Esophageal gongylonemosis in ruminants slaughtered in Hamedan and Babol, Iran

Members of the genus Gongylonema are thread-like nematodes that infect the upper digestive tract of birds, various mammals, and humans. To date, the infection with Gongylonema species has been reported in over 60 human cases, including one in Iran. This study was planned to investigate the state of infection in cattle, sheep, and goats slaughtered in Hamedan industrial abattoir, and sheep and goats slaughtered in Babol industrial abattoir. From March 2018 to June 2019, full-length esophagi were collected from 384 cattle (Hamedan) and 584 sheep and goats (384 from Hamedan and 200 from Babol). The esophagi were cut longitudinally and inspected for observation of zigzag burrowed tunnels in the mucosa. The tissue-embedded worms were carefully retrieved, preserved in ethanol/glycerine and examined microscopically. Out of 968 examined animals, three (0.8%) cattle harbored Gongylonema spp. nematodes in their esophagus. The relative length of the left spicule/body length in the only male nematode was 48.94, suggesting of G. pulchrum. This study provides the first information on Gongylonema infection of livestock in Hamedan province. The low infection rate of cattle and absence of infection in small ruminants suggests that climate change and/or improvement of rearing conditions and hygiene measures might have led to this. A combination of molecular and morphological methods is crucial in speciation of Gongylonema spp. in ruminants, especially G. pulchrum and G. nepalensis, which are almost identical morphologically wise.