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 protozoan parasitic diseases during the twentieth century and the influence of actors from different spheres on these concepts.
Based on two case studies—malaria and toxoplasmosis—different targets of validation will 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 will be 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 will expand the historical understanding of interactions between the political and the biomedical sphere. It can furthermore provide 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.