Hubertus Nederbragt

Somatic cell count is a diagnostic test of milk for mastitis in cows. Its specificity and sensitivity are less than 1.0, making test results uncertain. I discuss epistemological problems of the test such as underdetermination, undercalibration and underdiscrimination, in the solution of which biomedical and economic factors may play a role. Diagnostics of the SCC should be considered as an epistemological network, functioning in a network in which farmers, veterinarians, epidemiologists and milk industry shift their position following biomedical, technological and economic changes, which is described as an actor-network to understand how human and non-human agents in mastitis may be associated

The relation between biomedical knowledge and clinicalknowledge is discussed by comparing their respectivestructures. The knowledge of a disease as a biologicalphenomenon is constructed by the interaction of factsand theories from the main biomedical disciplines:epidemiology, diagnostics, clinical trial, therapydevelopment and pathogenesis. Although these facts andtheories are based on probabilities andextrapolations, the interaction provides a reliableand coherent structure, comparable to a Kuhnianparadigma. In the structure of clinical knowledge,i.e. knowledge of the patient with the disease, notonly biomedical knowledge contributes to the structurebut also economic and social relations, ethics andpersonal experience. However, the interaction betweeneach of the participating ``knowledges'' in clinicalknowledge is not based on mutual dependency andaccumulation of different arguments from each, as inbiomedical knowledge, but on competition and partialexclusion. Therefore, the structure of biomedicalknowledge is different from that of clinicalknowledge. This difference is used as the basis for adiscussion in which the place of technology,evidence-based medicine and the gap between scientificand clinical knowledge are evaluated.