“Parasite” in the context of infectious diseases is an umbrella term for a wide variety of eukaryotic organisms. Medical parasitology therefore has been concerned with a plurality of host species and causative agents of diseases, often exhibiting complex life cycles and pathologies. Consequently, diagnostic tests and experimental systems have not been generalizable and easily adaptable for a new taxon of interest, posing specific challenges to medicine and biomedical research. This project investigates the history of accuracy and validity as conceptual constructs in laboratory diagnostics of a disease caused by the protozoan parasite Toxoplasma gondii, with a focus on the second half of the twentieth century and the influence of actors from different spheres on these concepts.
Based on one central case study—toxoplasmosis—different targets of validation provide the historiographic focus, such as diagnostic tests, public health guidelines, acquisition of specimens and references, biological knowledge, experimental models, specificity, and sensitivity. The dynamics of the assessment, refinement, and discursive construction of these targets is investigated through their trade-offs with layers of validity: How, why, and by whom have they been considered valid in relation to incentives of involved actor groups, clinical relevance, applicability, gold standards, or the informative value of tests? Focusing on practices developed and refined under the influence of potentially conflicting incentives expands the historical understanding of interactions between the political and the biomedical sphere. It furthermore provides a historical dimension for contemporary debates on the applicability, costs, and pragmatic aims of diagnostic tests, in a spectrum from individualized medicine to global health initiatives. By particularly investigating toxoplasmosis surveillance during pregnancy in the Austrian “Mutter-Kind-Paß” (Mother-Child Health Passport), introduced in 1975, the project also investigates translational processes between the laboratory, the clinic, public health and the status of serological knowledge.