ECHINOCOCCUS GRANULOSUS SENSU STRICTO IN ALGERIA: ASSESSING GENETIC DIVERSITY THROUGH NAD5 AND COX1 MITOCHONDRIAL DNA REGIONS

INTRODUCTION: Cystic echinococcosis (CE), caused by echinococcus granulosus, is a widespread parasitic zoonosis, endemic worldwide, posing a significant public health threat particularly in rural communities (Deplazes et al., 2017. Adv Parasitol, 95:315-493). Algeria exhibits a high endemicity of CE, however epidemiological and molecular data is fragmented and geographically segregated. Previous literature based on mitochondrial cytochrome c oxidase subunit 1 (cox1) gene analysis highlights the predominance of G1 genotype in all intermediate hosts, including humans (Moussa et al., 2021. Parasitol Res, 120:3195-3202; Laatamna et al., 2019. Parasitol Res, 118:89-96). Aiming at investigating genotypic diversity, hydatid cyst sampling was conducted in rural areas of the Setif region in Algeria and analyzed using two mitochondrial genetic markers, cox1 and nad5. MATERIALS AND METHODS: A total of 47 cysts were collected from ovine, bovine, goat and from human intermediate hosts. PCR was used to amplify partial fragments of the mitochondrial cox1 and nad5 genes, useful to identify strains (bart et al., 2006. Parasitology, 133:571-79; Kinkar et al., 2018. Infect Genet Evol, 64:178-84). Cyst fertility was determined based on the presence of protoscoleces. Cox1 and nad5 sequences analyses and median-joining networks were performed to explore strain identity, and datasets from Genbank were used for comparison with available homologous sequences of e. granulosus s.s. circulating in Algeria. RESULTS AND CONCLUSIONS: Readable nucleotide sequence alignments were obtained for 42 and 27 samples for cox1 and nad5, respectively. Haplotype G1 predominated, constituting 59.52% (cox1) and 51.85% (nad5) of the population. Microvariants accounted for 38.09% (cox1) and 44.44% (nad5) of the population, while the G3 genotype was observed in one human sample alone, as confirmed by both markers. Human and ovine cysts exhibited 100% fertility, while cattle cysts showed a lower fertility rate of 62.50%. The obtained data confirmed the dominance of the G1 strain of e. granulosus s.s. in intermediate hosts in Algeria, consistently with previous reports (Moussa et al., 2021. Parasitol Res, 120:3195-3202). The detection of the G3 haplotype in humans, previously limited to the central-desertic region (Kinkar et al., 2018. Parasitology, 145:1613-22), expands its distribution to the northern rural area of Algeria as well. The network showed a close vicinity of the G3 haplotype to those found in camels, suggesting a potentially greater role of this host on the parasite life cycle. A lower fertility of the cysts found in cattle aligns with their minor role in CE transmission among the examined livestock (Romig et al., 2017. Adv Parasitol, 95:213-314).