Genotyping of Cystic Hydatidosis Agents in Birjand, Eastern Iran

Cystic echinococcosis (CE), called hydatidosis, is caused by the larval stage of Echinococcus granulosus spp. This disease is reported from different parts of Iran, where numerous cyst surgeries are done. It has been determined that there are different genotypes of E. granulosus. A particular genotype of E. granulosus may create different clinical symptoms. Therefore, we used molecular methods to determine the genotypes of hydatid cysts surgically removed in Birjand hospitals.
In this cross-sectional study, all available paraffin-embedded samples (9 cases) of patients during 2006 to 2015 who underwent surgery for hydatidosis were studied. The diagnoses were confirmed retrospectively by pathologists from the department of pathology, Birjand University of Medical Sciences. The profile of cyst size, location, and fertility of the cysts were recorded and their mitochondrial cox1 and nad1 genes were sequenced. The data were analyzed using bioinformatics software to identify their genotypes.
All the human isolates (8/9) except one were genotype G6 of Echinococcus canadensis, while one isolate belonged to G1 genotype (sheep strain) of E. granulosus sensu stricto (s.s.). The localization of the parasite in the patients infected with G6 was determined to be as follows: liver (3), lung (3), and intra-abdominal (2). In the patient infected with genotypes G1 of E. granulosus, the cyst was isolated from the abdominal cavity; only this patient had undergone a previous surgery for the treatment of hydatid cysts. All the nad1 sequences of G6 cysts of E. canadensis belonged to a haplotype, which was the case of cox1 sequences.
It seems that the main cause of human hydatidosis in South Khorasan province is genotype G6 of Echinococcus canadensis. It should be noted that CE caused by G6 genotype grows faster than those caused by G1. Some studies have revealed a higher tendency of this genotype to infect the brain and pulmonary tissue that shows the clinical significance of G6 genotype in this region.