SCABIES – DEFINITION , SIGNS AND SYMPTOMS,DIAGNOSIS , TREATMENT.
SCABIES – OVERVIEW
Scabies, also called seven-year itch, is a highly contagious skin infestation by the mite Sarcoptes scabiei.The most common symptoms are worse itchiness and a pimple-like rash. Occasionally tiny burrows may be seen in the skin. When first infected, usually two to six weeks are required before symptoms occur. If you develops a second infection( again infection) later in life, symptoms may begin within a day. These symptoms can be present across most of the body or just certain areas such as the wrists, between fingers, or along the waistline. The head may be affected, but this is typically only in young children. The itch is often worse at night. Scratching may cause skin breakdown and an additional bacterial infection of the skin.
Scabies is caused by infection with the female mite Sarcoptes scabiei (Culprit) .The mites burrow into the skin to live and deposit eggs. The symptoms of scabies are due to an allergic reaction to the mites. Often only between ten and fifteen mites are involved in an infection.
Scabies is most often spread during a relatively long period of direct skin contact with an infected person such as that which may occur during sex. Spread of disease may occur even if the person has not developed symptoms yet. Crowded living conditions such as those found in child care facilities, group homes, and prisons increase the risk of spread. Areas with a lack of access to water also have higher rates of disease.Crusted scabies is a more severe form of the disease. It typically only occurs in those with a poor immune system and people may have millions of mites, making them much more contagious. In these cases spread of infection may occur during brief contact or via contaminated objects. The mite is very small and usually not directly visible. Diagnosis is based on the signs and symptoms.
A number of medications are available to treat those infected, including permethrin, crotamiton and lindane creams and ivermectin pills. Sexual contacts within the last month and people who live in the same house should also be treated at the same time. Bedding and clothing used in the last three days should be washed in hot water and dried in a hot dryer. As the mite does not live for more than three days away from human skin more washing is not needed. Symptoms may continue for two to four weeks following treatment. If after this time there continue to be symptoms retreatment may be needed.
Scabies is one of the three most common skin disorders in children, along with ringworm and bacterial skin infections. equally common in both sexes The young and the old are more commonly affected.
SIGNS AND SYMPTOMS
The characteristic symptoms of a scabies infection include intense ITCHING and superficial burrows. The burrow tracks are often linear, to the point that a neat “line” of four or more closely placed and equally developed mosquito-like “bites” is almost diagnostic of the disease.
Because the host develops the symptoms as a reaction to the mites’ presence over time, there is typically a delay of four to six weeks between the onset of infestation and the onset of itching. Similarly, symptoms often persist for one to several weeks after successful eradication of the mites. As noted, those re-exposed to scabies after successful treatment may exhibit symptoms of the new infestation in a much shorter period—as little as one to four days.
The superficial burrows of scabies usually occur in the area of the finger webs, feet, ventral wrists, elbows, back, buttocks, and external genitals.Except in infants and the immunosuppressed, infection generally does not occur in the skin of the face or scalp. The burrows are created by excavation of the adult mite in the epidermis.
HOW THE DOCTORS WILL DIAGNOSE SCABIS??
Scabies may be diagnosed clinically in geographical areas where it is common when diffuse itching presents along with either lesions in two typical spots or there is itchiness of another household member. The classical sign of scabies is the burrows made by the mites within the skin.
To detect the burrow, the suspected area is rubbed with ink from a fountain pen or a topical tetracycline solution, which glows under a special light. The skin is then wiped with an alcohol pad.
If the person is infected with scabies, the characteristic zigzag or S pattern of the burrow will appear across the skin; however, interpreting this test may be difficult as the burrows are scarce and may be obscured by scratch marks.
A definitive diagnosis is made by finding either the scabies mites or their eggs and fecal pellets. Searches for these signs involve either scraping a suspected area, mounting the sample in potassium hydroxide and examining it under a microscope, or using dermoscopy to examine the skin directly.
PATHOPHYSIOLOGY OF SCABIES
The symptoms are caused by an allergic reaction of the host’s body to mite proteins, though exactly which proteins remains a topic of study. The mite proteins are also present from the gut, in mite feces, which are deposited under the skin. The allergic reaction is both of the delayed (cell-mediated) and immediate (antibody-mediated) type, and involves IgE (antibodies, it is presumed, mediate the very rapid symptoms on reinfection).The allergy-type symptoms (itching) continue for some days, and even several weeks, after all mites are killed. New lesions may appear for a few days after mites are eradicated. Nodular lesions from scabies may continue to be symptomatic for weeks after the mites have been killed.
MANAGEMENT & TREATMENT FOR SCABIES
A number of medications are effective in treating scabies. Treatment should involve the entire household, and any others who have had recent, prolonged contact with the infested individual. Options to control itchiness include antihistamines and prescription anti-inflammatory agents. Bedding, clothing and towels used during the previous three days should be washed in hot water and dried in a hot dryer.
Permethrin ( highly effective)
Permethrin is the most effective treatment for scabies, and remains the treatment of choice. It is applied from the neck down, usually before bedtime, and left on for about eight to 14 hours, then washed off in the morning.Care should be taken to coat the entire skin surface, not just symptomatic areas; any patch of skin left untreated can provide a “safe haven” for one or more mites to survive. One application is normally sufficient, as permethrin kills eggs and hatchlings as well as adult mites, though many physicians recommend a second application three to seven days later as a precaution.
Crusted scabies may require multiple applications, or supplemental treatment with oral ivermectin (below). Permethrin may cause slight irritation of the skin that is usually tolerable.
Oral Ivermectin is effective in eradicating scabies, often in a single dose. It is the treatment of choice for crusted scabies, and is sometimes prescribed in combination with a topical agent.It has not been tested on infants, and is not recommended for children under six years of age.
Topical ivermectin preparations have been shown to be effective for scabies in adults, though only one such formulation is available in the United States at present, and it is not FDA approved as a scabies treatment.It has also been useful for sarcoptic mange (the veterinary analog of human scabies)
FLASH REVIEW( THINGS TO REMEMBER)
SCABIES – Sarcoptes scabiei , female mite.severe itchiness, zigzag lesions, IgE antibody reaction , permethrin – Gold standard for scabies…….
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