保存在自来水中的微小隐孢子虫卵囊活性及感染性研究

Effect of the tap water on the survival and infectivity of C.parvum oocysts

微小隐孢子虫卵囊（CPO）保存在4℃自来水中1-30个月,通过体外脱囊技术检测CPO的脱囊率评价其活性,通过检测CPO感染免疫抑制BALB/c小鼠的潜伏期、排卵囊数量和末端回肠绒毛中的隐孢子虫数量来评价其感染性。结果表明,保存在自来水中1-13个月的CPO出现脱囊;小鼠在感染保存1-13个月的CPO后3-8 d开始排出大量的CPO,在末端回肠绒毛中寄生有大量的隐孢子虫;CPO的保存时间与潜伏期之间存在强烈的相关性（r^2=0.98）。因此,CPO在自来水中能保持活性和感染性至少13个月,水是保存CPO的良好介质,水中活性CPO的长期存在对饮用水工业是一个严重的挑战。

The present study was undertaken to evaluate the survival and infectivity of C.parvum oocysts（CPO） stored for 1,4,7,10,13,16,20,25 and 30 months at 4℃ in the tap water（water）,respectively.An excystation protocol was performed in vitro to evaluate viability of CPO.BABL/c mice were immunosuppressed to evaluate the infectivity of CPO by detecting the prepatent period of C.parvum infection,the quantity of oocysts excreted,and the number of parasites colonized on the ileum villi.The results showed that CPO preserved in water for 1-13 months were capable of excystation in vitro and infecting mice in vivo.The prepatent period was extended from 3 to 8 days and large numbers of oocysts were isolated from faeces of mice inoculated CPO preserved for 1-13 months in water.Cryptosporidia were found in the terminal ilea of mice inoculated with oocysts stored in water for 1-13 months.There was a strong correlation between prepatent period and duration of oocyst storage（R2=0.98）.It is concluded that CPO may be stored at 4 ℃ in water for at least 13 months for the purposes of laboratory research.Water is a good medium of keeping viability and infectivity of CPO for a long time,and the presence of viable CPO in water is a severe challenge to the drinking water treatment industry.