A critical reappraisal of the use of enzyme-linked immunosorbent assays in the study of snake bite.

The enzyme-linked immunosorbent assay (ELISA) has been the most widely used serological test in snake bite immunodiagnosis and epidemiology. The technique has been applied, however, without due consideration of the many factors which would affect an inherently sensitive test system, especially in tropical rural areas where large scale snake bite studies are usually carried out. This review discusses the effects of non-specific reactivity, cross reactivity and the quality of reagents on both the sensitivity and specificity of venom antigen and antibody detection assays. Simple laboratory modifications to optimize the assays are described. The importance of using the predictive value to assess the validity of applying the same test system in different circumstances is stressed. To fulfil its potential as the most versatile immunoassay technique in snake bite research, the test conditions of the ELISA will have to be much more stringently controlled in future.