Studies on the infectivity and freeze resistance of Trichinella spiralis in mice

Objective To observe the infectivity and freeze resistance of Trichinella spiralis.Methods Twenty female Kunming mice were randomly divided into one control group and three test groups,so 4groups(with 5mice per group)in total.For the control group each mouse was inoculated orally with 150muscle larvae of T.spiralis. Test Group one's samples were stored at-18℃for 1h;test group two's samples were stored at-18℃for 4h; test group three's samples were stored at-18℃for 24h.All samples were taken out and thawed;muscle larvae of T.spiralis were collected by the magnetic stirrer method.Then,each mouse was orally inoculated with 150 disposed muscle larval of T.spiralis.All infected mice were sacrificed on the 28th day after infectio,and muscle larval of T.spiralis were examined respectively by diaphragma compression method and digestion method for all infected mice.Results The average number of muscle larvae stored at-18℃ for 1hand 4hwere 2 397.60and 319.60,respectively.These two groups'averages were obviously lower than that of the muscle larvae control group(P 0.01).Group two(4h)'s averages were lower than that of the group one(1h)(P 0.05).ConclusionFreezing does the vital harm to the muscle larval of T.spiralis.The activity and infectivity of muscle larvae are dependent on both freezing periods and muscle depth.