水牛感染血吸虫后病原消亡时间与防制对策的关系

The Time of No Egg Excretion from Faeces of Water Buffalo Infected with Schistosoma japonica and its Relevant Control Strategy

目的 观察水牛感染血吸虫后排卵量和毛蚴出孵规律及其消失时间。 方法 选择购自血吸虫病非流行区8～ 10月龄水牛 9头 ,每头水牛感染血吸虫尾蚴 2 0 0 0条。从感染后第 5 0d开始定期收集粪便作定量检查血吸虫卵和毛蚴 ,连续观察 3 2个月。 结果 在感染血吸虫后第 5 0d 9头水牛均在粪便中发现血吸虫卵和毛蚴 ,平均EPG和MPG分别为 4.65± 2 .0 8和 4.3 6± 2 .19;感染后第 60d分别达 41.0 5± 2 .0 9和 2 5 .97± 2 .45 ,显著高于第 5 0d。感染后第 80d ,MPG为最高 41.73± 3 .2 9,感染后第 90d ,EPG达最高 5 5 .0 4± 1.44。以后随着观察时间的延长 ,EPG和MPG逐渐降低 ,至 3 3 0d全部为阴性。感染后第 5 0d毛蚴孵出率最高 94.45± 6.412 % ,第 60d降为 65 .89± 19.0 1% ,第 80d有所回升85 .76± 10 .5 0 % ,以后逐渐降低 ,至 3 3 0d全部为 0。感染后 1年 ,粪便中未再检出血吸虫卵。肝、脾和肠组织中的虫卵不能孵出毛蚴 ,但沉积在组织中的血吸虫卵仍可造成该组织损害。 结论 1岁以内的水牛感染血吸虫后 1年无需治疗虫体均可消亡 ,粪卵排出消失 ,但在肝脾组织中的血吸虫卵沉着所致病变仍存在。

Objective To observe the pattern and quantity of egg excretion and the time of no egg excretion from faeces after water buffalo was infected with Schistosoma japonica. Methods 9 water buffalos aged 8-10 months were selected from non-endemic area. Each water buffalo was challenged with 2000 Schistosoma japonica cercariae. From day 50 post-challenge, Kato-katz thick smear stool test and miracidium-hatching tests were done and continued for 32 months. Result Eggs and miracidium were found from 9 water buffalos stool at day 50 post-challenge. The means EPG and MPG were 4.65 ±2.08 and 4.36±2.19 respectively, and increased to 41.05±2.09 and 25.97±2.45 at day 60 post-challenge respectively. The means of EPG and MPG at day 60 post-challenge were significantly higher than those at 50 day post-challenge. The mean of MPG was the highest at day 80 post-challenge (41.73±3.29). The mean of EPG reached the highest level at day 90 post-challenge (55.04±1.44). Then EPG and MPG decreased regularly over time and turned negative at day 330 post-challenge. Miracidium-hatching rate was the highest at day 50 post-challenge (94.45±6.412%), then decreased to 65.89 ±19.01% at day 60 post-challenge. It increased again at day 80 (85.76±10.50%) and then decreased regularly to negative at day 330 post-challenge. One year post-challenge, eggs can not be examined from feaces, and the eggs from liver, spleen and intestinal tissues can not be hatched to Miracidium. However, the eggs in the body tissue can still cause damage. Conclusion Schistosoma japonica can be eliminated and excrete no eggs from feaces without any treatment in one-year-old water buffalos. But the damage caused by eggs deposited in liver and spleen tissues still exist.