Serological diagnosis of typhoid fever by enzyme-linked immunosorbent assay (ELISA)

Serum sample from 22 bacteriologically proved cases of typhoid fever, 41 febrile cases who were culture negative and 70 sick and healthy age-matched controls were tested for enzyme-linked immunosorbent assay (ELISA) IgG and IgM antibodies using Salmonella typhi LPS antigen. IgG and IgM antibodies were present in 72.7% and 81.8% respectively as against Widal test which was positive in 40.9% in proved cases. In febrile controls IgG and IgM ELISA antibodies were present in 80.4% and 60.9% respectively as against 53.6% by Widal test. This difference between the two tests was statistically significant P less than 0.001. ELISA test was more sensitive than the Widal test and hence it may be useful in rapid serodiagnosis of typhoid fever and also in circumstances where bacteriological techniques are not available.