Scabies: Symptoms, Transmission, and Diagnosis
Scabies is an infectious and communicable disease of the skin caused by the itch mite. It is characterized by pruritic papular lesions along the burrows containing the mites and their eggs. The lesions are chiefly found around the finger webs, wrists, elbows, a/cilia, nipples,s beltline areas, around the umbilicus, lower abdomen, genitals, thighs, and buttocks.
It causes itching which aggravates at night, possibly because of the increase in mite activity as body warmth increases under sheets or blankets. Secondary streptococcal infections may lead to rheumatic fever and glomerulonephritis. The disease is quite contagious.
Epidemiology of Scabies
Occurrence: Scabies is endemic all over the world. Its incidence is quite high in the BangladeshIndia-Pakistan subcontinent. It forms at least 10% of the skin diseases as seen in the OPD of the Calcutta School of Tropical Medicine. Its incidence is high in Bangladesh. Of the total attendance at the Central Skin and Social Hygiene Centre, Chittagong, during 1990 the scabies cases constituted 19.4%. At the skin and venereal disease OPD of the Sylhet Medical College, the incidence of scabies cases were found very high (nearly 50%).
Agent: Sarcoptes scabiei, the itch mite is the causative agent. It cannot survive long away from its human host.
Host: All ages, sexes, and races are susceptible to scabies; some resistance may be produced as immuno-deficient persons suffer from extensive lesions. It is not uncommon to see several family members infested while others completely spared. Differential susceptibility is not well understood, but mite allergy may play a role.
Environment: People living in unsanitary and poor housing conditions suffer more from the disease. Poverty-stricken people with poor hygienic habits and unclean clothing are the usual victims of the disease, but scabies ignores all social and economic barriers.
Reservoirs: Patients are the reservoirs. Animals are also affected by Sarcoptes and men contract the disease from animals through contact. The disease runs a mild course in man and Sarcoptes of animals do not reproduce in human skin. Human scabies affects animals.
Mode of transmission: The disease spreads usually by close personal contact, such as sleeping together, playing together, nursing or examining a patient. Sometimes it may spread through the use of contaminated towels, bed linen, and clothing. Even casual contact, such as shaking hands may spread the organism.
Period of communicability: Until the patient is cured completely or mites and eggs are destroyed by treatment. Incubation period: It varies from 2 to 6 weeks before the first experience. 1-4 days after re-exposure.
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The clinical picture with typical lesions in the target areas is usually diagnostic. Diagnosis is based on (a) intense itching at night, (b) when more than one member in the family have itching, (c) face and scalp are not usually affected in adults, (c) itching of nipples in female and itching papules in males on penis or scrotum. Diagnosis is confirmed by a demonstration of mite under a microscope.
Preventive measures: People should be educated in practicing good health habits with an emphasis on the improvement of personal hygiene. All patients should be diagnosed and treated early to prevent further spread of the disease.
Control measures: Children should be excluded from the school -until the day after treatment. All affected persons of a family should be treated simultaneously. Before treatment, all patients should have a good soap and warm water bath. The drugs used are: (a) Benzyl benzoate (25%) emulsion. It is smeared to the whole body from neck to feet except face and genital areas for 3 successive days; other drugs are; (b) monosulfiram (Tetmosol), (c) gamma benzene hexachloride (GBH) 1%, (d) crotamiton(10%) cream or lotion. (e) sulfur ointment (5-10%) in vaseline.