Repellent efficacy of four commercial DEET lotions against Amblyomma hebraeum (Acari: Ixodidae), the principal vector of Rickettsia africae in southern Africa.
African tick bite fever, caused by Rickettsia africae, is an emerging zoonotic infection in rural sub-Saharan Africa and the French West Indies. We tested the repellent efficacy of four commercial diethyl-3-methylbenzamide (DEET) lotions against Amblyomma hebraeum Koch, the principal vector of R. africae in southern Africa, by using a human bioassay in which repellent-treated fingers were presented to questing tick nymphs hourly for 4h. Three lotions with 19.5, 31.6 and 80% DEET concentrations, respectively, had a repellent efficacy of > or =90% at 1h post-application, of > or =77% at 2h post-application and of <70% during the rest of the experiment. By contrast, a lotion with 2% DEET plus 1% citronella oil provided only a 59% repellency at 1h post-application, with a drop to <22% during the following hours. Hourly negative control trials repelled <5% of tick attacks. Our results suggest that commercial repellents containing > or =19.5% DEET provide a significant but short-lasting protection against questing A. hebraeum ticks.
Division of Infectious Diseases, Department of Internal Medicine, Aker University Hospital, N-0514 Oslo, Norway. mogens.jensenius@ioks.uio.no
Mogens
M
Jensenius
Anne-Marié
AM
Pretorius
Francoise
F
Clarke
Bjørn
B
Myrvang
D000287:Administration, Topical; D000328:Adult; D017954:Africa South of the Sahara; D000818:Animals; D003671:DEET / Q000008:administration & dosage; D006801:Humans; D007302:Insect Repellents; D008297:Male; D013983:Tick Control / Q000379:methods*
D007302:Insect Repellents; D003671:DEET