en Public Health Public Health پژوهشي Original Article <div style="text-align: justify;"><span style="font-size:14px;"><span style="font-family:Times New Roman;"><strong>Background:</strong> Gastrointestinal infections in ruminants are a major cause of economic losses. The present study aimed to evaluate the prevalence and seasonal variations of gastrointestinal helminth parasitic infections in the slaughtered animals in Mazandaran province, northern Iran.<br> <strong>Methods:</strong> This descriptive study was conducted on 300 cattle ruminants (sheep and goats) in Mazandaran province during September 2015-March 2017. The animals were assessed using parasitological methods. The contents of abomasa, small intestine, muscles, and liver were evaluated macroscopically and microscopically.<br> <strong>Results:</strong> Among 300 ruminants, 178 (59.33%) were positive for various species of gastrointestinal helminthes, including <em>T. colubriformis</em>, <em>O. circumcincta</em>, <em>M. marshalli</em>, <em>H. contortus</em>, <em>Habronema spp</em>., <em>P. skrjabini</em>, <em>T. saginata</em>, <em>Echinococcus </em>spp., <em>Fasciola </em>spp., and <em>Dicrocoelium </em>spp. Babol was the most infected city (<em>P</em> = 0.001), and spring and summer had higher infection rates. Females were significantly more infected than males, and the animals aged more than nine months were infected more commonly than younger animals (<em>P</em> < 0.05).<br> <strong>Conclusion:</strong> According to the results, the rate of gastrointestinal helminth infection was relatively high among the slaughtered ruminants in northern Iran in terms of economic and zoonotic importance, which threatens animal production and public health.</span></span></div> Helminthes infections, Ruminants, Abattoir, Iran, 142 146 http://jhehp.zums.ac.ir/browse.php?a_code=A-10-88-3&slc_lang=en&sid=1 Bahman Rahimi Esboei bahman5164@yahoo.com 100319475328460010306 100319475328460010306 Yes Department of Parasitology and Mycology, School of Medicine,Tonekabon Branch, Islamic Azad University, Tonekabon, Iran. Iraj Mobedi mobedo.iraj@yahoo.com 100319475328460010307 100319475328460010307 No Department of Parasitology and Mycology, School of Public Health, Tehran University of Medical Science, Tehran, Iran. Azadeh Mizani mizani.azadeh@yahoo.com 100319475328460010308 100319475328460010308 No Department of Parasitology and Mycology, School of Medicine, Mazandaran University of Medical Science, Sari, Iran. Roghaye Zare zare.roghi@gmail.com 100319475328460010309 100319475328460010309 No Department of Epidemiology and Biostatistics, School of Public Health, Tehran University of Medical Science, Tehran, Iran. Hossein Vazini hossein.v2010@gmail.com 100319475328460010310 100319475328460010310 No Department, Basic Sciences Faculty, Hamedan Branch, Islamic Azad University, Hamedan, Iran.