Difficulty of Speciation in Medical Parasitology

As many others parasites, speciation of flukes depends on the genetic characteristics and on ploidia. Ploidia of flukes can be different in a same species. In Asia, diploid, triploid and hybrid (2n/3n) populations are encountered. The comparison of morphological parameters between diploid and triploid flukes showed that they were morphologically different. Nevertheless, a genetic relationship between parthenogenetic organisms would exist regardless of their ploidia. In the Fasciola genus, the main consequence of the high level of diversity is the frequent probability of development of resistance to anthelmintics and fast adaptation to climatic changes. In the Paragonimus genus, diversity can enhance different forms of pathogenicity, can also be related to the species of intermediate hosts, and to the definitive host. The strain of flukes plays a part in the visceral localization of P. westermani adults.