Cells that count: philosophy of a diagnostic test for bovine mastitis.

Cells that count: networks of a diagnostic test for bovine mastitis.

Social Epistemology, 2014, in press. 

Can be accessed http://www.tandfonline.com.proxy.library.uu.nl/doi/full/10.1080/02691728.2013.818730#.Uuoa3D3ox8E

Abstract

Somatic cell count (SCC) 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.

Introduction

The aim of the paper is to investigate and discuss the epistemology of a diagnostic test and discuss the role of such a diagnostic test in the framing of disease. The background of this investigation is a study I am performing of the history and philosophy of bovine mastitis, a disease or syndrome of lactating cows that has considerable economic consequences but was hardly a problem at all before milk became a modern commercial product at the end of the 19^th century. I use this study of the history of mastitis as an effort to frame the disease in terms of Rosenberg’s definition of framing disease: ‘In some ways disease does not exist until we have agreed that it does, by perceiving, naming, and responding to it’ (Rosenberg  1992). The way mastitis has been framed, and is still reframed continuously, is in my view driven by both biomedical and social (i.e. non-epistemological) factors, such as technology and commercial interests.

The perceiving and naming of a disease is strongly related to its diagnosis and I have argued before that the diagnosis is part of a system of biomedical knowledge of the disease in which it is interconnected to epidemiology, pathogenesis (i.e. the etiology and pathophysiology) and therapy (Nederbragt 2000). This interconnectedness and mutual dependence of the pieces of knowledge from the different biomedical disciplines result in a more or less stable knowledge of the disease as a biomedical entity. Framing a disease reaches beyond the biomedical; it is a process that must be traced back in the past and the frame can only be understood with knowledge of its history. For a diagnosis to point to a disease in this frame at least some agreement must exist of what the disease is; so both disease and its diagnosis must co-evolve. When we assume non-epistemological influences in the framing of the disease we should also assume such influences in the framing of the diagnostic test of the disease. This will be a main theme in this paper.

The framing of a diagnostic test may be seen as an effort to standardize the test, notwithstanding the uncertainties connected to the outcome of the test. I shall discuss these uncertainties in an epistemological approach, making use of more or less traditional concepts. The uncertainty of tests is a common theme in the discipline of epidemiology. Notwithstanding these uncertainties, diagnosis is, according to Rosenberg (2002), ‘central to the definition and management of the social phenomenon that we call disease’. Apparently, it is necessary that the diagnostic test as an epistemological network moves, via the network of the subdisciplines that constitute the disease as a biomedical entity, to the social phenomenon that we call a disease.

I shall proceed as follows. First I will give a description of the most important aspects of bovine mastitis. I will then concentrate on the somatic cell count as a test for subclinical mastitis in milk and discuss three epistemological aspects of this test, ­i.e. underdetermination, undercalibration and underdiscrimination. These three form key factors in establishing the diagnostic test as an epistemic network. In the final paragraph I will sketch the biomedical-statistical network in which diagnosis participates and I will argue that for understanding a patient and her disease we have to weigh the evidence of the diagnostic test against the context of the patient; to be able to do this we have to leave the biomedical-statistical network and enter a social network. The significance of this approach is that we better understand the patient when we make associations between patient, diagnosis, disease and patient-environment. I shall argue that the application of some of the approaches of the actor-network theory may help us to understand how we can associate these actors and that this may clarify the incompatibility of knowledge of disease and knowledge of the patient that I discussed before (Nederbragt 2000).

Nederbragt, H. 2000. The biomedical disciplines and the structure of biomedical and clinical

Rosenberg, C.E. 1992. Framing disease. Illness, society and history. In Framing Disease. Studies in Cultural History, edited by C.E.Rosenberg and J.Golden, pp. xiii –xxvi, New Brunswick: Rutgers University Press.

For the complete paper, see the website of the journal Social Epistemology.

Those who have no access to this journal may send me an e-mail for a copy.