Ascariasis in people and pigs: new inferences from DNA analysis of worm populations

Ascaris is a large parasitic roundworm (nematode) of the small intestine of humans and pigs. These roundworms cause the socioeconomically important disease, ascariasis. For the past 20 years, molecular markers have been used in studies on Ascaris and ascariasis, and added valuable information to the understanding of these roundworms. Here, we provide a review of these studies on human and pig roundworms. We begin with a summary of studies using molecular phenotypic markers to compare Ascaris from humans and pigs, followed by a synopsis of comparisons using genetic markers. We then draw forth inferences in the aspects of host affiliation and infection success, transmission between and among humans and pigs, evolutionary history of Ascaris. We also highlight additional topics such as mating dynamics, diagnostics, and paleoparasitology where molecular epidemiological approaches have been utilized.