Abstract:

Objective To evaluate the preliminary effect of a grid-based design of anthelmintic bait delivery on wild canines control in echinococcosis hyper-endemic areas. Methods Gemeng and Gayi Townships with frequent wild canine activities, of Shiqu County in Garze Tibetan Autonomous Prefecture in Sichuan Province were selected as experimental and control groups, respectively. During April and October in 2016, areas of 20 m × 100 m and 30 m × 100 m were in Gemeng Township to deliver anthelmintic baits based on the grid-based design. The depositing locations were recorded by a handheld GPS system. Eight to 10 pellets of anthelmintic baits （each containing 50 mg praziquantel） were deposited every two months （i.e. in April, June, August and October）, meanwhile wild feces within a radius of 1 m from the depositing location were collected. In Gayi Township, an area of 200 m × 1 000 m was selected to collect no less than 50 samples of wild feces simultaneously. No baits were deposited there. The collected feces were identified preliminarily by morphological discrimination, and the fecal antigen positive rate was tested by ELISA. In addition, the density of small rodent intermediate hosts was measured in the two townships in April and August 2016. The density of plateau pika （Ochotona curzoniae） in Gemeng Township was estimated based on the presence of pika holes, while that in Gayi Township was based on the number of pikas captured within a 50 m × 50 m area. The plateau pikas were sacrificed to examine hydateid cyst infection in organs. Results During April and October 2016 in Gemeng Township, 240 spots were recorded with delivery of more than 15 000 baits （including loss）. The occurrence rate of feces in Gemeng Township was 35.4%-56.3%, comprising 51.9%, 31.5% and 16.6% from foxes, dogs and wolves, respectively, while the constitution ratio in Gayi Township was 5.5%, 94.5% and 0.0%, respectively. A total of 464 and 418 wild feces were collected in Gemeng and Gayi Townships, respectively, with an antigen-positive rate of 1.08% and 1.20% respectively （P > 0.05）. The densities of plateau pika in Gemeng Township were 273/hm² （1 hm² = 10 000 m²） in winter and 498/hm² in summer, with a hydateid cyst infection rate of 6.8% （3/45）. The densities of plateau pika in Gayi Township were 784/hm² in winter and 632/hm² in summer, with a hydateid cyst infection rate of 3.7% （13/354）. ConclusionThe grid-based design can be used to survey the distributions of intermediate and terminal hosts of echinococcosis. However, more time is needed to examine the real effect of baits delivery in recorded spots.

Key words: Echinococcosis, Wild canids, Grid design and management, Effect