequate interpretation and labelling of the Widal test in order to reduce wrong interpretation.