Diagnostic value of the Widal test for typhoid fever in Singapore

A study was conducted to assess the diagnostic value of the Widal test in patients with bacteraemic typhoid fever. The Widal test was carried out on 25 bacteriologically proven cases of typhoid fever and 50 patients with non-typhoid fever. All the patients with non-typhoid fever had an O agglutinin titre of less than 1:40, while 82% had an H agglutinin titre of less than 1:40. In the patients with typhoid fever, 56% had an O agglutinin titre of greater than or equal to 1:40 and 72% had an H agglutinin titre of greater than or equal to 1:40. Typhoid patients with titres greater than or equal to 1:40 for O and H antigens of Salmonella typhi were significantly different (P less than 0.01) from those with non-typhoid fever. The O agglutinin was highly specific (100%) in the diagnosis of the disease. The study shows that a single Widal test is useful in the diagnosis of typhoid fever in Singapore.