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Variable response of crusted scabies to oral ivermectin ... crusted scabies, oral ivermectin, variable

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  • © 2009 The Author

    JEADV

    2009,

    23

    , 793–797 Journal compilation © 2009 European Academy of Dermatology and Venereology

    DOI: 10.1111/j.1468-3083.2009.03177.x

    JEADV

    Blackwell Publishing Ltd

    ORIGINAL ARTICLE

    Variable response of crusted scabies to oral ivermectin: report on eight Egyptian patients

    A Nofal*

    Dermatology Department, Faculty of Medicine, Zagazig University, Zagazig, Egypt

    *Correspondence:

    A Nofal.

    E-mail:

    ahmadnofal5@hotmail.com

    Abstract

    Background

    Several reports have proved the efficacy of oral ivermectin in the treatment of crusted scabies. However,

    the response varied greatly between different studies.

    Objective

    The aim of this study was to evaluate the response of crusted scabies to oral ivermectin in eight Egyptian

    patients.

    Patients and Methods

    Eight patients with crusted scabies, diagnosed clinically and confirmed microscopically, were

    involved in this study. Patients received a single oral dose of ivermectin (200ug/kg) and re-examined at 2, 4, 6 and 8

    weeks. A second dose of ivermectin was given in case of treatment failure at the end of the second week. A third dose

    of ivermectin, combined with permethrin 5% and salicylic acid 5% was given at the end of the fourth week for the

    nonresponders to the second dose.

    Results

    Two patients were completely cured after a single dose of ivermectin, 4 patients required a second dose at a

    2-week interval to achieve cure and 2 patients cleared from scabies after the combined therapy. No recurrence was

    reported at the end of 8 weeks. An inverse relation was observed between the response to ivermectin and the severity

    of immunosuppression, crust thickness and mite burden.

    Conclusion

    Oral ivermectin is an effective alternative therapy for the treatment of crusted scabies. The response of

    crusted scabies to oral ivermectin is variable and combination therapy with topical scabicides and keratolytics seems to

    be the best choice.

    Received: 1 October 2008; Accepted 9 December 2008

    Keywords

    crusted scabies, oral ivermectin, variable response

    Conflicts of interest

    None declared.

    Introduction

    Crusted scabies is a severe variant of scabies caused by hyperinfestation with the ectoparasite

    Sarcoptes scabiei

    . It is highly contagious, has a high morbidity and may be associated with secondary bacterial infection.

    1

    Crusted scabies is characterized by high mite burden, extensive hyperkeratotic scaling and crusted lesions, variable pruritus, and generalized lymphadenopathy, erythroderma and eosinophilia in some cases.

    2,3

    The increased incidence of crusted scabies, particularly among patients with HIV infection, the very frequent spread of scabies to close contacts, and the frequent failures of topical scabicides initiate the efforts to find an effective alternative regimen for crusted scabies.

    4

    Ivermectin is an antihelmintic agent similar to the macrolide antibiotics but without antibacterial activity. It has been used to

    treat a variety of infestations in animals. In humans, ivermectin has been proved effective in the treatment of onchocerciasis, strongyloidiasis, loiasis, bancroftian filariasis, and cutaneous larva migrans. The safety of ivermectin has been demonstrated by its extensive use against nematodes where the adverse effects were rare and minor.

    5,6

    There have been several reports of the successful use of oral ivermectin in the treatment of crusted scabies. However, the response varied greatly between different studies and there is no definitive consensus on the optimal dosing regimen. A complete cure has been reported after a single dose, multiple doses and a combination therapy with topical antiscabetics and keratolytics.

    1–9

    The aim of this study was to evaluate the response of crusted scabies to oral ivermectin in eight Egyptian patients.

  • 794

    Nofal

    © 2009 The Author

    JEADV

    2009,

    23

    , 793–797 Journal compilation © 2009 European Academy of Dermatology and Venereology

    Patients and methods

    Subject selection

    The study included eight patients with crusted scabies who were attending the Outpatient and Inpatient Clinics of Dermatology at Zagazig University Hospitals, Zagazig, Egypt, during the period from 15 May 2005 to 15 December 2006. Patients who had received any antiscabetic treatment in the previous month before enrolment to the study, children weighing less than 15 kg, and pregnant and lactating women were excluded from the study. Crusted scabies was diagnosed on clinical basis and confirmed microscopically by demonstration of mites, eggs or faecal pellets in the skin scrapings. Severity of mite infestation was graded according to the number of mites per field into mild (1–5), moderate (6–10) and severe (> 10). Before treatment, a thorough history taking and detailed systemic and dermatologic examinations were done. The intensity of pruritus was recorded and secondary infection, if present, was treated before the start of the study. Written consent was obtained from all patients after they have been informed about the details of the study.

    Drug administration

    Ivermectin was administered under supervision as scored 6-mg tablets at a dose of 200

    μ

    g/kg body weight. People known to be in close contacts with the patients were given oral ivermectin by the same dose to minimize the risk of reinfestation. Patients were given standard instructions to prevent fomite transmission by high temperature laundering of all infested clothes and bedding. They were also advised not to use any topical antiscabetic, unless prescribed, during the study period. No restriction, however, was advised concerning the use of medications required for treatment of the underlying diseases. Routine laboratory tests were done before, during and after ivermectin therapy.

    Evaluation and follow-up

    All patients were evaluated at regular intervals of 2, 4, 6, and 8 weeks for clinical and microscopical cure. Patients were considered cured if at the end of 2 weeks there were no pruritus, no clinical evidence of scabies and no positive signs of skin scrapings. A second dose of ivermectin was given at the end of the second week in case of treatment failure, which was defined as persistence of pruritus, clinical signs or microscopical evidence of scabies. A third dose of ivermectin, combined with permethrin 5% and salicylic acid 5% was given at the end of the fourth week for the non-responders to the second dose.

    Results

    Eight patients (5 women and 3 men) were included in the present study. Their ages ranged from 25 to 78 years. They presented with different severities of itching immunosuppression, mite infesta- tion and crust thickness (Table 1). Erythroderma, generalized lymphadenopathy, secondary infection and eosinophilia were

    found in 1, 2, 3 and 4 patients, respectively. Prior therapy was reported in 6 patients; sulphur in 1 patient, crotamiton in 1 patient and permethrin in 4 patients. The response to oral ivermectin was variable. By the end of the second week, after a single dose of oral ivermectin, 2 patients (nos 4, 5) were completely cured (Fig. 1)

    Figure 1 Mild crusted scabies (case no. 4). (a) Before treatment. (b) After treatment with single dose of ivermectin.

  • Efficacy of oral ivermectin in crusted scabies

    795

    © 2009 The Author

    JEADV

    2009,

    23

    , 793–797 Journal compilation © 2009 European Academy of Dermatology and Venereology

    and 6 patients showed minor or partial improvement of clinical signs of scabies and still had positive skin scrapings. After the second dose of ivermectin, 4 patients (nos 1, 2, 6, 7) became completely cured by the end of the fourth week and the other 2 patients (nos 3, 8) achieved complete cure by the end of the sixth week after a third dose of ivermectin combined with the topical therapy (Fig. 2). By the end of the last visit at 8 weeks, all patients were free of scabies both clinically and microscopically without evidence of relapse or reinfestation. No major adverse effects or changes in the laboratory data were reported after ivermectin therapy.

    Discussion

    Scabies represents a challenge to physicians, both in their choice of optimal treatment which remains to be determined and in the community-based epidemics. These issues are of greater concern when dealing with crusted scabies, particularly in immuno- suppressed individuals.

    4

    Although conventional topical agents are effective in the man- agement of classical scabies, they are less successful in treating the more severe variant, crusted scabies. This may be attributed to the high mite burden reported in these patients, inadequate application due to non-compliance, difficulties in treatment of close contacts, variable penetration of the heavy crusts and emergence of resistance resulting from extensive use of these preparations.

    4,10,11

    Several clinical trials have proved the efficacy of oral ivermectin in the treatment of crusted scabies.

    1–9

    Hence, it was considered worthwhile to generate more data regarding the human use of oral ivermectin in the treatment of crusted scabies, particularly the possible factors that could modify its efficacy.

    The results of the present study showed that two patie