Immunodiagnosis of Haemonchus contortus infection in sheep by indirect enzyme linked immunosorbent assay (ELISA)

Indirect plate enzyme-linked immunosorbent assay was standardized and evaluated for its effectiveness in immunodiagnosis of haemonchosis in experimental and clinical cases in sheep by using somatic whole adult antigen of H. contortus. Plate ELISA was standardized using 5 µg/well antigen concentration with 1:100 and 1:1000 of sera and conjugate dilution. Indirect plate ELISA was able to demonstrate the antibody titre at different weeks post infection in experimental sheep. A comparison of plate ELISA on suspected field sera and faecal sample examination by floatation method revealed that 74 samples were found to be positive by ELISA but only ten by faecal examination. Sensitivity of plate ELISA was found to be 80.0%, whereas specificity was 21.42% indicating that this test is quite sensitive for clinical cases; an early diagnosis, however, lacks specificity.