Heterogenity of Echinococcus canadensis genotype 6 - the main causative agent of cystic echinococcosis in Birjand, Eastern Iran.

Little is known about the genotypes of Echinococcus spp. and their life cycles in eastern Iran. We analysed the partial sequences of the nad1 and cox1 genes from 17 isolates from hydatid cyst-infected patients (n=9), camels (n=5) and sheep (n=3) in Birjand, eastern Iran. A new primer pair was also used to amplify the long fragment (1180bp) of the cox1 gene. All camel and eight human isolates were G6 strains of Echinococcus canadensis while one human isolate and the three sheep isolates were G1 genotypes (sheep strain) of E. granulosus sensu stricto (s.s.). Nad1 and cox1 sequence analyses showed high G6 genetic homogeneity, similar to previously reported G6 strains from southeast and central Iran, Sudan and Mauritania. Low nucleotide and haplotype diversity similar to G6 strains from Russia (Altai republic) and Kazakhstan was also found, consistent with a bottleneck effect. In this study, G6 was the most common Echinococcus genotype. Genetic homogeneity of east, southeast and central Iranian G6 and its low genetic diversity may be due limited mobility and contact between humans and camels from other regions because of large, inhospitable deserts.