Surface water contamination with Echinococcus granulosus eggs in the endemic regions of cystic echinococcosis in the southeast of Iran: significance and public health implications.

Cystic echinococcosis (CE), caused by the dog tapeworm, Echinococcus granulosus, is a worldwide public health concern in different endemic countries. CE is transmitted through the ingestion of the parasite eggs excreted in dog feces. However, limited molecular parasitological evidence is available regarding the environmental sources of CE transmission to humans and animals. Water is probably one of the environmental sources of CE transmission; however, very few studies have investigated the presence of E. granulosus eggs in water. The aim of this study was to investigate the contamination of surface water sources with E. granulosus. Three hundred samples, each of 10 L volume, were collected from rivers, streams, agricultural fields, ponds, pools and marshes in six counties in the south of Kerman province, Iran. After filtration, the samples were analyzed by microscopy, PCR assay and nested-PCR-sequencing. Echinococcus granulosus DNA was detected in 1.7% of the samples, mainly collected from streams, agricultural lands and marshes in Jiroft and Anbarabad. PCR-sequencing identified the parasites as E. granulosus sensu stricto, G1 genotype. The findings of the study indicate the potential of water as an environmental source of human CE, suggesting the role of water in perpetuating the life cycle and transmission of E. granulosus eggs.