Summary about Disease
Scabies is a contagious skin infestation caused by the microscopic human itch mite Sarcoptes scabiei. The mites burrow into the upper layer of the skin where they live and lay their eggs. This causes intense itching and a pimple-like skin rash. Scabies can affect people of all ages and socioeconomic backgrounds worldwide.
Symptoms
Intense itching, especially at night.
A pimple-like itchy rash.
Tiny blisters or bumps.
Thin, irregular, wavy lines (burrows) on the skin.
Sores caused by scratching.
Common locations for the rash include between the fingers, in the armpits, around the waist, on the wrists, inner elbows, soles of the feet, around the nipples, on the penis, and on the buttocks. In infants and young children, the rash can also be on the scalp, face, neck, palms, and soles.
Causes
Scabies is caused by infestation with the human itch mite, Sarcoptes scabiei. The mites are typically transmitted by direct, prolonged skin-to-skin contact with a person who has scabies. Less commonly, scabies can be spread by sharing items such as clothing, bedding, or towels used by an infested person.
Medicine Used
Permethrin cream (5%): This is the most commonly prescribed treatment. It is applied to the entire body from the neck down and washed off after 8-14 hours. A second application may be needed after one week.
Ivermectin (oral): This is an oral medication usually prescribed for people who cannot tolerate topical treatments or who have crusted scabies. It is typically taken as a single dose, followed by a second dose one to two weeks later.
Other topical medications: Lindane lotion (use with caution due to potential side effects), crotamiton cream, and sulfur ointment may also be prescribed, although they are generally less preferred.
Antihistamines and topical steroids can be used to help control the itching.
Is Communicable
Yes, scabies is highly communicable, primarily through direct, prolonged skin-to-skin contact. It can also, though less commonly, be spread by sharing contaminated items like clothing or bedding.
Precautions
Avoid close contact: Avoid direct skin-to-skin contact with individuals who have scabies.
Wash clothing and bedding: Wash all clothing, bedding, and towels used by the infested person in hot water and dry them on high heat. Items that cannot be washed should be dry-cleaned or sealed in a plastic bag for at least 72 hours.
Treat all household members and close contacts: Everyone in the household and close contacts should be treated at the same time, even if they do not have symptoms.
Avoid sharing personal items: Do not share clothing, towels, or bedding with others.
Clean and disinfect: Clean and disinfect surfaces that may have been contaminated with mites.
Inform others: If you have scabies, inform close contacts so they can seek treatment.
How long does an outbreak last?
If left untreated, a scabies infestation can persist for months or even years. With proper treatment, the symptoms usually resolve within a few weeks. However, itching may continue for several weeks even after the mites are killed, as the body reacts to the dead mites and their waste products. A second treatment course is sometimes required to fully eradicate the mites.
How is it diagnosed?
Scabies is typically diagnosed based on a physical examination and the characteristic symptoms (intense itching and rash). A doctor may confirm the diagnosis by taking a skin scraping and examining it under a microscope to look for mites, eggs, or fecal matter. However, the absence of mites in a scraping does not necessarily rule out scabies, as the mites can be difficult to find.
Timeline of Symptoms
Initial infestation: It can take 2-6 weeks for symptoms to appear after the first infestation. During this time, the person is contagious but may not experience any itching or rash.
Re-infestation: If someone has had scabies before, symptoms usually appear much more quickly, often within 1-4 days of re-exposure.
During infestation: The characteristic intense itching, rash, and burrows develop and persist until treated. The itching is often worse at night.
After treatment: Itching may continue for 2-4 weeks after successful treatment as the body reacts to the dead mites. Skin irritation can also persist for some time.
Important Considerations
Crusted Scabies: This is a severe form of scabies that is highly contagious and often occurs in individuals with weakened immune systems, elderly individuals, or those with disabilities that prevent them from scratching. It is characterized by thick crusts of skin that contain large numbers of mites. Crusted scabies requires more aggressive treatment.
Itching After Treatment: The itching associated with scabies can persist for several weeks after successful treatment. This is due to an allergic reaction to the dead mites and their waste. Calamine lotion, antihistamines, and topical corticosteroids can help relieve the itching.
Secondary Infections: Scratching can lead to secondary bacterial infections of the skin. These infections may require antibiotic treatment.
Treatment Failure: If symptoms persist despite treatment, it is important to consult a doctor. Possible reasons for treatment failure include incorrect application of the medication, re-infestation, or resistance to the medication.
Public Health Importance: Scabies outbreaks can occur in crowded living conditions such as nursing homes, hospitals, and prisons. Public health measures, such as screening and treatment of all individuals in affected facilities, are important to control outbreaks.