Comparison of effect of three DEET formulations preventing Schistosoma japonicum infection in mice / 中国血吸虫病防治杂志

ABSTRACT

Objective To compare the effica cy of three N,N-diethyl-m-toluamide (DEET) formulations against Schistosoma japonicum infection in mice. Methods Three 10% DEET formulations (DEET isopropanol solution,DEET cr eam and DEET vaseline ointment)were prepared and two experiments, no-dipping or dipping after applying DEET preparation ,were designed. In each experiment, mice were randomly divided into three experiment groups and three control groups . D ifferent DEET preparations were applied in the experiment groups and isopropanol solution, “yumeijing” cream , vaseline ointment were applied in the control g roups, respectively. At different time points after skin application (0.5, 1, 2 , 4 h and 8 h),the mice were infected with (50?5) Schistosoma j apon icum cercariae on the abdominal skin in no dipping experiment. I n dipping experiment,after mice skin were applied and were dipped for 10,30 min, 1 ,2 h and 4 h, respectively, the mice were infected with (50?5) cercariae. Af ter 6-7 weeks ,all the mice were sacrificed and the worms were collected by hea rt perfusion and counted.Worm reduction rates were calculated and rank sum tests w ere carried out. Results In no-dipping experim ent,three DEET formulations provided 100.0% protection in mice at least for 1 h .A t 2 ,4 h and 8 h ,the worm reduction rates were 94.8%,89.9% and 13.3% for DE ET isopropanol solution, 100.0%,97.8% and 50.7% for DEET cream and 100.0%,9 9.0% and 9 8.0% for DEET vaseline oinment, respectively. In dipping experi-ment, given 50.0% wor m reduction rate as efficient in preventing penetration by the cercariae, the e ffective times were 10 min for DEET isopropanol solution,30 min for DEET cream a nd 2 h for DEET vaseline oinment,respectively. Conclusion Three DEET formulations are effectiv e in preventing Schistosoma japonicum infection in mice.DEET vaseline oinment can provide better protection than the other two D EET formulations.