Occurrence and cyst burden of Giardia duodenalis in dog faecal deposits from urban green areas: Implications for environmental contamination and related risks

To investigate the prevalence and cyst burden of Giardia duodenalis as well as the genetic identity and possible zoonotic potential of isolates in canine faeces left on soil, a total of 143 freshly passed faecal specimens were collected in four different green urban areas and examined by Real-time PCR. Overall, 30.8% of faeces from different dogs that defecated in urban areas were found to harbour Giardia cysts, with single area positivity proportions ranging from 4.2% to 47.8%; significant (P < 0.05) and highly significant (P < 0.01) differences were found in the prevalence among different areas investigated. The number of cysts ranged from 2 to 1428 per gram of faeces. Results emphasize that a high risk of dog-to-dog Giardia transmission may occur in public areas where high quantities of faeces from infected dogs are daily left to cumulate on the ground. Results suggest there is a low risk for zoonotic transmission of Giardia: only 0.6% of canine faeces contaminating urban areas were carrying subgenotype A1, which is considered as the most potentially transmissible to humans.