[Principles and methods of immunological diagnosis in infectious and parasitic pathology]

Immunological methods have always represented a major contribution to the diagnosis of infectious diseases. Recent technical advances in immunochemistry make this contribution even more essential than in the past. The author reviews the classic principles of immunological diagnosis in infectious pathology. In the best cases, this diagnosis is based on parasite identification (in the broad sense), or identification of specific products from the parasite. It is also possible to consider shortening culture time, when necessary, by performing an early immunological identification. The most recent developments in this field are presented. When the identification of the parasite or its secretion products is not feasible, one must be content to demonstrate the occurrence of a specific immune response, essentially of humoral nature. The author reminds of the basic theoretical difficulties preventing a real analytic antibody titration. The importance of the expression of the results as well as the predictive value of the tests, is stressed. Finally, the author analyzes some of the recent advances such as the development of immuno-enzymatic techniques, rapid testing which can be performed by non-biologists, the contribution of monoclonal antibodies and the possibility of using them in a new detection diagram of antibodies. The author reminds of the difficulty in the standardization of immunological methods, especially the determination of antibodies.