Morphological and Morphometrical Description of Trichostrongylus Species Isolated from Domestic Ruminants in Khuzestan Province, Southwest Iran

Backgrounds: Genus Trichostrongylus (Nematoda: Trichostrongylidae) is one of the most impor-tant zoonotic nematodes with wide geographic distribution in the world. The purpose of the present study was to describe morphological and morphometrical characteristics of male Trichostrongylus species, currently prevalent in domestic ruminants of Khuzestan Province, south-west Iran.Methods: Gastro-intestinal organs of 1600 sheep, goats, cattle, and buffalos, slaughtered in Khuzestan Province, southwest Iran, were examined for infectivity with Trichostrongylus spe-cies. For examination and measurements of helminthes, Azo-carmine staining was per-formed, followed by camera lucida drawings of morphological characters and measurements of morphometrical criteria with a calibrated microscope. Using valid nematodes systematic keys, almost all the parasites were identified at the level of species.Results: Overall, 114 animals were found infected with at least one species of Trichostrongy-lus. Considering morphological characteristics of male Trichostrongylus, six species were identi-fied including T. colubriformis, T. vitrinus, T. probolorus, T. capricola, T. longispicu-laris and Trichostrongylus sp. Conclusion: Although, compared to the previous decades, currently Trichostrongylus is much less prevalent in the domestic ruminants of the study area, but still different species occur in these animals.