title: Diagnostic value of the Widal test in areas endemic for typhoid fever.
abstract: The usefulness of a single Widal test to diagnose typhoid fever in endemic areas was investigated. Reciprocal Salmonella typhi O and H titers greater than or equal to 40 and greater than or equal to 80, respectively, occurred in approximately 90% of 42 Mexican patients with bacteriologically-confirmed typhoid fever at the time of presentation to hospital and, by day 4 to 5 of clinical illness, in 70% of U.S. adult volunteers who developed typhoid fever in the course of vaccine efficacy trials but in only 0.7% (O) to 3% (H) of 275 healthy individuals from a non-endemic area. Healthy Peruvians from areas endemic for typhoid fever commonly had antibody which was age-related. Peak prevalence was found in 15- to 19-yr-olds in whom 29% had O titers greater than or equal to 40 and 76% had H titers greater than or equal to 80. A single Widal test in an unvaccinated individual showing elevated O and H titers is strongly suggestive of typhoid fever if the person comes from a non-endemic area or is a child less than 10 yr of age in an endemic area. Because of the high prevalence of antibody amongst healthy invididuals over 10 yr of age in endemic, areas, a single Widal test offers virtually no diagnostic assistance in adolescents and adults.
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000372:Agglutination Tests; D000907:Antibodies, Bacterial / Q000032:analysis; D000942:Antigens, Bacterial / Q000032:analysis; D002648:Child; D002675:Child, Preschool; D006801:Humans; D008396:Maryland; D008800:Mexico; D008875:Middle Aged; D010568:Peru; D012485:Salmonella typhi / Q000276:immunology; D014435:Typhoid Fever / Q000175:diagnosis* / Q000453:epidemiology / Q000276:immunology
chemical_list: D000907:Antibodies, Bacterial; D000942:Antigens, Bacterial