Characterisation and molecular detection of Echinococcus granulosus in Duhok Governorate

Cystic hydatid disease, caused by Echinococcus granulosus, is a major zoonotic infection with significant public health and economic impact in endemic regions, including Iraq. This study aimed to detect the mitochondrial cytochrome c oxidase subunit I (COI) gene in E. granulosus and to characterise hydatid cysts based on morphological and pathological features, including cyst wall layers, cyst type, and organ involvement, in Duhok Governorate, the Kurdistan Region of Iraq (KRI). In this study, characterisation refers to the classification of hydatid cysts by type (fertile, infertile, or calcified) and organ involvement. Of the 58 hydatid cyst samples collected, 17 were from humans, and 41 were from sheep. Cysts were classified according to organ involvement and cyst type (fertile, infertile, or calcified). Among sheep samples, 75.6 % were fertile, 21.9 % infertile, and 2.4 % calcified, whereas human samples showed 82.4 % fertile, 5.9 % infertile, and 11.8 % calcified cysts. Molecular detection using PCR targeting the COI gene confirmed the presence of E. granulosus DNA in 40 sheep and 15 human samples. Nineteen PCR-positive samples were selected for sequencing, resulting in 13 high-quality sequences (three human and ten sheep isolates) that were successfully submitted to GenBank. Statistical analysis showed no significant association between host type and host gender, infection type, or PCR positivity (p > 0.05). However, significant associations were observed between cyst type and organ involvement, cyst type and PCR results, and PCR results and affected organs (p < 0.05). Overall, the findings support the usefulness of COI-based PCR for molecular detection of E. granulosus and highlight the value of integrating cyst characterisation with molecular approaches to improve epidemiological understanding and support control strategies in endemic areas.