Oral Ivermectin Treatment in Two Cases Of Scabies: Effective in Crusted Scabies Induced by Corticosteroid but Ineffective in Nail Scabies

Abstract

We report two cases of scabies treated with oral ivermectin (200 micro g/kg). Case 1, a 72-year-old man, developed crusted scabies with the use of oral corticosteroids due to a misdiagnosis by an earlier physician. The patient was successfully treated with two doses of oral ivermectin at a 7 day interval with concomitant topical use of crotamiton and keratolytic agents. However, the nail scabies in this patient failed to respond to these treatments. Live mites were detected from all his toenails two weeks after the second dose of ivermectin. A complete cure of the nail scabies was achieved by occlusive dressing of 1% gamma-BHC on all toenails for one month. Case 2, a 52-year-old woman, had been treated with oral corticosteroid for mesangial nephritis. She developed common scabies, but a topical scabicide, crotamiton, was not effective. Two weeks after treatment with a single dose of oral ivermectin, eggs were still detected from a burrow on her trunk. Her treatment was completed after a further two doses of oral ivermectin were administered at 7 day intervals. In both patients, the administration of oral ivermectin did not induce any clinical or laboratory side effects. Oral ivermectin is effective for crusted scabies, but not effective for nail scabies. Two doses of oral ivermectin, administered with a one-week interval, is an appropriate treatment regimen.

A case of crusted scabies with a bullous pemphigoid‐like eruption and nail involvement

“…The efficacy of oral ivermectin in the treatment of crusted scabies and nail scabies in this case should be discussed. Oral ivermectin has been used as an effective antiscabetic treatment since 1993 21 . However, the same dose for common scabies is insufficient for the treatment of crusted scabies, and combined simultaneous treatment with topical agents has been recommended 21,22 .…”

“…Ohtaki et al. 21 and Huffam et al. 22 both recommended that, in crusted scabies, oral ivermectin should be administered with the topical application of a scabicide.…”

“…Ohtaki et al. 21 also reported that oral ivermectin was inadequate to treat nail scabies. In this case, we continued to find large numbers of mites and eggs on the toe nails and nail beds even after two oral treatments of ivermectin.…”

Ivermectin: panacea for resource-poor communities?

“…Increasingly used to treat scabies (which afflicts >130 million people at any one time). Oral ivermectin has been used since 1993 to treat both common scabies and crusted scabies, particularly to control outbreaks in nursing homes where whole-body application of topical agents is impractical [35]. It is the only oral drug available, with tablets approved for use in Europe (2002), Japan (2006), and New Zealand (2005/ 2006).…”

Guideline for the diagnosis and treatment of scabies in Japan (second edition)

“…In cases of nail scabies, mites are found below and/or above the nail plates. Although the efficacy of ivermectin against nail scabies has not been evaluated in preclinical studies, its ineffectiveness against nail scabies has been clinically reported 69,76 . Particularly in cases where mites are found above the nail plate, the drug is unlikely to reach the pathogen.…”