Genetic variability and haplotypes of Echinococcus isolates from Tunisia

Abstract

Background: The species/genotypes of Echinococcus infecting a range of intermediate, canid and human hosts were examined as well as the intraspecific variation and population structure of Echinococcus granulosus sensu lato (s.l.) within these hosts. Methods: A total of 174 Echinococcus isolates from humans and ungulate intermediate hosts and adult tapeworms from dogs and jackals were used. Genomic DNA was used to amplify a fragment within a mitochondrial gene and a nuclear gene, coding for cytochrome c oxidase subunit 1 (cox1; 828 bp) and elongation factor 1-alpha (ef1a; 656 bp), respectively. Results: E. granulosus sensu strictowas identified fromall host species examined, E. canadensis (G6) in a camel and, for the first time, fertile cysts of E. granulosus (s.s.) and E. equinus in equids (donkeys) and E. granulosus (s.s.) fromwild boars and goats. Considerable genetic variation was seen only for the cox1 sequences of E. granulosus (s.s.). The pairwise fixation index (Fst) for cox1 E. granulosus (s.s.) sequences fromdonkeyswas high andwas statistically significant comparedwith that of E. granulosus populations fromother intermediate hosts. A single haplotype (EqTu01) was identified for the cox1 nucleotide sequences of E. equinus. Conclusions: The role of donkeys in the epidemiology of echinococcosis in Tunisia requires further investigation.