Scabies is caused by Sarcoptes scabei variant hominis, the itch mite. Mites are tiny animals related to spiders. The female mite is the troublemaker. She burrows into the skin, lays eggs and deposits feces there. The characteristic itching takes weeks to months to develop and is based on allergic mechanism.
The diagnosis of scabies depends on the following characteristics:
- Small burrows located on the hands, elbows, wrists, breasts of women, genitalia of men, or other areas. The head and neck are spared, except in infants.
- In about 1/3 to 1/2 of the cases, the mite, eggs, and/or feces can be demonstrated.
- The itching is most pronounced at night.
- Other family members (and household contacts) frequently itch, too.
Much has been written in the recent years about the best and safest treatment for scabies, and there is no general agreement. Most authorities, however, favor the use of 1% benzene hexachloride (Kwell).
Kwell is applied over the entire skin from the neck down, especially between the fingers and toes. It is important to reach all areas, except the face, with especially careful attention to the sites of greatest involvement. The medicine should be left on for 12-24 hours and washed off.
Two applicants of Kwell are all that is necessary. It is a toxic and irritating and should not be reapplied.
Until recently, children under two were treated with other agents. These agents are not as effective and useful for scabies, and have not proven to be any safer than Kwell.
Both 5% permetherin cream (Elimite) and Lindane (Kwell) Lotion are effective. It is rubbed into the skin from the scalp to the feet and left on overnight. A second treatment should be done in one week. No matter whether you use Kwell or Elimite, it is of the utmost importance that all other household members and close contacts be treated.
In the past year, ivermectin, has been approved for use. this is an oral agent which is probably more effective than the topicals; but also easier to use. Ivermectin (Stromectol) is not approved at this time for young children.
Ordinary laundering or dry cleaning of clothing, bed linens, and blankets is all that is required. Some patients, because of their scratching developed impetigo, and this will have to be treated with antibiotics. After treatment, it is uncommon for itching to last for 2-4 weeks.
Re-infestation: This is suspected in patients who persist in itching for more than two-four weeks after treatment. If evidence of active scabies is found, then re-treatement may be advisable. The patient should be questioned closely about the possible source for re-infestation.