Larval hook length measurement for differentiating G1 and G6 genotypes of Echinococcus granulosus sensu lato.

OBJECTIVE Echinococcus granulosus is a globally important cestode parasite causing remarkable medical and economical losses in the world. Ten genotypes (G1-G10) have been identified within this complex species. Protoscoleces rostellar hook characters e.g. total large and small hook lengths may be useful to differentiate genotypes. This study investigates the value of rostellar hook morphometry on genetically identified isolates of E. granulosus using mitochondrial cox1 and nad1 sequencing. METHODS In total, 24 hydatid cyst samples of livestock and human origin were collected. The isolates were then sequenced for the mitochondrial cox1 and nad1 genes and total large and small rostellar hook lengths of protoscoleces were measured. RESULTS Total large and small hook lengths could differentiate between G1 and G6 genotypes; however, G1 and G3 were not distinguishable by hook morphometry. Only large hook length was significantly different between the G3 and G6 isolates. CONCLUSION The G6 genotype is readily distinguishable from G1 by using both small and large hook lengths; however, only total large hook length was significantly different between the G3 and G6 genotypes.