Human cystic echinococcosis in Turkey: a preliminary study on DNA polymorphisms of hydatid cysts removed from confirmed patients

Cystic echinococcosis caused by the larval stages of Echinococcus granulosus sensu lato s.l is endemic in Turkey with a high public health impact particularly in rural areas. The aim of this study was to investigate the genetic variation and population structure of E. granulosus s.s using metacestode isolates removed from surgically confirmed patients originating from several regions in Turkey and to investigate the occurrence of autochthonous transmission. Using DNA extracted from a total of 46 human-derived CE isolates, we successfully analysed an 827-bp fragment within the cox1 mitochondrial gene and confirmed the causative agent of human cystic echinococcosis in patients included in this study to be Echinococcus granulosus s.s (G1 and G3 genotypes). The haplotype parsimony network consisted of 28 haplotypes arranged within three main clusters and the neutrality indices were both negative and significant indicating negative selection or population expansion. The assessment carried out in this study using GenBank nucleotide sequence data from Turkey for sheep and cattle hosts demonstrated the importance of autochthonous transmission with sheep, cattle and humans harbouring the same haplotypes. Further studies are required to investigate the biological significance, if any, of E. granulosus s.s haplotypes and the genetic variability of CE from human patients using longer nucleotide sequences and a larger sample set.