Biological diagnosis of congenital toxoplasmosis: methods

The biological techniques used, for diagnosis, in the field of congenital toxoplasmosis are numerous and very different from each other. This is due to the fact that each step of the diagnosis (acquired immunity or not, determination of seroconversion, ante-natal diagnosis, diagnosis at birth and follow-up of the child) has its own particularities and needs one type of methods. For instance, the determination of a toxoplasmic seroconversion is based on the results of serological methods, while the ante-natal diagnosis performed in amniotic fluid relies on the detection of the parasite (entire parasite or DNA)[1]. Furthermore, in each category of methods (serological methods, detection of the parasite, etc...), many different kits or different techniques are available[2]. This has induced the publication of a huge number of articles devoted to the biological diagnosis of congenital toxoplasmosis. Our goal, in this chapter, is not to give a complete list of the kits and techniques available and employed, what would be quite impossible (a complete book would not be enough to cite all the references related to this topic), but to make an overview of these methods, focusing on their advantages, drawbacks, and on the kind of biological samples they can be applied on. The interpretation of the results will be developed in other chapters of this book. Serological methods, and parasite detection techniques will be successively presented and discussed.