The itchy rash of scabies develops when a pregnant female mite burrows into the outer surface (superficial) skin and lays eggs. The human immune system is highly sensitive to the presence of the mite and produces a massive allergic response, which causes intense itching. Although a typical infection includes only 10–20 mites, people are so sensitive to the mite that hundreds of itchy skin lesions are created. Without treatment, the condition will not usually improve.
Scabies is not caused by lack of personal hygiene, though it is more frequently seen in people who live in crowded conditions.
Other individuals at risk include:
- Mothers of young children
- Sexually active young adults
- People living in nursing homes
- Nursing home staff
- The areas between the fingers (finger webs)
- Inner wrists, inner elbows, and armpits
- Breasts of females and genitalia of males
- Navel (umbilicus)
- Lower abdomen
- Backs of knees
- Trunk, arms, and legs
- Head and neck
- Palms of the hands and soles of the feet
Scabies is intensely itchy, especially at night.
Scratching the itchy lesions can create breaks in the skin, and these breaks can become infected with bacteria.
People who are exposed to scabies may not develop itchy lesions for up to 6 weeks after becoming infested, as the immune system takes some time to recognize the mites and develop an allergic response to them. However, individuals who have had scabies before may develop the rash within several days of re-exposure.
Scabies requires prescription medication in order to stop the infestation. Once your child is under a doctor's care, there are steps you can take to prevent scabies from coming back:
- Mites cannot survive off the human body for more than 48–71 hours. Therefore, wash all clothing, bedding, and towels used by the infested person in the previous 72 hours in hot water and dry these items in a hot dryer.
- Vacuum all carpets, rugs, and upholstered furniture, and discard the vacuum bags.
In most cases of scabies, the doctor may recommend a topical cream or lotion, such as:
- Permethrin cream – Apply at night, and rinse off in the morning. Use the permethrin cream again in 1 week.
- Crotamiton cream – Apply once daily for 2 consecutive days, and rinse off 48 hours after last application.
- Sulfur ointment – Apply nightly for 3 consecutive nights, and rinse off 24 hours after last application. This is often the best choice for babies and for pregnant and nursing women because it is very safe to use.
- Lindane lotion or cream – Wash the cream or lotion off after 8 hours. Lindane may be toxic to some people. Infants and young children should not be treated with lindane, nor should pregnant or breast-feeding women or people with diseases affecting the nerves (neurological diseases).
- Apply to the entire body from the neck down.
- Smear the product beneath your child's fingernails and toenails.
- Apply to body folds, including inside the navel, in the buttock crease, and between the toes.
- Ivermectin pills – Take once and then repeat 1–2 weeks later. Ivermectin should not be used for children aged younger than 5 years or who weigh less than 15 kg (about 35 lb), or pregnant or lactating women.
- Antihistamine pill.
- Antibiotic pills – If any scratched areas appear to be infected with bacteria, your physician may prescribe oral antibiotics.
Your doctor should remind you to launder towels, bed linens, and clothes used by your child in the previous 72 hours and to vacuum carpets, rugs, and upholstered furniture.
Household members, sexual partners, and anyone else with prolonged skin-to-skin contact with an infested person should also seek treatment from their doctors. Since the initial development (incubation time) for scabies infestations can be from 6–8 weeks, people may be infected with scabies, but since they do not yet feel itchy, they are unaware that they have infestation. If untreated, these close contacts could pass the mites back to your child. Ideally, everyone should be treated at the same time in order to prevent re-infestation.