Sf. Walton et al., Studies in vitro on the relative efficacy of current acaricides for Sarcoptes scabiei var. hominis, T RS TROP M, 94(1), 2000, pp. 92-96
Citations number
39
Categorie Soggetti
Medical Research General Topics
Journal title
TRANSACTIONS OF THE ROYAL SOCIETY OF TROPICAL MEDICINE AND HYGIENE
Resistance of Sarcoptes scabiei to various topical therapies has been descr
ibed, but clinical assessment of treatment failure is problematic and in-vi
tro assays are generally not available. We describe a simple in-vitro analy
sis used to evaluate the relative efficacy of a range of topical, oral, and
herbal treatments available in Australia for the treatment of scabies. S.
scabiei var, hominis mites were collected from skin scrapings obtained from
7 crusted scabies patients over a period of 2 years (1997 and 1998). Larva
e, nymphal instars, and adult mites were tested within 3 h of collection an
d continuously exposed to selected commercially available treatment product
s until death, with the elapsed time recorded. Neem was the only product to
show little acaricidal activity. Survival curves indicated that, of the ot
her agents, 5% permethrin (Lyclear) had the slowest killing time, with 35%
of mites still alive after 3 h, and 4% still alive after 18-22 h of constan
t exposure. In contrast, no mites were alive after 3 h exposure to 25% benz
yl benzoate (Ascabiol), 1% lindane (Quellada), 5% tea tree oil and 100-8000
ng/g of ivermectin (Equimec). Despite the slower killing time with 5% perm
ethrin, there was no evidence of any mite tolerance in vivo or treatment fa
ilure in any patients or contact cases.