REDUCTIONISM ONCE AGAIN - HELICOBACTER-PYLORI AS AN EXAMPLE

The contrasting evidence for a multifactorial pathogenesis of gastrodu odenal disease rather than the reductionistic, monocausal role of Heli cobacter pylori is presented. Evidence for the former is derived from epidemiological, physiological, immunological and experimental behavio ral studies in animals. The high prevalence of the bacterium in popula ries and the low incidence of peptic ulcer strongly suggests that it a lone cannot play the only pathogenetic role. The evidence that peptic ulcer is not one disease raises the problem of identifying the contrib utions of psychosocial factors in combination with infection by H. pyl ori in the various forms of the human disease. The most likely role it plays is that of an ''opportunist'', when the gastroduodenal mucosal ''defense'' is compromised by many possible factors.