Infectivity and Freeze Resistance of Trichinella Isolates in Pigs and Mice in Heilongjiang Province, China

Infectivity and freeze resistance of Trichinella from swine and dog, and the international standard isolates: Trichinella spiralis and Trichinella nativa in pigs and mice were compared in Heilongjiang province,China. It was found that infectivity of swine isolate ,dog isolate , T. spiralis and T. nativa in pigs was significantly different. Swine isolate and T. spiralis were highly infective to pigs with Reproductive Capacity Indexes(RCI) of 385.68 and 300.55 respectively, however, pigs were relatively refractor to dog isolate and T. nativa with RCIs of 0.064 and 0.033 respectively. Dog isolate and T. nativa were more resistant to freeze than swine isolate and T. spiralis in pig and mouse muscle. Swine isolate and T. spiralis would become uninfective after 72 hours at - 22℃ and 24 hours at - 32℃ in pigs ,and 12 hours at - 32℃ in mice,but dog isolate and T. nativa could survive after 192 hours at - 22℃ and 72 hours at - 32℃ in pigs, and 48 hours at - 32℃ in mice. It is concluded that Trichinella from swine and dog in Heilongjiang province, China belong to Trichinella spiralis and Trichinella nativa respectively, Trichinella from dog is not infective to pigs,and would not present a major zoonotic threat to the human consumer via pigs inadvertently becoming infected.