Morphological and molecular characterisation of Echinococcus granulosus in livestock and humans in Punjab, Pakistan

Cystic echinococcus poses an important economic and public health problem to Pakistan. Our study determined the prevalence and genotypes of Echinococcus present in domestic livestock and humans in Punjab, Pakistan. Out of 39,738 animals examined, 6.67% of animals were found infected. The prevalence and fertility of hydatid cysts was highest in camels (prevalence 17.29%; proportion fertile 95%), followed by sheep (prevalence 7.52%; proportion fertile 86.4%), buffalo (prevalence 7.19%; proportion fertile 84.3%), goats (prevalence 5.48%; proportion fertile 79.09%) and cattle (prevalence 5.18%; proportion fertile 75.25%). Phylogenetic analysis of the cytochrome oxidase-1 gene revealed that the common sheep strain (G1) and buffalo strain (G3) are cycling among livestock in Punjab and that these strains are highly adapted to goats, camels and cattle. Both human cysts were found to belong to the common sheep strain (G1) of E. granulosus, reinforcing this strain has the most potential for zoonotic transfer. Both morphological and molecular results support earlier studies suggesting that Echinococcus of sheep and buffalo origin is phenotypically and genetically similar which adds further evidence to support its recognition as one species viz, Echinococcus granulosus sensu stricto.