Abstract
BackgroundThe pastoral area of the eastern Tibetan Plateau is highly endemic for human echinococcosis. Domestic dogs are the main definitive host for the transmission of both Echinococcus granulosus (sensu lato) and E. multilocularis to humans. To control the infection risks, a national-level canine echinococcosis prevention and control programme has been implemented since 2015 in Shiqu County, Ganze Tibetan Autonomous Prefecture, Sichuan, China. The objective of this study was to evaluate its effect on Echinococcus spp. prevalence in dogs.MethodsWe surveyed 69 households with 84 owned dogs, for dog fecal samples and dog keeping information in the villages of Rizha and Eduoma. A total of 105 dog fecal samples (75 from owned dogs and 30 unknown dog fecal samples) were collected between 2015–2017 to determine Echinococcus spp. prevalence using copro-PCR. Eight variables based on household surveys were included into a logistic regression model for significant risk factors to canine echinococcosis prevalence in dogs.ResultsBetween 2015–2017, the overall Echinococcus spp. copro-DNA prevalence decreased significantly in dogs from 51.2% (2015) to 20.0% (2017) in Rizha, and insignificantly from 11.5% (2016) to 4.3% (2017) in Eduoma. Echinococcus multilocularis was the most prevalent species continually copro-DNA detected during the entire study period, while E. granulosus was rare and not detected in 2017. Echinococcus shiquicus copro-DNA prevalence (a probable non-zoonotic wildlife species) was as high in dogs as that of E. multilocularis, although only detected in 2015 in Rizha. Unleashed dog feces were mainly collected in Rizha in 2015. Although 93.2% of owned dogs were leashed, and the monthly praziquantel dosing rate reached 97%, E. multilocularis infection could still be detected in 11.1% of owned dogs in 2017. Monthly deworming, leashing dogs 24 h per day, and the avoidance of dogs feeding on livestock viscera were significant measures to prevent canine echinococcosis infection in owned dogs.ConclusionsCarrying out a canine echinococcosis prevention and control programme can significantly decrease Echinococcus spp. prevalence. The potential contact between leashed dogs and wild small mammals is still a risk for re-infection of owned dogs with E. multilocularis. This study shows that the long-term application of regular dog treatment with praziquantel in the vast and remote echinococcosis endemic areas of the eastern Tibetan Plateau can reduce transmission in dogs but remains a challenging intervention.
Highlights
The pastoral area of the eastern Tibetan Plateau is highly endemic for human echinococcosis
While E. granulosus is mainly transmitted between canids and livestock, E. multilocularis and E. shiquicus are mainly transmitted between canids and small mammals [10]
Only a small number of families or people in the village go to the summer pasture to keep livestock herds on behalf of the whole village and some of the owned dogs in the village are taken to summer pastures for shepherding, while families remaining in the village take care of the houses for owners working in summer pastures
Summary
The pastoral area of the eastern Tibetan Plateau is highly endemic for human echinococcosis. Shiqu County, in Ganze Tibetan Autonomous Prefecture, Sichuan Province, China, is located in the pasture areas of the eastern Tibetan Plateau, has been reported to have the highest international prevalence rate of human echinococcosis, and is one of the most serious endemic regions of the world [8, 9]. As a typical pastoral livestock husbandry county, pastoralism requirements and local Tibetan cultural traditions result in large numbers of owned and stray dogs to be kept in Shiqu County [8] Because of their close relationships to local people, dogs are considered as the main risk to humans becoming infected with echinococcosis by ingesting Echinococcus eggs voided in dog feces [9, 11]. Methods to control the dog population size and decrease Echinococcus prevalence are critical, but a great challenge over many years for the control and prevention of echinococcosis in pastoral Tibetan communities [6, 7]
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