Submitted to: Nature Magazine
Publication Type: Peer reviewed journal
Publication Acceptance Date: 7/21/2008
Publication Date: 7/30/2008
Citation: Rosenthal, B.M., La Rosa, G., Zarlenga, D.S., Dunams, D.B., Yao, C., Liu, M. Human dispersal of a widespread zoonosis in a domesticated host. Nature Magazine. PMID: 18718558. Interpretive Summary: By analyzing genetic variation in a pork parasite and in related parasites of wildlife, we find evidence that people spread this human pathogen to the Americas via infected pigs, probably during the Colonial Era. The key to avoiding human exposure may rest on effective control of the swine diet, rather than isolation from perceived wildlife reservoirs of infection.
Technical Abstract: We assessed the evolutionary consequences of swine husbandry for Trichinella spiralis, a food borne parasite that causes severe muscular disease. We find far less genetic diversity in parasites of domesticated pigs than in related parasites of wildlife hosts. In particular, pigs of European origin harbor extraordinarily uniform parasites despite their especially widespread distribution. The relatively recent domestication and dispersal of European pigs may explain these and similar data for the pork tapeworm, Taenia solium. Taken together, our findings establish that although hominids likely ingested food borne parasites millions of years before the advent of agriculture, the major zoonotic parasites of pigs were disseminated by people only within the last 500 years.