Strongyloides myopotami in ctenomyid rodents: Transition from semi-aquatic to subterranean life cycle

Strongyloides myopotami, a parasite of Myocastor coypus (nutria or coypu), was found during an extensive parasitological survey carried out on parasitic helminths of 5 species of subterranean rodents (tuco-tucos) belonging to the genus Ctenomys from Argentina and Uruguay. Strongyloides myopotami became known by causing “marsh itch” (also called “nutria itch” or “swimmer’s itch”), a severe rash caused by larvae that enter the skin in humans, and it is recognised as a zoonosis for people handling nutria fur. In the present study S. myopotami was found in 2 of the 5 examined species of Ctenomys (C. talarum from Argentina and C. pearsoni from Uruguay), both inhabiting the vicinity of water courses. Population descriptors of S. myopotami in C. talarum showed that a population of this parasite is well established in this rodent. The development of infective filariform larvae from eggs in the faeces of C. talarum and the prevalence of gravid parasitic females in this host can be considered as evidence of the establishment of a population of S. myopotami independent of the source population parasitizing M. coypus. Therefore, the presence of S. myopotami in these species of tuco-tucos indicates a change from a semi-aquatic to subterranean life cycle. Evidence that tuco-tucos are reservoirs for these nematodes and therefore may be a risk to human health in the areas studied is provided.