Epidemiology and risk factor analysis for canine echinococcosis in a Tibetan pastoral area of Sichuan

To determine the prevalence and evaluate the risk factors of canine echinococcosis based on a field survey of dog infections with Echinococcus granulosus and E. multilocularis in Chalong, Kalong, Dade and Chazha Townships in a district of Ganzi County, Sichuan Province, China.Questionnaire associated with the acquisition of canine echinococcosis was administered to dog owners. Stray dogs were examined post-mortem and rectal faeces at necropsy were collected to validate a copro-antigen ELISA. Owned dogs were screened for Echinococcus spp. infection in faeces using the genus specific copro-ELISA and the effectiveness of dog treatment was assessed. Chi-square and one-way ANOVA were used for statistical analysis.The prevalence of Echinococcus spp. infection at necropsy in stray dogs was 60.9% (14/23) in 2000; E. multilocularis infection accounted for 34.8% (8/23) and E. granulosus for 26.1% (6/23). The specificity of the copro-ELISA was 80.0% and the sensitivity was 92.3%, compared with the results at necropsy. Fifty percent of owned dogs (290/580) tested was copro-antigen positive at the beginning of the project in 2000, which decreased to 17% (99/580) in the same cohort of owned dogs after praziquantel treatment (5 mg/ kg) at 6-monthly period from 2003 to 2005. Analysis for risk factors associated with copro-antigen positive dogs showed that the never tethered dogs had a higher rate (40.4%, 65/161) than dogs tethered during the day (32.3%, 109/337), or tethered at night [29.2% (21/72)], or those always tethered [20%(2/10)](P0.01). Dogs that their owners lacked hydatid transmission knowledge [38.1% (121/318)] and did not have de-worming practice [47.7% (92/193)] had significantly higher copro-antigen positive rate than those dogs that their owners knew relevant knowledge [28.6% (75/262)] and were dewormed regularly [20.4% (79/387)](P0.05 and P0.01). There was no correlation between the prevalence and dog sex or age or the varieties of livestock that the owner raised.Local dogs show high prevalence with both E. granulosus and E. multilocularis. The copro-ELISA can be used to detect infection of Echinococcus in dogs. Allowing dogs to roam, lack of the basic knowledge of hydatid disease transmission and no de-worming practice for dogs are significant factors for the transmission of canine echinococcosis.