title: Principia aetiologica: taking causality beyond Koch's postulates.
abstract: There is no single accepted method to establish a causal relationship between an infective agent and its corresponding infectious disease. Different biomedical disciplines use a patchwork of distinct but overlapping approaches. To a greater or lesser extent these are based on criteria known as the Koch-Henle postulates, or 'Koch's postulates' for short. Deficiencies in Koch's postulates were recognized by their principal author shortly after their formulation. Now, over a century later, a more rigorous method to test causality has still to be finalized. One contender is a method that uses molecular methods to establish a causal relationship ('molecular Koch's postulates'). Recognizing the wider range of contemporary approaches used to build an argument for a causal relationship, the use of a more inclusive approach to establish proof of causality is proposed. This method uses an argument built from a series of assertions. Assertion 1: congruence or reproducible correlation of a taxonomically defined life form with the clinico-pathological and epidemiological features of infection. Assertion 2: consistency of the demonstrable biological response in the subject to an encounter with the prospective infective agent. Assertion 3: progressive or cumulative dissonance as an explanation for pathophysiological processes at every known level of biological organization in the subject. Assertion 4: curtailment of that pathophysiological process on the deliberate introduction of a specified biomedical intervention. Evidence to implicate the candidate biological entity as an initiator of or primer for cumulative dissonance places it in a subcategory of micro-organisms to be known as 'priobes'. A priobe is the sufficient and necessary antecedent cause of a pathophysiological process evident as an infectious disease.
authors.affiliation: Division of Microbiology and Infectious Diseases, PathWest Laboratory Medicine WA, QEII Medical Centre, and School of Biological and Chemical Sciences, University of Western Australia, Nedlands, WA 6909, Australia.
authors.forename: Timothy J J
authors.initials: TJJ
authors.lastname: Inglis
mesh_terms: D015984:Causality; D003141:Communicable Diseases / Q000453:epidemiology* / Q000209:etiology*; D008828:Microbiological Techniques / Q000379:methods*