Key messages

  • Scabies is a highly contagious parasitic skin infestation.
  • Crusted (Norwegian) scabies infestations are particularly problematic for older people, people who are immunosuppressed, and people who are frail or weak.
  • Both cases and contacts should be treated as soon as possible.
  • Linen, clothing and towels should be washed appropriately to prevent reinfestation.

General information about scabies

Typical scabies

Human scabies is an infestation of the skin by the human itch mite called Sarcoptes scabiei. The female scabies mite burrows into the upper layer of the skin, where it lives and lays its eggs. When the mites hatch, they move out of their burrows from under the skin. They make more burrows and lay more eggs. While on the skin’s surface, mites hold on to the skin using sucker-like pads on the anterior legs.

The mite undergoes four stages in its life cycle: egg, lava, nymph and adult.

Life stages of the human itch mite

1. The female mites deposit two or three eggs per day as they burrow under the skin.

2. Eggs hatch in 3–4 days. After the eggs hatch, the larvae migrate to the skin surface and burrow into the skin. These short burrows are called molting pouches and are almost invisible.

3. The larval stage lasts about 3–4 days.

4. Mating occurs after the active male penetrates the molting pouch of the adult female.

5. Mating takes place only once and leaves the female fertile for the rest of her life. After mating, the male dies. The impregnated female leaves the burrow and wanders on the surface of the skin until she finds a suitable site for a permanent burrow, where she lays eggs for the rest of her life (1–2 months).

Crusted (Norwegian) scabies

Crusted scabies, also called Norwegian scabies, is a severe form of scabies that can occur in people who are immunocompromised (have a weak immune system), elderly, disabled or debilitated.

In typical scabies, the estimated number of mites per person is 10–15. In crusted scabies, mites are much more numerous (up to 2 million). Because people are infested with a large number of mites, they are more contagious.

Epidemiology and risk factors – scabies

Transmission

The scabies mite is usually spread by direct, prolonged, skin-to-skin contact with a person who has scabies.

Generally, contact must be prolonged, such as sleeping or having sex with a person infested with scabies. The longer the skin-to-skin contact, the greater the likelihood of transmission. The risk of transmission from skin-to-skin contact is higher with people who have crusted (Norwegian) scabies.

Scabies is sometimes spread indirectly by sharing articles such as clothing, towels or bedding used by an infested person; such indirect spread can occur much more easily when the infested person has crusted (Norwegian) scabies.

Scabies can also spread more easily in crowded conditions where close body and skin contact is frequent, such as in families, residential aged care facilities and prisons.

People at risk

Scabies is found worldwide, and can affect people of all races and social classes.

Facilities such as residential aged care facilities and prisons are often sites of scabies outbreaks.

Common symptoms of scabies

Typical scabies

The common symptoms of scabies are:

  • intense itching, which may be worse at night, or after a hot bath or shower
  • a pimple-like itchy skin rash (bumpy red rash); itchy skin may become thick, scaly, scabbed and criss-crossed with scratch marks
  • burrows that appear on the skin as short, wavy, raised, reddish or darkened lines and can be a centimetre or more in length.

The itch and rash are caused by sensitisation (a type of allergic reaction) to mites and their faeces. Itching and rash may affect much of the body or may be limited to common sites such as:

  • between the fingers
  • wrists
  • elbows
  • penis
  • nipple
  • waist
  • buttocks
  • shoulder blades.

The head, face, neck, palms and soles are often involved in infants and very young children, but not usually in adults and older children.

Burrows may be difficult to find. Look for burrows in the webbing between the fingers; in the skin folds on the wrist, elbow or knee; and on the penis, breasts or shoulder blades.

Crusted (Norwegian) scabies

Symptoms of crusted (Norwegian) scabies include thick crusts of skin that contain large numbers of scabies mites and eggs.

The usual severe itch and rash may be absent in people with crusted (Norwegian) scabies.

Complications of scabies infestations

The intense itching and scratching can cause skin sores. These sores can become infected with bacteria on the skin, such as Staphylococcus aureus or beta-haemolytic streptococci.

Sometimes bacterial skin infections can lead to an inflammation of the kidneys called post-streptococcal glomerulonephritis.

Incubation period of scabies

In people who have never had scabies, it will take 4–6 weeks for symptoms to begin. During this period, the infested person can spread scabies.

In people who have previously been infested with scabies and are exposed again, symptoms can begin within 1–4 days.

Diagnosis of scabies

Diagnosis is usually made clinically by examining the body for a scabies-like rash or burrows.

The diagnosis can be confirmed by taking skin scrapings of non-excoriated or non-inflamed areas (burrows and pimple-like rash) using a stitch cutter. Gently scrape the suspected area or burrow using the back of the stitch cutter or by carefully removing the mite from the end of the burrow using the tip of a needle. Collect the specimen (skin scrapings or mite) into a specimen container and transfer it to your pathology service, where it will be examined under a microscope.

A negative result from a person who has had skin scrapings is not conclusive because the infested person may have few mites, and these can be missed easily.

General treatment for scabies

Scabies can be treated with anti-scabies lotions or creams.

Treatment lotions and creams are available from pharmacists, and a prescription is not required.

Recommended treatments include:

  • permethrin preparations (for example, Lyclear scabies cream)
  • benzyl benzoate 25% preparations (for example, Benzemul application lotion).

Follow the manufacturer’s instructions for application.

Scabicide lotions or creams, including benzoate 25% preparations, should be applied to all areas of the body from the neck down to the feet and toes. The treatment may also need to be applied to the face, neck and scalp if these areas are involved.

The lotion or cream should be applied to a clean body and left on for the recommended time before it is washed off.

Two or more applications, each about 1 week apart, may be necessary to eliminate all mites, particularly when treating crusted (Norwegian) scabies.

Some patients with severely crusted scabies lesions, or in whom the lotions or creams have failed, may require treatment with a medication called ivermectin.

Because the symptoms of scabies are due to a hypersensitive reaction (a type of allergic reaction) to mites and their faeces, itching may continue for several weeks after treatment, even if all mites and their eggs are killed.

If itching is still present more than 2–4 weeks after treatment, or if new burrows or pimple-like rash lesions continue to appear, retreatment may be necessary.

Consult an experienced dermatologist for assistance in differentiating skin rashes and confirming the diagnosis of scabies.

After treatment

Clean clothing should be worn after treatment.

Mites generally do not survive more than 2–3 days away from human skin.

Bedding, clothing and towels used by infested people any time during the 3 days before treatment should be machine washed and dried using the hot water and hot dryer cycles, or be dry-cleaned.

Items that cannot be dry-cleaned or laundered can be disinfested by storing in a closed plastic bag for several days to a week (at least 72 hours).

Prevention and control of scabies

Early detection, treatment and implementation of appropriate infection control precautions are essential in preventing scabies outbreaks.

Facilities should maintain a high level of suspicion that undiagnosed skin rashes and conditions may be scabies, even if the characteristic signs or symptoms of scabies (for example, itching) are absent.

A scabies outbreak suggests that transmission has been occurring within the facility for several weeks to months, with the likelihood that some infested staff or patients may have had time to spread scabies elsewhere in the community, including other facilities.

Measures to control scabies in a facility depend on factors such as how many cases are diagnosed or suspected, how long infested people have been at the facility while undiagnosed and/or unsuccessfully treated, and whether any of the cases are crusted (Norwegian) scabies.

Preventing transmission of scabies

Guidelines for preventing transmission vary depending on the type of scabies, the number of cases, and the degree and duration of skin exposure that a person has had to an infested person.

Guidelines include the following:

  • a single case of scabies – see Appendix 1
  • multiple cases of scabies – see Appendix 2
  • crusted (Norwegian) scabies (single or multiple cases) – see Appendix 3.

Role of animals in scabies transmission

Animals do not spread human scabies. Pets can be infested with a different kind of scabies mite that cannot survive or reproduce on humans. The animal mite causes mange. If the animal has close contact with humans, the mite can get under the skin of humans, and cause temporary itching and skin irritation; however, the mite cannot reproduce on the skin and will die in a couple of days. The animal should receive veterinary treatment for mange.

Appendix 1 – a single case of scabies

Surveillance

Have an active program for early detection of infested patients and staff.

When a single case is indentified, check that there are no other cases in the facility.

Maintain a high index of suspicion that scabies may be the cause of undiagnosed skin rashes. Suspected cases should be evaluated by their doctor and, if necessary, confirmed by obtaining skin scrapings.

All new patients should be screened for scabies.

Maintain records with the patient’s name, age, sex, room number, room-mate names, skin scraping status and results, and names of all staff who provided hands-on care to the patient before the implementation of infection control measures.

Diagnostic services

Consult with a dermatologist for assistance in differentiating skin rashes and confirming the diagnosis of scabies.

Ensure that a staff member is trained and experienced in obtaining skin scrapings to identify scabies mites.

Control and treatment

Isolation

Where possible, isolate a suspected or confirmed case in a single room until 24 hours after the first treatment has been completed.

Treatment

Identify and treat all people suspected or confirmed to have scabies, and staff or relatives who have had prolonged, direct, skin-to-skin contact with an infested person before they were treated.

Offer treatment to household members (for example, spouses and children) of staff who are receiving scabies treatment.

Contact precautions

  • All staff and visitors should wear gloves and gowns on entering the single room or when having direct patient contact.
  • Gowns and gloves should be single use.
  • Gowns and gloves should be changed between each patient.
  • Hands should be washed thoroughly after removing gloves.

Staff exclusion

Staff can return to work 24 hours after the first treatment has been completed.

Staff should be monitored to ensure that treatment has been effective.

Environmental disinfection

Mites generally do not survive more than 2–3 days away from human skin.

Bedding, clothing and towels used by infested people any time during the 3 days before treatment should be machine washed and dried using the hot water and hot dryer cycles, or be dry-cleaned.

Items that cannot be dry-cleaned or laundered can be disinfested by storing in a closed plastic bag for several days to a week (at least 72 hours).

Ensure that bedding and clothing used by a person with crusted scabies are collected and transported in a plastic bag, and emptied directly into a washer to avoid contaminating other surfaces and items.

Ensure that laundry personnel use gowns and gloves when handling contaminated items.

Routine cleaning and careful vacuuming of furniture and carpets in rooms used by people with suspected or confirmed scabies are recommended.

Communication

Provide information about scabies to all staff (nursing, medical, allied and environmental services staff).

Maintain an open and cooperative attitude between management, staff and visitors.

Appendix 2 – multiple cases of scabies

Surveillance

Have an active program for early detection of infested patients and staff.

When multiple cases are indentified, check that there are no cases of crusted (Norwegian) scabies in the facility.

Maintain a high level of suspicion that scabies may be the cause of undiagnosed skin rashes. Suspected cases should be evaluated by their doctor and, if necessary, confirmed by obtaining skin scrapings.

All new patients should be screened for scabies.

Notify other institutions to or from which infested or exposed patients may have transferred.

Maintain records with the patient’s name, age, sex, room number, room-mate names, skin scraping status and results, and names of all staff who provided hands-on care to the patient before the implementation of infection control measures.

Use epidemiologic data about distribution of confirmed cases by building, room, floor, wing, occupation (for staff), date of admission and date of onset of a scabies-like condition to determine:

  • levels of risk for patients and staff
  • the extent of the outbreak (for example, confined or widespread in the facility)
  • relatedness of cases in time and space.

Diagnostic services

Consult a dermatologist for assistance in differentiating skin rashes and confirming the diagnosis of scabies.

Ensure that a staff member is trained and experienced in obtaining skin scrapings to identify scabies mites.

Control and treatment

Isolation

Where possible, isolate a suspected or confirmed case in a single room until 24 hours after the first treatment has been completed.

Treatment

Identify and treat all people suspected or confirmed to have scabies, and staff or relatives who have had prolonged, direct, skin-to-skin contact with an infested person before they were treated.

Offer treatment to household members (for example, spouses and children) of staff who are receiving scabies treatment.

Contact precautions

  • All staff and visitors should wear gloves and gowns on entering the single room, or when having direct contact with patients suspected or confirmed to have scabies.
  • Gowns and gloves should be single use.
  • Gowns and gloves should be changed between each patient.
  • Hands should be washed thoroughly after removing gloves.

Staff exclusion

  • Staff can return to work 24 hours after the first treatment has been completed.
  • Staff should be monitored to ensure that treatment has been effective.

Environmental disinfection

Mites generally do not survive more than 2–3 days away from human skin.

Bedding, clothing and towels used by infested people any time during the 3 days before treatment should be machine washed and dried using the hot water and hot dryer cycles, or be dry-cleaned.

Items that cannot be dry-cleaned or laundered can be disinfested by storing in a closed plastic bag for several days to a week (at least 72 hours).

Ensure that bedding and clothing used by a person with crusted scabies are collected and transported in a plastic bag, and emptied directly into a washer to avoid contaminating other surfaces and items.

Ensure that laundry personnel use gowns and gloves when handling contaminated items.

Routine cleaning and careful vacuuming of furniture and carpets in rooms used by people with suspected or confirmed scabies are recommended.

Communication

Establish procedures for identifying and notifying at-risk patients and staff who are no longer at the institution.

Provide information about scabies to all staff (nursing, medical, allied and environmental services staff).

Maintain an open and cooperative attitude between management, staff and visitors.

Appendix 3 – crusted (Norwegian) scabies (single or multiple cases)

Surveillance

Have an active program for early detection of infested patients and staff. Maintain a high index of suspicion that scabies may be the cause of undiagnosed skin rashes. Suspected cases should be evaluated by their doctor and, if necessary, confirmed by obtaining skin scrapings. All new patients should be screened for scabies.

Notify other institutions to or from which infested or exposed patients may have transferred.

Remember that people with crusted scabies are infested with very large numbers of mites; this increases the risk of transmission from both brief skin-to-skin contact, and contact with items contaminated with skin scales and crusts shed by a person with crusted scabies, such as bedding, clothing, furniture, rugs, carpeting and floors.

Use epidemiologic data about distribution of confirmed cases by building, room, floor, wing, occupation (for staff), date of admission, and date of onset of a scabies-like condition to determine:

  • levels of risk for patients and staff
  • the extent of the outbreak (for example, confined or widespread in the facility)
  • temporal relationships among cases.

Maintain records with the patient’s name, age, sex, room number, room-mate names, skin scraping status and results, and names of all staff who provided hands-on care to the patient before the implementation of infection control measures.

Maintain ongoing surveillance for scabies among all patients and staff to identify new or unsuccessfully treated cases of scabies.

Diagnostic services

Consult a dermatologist for assistance in differentiating skin rashes and confirming the diagnosis of scabies.

Ensure that a staff member is trained and experienced in obtaining skin scrapings to identify scabies mites.

Control and treatment

Isolation

Isolate suspected or confirmed case of crusted (Norwegian) scabies in a single room until all treatments have been successfully completed.

With crusted (Norwegian) scabies, treatment may be prolonged.

Treatment

Identify and treat all people suspected or confirmed to have scabies, and staff or relatives who have had both brief skin-to-skin contact and contact with items such as bedding, clothing, furniture, rugs, carpeting, floors, and other objects that can become contaminated with skin scales and crusts shed by a person with crusted scabies.

Offer treatment to household members (for example, spouses and children) of staff who are receiving scabies treatment.

Treat patients, staff and household members at the same time to prevent exposure and continuing transmission.

A keratolytic agent may be required. Keratolytic creams soften and thin the skin, causing the outer layer to loosen and shed.

Generally, crusted (Norwegian) scabies must be treated on more than one occasion, at least 1 week apart. Oral antiparasitic agents (for example, ivermectin) may be necessary.

Contact precautions

  • All staff and visitors should wear gloves and gowns on entering the single room or when having direct contact with patients suspected or confirmed to have scabies.
  • Gowns and gloves should be single use.
  • Gowns and gloves should be changed between each patient.
  • Hands should be washed thoroughly after removing gloves.

Staff exclusion

  • Staff can return to work 24 hours after the first treatment has been completed.
  • Staff should be monitored to ensure that treatment has been effective.

Environmental disinfection

Mites generally do not survive more than 2–3 days away from human skin.

Bedding, clothing and towels used by infested people any time during the 3 days before treatment should be machine washed and dried using the hot water and hot dryer cycles, or be dry-cleaned.

Items that cannot be dry-cleaned or laundered can be disinfested by storing in a closed plastic bag for several days to a week (at least 72 hours).

Ensure that bedding and clothing used by a person with crusted scabies is collected and transported in a plastic bag, and emptied directly into a washer to avoid contaminating other surfaces and items.

Ensure that laundry personnel use gowns and gloves when handling contaminated items.

Routine cleaning and careful vacuuming of furniture and carpets in rooms used by people with suspected or confirmed scabies are recommended.

Clean the room of patients with crusted scabies regularly to remove contaminating skin crusts and scales, which can contain many mites.

Communication

Establish procedures for identifying and notifying at-risk patients and staff who are no longer at the institution.

Ensure a proactive approach to scabies, including providing information about scabies to all staff (nursing, medical, allied and environmental services staff) and, where appropriate, their household members, along with visitors to the facility.

Maintain an open and cooperative attitude between management, staff and visitors.

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