Tehran University of Medical Sciences Iranian Journal of Parasitology 1735-7020 5 2 2010 06 15 10 18 EN A Halajian Department of Parasitology, Faculty of Veterinary Medicine, Tehran Science and Research Branch, Islamic Azad University, Tehran, Iran A Eslami Department of Parasitology, Faculty of Veterinary Medicine, Tehran Science and Research Branch, Islamic Azad University, Tehran, Iran N Salehi Department of Parasitology, Faculty of Veterinary Medicine, University of Tabriz, Tabriz, Iran J Ashrafi-Helan Department of Parasitology, Faculty of Veterinary Medicine, University of Tabriz, Tabriz, Iran H Sato Laboratory of Veterinary Parasitology, Faculty of Agriculture, Yamaguchi University, 1677-1 Yoshida, Yamaguchi 753-8515, Japan 2015 10 03 Background: The gullet worm, Gongylonema pulchrum Molin, 1857, is a thread-like spirurid nematode found in a variety of mammals worldwide.  Its incidences in Iranian cattle of different breed or age have not been reported.  The aims of the present study are to disclose the infection status of G. pulchrum in cat­tle slaughtered in northern region of Iran. Methods: Full-length esophagi of cattle of 97 native dairy breed and 41 Holstein-Friesian breed were col­lected at four local abattoirs in Mazandaran Province, northern Iran, from March 2006 to August 2007, and were examined parasitologically.  Eight overlapping segments of the small- and large-subunits of rDNA were amplified by PCR, and the obtained nucleotide sequences were characterized. Results: The incidences of G. pulchrum in female and male native dairy breed were 38.9% and 24.0%, respectively, whereas those in female and male Holstein-Friesian breed were 4.2% and 0%, respectively.  The first internal transcribed spacer (ITS1) region of G. pulchrum rDNA showed an intra-individual varia­tion in the sequence and length, and the variation was ascribed to some unstable repeats of "A" or "CA". Conclusion: Distinct incidences of G. pulchrum infection in native dairy breed and Holstein-Friesian breed might be ascribed to different animal husbandry manners for each breed in Iran; the former breed grazes freely in the pasture, but the latter breed is usually held in a pen.  The rDNA sequence of Iranian G. pul­chrum, obtained for the first time by us, might facilitate a reliable species identification of the parasite with a wide spectrum of morphological variations. https://ijpa.tums.ac.ir/index.php/ijpa/article/view/130 https://ijpa.tums.ac.ir/index.php/ijpa/article/download/130/129