*''Trichinella spiralis''has multiple subspecies**旋毛虫''Trichinella spiralis spiralis''**''Trichinella spiralis nativa''**''Trichinella spiralis nelsoni''*''Trichinella britovi''*''Trichinella pseudospiralis'' *Species and subspecies are morphologically indistinguishable*Host specificity, geographical distribution and pathogenicity are different from each other