Widal agglutination testforserological diagnosis of typhoid fever inan endemic area

SUMMARY Apassivehaemagglutination test, usingsheepredbloodcells sensitised withSalmonellatyphilipopolysaccharide, was comparedwiththeWidal test fortheserological diagnosisoftyphoidfever in an endemic area. The results obtained on sera from 152 patients with bacteriologicallyconfirmedtyphoidand 183 patients whodid not havetyphoid were analysedin terms of sensitivity, specificity, simplicity, and rapidity ofthe respective tests. Thepassive haemagglutination test was found to be more sensitive(80%)thantheStyphi 0 antigen(71%)butmarginallylesssensitivethanthe Hantigen (82%)ofthe Widal test. Thefalse positive rate on control sera was 1 2%and6-6%,respectively, for the Widal 0 and Hantigens, and 1-6% for the passive haemagglutination test. Ourfindings indicate that thepassive haemagglutination test is comparablewiththeWidal test fortheserological diagnosisoftyphoidfeverinendemic areas, butis more simple, rapid,andeconomic.Thepassive haemagglutination test may be a useful alternative to theWidal