2021-07-02

Fascioliasis is a zoonotic infectious parasitic disease infecting domestic animals and humans. This study was conducted to estimate the prevalence of fascioliasis among cattle, sheep and goats in different abattoirs of Duhok governorate. During the period from January to December 2019, 9757 domestic animals were examined. Both species of Fasciola (Fasciola hepatica and Fasciola gigantica in addition to some elongated forms which require further confirmation by molecular techniques) were isolated from the bile ducts and gallbladders of infected local and imported animals. Fascioliasis was diagnosed in 2.00% (195/9757) of the slaughtered animals with the highest rate of infection in cattle 3.27% (66/2021) followed by sheep 1.76% (122/6932), while only 0.87% (7/804) of goats were infected. The overall, rate of fascioliasis was slightly higher among the local livestock as compared to imported one, which was 2.10% (111/5294) vs 1.88% (84/4463), respectively. Regarding location, the highest rate of infection in sheep and goats were at Shelidiza abattoir (6.58% and 1.64%), respectively, while that for cattle was at Zakho abattoir which was 3.91% with significant differences(p<0.05). According to gender, significantly (p<0.05) higher prevalence of infection was found in males (2.08%) than females (1.08%), with the highest being among male cattle (3.29%). Regarding Fasciola species, Fasciola hepatica was recorded at a rate of 66.15% (129/195), with the higher rate 59.49% (116/195) among sheep, while Fasciola gigantica was recorded among cattle only at a rate of 18.97% (37/195), and mixed infection with both species was recorded in 14.87% (29/195) mostly in cattle, which was 11.28% (22/195). Significant differences were observed among species of Fasciola in sheep, cattle and goats (p<0.05). Regarding the parasite burden (load) of infection, the heaviest burden of parasites was recorded in 38.46% (75/195) of infected slaughtered livestock with the heaviest being in sheep 55.74% (68/122), while 71.43% (5/7) of goats had the moderate worm burden and 62.12% (41/66) of cattle had the light burden. With respect to the location of parasite, most of the liver flukes were recovered from the bile ducts 67.69% (132/195), followed by gall bladder 21.54% (42/195) and the least 10.77% (21/195) from both the bile ducts and gall bladder. There was a significant relationship (p<0.05) between the season and the prevalence of fascioliasis among animals. In general, high number of infected sheep and cattle was recorded during Winter seasons (December, January and February), whereas, the lowest number of infected animals was recorded in Summer seasons (June, July and August); sheep and cattle. Regarding infected goats, the highest number of infected goats was reported in Summer season. Molecular techniques were used for confirmation of the identification of Fasciola species by the amplification of the Internal Transcribed Spacer (ITS1 and ITS2) rDNA as DNA marker. The amplified DNA of Fasciola hepatica and F. gigantica generated DNA fragments of 480 and 550 bps, respectively. Thirteen PCR products were successfully sequenced and recorded in GenBank under the accession numbers: MW161261, MW084365, MW084349, MW084348, MW082830, MW082585, MW052601 for Fasciola hepatica and MW161260, MW082589, MW084353, MW084350, MW052602, MW085034 for Fasciola gigantica. The phylogenetic tree of F. hepatica and F. gigantica showed high relatedness among isolates of the same species. Fasciola hepatica was assigned into two main clusters; three belonged to the first cluster and four to the second cluster. Fasciola gigantica was also assigned into two clusters, four of them belonged to the first cluster except Fasciola gigantica (MW161260) clustered as monophyletic among the first cluster and the remaining two isolates belonged to the second cluster.