Abstract:

Objective To understand the infection of dogs and wild animal hosts in alveolar echinococcosis endemic areas in Ningxia. Methods In 2021, 16 villages were randomly selected as investigation sites from Xiji County, Yuanzhou District and Haiyuan County, respectively, in the endemic area of alveolar echinococcosis. Feces of stray dogs were collected within 100 meters radius of the garbage drop points in the survey villages, meantime, domestic dogs were also collected from the villages. Feces from wild definitive hosts such as foxes and wolves were collected around the natural forest farm in each county. ELISA was used to detect Echinococcus antigens in the fecal samples of domestic dogs, stray dogs, foxes and wolves. Wild rats were captured within an area statting from the households outside the village, extending outwards for 1 km radius. Domestic rats were captured indoors in the households of the survey villages. After identification, the rats were dissected to examine the suspected lesions, including cysts, masses or nodules in the liver, lung, abdominal cavity and other organs, and tissue sections of suspected lesions were prepared to identify the protoscoleces microscopically after staining with hematoxylin-eosin. The infection rate of rats was calculated. SPSS19.0 software was used for statistical analysis, and the difference between the fecal antigen-positive rate and infection rate was compared by χ² examination. Results A total of 1 554 stray dogs and 2 567 domestic dogs were investigated in Xiji County, Yuanzhou District and Haiyuan County, and the positive rates of Echinococcus coproantigen were 4.76% (74/1 554) and 0.97% (25/2 567), respectively. The difference was statistically significant (χ² = 59.23, P < 0.05). The positive rates of Echinococcus coproantigen in stray dogs from Xiji County, Haiyuan County and Yuanzhou District were 6.51% (31/507), 3.48% (18/517) and 4.34% (23/530), respectively; which were higher than that of domestic dogs [1.30% (11/843), 0.70% (6/859) and 0.92% (2/217)] (χ² = 27.17, 14.58, 17.62； all P < 0.05). A total of 649 rodents were captured, which belong to 7 species. The infection rate of E. multilocularis cyst was 0.62% (4/649). The four rodents infected with E. multilocularis were all Spermophilcus alashanicus. The infection rate of E. multilocularis cyst in Sp. alashanicus was 1.09% (4/366). The infection rate of E. multilocularis cyst was 2.31% (3/130) in Xiji County and 0.86% (1/116) in Yuanzhou District, with no significant difference between the two counties (χ² = 0.77, P > 0.05). No positive rodents were found in Haiyuan County. The density of Sp. alashanicus of the survey sites were 3.02-11.48 individual/hm² (1 hm² = 10 000 m²). A total of 252 faecal samples from wild definitive hosts, including foxes and wolves, were detected in 3 counties (districts). The positive rate was 1.19% (3/252). All the antigen-positive faeces were from foxes, and the positive rate of fox feces was 2.61% (3/115). The positive rate of fox fecal samples was 3.92% (2/51) in Xiji County and 2.78% (1/36) in Yuanzhou District, with no significant difference between the two counties (χ² = 0.08, P > 0.05). No positive fecal samples were found in Haiyuan County. Conclusion The positive rate of E. multilocularis coproantigen remained considerably in stray dogs and foxes in Ningxia. The intermediate host, Sp. alashanicus, was found infected with E. multilocularis, indicating that its transmission chain still exists. It is necessary to strengthen investigation, management and deworming in stray dogs and other wild animal hosts.

Key words: Echinococcosis, Ownerless dogs, Survey, Ningxia Hui Autonomous Region