The fecal-oral transmission route of Trichinella spiralis
The feasibility of fecal-oral transmission of Trichinella spiralis larva and infectivity in feces were assessed.Six Wistar rats were infected with 4 000 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.spir-alis 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 posi-tive 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.
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