La querelle du contagionisme qui aboutit, pendant plusieurs décennies au XIX^e siècle, à la victoire d’une doctrine qui affirmait la non-contagiosité des grandes maladies épidémiques, a été racontée avec brio en 1948 par Erwin Ackerknecht. Son récit constitue un point de départ au rôle, maintenant reconnu, de l’idéologie en médecine. L’histoire sera reprise ainsi que l’interprétation donnée par Ackerknecht selon laquelle le succès de la doctrine provenait des convictions bourgeoises et libérales de ses partisans. Nous y ajouterons qu’il s’agissait d’une élite qui cultivait des intentions généreuses et qu’elle s’était coupée des gens ordinaires, dont les praticiens du terrain exerçant en province. L’exemple de l’épidémie récente de choléra en Haïti montre le risque toujours actuel d’une contamination de la médecine par l’idéologie et la politique ainsi que l’absolue nécessité de confronter les théories aux faits.

With the title “Anticontagionism between 1821–1867”, Erwin Ackerknecht's 1948 Fielding Garrison lecture to the American Association for the History of Medicine marked a milestone in the history of medicine by showing how medicine could be influenced by politics and ideology. His account tells of the quarrel, particularly lively in France, between supporters and opponents of contagionism, a quarrel which led to the official doctrine that major epidemic diseases were not contagious (this doctrine in the form of dogma was only abandoned at the end of the century thanks to the progress of medical knowledge). The order in which the Academy of Medicine reviewed the reports it had requested is important, from the first when Étienne Pariset was sent to Spain to study two epidemics of yellow fever and wrongly asserted the contagious nature of the infection (and this assertion was quickly challenged) to the second when it became aware of the unanimous anticontagionist reports of French doctors who had been working in Egypt on the victims of the plague epidemic of 1834–1835. The Academy, i.e. the elite of the profession, had forged an anticontagionist conviction which it asserted during the cholera epidemic of 1832 neglecting the contrary opinion of provincial practitioners. The anticontagionist dogma – and this is Ackerknecht's interpretation – came from the bourgeois and liberal convictions of its supporters. They considered contagionism to be a medieval doctrine which, in their view, neglected the lamentable living and housing conditions of the poorest, those who were the most numerous victims of the epidemics. Their liberal criticism also concerned the organisation of quarantines, which were considered inefficient and blocked trade. We would add that it was an elite with generous intentions and that it had cut itself off from ordinary people. The example of the recent epidemic of cholera in Haiti shows the ever-present risk of medical contamination by ideology and politics, and the absolute necessity of confronting theories with facts.