Abstract
Background:
Cystic echinococcosis (CE) is a parasitic infection caused by the larval form of Echinococcus granulosus (a member of the Taeniidae family). The infection is spread by fecal-oral contact with infected domestic dogs. CE threatens human health and destroys animal production all over the world. Echinococcus granulosus genotypes need to be correctly identified for better control and prevention.

Aim:
This study isolated the genotypes of E. granulosus from human, sheep, and cattle samples collected in Iraq using molecular and phylogenetic methods.

Methods:
Thirty hydatid cyst samples were collected: 10 from human patients in the hospital and 20 from sheep and cattle slaughtered in Al-Diwaniyah province. DNA was extracted using a commercial kit, and PCR amplification of the mitochondrial Cox1 gene was conducted. The amplified products were sequenced, and the sequences were studied using phylogeny.

Results:
The findings showed three genotypes of E. granulosus (G1, G2, and G3). G1 was more common in human isolates (98.40%–99.70% homology), G1 and G2 were also found in sheep (98.34%–99.70% homology), and G1 and G3 in cattle (98.40%–99.75% homology). Phylogenetic analysis identified a clear clustering of genotypes that belonged to the same host. The G1 genotype was detected as the most common strain that infects people, sheep, and cattle in Iraq. It is highly zoonotic and has the highest economic losses.

Conclusion:
This study confirmed the presence of three genotypes of E. granulosus in Iraq: G1, G2, and G3. G1 was most common in all hosts, particularly in humans. Phylogenetic analysis revealed that each host had closely related strains. G1 poses a serious public health and economic threat due to its high zoonotic potential.

Key words: Cattle, Echinococcus granulosus, Genotype, Human, Iraq, Sheep