Crusted scabies in two immunocompromised children: successful treatment with oral ivermectin

Treatment of scabies with oral ivermectin in 15 infants: a retrospective study on tolerance and efficacy

BACKGROUND

The incidence of scabies is increasing in Europe, and it often affects children and infants. Although numerous topical treatments have been approved for treatment of scabies in adults, they are often poorly tolerated in infants. One treatment, ivermectin, remains off label for infants weighing < 15 kg.

OBJECTIVES

To report our experience on the safety and efficacy of oral ivermectin in refractory scabies in infants.

METHODS

A retrospective study was performed in the dermatology and paediatrics departments of Rouen University Hospital between January 2009 and October 2012. Infants diagnosed with scabies were identified, and the data for those fulfilling the inclusion criteria were analysed.

RESULTS

Of 219 infants identified, 15 had received oral ivermectin and had been followed up for at least 3 months. All 15 patients were given two doses of ivermectin, 200 μg kg(-1), at baseline and 14 days later. Of 14 patients contacted 1 month after treatment, 12 had achieved healing. The other two were treated with ivermectin or benzyl benzoate; both healed. Overall, 3 months after the first ivermectin treatment, 13/14 patients had healed and only one had active disease.

CONCLUSIONS

Ivermectin is generally well tolerated in infants. The 80% rate of healing observed in infants who had failed to respond to at least two other topical treatments suggests that ivermectin could be considered for treatment of infants with recalcitrant or relapsing scabies.

Scabies: a ubiquitous neglected skin disease

Scabies has been a scourge among human beings for thousands of years. Its worldwide occurrence with epidemics during war, famine, and overcrowding is responsible for an estimated 300 million people currently infested. Scabies refers to the various skin lesions produced by female mites, and their eggs and scybala that are deposited in the epidermis, leading to delayed-type hypersensitivity reaction. Recent immunological findings such as cross-reactivity with house dust mite allergens and an altered T-helper-1/T-helper-2 pattern contribute to a better understanding of the pathomechanism. Furthermore, progress in molecular biology and cloning of relevant antigens could enable the development of a diagnostic ELISA system and candidate vaccines in the near future. Typical and atypical clinical presentations with pruritus as a hallmark of scabies occur in young, pregnant, immunocompromised, and elderly patients and include bullous and crusted (Norwegian) manifestations as well as those masked by steroid use (scabies incognito). This article reviews scabies management strategies in developed countries and resource-poor communities as well as typical complications, including the emergence of resistance and drug-related adverse events. Other problems such as post-scabies eczema and reinfestation, and newer treatments such as ivermectin are also discussed.

Scabies

Scabies is a neglected parasitic disease that is a major public health problem in many resource-poor regions. It causes substantial morbidity from secondary infections and post-infective complications such as acute post-streptococcal glomerulonephritis. Disease control requires treatment of the affected individual and all people they have been in contact with, but is often hampered by inappropriate or delayed diagnosis, poor treatment compliance, and improper use of topical compounds such as permethrin, lindane, or benzyl benzoate. In addition to concerns over toxicity with such compounds, parasite resistance seems to be increasing. Oral ivermectin is an alternative that has been used successfully in community control programmes. Plant derivatives such as turmeric, neem, and tea tree oil are also promising future treatments. The disease is strongly associated with poverty and overcrowding, and the associated stigma can ostracise affected individuals. Treatment of scabies in poor countries needs to integrate drug treatment programmes with efforts to improve the socioeconomic conditions and education programmes to reduce stigma. We expect the future to bring more sensitive and specific clinical and laboratory-based diagnostic methods, as well as new therapeutic strategies.

Ivermectin: pharmacology and application in dermatology

Ivermectin is a synthetic derivative of the antiparasitic class of compounds known as avermectins. It is a macrolide endectocide with activity against both endoparasites with cutaneous tropism (Strongyloides stercoralis, Ancylostoma braziliense, Cochliomyia hominivorax, Dermatobia hominis, Filaria bancrofti, Wucheria malayi, Onchocerca volvulus, Loa-loa) and ectoparasites such as Sarcoptes scabies, Pediculus humanus, Demodex folliculorum, and Cheyletiella sp. Ivermectin is of great interest in the treatment of patients with different forms of scabies, head lice, demodecidosis, cutaneous larva migrans, cutaneous larva currens, myiasis, and filariasis.

Crusted scabies in a healthy infant

Crusted scabies is generally seen in mentally retarded and immunosuppressed individuals. We report the case of a patient with crusted scabies with neither systemic disease nor immunosuppression; all the lesions were cured with applications of 5% permethrin lotion.

Oral ivermectin treatment in two cases of scabies: effective in crusted scabies induced by corticosteroid but ineffective in nail scabies

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.

Ivermectin is better than benzyl benzoate for childhood scabies in developing countries

OBJECTIVE

To compare single dose oral ivermectin with topical benzyl benzoate for the treatment of paediatric scabies.

METHODS

An observer-blinded randomized controlled trial was undertaken at Vila Central Hospital, Vanuatu. One hundred and ten children aged from 6 months to 14 years were randomized to receive either ivermectin 200 micro g/kg orally or 10% benzyl benzoate topically. Follow up was at 3 weeks post-treatment. Primary outcome measures were the number of scabies lesions, the itch visual analogue score and nocturnal itch. Secondary outcome measures were the skin's reaction to treatment, the passage of worms in stool and other side effects.

RESULTS

Eighty patients completed the study protocol. There was no significant difference between the two treatments; both produced a significant decrease in the number of scabies lesions seen at follow up. Ivermectin cured 24 out of 43 patients (56%), and benzyl benzoate 19 out of 37 patients (51%) at 3 weeks post-treatment. No serious side effects were noted with either treatment, but benzyl benzoate was more likely to produce local skin reactions (P = 0.004, OR 6.4, 95% CI 1.6-25.0)

CONCLUSIONS

Ivermectin is cheap and effective in the treatment of paediatric scabies. Ivermectin has minimal observed toxicity and has the additional beneficial effects of antiparasitic action in onchocerciasis, filariasis and strongyloidiasis. Ivermectin is better than benzyl benzoate for the treatment of paediatric scabies in developing countries.

Ivermectin in scabies

The standard treatment for scabies has long been based on topical scabicides. Ivermectin, a broad-spectrum anti-parasitic agent, was first used in veterinary medicine. This drug, active against nematodes and arthropods, is used in humans for the treatment of filariasis. For the past few years worldwide reports on the use of ivermectin in human scabies have suggested that this drug could be an alternative oral therapy.

Diagnosis and treatment of scabies: a practical guide

Scabies is a common, highly pruritic infestation of the skin caused by Sarcoptes scabiei var. Hominis. It is a very contagious parasitosis with specific lesions, such as burrows, and nonspecific lesions, such as papules, vesicles and excoriations. The typical areas of the body it affects are finger webs, wrists, axillary folds, abdomen, buttocks, inframammary folds and, in men, the genitalia. It is characterized by intense nocturnal pruritus. Scabies is spread through close personal contact (relatives, sexual partners, schoolchildren, chronically ill patients and crowded communities). Definitive diagnosis is made when the scabies mites or their eggs or fecal pellets can be identified on a light microscope. New techniques for diagnosis include the use of the epiluminiscence microscopy. The most common topical treatments for scabies include lindane and permethrin. Permethrin provides a greater margin of tolerability because of its low inherent toxicity and low percutaneous absorption. Oral ivermectin is the most recently developed treatment for scabies. A single oral dose of ivermectin 200 microg/kg of bodyweight is a well-tolerated and very effective treatment. It is especially indicated in crusted scabies, scabies in immunocompromised hosts and infestations in crowded communities. It is also useful as a simple treatment in the prophylaxis of close contacts.

Review of ivermectin in scabies

BACKGROUND

Currently available topical medications for scabies are messy and need prolonged application. This leads to poor patient adherence. Emerging drug resistance to topical scabicides has made eradication of scabies difficult.

OBJECTIVE

Availability of an effective oral scabicidal agent, ivermectin (Ivm), opens a new era in the management of scabies. This review summarizes the published literature on the use of ivermectin in the treatment of scabies.

CONCLUSION

A single oral dose of ivermectin of 200 mg/kg body weight is very effective in the treatment of human scabies. A second dose 7-10 days later substantially improves the cure rate. This suggests that ivermectin may not be effective against all the stages in the life cycle of the parasite. Endemic and epidemic scabies in institutions are better treated with Ivm. Crusted scabies ideally should be treated with a combination of Ivm and topical scabicides. Other standard measures and precautions should be taken. Additional controlled studies using a higher single oral dose or using parenteral or topical forms of Ivm are needed. The safety of Ivm in children less than 5 years old and in pregnant women has to be established. The U.S. FDA has not yet approved the drug for the treatment of human scabies.

Successful treatment of scabies with oral ivermectin in Nigeria

Currently, several topical scabicides are available but there is yet no oral or parenteral drug which has been established for the treatment of scabies in Nigeria. Ivermectin which is a modified avermectin, known to be an ectoparasiticidal agent in animals, has been used in adults for systemic parasitosis. In Nigeria, 25% benzyl benzoate is being extensively used for the treatment of scabies in adults. It is effective and readily available. The present study was carried out to evaluate the efficacy and safety of ivermectin in the treatment of patients with scabies at the skin clinic of the University of Nigeria Teaching Hospital, Enugu. Fifty-eight patients with scabies were recruited for the study; 13 (22.4%) were children aged between 5-14 years. Oral ivermectin was given in a single dose of 200 [microg/kg body weight to 29 patients. The remaining 29 patients had to apply 25% benzyl benzoate emulsion. All patients received a full physical and dermatological examination prior to onset of treatment and weekly for 4 weeks. Skin scrapings were taken to confirm the diagnosis of scabies. There was a 93% resolution of pruritus with ivermectin and 48% with benzyl benzoate. No side effects were observed with ivermectin. Our results show that oral ivermectin is a promising, effective and safe alternative in both children and adults of Nigeria when compared to 25% benzyl benzoate topical application.

Topical ivermectin: a new successful treatment for scabies

Ivermectin is the only one of the avermectins that has been widely used in humans, since it is recommended as the treatment of choice for onchocerciasis, a filariasis that produces "river blindness," a parasitic endemic infestation in countries of West Equatorial Africa and in some areas of Central and South America. Also, ivermectin has been used for treating human endo- and ectoparasites with effective results and with almost no side effects. To study the efficacy of ivermectin for scabies, which is very common in Colombia, a trial with this drug that could be easily administered, with fast application and high efficacy, was undertaken. For this purpose, six complete families with active scabies, consisting of 12 adults and 20 children ranging in age from 1 to 10 years, were treated with 1% ivermectin in a solution of propylene glycol applied topically to the affected skin. The dose employed was 400 microg/kg, repeated once the following week. All patients were cured, tolerated the medication well, and there were no side effects or signs of recurrence 2, 4, or 6 weeks after therapy. In addition to its efficacy, easy administration, and lack of side effects, ivermectin is a low-cost medication.

Management of endemic outbreaks of scabies with allethrin, permethrin, and ivermectin

BACKGROUND

At three residences for the elderly, recurrent scabies infestations became out of control. Due to the failure of repeated, nonsynchronized therapeutic efforts with conventional external anti-scabies treatments, an eradication program had to be developed. We describe a protocol for the management of outbreaks of scabies.

METHODS

According to the clinical examination and microscopically identified mites, all individuals of the population (IOP: patients, staff, and family members) were divided into two groups: (a) healthy and infested IOP; and (b) cases with crusted scabies. The first group was treated simultaneously once with external scabicides (allethrin or permethrin). All others were hospitalized and treated either with systemic ivermectin or with the latter in combination with permethrin.

RESULTS

In 252 IOP living in three residences for the elderly, clinical signs of scabies were reported in 91.5%, 78.5%, and 15.4% of the patients (age 55-97 years; mean, 80.5 years), 54.1%, 32.9%, and 16.6% of staff members, and in 7%, 3%, and 0% of family members. The infested IOP showed crusted scabies (index cases) in 5.3%, 5.0%, and 1.7%, common scabies in 43.1%, 36.7%, and 7.1%, and postscabiotic dermatitis in 10.3%, 7.6%, and 3.5%. In 99.2% of the synchronously treated IOP in group (a) (n = 240), the conventional treatment with permethrin cream 5% or allethrin spray was effective. Group (b) (n=12) received ivermectin (12 mg) once (n=5) or twice (n= 7) after an interval of 8 days. One index case received permethrin three times.

CONCLUSIONS

Outbreaks of scabies in populations of elderly people require special management for disease control. Synchronous treatment with external permethrin cream 5% or allethrin spray, including all IOP once, and close control offers a time-saving, cheap, and reliable method. Crusted scabies should be treated by oral administration of ivermectin once or twice after an interval of 8 days. Additional applications of permethrin and mechanical clearing of hyperkeratotic subungual areas shorten the course.