The dangers of using single locus markers in parasite epidemiology: Ascaris as a case study

Molecular markers are used widely to discriminate between closely related s pecies of parasites, and in many cases a single locus is used for this purp ose. This article aims to show how molecular data derived from a single gen etic marker or linkage group - in this case mitochondrial DNA - can lead to ambiguous conclusions and to illustrate how a multilocus approach has enha nced our understanding of the epidemiology of two closely related parasites , the nematodes Ascaris suum, which infects pigs, and Ascaris lumbicoides, which infects humans.