羊在日本血吸虫病传播中的作用II温度和湿度对羊粪中虫卵存活的影响及虫卵在自然环境中的存活状况

To investigate the survival of Schistosoma japonicum eggs in goat feces in natural marshlands and the factors affecting its survival, so as to provide evidences for understanding of the role of eggs in goat feces in the transmission of schistosomiasis and the development of the interventions pertaining to disease control and elimination.The goat animals of schistosomiasis japonica were modeled in laboratory, and the feces of infected goat were collected. In laboratory, the effects of environmental temperature and water content in goat feces on egg hatching were evaluated, and in the field, the effect of duration of goat feces on marshland on egg hatching and the effect of direct sunshine on egg survival were evaluated.At 25°C in laboratory, the hatching rate of eggs in goat feces washigh-positively correlated with the water content in goat feces (r = 0.87). If the water content reduced to 7.6% in goat feces, the eggs in goat feces lost the ability to hatch. Under the same water content in goat feces, the hatching rate of eggs gradually decreased with the extension of the duration of exposure of goat feces to -5 °C, which reduced to 0 following 5 h exposure. At 5, 15 and 25 °C, the hatching rates of eggs gradually decreased with the extension of the duration of exposure of goat feces, and themiracidium hatching ratesof eggs were 2.3%, 5% and 0.9% respectively following the exposure for 52 d. At 35°C, the hatching rate of eggs gradually decreased with the extension of the duration of exposure, which reduced to 0 following 13 d exposure. In winter (-2-10 °C), the hatching rate of eggs gradually decreased with the extension of the duration of exposure of goat feces on marshlands, which reduced to 0 after 21 d of exposure, and in spring (16-19 °C), the hatching rate of eggs gradually decreased with the extension of the duration of exposure of goat feces on marshlands, which reduced to 0.9% after 5 d of exposure. At the same time point on the same marshland, the hatching rate of eggs in goat feces exposed to marshlands with direct sunshine was lower than that without direct sunshine.The survival of S. japonicum eggs in goat feces is associated with environmental temperature and water content (humidity) in goat feces, and the temperature and humidity are major natural factors affecting egg hatching.[摘要]目的 调查羊粪中日本血吸虫虫卵在江滩自然环境中的存活情况及其影响因素, 为研究羊在日本血吸虫病传 播中的作用提供实验依据。方法 建立日本血吸虫感染山羊动物模型, 收集感染性山羊粪便, 观察环境温度和羊粪含水 量对羊粪中日本血吸虫虫卵孵化率的影响。选择江堤外一块草滩作为实验现场, 观察春、冬季羊粪在江滩的暴露时间对 虫卵孵化率以及阳光直晒对虫卵生存的影响。结果 在25 °C实验室环境中, 羊粪中日本血吸虫虫卵孵化率与羊粪含水量 呈高度正相关 (r = 0.87) 。当羊粪含水量降至7.6%时, 虫卵失去孵化能力。保持羊粪含水量不变, 将羊粪暴露在-5 °C环 境中, 随暴露时间延长, 粪便中虫卵孵化率逐渐降低; 暴露5h后, 孵化率降至0。将羊粪样本暴露于5、15 °C和25 °C环境 中, 随暴露时间延长, 粪便中虫卵孵化率逐渐降低, 暴露52 d后仍有2.3%、5.0%和0.9%虫卵存活并可孵化出毛蚴。将羊 粪暴露于35 °C环境中, 随暴露时间延长, 粪便中虫卵孵化率逐渐降低, 暴露13 d后孵化率降为0。冬季 (气温-2 ∼ 10 °C) 随暴露时间延长, 暴露于江滩滩面的羊粪中虫卵孵化率逐渐下降, 暴露21 d后孵化率降至0。春季 (气温16∼19 °C) 随暴 露时间延长, 暴露在江滩滩面的羊粪中虫卵孵化率逐渐下降, 暴露5 d后虫卵孵化率降至0.9%。同一滩块暴露相同时间 后, 暴露在有阳光直晒滩面羊粪中的虫卵孵化率低于无阳光直晒滩面。结论 羊粪中的日本血吸虫虫卵生存与环境温 度和羊粪含水量 (即湿度) 有关, 温度和湿度是影响虫卵孵化的主要自然因素。.