First documentation of in vivo and in vitro ivermectin resistance in Sarcoptes scabiei

Clin Infect Dis. 2004 Jul 1;39(1):e8-12. doi: 10.1086/421776. Epub 2004 Jun 11.


Ivermectin is increasingly being used to treat scabies, especially crusted (Norwegian) scabies. However, treatment failures, recrudescence, and reinfection can occur, even after multiple doses. Ivermectin resistance has been documented for some intestinal helminths in animals with intensive ivermectin exposure. Ivermectin resistance has also been induced in arthropods in laboratory experiments but, to date, has not been documented among arthropods in nature. We report clinical and in vitro evidence of ivermectin resistance in 2 patients with multiple recurrences of crusted scabies who had previously received 30 and 58 doses of ivermectin over 4 and 4.5 years, respectively. As predicted, ivermectin resistance in scabies mites can develop after intensive ivermectin use.

Publication types

  • Case Reports
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Animals
  • Drug Resistance / physiology*
  • Female
  • Humans
  • Insecticides / pharmacology
  • Ivermectin / pharmacology*
  • Male
  • Middle Aged
  • Sarcoptes scabiei / drug effects*
  • Scabies / parasitology*


  • Insecticides
  • Ivermectin