Phylogenetic Study of cox1 Gene in Echinococcus granulosus Sensu Lato Genotypes in Southwestern Iran

Cystic echinococcosis (CE) is a serious global health concern. CE is an endemic zoonotic disease in Iran. The substantial genetic diversity of Echinococcus granulosus is closely linked to its life cycle, transmission mechanisms and pathogenesis. This study aimed to explore the phylogenetic structure of the genotypes of E. granulosus sensu lato (s.l.) in southwestern Iran (SWI).

Seventy-two hydatid cyst samples were collected from various intermediate hosts, including goats, cattle, sheep, camels, buffalo and humans, primarily from the lungs, liver, spleen and heart of livestock slaughtered in local and industrial abattoirs, as well as from patients in several hospitals (Namazi, Golestan, Arvand and Shahid Beheshti) in southwestern Iran (Bushehr, Fars, Kohgiluyeh and Boyerahmad and Khuzestan provinces).

Sequence analysis revealed three genotypes of E. granulosus s.l. in the SWI: G₁ (n = 69, 95.8%), G₃(n = 1, 1.4%) and genotype like G₆/G₇ (n = 2, 2.8%). Twenty-one different haplotypes were identified in this study. According to the phylogenetic tree topology, the cox1 gene sequence similarities can be shown for some G₁ and G₆/G₇ isolates in some vast areas, but these genotypes generally show a heterogeneous population worldwide. High similarity was shown between G₃ isolates from some countries (Spain, Turkey, India and Iran) and different hosts (sheep, human and buffalo).

The presence of the G₆/G₇ genotype in the SWI may be due to the transmission of this genotype from other regions or the role of camel/wild boar and other possible intermediate hosts in the expansion of this genotype in the SWI. The results of the present study can be used in CE control programs, molecular epidemiology and phylogenetic studies in Iran and other countries for future goals.