The use of ivermectin for scabies

Ivermectin, a modified avermectin, is widely known to be an ectoparasiticidal agent in animals but its effect on human ectoparasites is not known.

As a part of a chemotherapy trial with ivermectin against Wuchereria bancrofti microfilaraemia, two males with clinical scabies were studied. Three skin scrapings were taken from the lesions of each of the cases and examined with potassium hydroxide solution for the presence of eggs, larvae or adult mites.

Following a single oral dose of ivermectin at either 100 micrograms or 20 micrograms/kg body weight both the itching and eruptions were reduced and the lesions healed after 14 days of treatment. Skin scrapings taken on days 7 and 30 after administering the drug did not reveal any mites. However, the lesions reappeared after 3 months.

The beneficial results on the healing of scabetic lesions following ivermectin therapy indicates that the drug may have a scabicidal effect. Reappearance of the lesions may have been due to an inadequate dose. This emphasizes the need for future controlled trials on the efficacy of ivermectin against human scabies infection. If proven, this may be an additional advantage in mass chemotherapy campaigns, when there is co-existence of filariasis, intestinal helminthiasis and scabies.