旋毛虫粪口传播途径的研究

The fecal-oral transmission route of Trichinella spiralis

目的了解旋毛虫粪口传播途径的可行性及粪便中旋毛虫幼虫的感染力。方法试验将6只Wistar大鼠分别一次性感染4000条旋毛虫幼虫,于0、4、8、12、16、24和48 h收集3只大鼠(A组)粪便,分别分成4份于室温下保存0、24、48和72 h,显微镜下计数粪便中幼虫数量,将每份含有旋毛虫幼虫的粪便喂给5只昆明小鼠,42 d后处死小鼠,计数幼虫数并计算生殖力指数(RCI);另外3只大鼠(B组)在感染后1~23 d收集粪便,提取DNA,通过PCR扩增旋毛虫线粒体atp6基因。结果A组大鼠感染旋毛虫幼虫后4~16 h排出幼虫,8 h排虫量达高峰,24 h及以后粪便中无旋毛虫幼虫。大鼠感染4、8、12、16 h后粪便中旋毛虫幼虫总数分别为350、400、145、40条。感染后4 h收集的大鼠粪便室温保存0、24、48 h后RCI分别为112.5、20.5、2;8 h收集的大鼠粪便室温保存0 h、24 h后RCI为66.7、9;12 h采集的大鼠粪便室温保存0和24 h后RCI为13.3和5;16 h收集的大鼠粪便室温保存0 h后RCI为10。B组大鼠中2只连续18 d扩增出旋毛虫线粒体atp6基因,1只连续20 d扩增出旋毛虫线粒体atp6基因。结论一次性大量食入旋毛虫幼虫后,可排出具有感染力的旋毛虫幼虫,可通过粪口途径进行传播。PCR可以检测粪便中的旋毛虫线粒体atp6基因,但不能确定旋毛虫是否具有感染力。

The feasibility of fecal-oral transmission of Trichinella spiralis larva and infectivity in feces were assessed.Six Wistar rats were infected with 4000 T.spiralis larvae at one time.The feces of three rats(group A)were collected at 0,4,8,12,16,24,and 48 h,and then divided into four aliquots and stored at room temperature for 0,24,48,and 72 h,respectively.The number of larvae in the feces was counted under a microscope,and each aliquot containing T.spiralis larvae was fed to five Kunming mice.All mice were killed 42 days after infection.The number and reproductive capacity index(RCI)of T.spiralis larva were calculated.The feces from another three Wistar rats(group B)were collected from 1 to 23 days after infection and DNA was extracted from each fecal sample for PCR detection of the mitochondrial atp6 gene of T.spiralis.The results showed that T.spiralis was discharged in feces at 4-16 h after infection,peaking at 8 h,with no detection after 24 h.The numbers of T.spiralis larva in fecal samples of three rats in group A were 350,400,145,and 40 at 4,8,12,and 16 h after infection,respectively.The RCI values of T.spiralis larva for samples collected at 4 h were 112.5,20.5,and 2 after storage at room temperature for 0,24,and 48 h,66.7 and 9 for samples collected at 8 h after 0 and 24 h,13.3 and 5 for samples collected at 12 after 0 and 24 h,and 10 for samples collected at 16 h after 0 h,respectively.Of the three rats in group B,two were positive for the atp6 gene for 18 consecutive days,and the third was positive for 20 consecutive days.These results indicate that one-time ingestion of T.spiralis larva in quantity can discharge infectious T.spiralis larvae,which can be transmitted through the fecal-oral route.PCR analysis is appropriate for detection of the T.spiralis atp6 gene in feces,but not infectivity of T.spiralis.