REFERAT

Scabies

Adviser :

dr. Suswardana, Sp.KK

Created by :

Lira Fitrianti

121. 0221.078

Departement of Dermatovenereology

RSAL Mintohardjo

FK UPN (Pembangunan Nasional University)

Periode 2013

Scabies

Abstract

Scabies is a human skin infestation caused by thr penetration of the obligate human parasitic mite Sarcoptes scabiei var. hominis into the epidermis. The diagnosis of scabies rests largely on the history and examination of the patient, as well as on the history of the family and close contacts. Classic manifestations of scabies include generalized and intense itching,

usually sparing the face and head. Pruritus is worse at night. For the treatment of classical scabies, permethrin 5% cream is our preferred agent. Ivermectin, administered orally at a dose of 200 μg per kilogram of body weight, is an effective alternative treatment.

Keyword : scabies, pruritus at night, paracitic.

INTRODUCTION

Scabies is a human skin infestation caused by thr penetration of the obligate human parasitic mite Sarcoptes scabiei var. hominis into the epidermis. The scabies mite is an arthropod of the order Acarina which was first identified in the 1600s, but was not recognized as the cause of the skin eruption until 1700s. There are estimatess that over 300 million people worldwide are infected with the scabies mite. Scabies affects all socioeconomic classes, with women and children being disproportionately infected. It tends to be more prevalent in urban areas, particularly in overcrowded regions.1

The scabies mite has four pairs of legs and measures 0.3 mm in diameter. It is therefore not easily seen with the naked eye. It lives its entire 30-days life cycle in and on the epidermis. The female mite burrows into the stratum corneum within 20 inutes and lays approxiatele eggs a day. The eggs hatch fter 4 days, and the larvae migrate to the skin surface and mature into adult. The 3 eggs a day. The a The male, which is slightly smaller than the female, fall off the skin and perishes.1

STRATEGIES AND EVIDENCEDiagnosis

The diagnosis of scabies rests largely on the history and examination of the patient, as well as on the history of the family and close contacts. Classic manifestations of scabies include generalized and intense itching, usually sparing the face and head. Pruritus is worse at night. The lesions are located mostly in the finger webs (Fig. 2A), on theflexor surfaces of the wrists, on the elbows, in the axillae, on the buttocks

and genitalia (Fig. 2B), and on the breasts of women (Fig. 2C). Inflammatory pruritic papules are present at most sites. Burrows (Fig. 2D) and nodules (generally in the genital regions and axillae) are specific for scabies but may be absent. Nonspecific secondary lesions, including excoriations, eczematization (Fig. 2E), and impetiginization, may occur anywhere.2

Scabies occasionally presents in atypical forms (Table 1) that are more difficult to diagnose than the classic forms and, therefore, may be more likely to lead to outbreaks. Atypical presentations in infants often involve the face, scalp, palms, and soles.2

Diagnostic Tests

Definitive diagnosis relies on the identification of mites, eggs, eggshell fragments, or mite pellets. Multiple superficial skin samples should be obtained from characteristic lesions — specifically, burrows or papules and vesicles in the site of burrows — by scraping laterally across the skin with a blade, taking care to avoid bleeding. The specimens can be examined with a light microscope under low power (Fig. 1).2

In atypical cases or when direct examination is not possible, a skin biopsy may potentially confirm the diagnosis (Fig. 4). However, mites orother diagnostic findings are frequently absent, and the histologic examination usually shows a nonspecific, delayed hypersensitivity reaction.2

Treatment

Our recommendations for the treatment of various scabies syndromes are summarized in (Table 2). For the treatment of classical scabies, permethrin 5% cream is our preferred agent. To ensure a reliable cure, the cream should be applied to the entire surface of the skin except around the eyes. Although some guidelines suggest that topical therapy need not be applied above the neck, we believe that including this area is particularly important in small children and the elderly, in whom the infection quite often involves the scalp. Particular attention should be paid to the areas that are most often involved, including the areas between the fingers and toes, under the arms, and under the fingernails and toenails; the wrists; the external genitalia; and the buttocks.23 To maximize exposure of the mites to the drug, it is generally recommended that the cream be applied in the evening and left on overnight. To eradicate any mites that were not exposed at the time of the first treatment, it is generally recommended that a second application be administered 1 to 2 weeks after the first. However, the efficacy of one application as compared with two applications has not been formally tested, and the optimal interval between doses has not been precisely defined.3

Ivermectin, administered orally at a dose of 200 μg per kilogram of body weight, is an effective alternative treatment. Since ingestion of food increases the bioavailability of ivermectin by a factor of two,24 taking the drug with food will enhance the penetration of the drug into the epidermis. Since ivermectin is not

ovicidal, it is recommended that two doses, separated by 1 to 2 weeks, be administered for the treatment of classical scabies. The serum half-life of ivermectin is 18 hours,24 with drug elimination occurring through metabolism in the liver and excretion of inactive metabolites through the kidneys. Adjustment of the dose is not necessary in patients with renal impairment. However, the safety of administering multiple doses of ivermectin in patients with severe liver disease has not been studied.3

Tabel 2. Therapies for scabies

SUMMARY AND RECOMMENDATIONS

Patients with scabies should be informed that scabies is benign but transmissible and that several treatments are available. Treatment should be recommended on the basis of a confirmed diagnosis. Topical permethrin is reasonable first-line therapy in the United States. Where permethrin is not available (e.g., in France), topical benzyl benzoate or oral ivermectin are good choices. Oral ivermectin is preferred for patients who cannot tolerate topical therapy and those who are unlikely to adhere to a regimen of such therapy.3

REFERENCES

1. WolffK, Goldsmith L. A, Katz S. I, Gilchrest B. A, Paller A. S, Leffeil D. J. Scabies. Fitzpatrick’s dermatology in general medicine. 7 ed. New York : Thhe McGraw Hill Medical; 2008. p. 2029-34.

2. Chosidow O. Scabies. N Engl J Med 2006;354:1718-27.

3. Currie B. J, McCarthy J. S. Permethrin and Invermectin for Scabies. N Engl J Med 2010;362:717-25.