Determination of immunity against tetanus infection by passive haemagglutination assay

Evaluation of anti-tetanus antibody level in human sera is of primary importance for a prophylaxis of tetanus infection. Many efforts have been made to develop simple, sensitive and reproducible in vitro methods for detecting and quantifying antibodies to tetanus toxin. We have recently developed an HA assay using lyophilized turkey red blood cells (TRBC-HA). In this paper we demonstrated that the TRBC-HA test is more sensitive than the most widely used sheep red blood cell assay (SRBC-HA) and that TRBC-HA assay shows a high correlation with the neutralization test (NT). Furthermore, comparisons of TRBC-HA assay with enzyme-linked immunosorbent assay (ELISA) and counterimmunoelectrophoresis (CIE) indicate that TRBC-HA and ELISA assays detected the same antibody level with a sensitivity up to 400-fold higher than that determined by CIE. However, TRBC-HA also offers many advantages over the ELISA test, because TRBC-HA can be performed in only 40 minutes instead of the 24 hrs. needed for the ELISA, it is less expensive than ELISA and requires no special equipment. Therefore, the overall results suggest that the TRBC-HA is the most appropriate method for rapid and sensitive determination of tetanus antibody levels.