Prevalence and partial molecular characterization of Gigantorhynchus echinodiscus in free-ranging anteaters (Myrmecophagidae, Edentata) in Mato Grosso do Sul state, Brazil.

The genus Gigantorhynchus comprises six valid species that require a terrestrial arthropod as an intermediate host. Cystacanths of G. echinosdiscus were previously reported infecting termites in Brazil. Since southern tamanduas (Tamandua tetradactyla) and giant anteaters (Myrmecophaga tridactyla) primarily feed on ants and termites, they are excellent definitive hosts for this species. This study established the prevalence and partial molecular characterization of G. echinodiscus in both species of anteaters using samples collected during necropsies of wildlife-vehicle collision victims in the state of Mato Grosso do Sul, Brazil. From a total of 40 necropsies, 21 of 34 giant anteaters (61.8 %) and all 6 southern tamanduas (100 %) were positive for Gigantorhynchus echinodiscus. Our findings on prevalence, associated with the fact that all animals had good body condition during necropsy, suggest an ancient relationship between this parasite and anteaters, which was previously demonstrated with the description of acanthocephalan eggs in anteater coprolites from archeological sites. This may be a case of a relatively stable relationship, tending toward a parasite-host balance resulting from long-term coevolution between the species.