Evaluation of N,N-diethyl-m-toluamide (DEET) as a topical agent for preventing skin penetration by cercariae of Schistosoma mansoni.
The effect of skin application of N,N-diethyl-m-toluamide (DEET) on the penetration and migration behavior of cercariae of Schistosoma mansoni was evaluated in vitro and in vivo in a mouse model. These studies showed that DEET at concentrations of 7.5% or higher was 100% effective in immobilizing and killing cercariae of S. mansoni in vitro. Ultrastructural studies on such DEET-exposed cercariae showed transformative and degenerative changes involving both tegument and deeper parenchymal structures. Fatal tissue lesions were evident as early as 5 min postexposure to DEET, and became more extensive with increasing exposure time. Cutaneous application of DEET (as a pure chemical in isopropanol or as a commercial insect repellent preparation) was more than 99% effective in preventing entry of S. mansoni cercariae into the mouse tail skin. Radiolabeling and tracer studies confirmed that 7.5% DEET applied to the skin prior to infection was highly effective in preventing schistosomular migration to the lungs.
Salafsky
B
B
Department of Biomedical Sciences, College of Medicine, University of Illinois, Rockford 61107, USA.
Ramaswamy
K
K
He
Y X
YX
Anderson
G L
GL
Nowicki
D K
DK
Shibuya
T
T
D000287:Administration, Topical; D000818:Animals; D003671:DEET / Q000008:administration & dosage / Q000494:pharmacology / Q000627:therapeutic use*; D004195:Disease Models, Animal; D007302:Insect Repellents / Q000008:administration & dosage / Q000494:pharmacology / Q000627:therapeutic use*; D008297:Male; D051379:Mice; D008854:Microscopy, Electron; D012550:Schistosoma mansoni / Q000187:drug effects* / Q000502:physiology / Q000648:ultrastructure; D012555:Schistosomiasis mansoni / Q000517:prevention & control*; D012867:Skin / Q000469:parasitology
D007302:Insect Repellents; D003671:DEET