WIDAL TEST (SLIDE METHOD) SALMONELLA TYPHI `O` , SERUM 1:20 SLIDE AGGLUTINATION SALMONELLA TYPHI `H` , SERUM 1:20 SLIDE AGGLUTINATION S.PARATYPHI A `H` , SERUM 1:20 SLIDE AGGLUTINATION S.PARATYPHI B `H` , SERUM 1:20 SLIDE AGGLUTINATION Comment: Note: 1. Titres 1:80 and above of “O” antigen & 1:160 and above of “H” antigen are significant 2. Rising titers are significant Comments: This test measures somatic O and flagellar H antibodies against Typhoid and Paratyphoid bacilli. The agglutinins usually appear at the end of the first week of infection and increase steadily till third / fourth week after which they start declining. A positive Widal test may occur because of typhoid vaccination or previous typhoid infection and in certain autoimmune diseases. Non-specific febrile disease may cause this titer to increase. The test may be falsely negative in cases of Enteric fever treated with antibiotics in the early stages. The recommended test especially in the first week af