关键词: 血吸虫病, 野生动物, 钉螺, 野粪调查

Abstract:

Objective To analyze the risk factors for schistosomiasis transmission in a hilly transmission interruption demonstration plot located at the south bank of Yangtze River. Methods The 2016-2017 schistosomiasis endemic information in local residents and livestock in a hilly transmission interruption demonstration plot located at the south bank of Yangtze River was collected. Field investigations were also carried out at benchland, cement ditch, field drain, flood discharge ditch, trunk canal, wasteland, desolate sands in the demonstration plot, where snails were surveyed through systematic sampling in combination with environmental sampling, and wild rodents were captured using cages or traps which were placed monthly, 3 days each time, for 3 consecutive months. The loop-mediated isothermal amplification (LAMP) method was used to detect the schistosome DNA in snails. The rodents captured were sacrificed and liver tissues were collected for egg examination in tissue homogenates. Feces from wild animals in the field were collected, and examined by the miracidium hatching method. Results A total of 12 232 (5 408/6 824) local residents were examined in 2016 and 2017 in the demonstration plot, of whom 152 showed positive serological test results and none showed positive fecal examination result. A total of 688 cattle were examined by serological test, of which only 1 showed positive result, and none showed positive fecal examination result. Meanwhile, 2 152 frames of snails were investigated in the 7 selected areas and 1 401 snails were obtained, including 1 398 live snails (427 frames), with an average density of 3.27 live snails/frame. The LAMP results showed that 5 out of 24 tubes of mixed DNA resulted in positive products, distributed at 3 sites. A total of 825 cages/traps were placed, and only 35 rodents were captured, distributed at 6 sites. None of the rodents were found to be infected with Schistosoma japonicun after stool hatching, while microscopic examination of the liver tissue revealed two rodents infected with Clonorchis sinensis. The purchased 2 samples of wild boar liver and one wild rabbit also showed negative results of microscopic examination and fecal hatching. A total of 137 fecal samples were collected, mainly from two spots (54 and 44 from each). The fecal samples were from cattle, goats, horses, swines and dogs, mostly from cattle (66 samples), and least from swines (4). Twenty-six were determined as positive by hatching, infection a positive rate of 19.0%, consisting of 15 cattle feces, 2 horse feces, 3 goat feces, 3 swine feces, and 3 dog feces. Conclusion No human cases of schistosomiasis were found in the demonstration plot. There has been a scenario of multiple livestock sources of infection in the demonstration plot, with an infection rate of 19.0% in livestock feces. The infected livestock feces are a crucial factor for the transmission of schistosomiasis in this area.

Key words: Schistosomiasis, Wildlife, Snail, Investigation of field feces