Knowledge-based interpretation of toxoplasmosis serology test results including fuzzy temporal concepts

Transplacental transmission of Toxoplasma gondii from an infected pregnant woman to the unborn occurs with a probability of about 60 percent and results in fetal damage to a degree depending on the gestational age. The computer system ToxoNet processes the results of serological antibody tests performed during pregnancy by means of a knowledge base containing the medical knowledge concerning the interpretation of toxoplasmosis serology test results. The interpretation algorithm infers the stage of maternal infection to determine the degree of imminent fetal damage. For this purpose, it matches the results of all serological investigations of maternal blood with the content of the knowledge base and generates interpretive reports consisting of a diagnostic interpretation and recommendations for therapy and further testing. In order to take the varying immune responses of individual patients into account, certain intervals between two consecutive tests have to be maintained. These time intervals are modelled as fuzzy sets, since they allow the formal description of temporal uncertainty. ToxoNet comprises the knowledge base, an interpretation system, and a knowledge acquisition and modification program.