Scabies is a very contagious skin condition that is caused by a mite that is so small it can only be seen with a magnifying glass or under a microscope. The mite cannot live more than three days without a human host, but it can survive up to a month when living on a human. The mite also lays eggs in human skin, which hatch and grow into adult mites. This means that symptoms of the condition can last for months or even years.
The rash caused by scabies is extremely itchy and is sometimes called "the seven-year itch". The rash can be subtle, and sometimes scabies is hard to diagnose. The mite is spread from person to person by close contact. Animals can harbor a similar mite, but when the animal mite is passed to people, it cannot reproduce and dies within a few days.
Scabies affect everyone regardless of age, gender, race, social class, or personal-hygiene habits. However, it is most common among household members and sexual partners of affected individuals. Scabies is also common in congested areas, such as nursing homes and hospitals, where it can spread widely. In people who have poor immune systems or who are malnourished, scabies can cause a syndrome called "crusted scabies" or "Norwegian scabies", which causes skin thickening and a scaly rash.
Other conditions are sometimes confused with scabies. The scabies mite has no relation to body lice, although the treatment of the resulting skin disease is sometimes the same. Scabies are also different from bed bugs. In contrast to scabies, bed bugs are visible to the naked eye and can live for long periods of time without feeding.
Chiggers are a type of mite that can feed off human blood, but unlike scabies, they are acquired through contact with vegetation and feed for only a few days. Less commonly, the rashes of other skin diseases such as ringworm, shingles, eczema, allergic reactions (hives), or impetigo may be confused with that of scabies.
Symptoms include severe and continuous itching, especially at night. An indication that you may have scabies is if other members of your household are experiencing the same symptoms.
What do scabies look like?
The skin may show signs of small insect-type bites, or the lesions may look like pimples. The skin may also be red and or have sores due to scratching of the area. Open scabs or sores are susceptible to infection with bacteria.
A burrow (a short S-shaped track that indicates the mite's movement under the skin) may also be visible. The average affected person has only five to 10 mites on their body at a time. Burrows may be small enough to be overlooked. Thus, scabies also should be considered whenever there is intense itching without an obvious rash, bite, or burrow.
Scabies frequently occur in the crevasses of the body such as between the fingers and toes, the buttocks, the elbows, the waist area, the genital area, and under the breasts in women.
In crusted (Norwegian) scabies, the body is covered with a thick, dry, and scaly rash. The rash of crusted scabies may or may not itch, but it contains thousands to millions of mites. Crusted scabies is the most contagious form of scabies and the hardest to treat.
Scabies is caused by an eight-legged mite (Sarcoptes scabiei var. hominis) that is less than 0.5 mm long. The life cycle of the scabies mite starts when the female tunnels (burrows) into the skin and deposits her eggs. Larvae hatch from the eggs within three to 10 days and molt to become nymphs. Nymphs mature into adults that deposit additional eggs and live approximately 4 weeks.
Burrowing and movement of the mites cause intense itching due to a type of allergic reaction. If the person has never been exposed to scabies before, he or she may not show symptoms until four to six weeks after the initial infestation. Individuals who have been exposed in the past usually show symptoms within a few days.
Where does scabies come from?
Scabies is almost always spread by protracted skin-to-skin contact with a person who carries the mite. The mites often begin to burrow at the site where they enter the body. Thus, skin transmission during sexual intercourse results in an infestation in the groin area.
It is important to point out that scabies is not always asexually transmitted disease (STD) and may be acquired through casual contact. Less commonly, scabies infestation can happen through the sharing of clothes and bedding. Theoretically, you can get scabies from touching something that the mite is on, but that is not a major mode of transmission.
Although you cannot cure a case of scabies without prescription medication from a doctor, there are certain things you can do at home to keep from re-infesting yourself or your family.
- Wash all clothing, towels, and bed linens that you have used in the last three days. Use hot water. You should use the dryer at high heat rather than air drying. Since the mites can survive on nonliving objects for several days, place the objects that are not machine washable (such as coats and stuffed toys) into a bag and store for a week.
- Use the medication as prescribed and instructed. Do not use it more than instructed because you risk causing chemical irritation of your skin.
- You can also treat itching with antihistamine medications such asdiphenhydramine (Benadryl), hydroxyzine (Atarax), cetirizine (Zyrtec), andpromethazine (Phenergan).
- Cut your nails, and clean under them thoroughly to remove any mites or eggs that may be present.
- Thoroughly vacuum your rugs, furniture, bedding, and car interior and throw the vacuum-cleaner bag away when finished.
- Try to avoid scratching. Keep any open sores clean.