Scabies Sitti Rahmah Umniyati

Scabies is a skin disease caused by a mite called Sarcoptes scabiei. It affects people of all ages. It is usually associated with crowded living conditions, and its outbreaks often accompany wars, famine and human migration

Learning objective Explain the signs and symptoms. etiology, life cycle, pathogenesis, diagnosis, prognosis, treatment, epidemiology and control of scabies.

Scabies burrows between the fingers Scabies rash on the hands. Burrows are visible.

A patient who was infested with scabies shows the typical pruritic red papules in the interdigital spaces of hand shows the typical pruritic red papules in the finger

A nursing home patient who was infested with scabies shows the typical pruritic red papules in the axilla. shows scabies infestation on the flexural wrist

Scabies with inflamed lesions in periumbilical distribution Scabies with flexural wrist involvement

Sarcoptes scabiei (itch mites) Phylum: Arthropoda Class: Arachnida Order: Acarina Family: Sarcoptidae Genus: Sarcoptes Species: Sarcoptes scabiei

Life Cycle Form a lateral branch 3 days First nymph male Burrows Into the skin 2to3 mm at night 2nd nymph Female

The life cycle is completed in 8-15 days The life cycle is completed in 8-15 days. The female mite burrows into the skin, and tunnels through the upper layers of the epidermis, depositing fertile eggs. Six-legged larvae hatch from these eggs , leave the tunnel, and form a lateral branch. Once in place the larvae eat, molt, and transform into eight-legged nymphs. The female has 2 nymphal stages, the male only a single one. After fertilization, young adult female begin construction of a new tunnel.

The male excavates lateral pockets in the burrows The female during her life span 0f 4-5 weeks deposits up to40-50 eggs, 2-4 at a time, in the burrow. The female may survive off the host for 2-3 days at room temperature.

Mode of transmission Scabies usually spreads through direct contact with an infected person. Clothing and bedding may also carry the mite and transmit the disease.

Incubation period For people without previous exposure of the disease, incubation period is around two to six weeks. People who have been previously infested may develop symptoms earlier, usually within 1-4 days after re-exposure.

Diagnosis Diagnosis can be confirmed by picking up adult female mites at the ends of their borrows or by scraping the affected skin lightly covered with mineral oil. The srapings are then examined under a microscope to search for immature or adult mites or for eggs Other methods that have been proposed for obtaining specimens are the use of cellophan tape and various synthetic glues.

Differential diagnosis Impetigo Scabies

Differential diagnosis Scarlet Fever Scabies

Pathogenesis Infection begin when fertile female mites are transfered from infected individuals by direct contact Female, usually at night , burrows into the skin, progressing at the rate of about 2-3 mm per day. The burrow is confined to the corneous layer of the skin Lesions appear as short, sinous, or slightly raised , cutaneous burrows Thread-like lesions or vesicles may be seen on the skin

Itching and skin eruption are usually delayed for several weeks. The typical scabies rash appears on various part of the body represent a generalized response to the allergen. Minute vesicular swelling , posibbly produce by the iritating fecal deposits or excretions

Warmth , causes scratching, which spreads the infestation, iritates the lesions, and induces secondary bacterial infection. As a result multiple papular vesicular, and pustular lesions may be produced. The face and scalp may be affected in infants and children, whereas adults seldom has lesions in these areas.

Norwegian scabies A rare condition known as Norwegian, or crusted scabies my result from hyperinfection with thousands to millions of mites. The consequence is a crusted dermatoses of the hands and feet and often much of the body. This condition is characteristic of infected individuals who cannot take care of themselves and is often reported in mental hospitals. It is also reported in individuals treated with immunosusuppressive drugs.

Treatment Infestation with the itch mites can be eradicated by the use of 1% gamma benzene hexachloride in a lotion BASE. The medication should be applied in the evening after the lesions have been cleaned and soften by soaking in a warm water and should be left of overnight. One or two additional application, at weekly intervals may be necessary to kill those mites that hatch subsequent to the initial treatment.

For pediatric use, 10 per cent concentration , N-ethyl-o crotonotoluide (Eurax) in a cream or lotion base, is prefered by many physicians. It is applied to the skin of whole body from the chin downs and a second application is made after 24 hours A cleansing bath is given after another 24 hours. Allergic reactions and local irritation have been reported. Treatment of choice for scabies is to apply permethrin (Elimite) overnight from the neck down, and to ensure that everyone in the patient's family is treated at the same time

Epidemiology Scabies is transmitted by personal contact especially by person sleeping together, less frequently by towels, clothing and bed linens. Infectivity is low and the indication tends to run a limited course in healthy persons of cleanly habits

Conclusion The main symptom is intensive itchiness which is more severe at night. The common affected areas are finger webs and the skin folds of wrists, armpits, buttocks, groins, elbows, nipples and lower abdomen. The face and scalp are usually not affected, except in small infants. Thread-like lesions or vesicles may be seen on the skin

Control Prevention of scabies requires the treatment of infected individuals, the sterilizations of garments and bedding, and personal cleanliness

Reference Markell, E.K., Voge, M., John, D.T. 1986 Medical Parasitology,6th edition, W.B. Saunders Company, Philadelphia, London, Toronto, Mexico City, Rio De Janeiro, Sydney, Tokyo, Hongkong Despommier, D.D., Gwadz, R.W., Hotez, P.J., Karapelou J.W., Grave, E.V 1995. Parasitic Diseases, 3rd ed. Springer Verlag, New York, Belgia, Heidelberg, London, Paris, Tokyo, Hongkong, Barcelona, Budapest

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