What is/are scabies?

Scabies is a skin-condition characterised by intense itching (pruritis), raised papules, diffuse or localised rash and small blisters on the skin. The condition is caused by an infestation by a small burrowing mite called Sarcoptes scabiei which burrows into the outermost layer of the skin (stratum corneum) of hosts. Scabies mites are approximately 0.3-0.5mm in length so effectively invisible to the human eye. The itching and rash of a scabies infestation is caused by the body’s immune response to the mite.

In a normal scabies infestation, there will usually be 5-10 mites across any one person’s entire body although this mite number may be higher if a person is a close contact of someone with Crusted Scabies. See What is Crusted Scabies?

What is Crusted Scabies?

Crusted Scabies (previously known as Norwegian Scabies) is a severe, chronic form of scabies. It can be highly contagious and is believed to develop when a person infected with scabies has a weakened immune system among other factors, allowing the scabies mites to breed prolifically.

People with scabies usually have a small number of mites (e.g. 10-15 mites) on their body. Those with Crusted Scabies have an extreme number (e.g. hundreds of thousands of mites).

Considered core transmitters of scabies, people with Crusted Scabies spread scabies to others in their household and community. Undiagnosed and/or poorly managed Crusted Scabies can lead to recurrent infestations in close contacts. See What is/are scabies?

Why does Crusted Scabies mainly affect remote Indigenous communities?

The health status of Australia's Aboriginal and Torres Strait Islander peoples is poor in comparison to the rest of the Australian population. Additionally, Indigenous peoples do not have an equal opportunity to be as healthy as non-Indigenous Australians.

This means many people living in remote Indigenous communities have existing chronic conditions such as diabetes and renal diseases which weakens their immune function and makes them susceptible to developing Crusted Scabies.

Why don’t some people with Crusted Scabies seek treatment?

Due to their disfigured appearance, caused by the crusted lesions, feelings of shame and embarrassment are often behind those who do not seek treatment.

Also, until quite recently, Crusted Scabies was not well understood in the Primary Healthcare setting. The diagnosis is not straight forward, so few health workers knew what it was, and it was rarely diagnosed and treated accurately.

Who does Crusted Scabies affect?

Crusted Scabies does not discriminate. However, in Australia, it mainly affects people with poor immune function, living in remote Indigenous communities, who have existing chronic conditions such as diabetes and renal disease. Crusted Scabies cases are also reported in nursing homes and among people who live rough in mainstream Australia.

Are there other countries with crusted scabies?

Yes, Crusted Scabies is also evident in developing countries (and some populations of developed countries) that have high incidences of scabies. It is important to note that the highest rate of Crusted Scabies is reported as being in the remote communities of the Northern Territory, Australia.

Do scabies mites live in dirt or mud?

No. Scabies mites only live on humans.

Can scabies be spread by dogs to humans?

No. Scabies mites which infect humans are genetically different to those in dogs and other animals. Dogs can have scabies which can cause Sarcoptic mange and the mites which infest dogs can move on to the skin of a human. This can cause itch in humans however it is believed these mites do not cause permanent scabies infections in humans.

Can scabies be spread by swimming in a pool?

Scabies mites do not spread in a swimming pool. Scabies are spread by prolonged skin-to-skin contact or uncommonly (except in the case of a person with Crusted Scabies) by sharing items of clothing, bedding, towels, or linen with someone with scabies.

What are the impacts of scabies infestations in people?

Scabies infestations, in addition to being very uncomfortable due to intense itch (often preventing sleep - causing fatigue and distraction at work or school), can cause the skin to be scratched open by the person who has scabies. These open sores can then become infected, most concerningly with Group A Streptococcus which, if untreated, may cause acute rheumatic fever possibly leading to rheumatic heart disease. Scabies is known to underlie many skin infections in the Northern Territory.

What are the signs and symptoms of scabies?

A typical case of scabies is commonly characterised by intense itch (pruritis), particularly at night, which may affect most of the body or may be isolated to areas of the body such as the wrists, finger webbing, armpits, etc. A pimple-like rash of small bumps (papules) may be present at the site of the itch and there may be small blisters (vesicles) as well. Small raised and crooked burrows on the skin might be seen from the female mite burrowing in the skin although these can often be very difficult to find. In adults, the rash and papules are commonly seen on wrists, finger webbing, armpits, waist, nipples, penis, belt line and buttocks though less commonly on the neck, face, head, palms, and soles. These areas may present with a rash in infants, young children, and the elderly.

It is important to note that people with Crusted Scabies may not experience the characteristic itch.

How long do scabies mites live off a human host?

Studies have shown that scabies mites usually die away from a host within 48-72 hours, although some newer research has found some environments might allow scabies mites to live for up to 8 days off a human host.

Does soap kill scabies mites?

No. Soap, detergents or alcohol rubs do not kill scabies mites. Scabies infestations are not related to hygiene. See What kills scabies mites?

Does the sun kill scabies mites?

No. The sun does not directly kill scabies mites; however, high temperatures do (>50 degrees Celsius). As an example, placing linen/clothes which may have scabies mites on them inside a sealed black plastic bag placed in full sun on a hot day will help to kill scabies mites. See What kills scabies mites?

What kills scabies mites?

For treating people:

• Some medications kill scabies mites when they are used according to manufacturer’s guidance. See What medications kill scabies mites?

For treating items of clothing/bedding/linen:

• High temperatures kill scabies mites. Temperatures above 50 degrees Celsius for more than 10 minutes will kill scabies mites. This could mean clothing or linen placed in a very hot washing machine cycle or a very hot tumble dryer (for more than 20 minutes). For items which cannot be washed, putting items inside a sealed black plastic bag placed in full sun on a hot day may help to kill scabies mites. If the weather is not very hot this will not be enough to kill scabies mites. Instead try isolating items for 8 days.
• Scabies mites die after 8 days when they are away from a human host. This means when scabies mites might be on clothes, bedding or linen, these items can be isolated (either by not being used and kept away from humans or by being sealed inside plastic bags) for 8 days. After 8 days, any mites on those items will have died.

Is Crusted Scabies a notifiable disease in the Northern Territory?

Yes, in the Northern Territory, Crusted Scabies was made a notifiable disease under the Notifiable Diseases Act] in January 2016.

Is Crusted Scabies a notifiable disease in other areas of Australia?

As of October 2020, Crusted Scabies is only a notifiable disease in the Northern Territory of Australia.

Why is Crusted Scabies a notifiable disease in the Northern Territory?

The World Health Organisationlists Scabies and other ectoparasites as a category A Neglected Tropical Disease (alongside other diseases such as Trachoma, Dengue and Leprosy). This means it is a condition affecting millions of people worldwide and requires elimination processes to be implemented to reduce the global burden of the disease.

Considered core transmitters of scabies, people with Crusted Scabies spread scabies to others in their household and community. Undiagnosed and/or poorly managed Crusted Scabies can lead to recurrent infestations in close contacts. Specialists in the NT made the decision to list Crusted Scabies as a notifiable disease. This means the Centre for Disease Control monitors and case manages presentations and records the impact each client has on the health of the public.

How is Crusted Scabies diagnosed in the Northern Territory?

Crusted Scabies is diagnosed by medical professionals in a two-part process. Firstly, the case must have been confirmed as clinically appearing to be Crusted Scabies based on consultation with an infectious diseases specialist or dermatologist. Secondly, a skin scraping collected from the person must have a positive identification of Sarcoptes scabiei mites and/or eggs by a laboratory.

Crusted scabies is a notifiable condition in the Northern Territory of Australia and needs to be reported to the NT Centre for Disease Control

Why does a medical practitioner need to consult a dermatologist or Infectious Diseases specialist to make a diagnosis?

While there are many medical practitioners who are practiced in recognising Crusted Scabies, in the Northern Territory, Crusted Scabies is a notifiable disease and in order to meet criteria, the case must be consulted by an infectious diseases specialist or dermatologist, as well as have a positive skin scraping for Sarcoptes scabiei. This is to ensure misdiagnosis does not occur and the correct Public Health Response can be initiated by the NT Centre for Disease Control.

Who do I contact if I suspect a client has Crusted Scabies?

Medical professionals who suspect their client has Crusted Scabies should contact the infectious disease specialist unit or dermatology unit at their nearest hospital for guidance on diagnosis and management.

What is grade 1, 2 or 3 Crusted Scabies?

Crusted Scabies is graded based an algorithm designed to diagnose the severity of infection. It is suspected that grade 3 cases of crusted scabies have a higher mite load than grade 2 and grade 1 in turn. Grading criteria can be found in the CARPA Standard Treatment Manual latest edition.

Who can collect a skin scraping for Crusted Scabies?

A health professional who has a pathology request form signed by a medical practitioner, a nurse practitioner or an eligible midwife may collect a skin scraping from a client.

Should a skin scraping be collected for scabies?

A medical professional should only collect a skin scraping for pathology (mycology dermatophytes) when they suspect Crusted Scabies. A simple case of scabies (including infected scabies) does not require a skin scraping (unless ruling out Crusted Scabies) and in fact it is very rare to collect scabies mites from a skin scraping in a person with simple scabies.

It is important to include information on pathology forms for skin scrapings which identifies where the skin scraping was collected from on the client (i.e. left heel) and to very clearly state the pathology request is for mycology dermatophytes - scabies. The laboratory may only look for fungal elements if the form does not state scabies.

How can a health professional collect a skin scraping for Crusted Scabies?

Directions on how medical professionals can perform a skin scraping can be found in the One Disease resource: Managing Crusted Scabies in Remote Communities 2017 or in the One Disease video Skin Scrapings Procedure.

Who can I contact for professional treatment and diagnosis advice for scabies and Crusted Scabies?

Resources regarding scabies and Crusted Scabies can be found here.

Medical professionals who suspect their client has Crusted Scabies should contact the infectious disease specialist unit or dermatology unit at their nearest hospital for guidance on diagnosis and management.

What other conditions look like Crusted Scabies?

There are several clinical conditions which can appear like Crusted Scabies and in fact many clinicians can have difficulty diagnosing Crusted Scabies. Some of these conditions might include tinea, psoriasis, impetigo, or dermatitis. Therefore, skin scrapings should be taken for laboratory testing as well as consultation with your nearest hospital infectious disease unit or dermatology unit.

What is a Scabies Free Zone?

A Scabies Free Zone may apply to a household, a family group, or a community. In most instances, a Scabies Free Zone indicates a household which has been successfully treated for scabies. This means all household members have been treated for scabies on the same day and again 7-10 days later to ensure no scabies remain in the household. See How is scabies treated?

Can Crusted Scabies be cured?

While a single case of Crusted Scabies can be cleared and a client can be declared mite-free, as a condition, Crusted Scabies can reoccur. Put simply, a client with Crusted Scabies who has been cleared of mites, is always susceptible to re-infestation and developing Crusted Scabies from simple scabies infestations. This is why making sure Crusted Scabies clients remain in Scabies Free Zones and have long-term skin checks is so important. See What is a Scabies Free Zone?

How is Crusted Scabies treated?

In the Northern Territory, it is recommended that Crusted Scabies clients receive treatment in hospital. Practitioners may encourage Crusted Scabies clients to receive hospital treatment and should provide a referral for this or directly refer their clients to the hospital. It is possible (although cumbersome) to treat grade 1 Crusted Scabies in the client’s home or residential facility with frequent clinical supervision and consultation with infectious diseases unit. This involves a combination of alternating topical creams (scabies creams and/or lotions as well as skin softening creams) and oral medications prescribed by a doctor, along with daily household, bedding, and clothing treatment until cleared of scabies. See CARPA Standard Treatment Manual latest edition for guidance.

Is there an existing clinical protocol that is routinely followed to treat Crusted Scabies?

In the Northern Territory, there are hospital clinical guidelines for crusted scabies treatment in hospital. For community treatment of grade 1 crusted scabies, the CARPA Standard Treatment Manual latest edition provides guidance.

How is scabies treated?

Scabies is treated with either topical application with two doses 7-10 days apart of Permethrin 5% as per manufacturer’s advice or in some cases, with topical lotion Benzyl Benzoate (Benzemul) or oral Ivermectin (Stromectol) prescribed by a medical practitioner.

Treatment must be provided for the person with scabies as well as all contacts in their home. Topical creams or lotions should be left on overnight or all day before being washed off.

Scabies medications cannot kill scabies mite eggs so a repeat treatment must be provided for the person and anybody else in their home who has active scabies in 7-10 days to kill scabies mite eggs which have hatched after the first treatment.

After effective topical treatment, mites will be dead although the itch may persist for several weeks while the body recovers from the immune response (allergic reaction) to the mites and their faeces (scybala).

For scabies cream and lotion application guidance see How should scabies cream or lotion be applied?

For Crusted Scabies treatment see How is Crusted Scabies treated?

Can scabies be cured?

Yes, scabies infestations can be ‘cured’. See How is scabies treated?

It is important to remember:

• Scabies medications cannot kill scabies mite eggs so a repeat treatment must be provided for the person and anybody else in their home who has active scabies in 7-10 days to kill scabies mite eggs which have hatched after the first treatment.
• After effective topical treatment, mites will be dead although the itch may persist for several weeks while the body recovers from the immune response (allergic reaction) to the mites and their faeces (scybala).

What medications kill scabies?

Scabies mites are killed by pharmacy/prescription medications, Permethrin, Ivermectin or Benzyl Benzoate medications.

• Permethrin 5% (Lyclear) is used for normal scabies infestations and is very effective.
• Benzyl Benzoate and Ivermectin (Stromectol) are used mostly for Crusted Scabies clients or for clients who may have difficult treating a scabies infestation with Permethrin.

How long does it take for scabies treatment (medication) to work?

Live scabies mites on the body will be dead within 8 hours if using topical 5% permethrin cream (when applied correctly). The second treatment is crucially applied 7-10 days later to kill any mites that have hatched from eggs after the first treatment.

How will a person know if the scabies treatment (medication) worked?

If the person has followed manufacturer’s guidelines on topical treatment and treated their close contacts, the scabies treatment should have worked. Sometimes itch may occur for several weeks after successful treatment. Rash and papules should clear within several weeks and skin should return to normal, however if new papules or rash occurs after treatment, further treatment may be required.

My client has received treatment which I believe was effective, but they are still itchy. Why?

After effective topical treatment, mites will be dead although the itch may persist for several weeks while the body recovers from the immune response (allergic reaction) to the mites and their faeces (scybala). Rash and papules should clear within several weeks and skin should return to normal, however if new papules or rash occurs after treatment, further treatment may be required.

How should scabies cream or lotion be applied?

The CARPA Standard Treatment Manual 7th edition provides the following guidance for applying scabies creams or lotions:

• Put on clean, dry skin
• Start with head including scalp and face — avoid eyes, lips, mouth
  • If hair very thick or infestation very bad — may need to shave head. Always get permission from person/carer
• Work carefully down whole body. Always apply cream:
  • Between fingers and toes, soles of feet, under nails
  • Body creases — behind ears, under jaw, neck, armpits, groin, bottom, under breasts
  • Joints and joints creases — elbows, knees, heels
• Advise to put on hands again after washing, put on child's hands again before bed
• Topical creams or lotions should be left on for at least 8 hours before being washed off.
• Treat all close contacts with scabies medication.
• A second dose/treatment should be applied 7-10 days later to kill any scabies mite eggs which have hatched after the first treatment.
• If infected sores are present, treat at the same time as treating for scabies.

My client keeps having scabies re-infestations.

When clients have regular scabies re-infestations consider the possibilities below:

• If they received topical treatment, was it applied correctly or left on for the right amount of time? See How should scabies cream or lotion be applied?
• Did they receive a second dose of scabies medication, 7-10 days after the first dose to kill any eggs that hatched after the first dose? See How is scabies treated?
• Was everybody in the household treated for scabies at the same time? See How should scabies cream or lotion be applied?
• Could there be a person in the household with Crusted Scabies who needs treatment? See What is Crusted Scabies?

My client has sores and scabies. Should I wait for sores to heal before treating for scabies?

See next question Can I apply scabies cream or lotion to areas where sores are present?

Can I apply scabies cream or lotion to areas where sores are present?

While treating secondary sores is important to prevent further infection; it is also important to treat scabies to prevent further sores arising from itching. According to the CARPA Standard Treatment Manual 7th edition, sores and scabies should be treated at the same time.

Lyclear (Permethrin 5%) is indicated for cutaneous or external use. This means you should avoid the eyes and mucous membranes such as the inside of the mouth or genitals. If a minor wound is present and it is scabbed or dry, topical scabies cream can be rubbed over the area. Topical cream applied to larger open wounds will be painful for the client and may complicate the wound so cream can be applied around these sores or a doctor’s prescription may be acquired for oral treatment (providing it is not contraindicated in the client – see CARPA Standard Treatment Manual latest edition.

For application guidance, see How should scabies cream or lotion be applied?

Should the house/room be fumigated after Crusted Scabies has been diagnosed?

While fumigation has been recommended in the past, it is no longer a suggested treatment method for clearing an environment of scabies. Instead some other household measures can be followed. See How can a person kill scabies mites that might be in their house/clothing?

It is important to note that these measures are not related to improving hygiene, rather to physically removing mites. Scabies infestations are not linked to hygiene practices. Creating a Scabies Free Zone through contact treatment is the best method for treating a home. See What is a Scabies Free Zone?

How can a person kill scabies mites that might be in their house/clothing?

In a simple case of scabies, it is very unlikely there are scabies mites in their house or clothing which would cause further infestation. In a case of Crusted Scabies or if a client wishes to treat their home regardless, they can try the processes below.

It is very important to remember, creating a Scabies Free Zone in the household via full treatment with scabicidal medication for everyone in the household is the most effective method of clearing an environment of scabies and should always be the first line of treatment. See What is a Scabies Free Zone.

• Soft furnishings and carpets can be vacuumed (the vacuum will need a very fine vacuum filter) to remove any mites. The vacuum bag should then be discarded, or if it has no bag, the vacuum should be left in an isolated space for 3-7 days to kill any mites in the vacuum cleaner.
• Hard furnishings and floors can be wiped down with detergent and water or mopped with floor cleaner.
• Linen, clothing, and towels that have been used in the last several days can be hot washed above 50°C for >10 minutes and/or dried in a tumble drier on the hottest setting for >20 minutes.
• Items which cannot be hot washed or dried such as shoes or delicate items can be placed in a sealed plastic bag and isolated for 8 days until any mites have died.
• Mattresses can be covered with a mite-proof mattress protector (such as those lined with plastic)

How does a person catch scabies?

Scabies mites are spread from person to person by direct, prolonged human skin-to-skin contact such as when sharing a bed, holding a child or prolonged exposed contact while caring for a client. Usually, only people with Crusted Scabies actively shed mites into the environment which can then infest close contacts via fomites (items the person has been in contact with such as chairs, beds, or tables).

How does a person get Crusted Scabies?

Crusted Scabies develops in people with weakened immune systems, who have untreated cases of scabies. In simple scabies, there are usually about 10-15 live mites present. However, in cases of Crusted Scabies, there may be hundreds of thousands of scabies mites, in some cases more than a million.

What does Crusted Scabies look like?

Crusted Scabies can present differently depending on the grade and whether it is complicated by other skin conditions such as fungal infection. Usually, it presents with scaly, crusted lesions on the hands, feet, scalp, face, torso, bottom and/or pressure-bearing areas such as the elbows. Some example images of Crusted Scabies can be found on the Scabies, Crusted Scabies and Other Common Skin Conditions in Central and Northern Australia Poster although it is important to always consult a infectious diseases specialist or dermatologist if you suspect Crusted Scabies as it is a difficult diagnosis to confirm. See How is Crusted Scabies diagnosed?

How can a health professional prevent themself from catching scabies mites when caring for a person with scabies?

Scabies is prevented by avoiding prolonged skin-to-skin contact. When in contact with a person with scabies (not Crusted Scabies), simple contact precautions will suffice. Protecting areas that will contact the person for prolonged periods of time such as hands and arms with disposable gloves and a disposable gown and following with manual hand washing with soap and water is enough to prevent a scabies infestation in most cases.

However, if a person has Crusted Scabies, in a carer or clinical setting, full contact precautions are required including disposable gloves, gown, shoe booties and haircap and hand washing after contact with soap and water.

After a person has been diagnosed with scabies, how can they protect people around them from getting scabies?

The best thing your client can do to protect those around them after they have been diagnosed with scabies is treat themself and their close contacts immediately with topical scabicide therapy or oral scabicide therapy with a doctor’s prescription. If the therapy has been applied as per manufacturer’s directions, they should be able to return to work duties within 24 hours. Scabies medications cannot kill scabies mite eggs so you must provide a repeat treatment for them and anybody else who has active scabies in 7-10 days to kill scabies mite eggs which have hatched after the first treatment.

How soon will a person know if they have caught scabies?

The time in which it takes for a person to know if they have caught scabies varies between individuals. If a person has never had scabies before, it will likely take several weeks (even as many as eight weeks) before the body launches an immune response (like an allergic reaction) to the mites, triggering the characteristic itch. If a person has had scabies before however, their body may recognise the mites sooner and the immune response will be much sooner, as early as a few days.

Why does a Crusted Scabies client need a chronic care management plan?

It is important Crusted Scabies clients are placed on a chronic care management plan to address the high risk of reinfection, the need for good communication between acute and primary care providers and to provide ongoing education to the client.

What should a chronic care management plan for Crusted Scabies look like?

A chronic care management plan for Crusted Scabies should include:

• Skin reviews at 2-4 weeks after hospital discharge and then every 4 weeks to check for signs of reinfection, especially hands, shoulders, and bottom.
• Ongoing education opportunities as the client and their family needs to understand Crusted Scabies, self-management methods and the importance of a ‘Scabies Free Zone’.
• Providing the client with scabicidal treatment (scabies medications) and keratolytic creams (skin softening creams) so they and their household members can apply the creams if re-infestations occurs or is suspected. If re-infection is suspected, consultation with infectious disease specialist should occur for management.

A chronic care management plan for Crusted Scabies should remain active as long as the client lives in a scabies-endemic region/area and should not be cancelled because a client has had successful treatment for Crusted Scabies or because they have maintained a Scabies Free Zone.

How long do Crusted Scabies clients need to be on a chronic care management plan for Crusted Scabies?

Due to the high risk of re-infestation for clients who have recovered from Crusted Scabies, a chronic care management plan for Crusted Scabies should remain active for as long as the client lives in a scabies endemic area. All remote Northern Territory regions and overcrowded households should be considered scabies-endemic areas. This may mean the client’s care plan is active for lifelong follow-up.