Environmental contamination with Echinococcus granulosus sensu lato: a cross-climatic survey of vegetables, soil, and dog feces in Iran

Cystic echinococcosis (CE) is a major parasitic zoonosis prevalent in many regions of the world, including the Middle East and North Africa. The disease is sustained through environmental transmission of Echinococcus granulosus sensu lato eggs; however, comprehensive data on environmental contamination across diverse matrices and climatic conditions remain limited in many endemic regions. The environmental prevalence and distribution of E. granulosus sensu lato contamination were investigated in 1,150 vegetable, soil, and dog fecal samples collected from 87 farms representing four distinct climatic zones of Iran (Mediterranean humid, hot humid, hot arid, and cold semi-arid) using a combination of parasitological screening of taeniid eggs (sequential sieving and ZnCl 2 floatation method) and molecular confirmation by nested PCR targeting the mitochondrial nad1 gene. E. granulosus sensu lato was detected in 33.3% of farms (29/87) and 5% of all samples (54/1150). The contamination rates varied significantly by matrix: highest in soil (27.6%), followed by dog feces (16.3%), and lowest in vegetables (0.7%). All successfully sequenced isolates (54/58) were identified as E. granulosus sensu stricto . Phylogenetic analysis revealed ten distinct haplotypes, indicating genetic diversity within environmental isolates. The findings demonstrate widespread environmental contamination across all climatic regions, underscoring the persistence of the parasite’s transmission cycle. The detection of E. granulosus DNA/eggs on vegetables suggests a potential foodborne transmission route; however, the viability and infectivity of the detected eggs were not assessed. This study provides evidence that effective CE control in endemic regions requires integrated “One Health” interventions targeting canine deworming, safe disposal of livestock offal, and public health education on hygiene and vegetable washing, alongside robust environmental monitoring.