Effects of ethanol on the viability and infectivity of Trichinella spiralis larvae.

Objective To observe the effects of different concentrations(volume fraction) of ethanol solution on the infectivity of Trichinella spiralis larvae.Methods In a simulated gastric environment,100 muscle larvae of T.spiralis were treated with different volume fractions of an ethanol solution for different amounts of time and larval viability was identified by methylene blue eosin-borax(M.E.B.) staining.Sixty-four male Kunming mice were randomly divided into 8 groups(8 mice per group).Six groups of mice were orally inoculated with 500 larva or muscle containing 500 larva treated with different volume fractions of an ethanol solution for different amounts of time;the other two groups of mice were inoculated with 500 larva treated with saline as controls.Four mice from each group were sacrificed on days 7 and 42 post-infection,and the intestinal female adult worms and muscle larvae were observed.Results The mortality rate of T.spiralis muscle larvae treated with 0.20 and 0.25 of ethanol solution for 240 min was 0 and 1.4%,respectively.The time when all the larvae were respectively killed in 0.30,0.35,0.40,0.45,0.50,0.55,and 0.60 of ethanol solution was 180,90,45,30,30,20,and 20 min.The mortality rate of muscle larvae treated with 0.65 of ethanol solution for 1 and 6 min was 44.4% and 100%.The difference between the mortality rates of T.spiralis muscle larvae treated with different volume fractions of the ethanol solution for different amounts of time was statistically significant(P0.05).Trend analysis showed that the larval mortality in 0.25-0.60 of ethanol solution increased along with an increase in ethanol concentration and prolongation of the treatment time(P0.05).Intestinal female worms and muscle larvae were not found on days 7 and 42 after the mice were inoculated with the larvae treated with different volume fractions of the ethanol solution for different amounts of time.Conclusion Ethanol has stronger killing action on T.spiralis muscle larvae,and larvae lost their infectivity and reproductive capacity completely after they were treated with ≥0.35 of ethanol solution for 30 min.