Scabies Medical Briefing

Scabies mite

Written by Dr Adrian Hyzler, Chief Medical Officer and Head of Medical Communications

Updated: October 2019

Scabies is a common and very itchy skin condition caused by a tiny mite called Sarcoptes Scabiei – the actual mite is smaller than a pin-head. It is a parasitic infection that affects people of all ages, all over the world. There are usually about 10-15 adult mites on the skin of an infected person.

TRANSMISSION | How do you get scabies?

Scabies is contagious but it usually requires prolonged skin-to-skin contact with a person who has scabies – it is not generally spread by a casual handshake.

It can sometimes also be spread by contact with items such as clothing, bedding, or towels that have been used by a person with scabies, but such spread is very uncommon.
The most common scenario is that it spreads within households to members of the same family. It should be remembered that you can still spread scabies before you have any symptoms – this period can be up to six weeks.

Scabies on pets is caused by a different type of mite and therefore cannot infect humans.

KEY FACTS…

  • Scabies is a common, itchy skin condition caused by mites.
  • It is transmitted human-to-human through prolonged skin-to-skin contact.
  • Symptoms develop two to six weeks after becoming infested with mites.
  • Topical treatments are available.
  • It is important that all house-hold members, close friends and sexual partners within the last month should be treated at the same time to avoid re-infestation.
  • Prevention methods include avoiding prolonged skin contact / contact with items such as bedding, towels and clothing used by an infested person.

SYMPTOMS | What are the symptoms of scabies and how is it diagnosed?

It usually takes between two and six weeks after becoming infested with mites before symptoms present. However, if you have had it before it will take only a few days.

The first thing you will notice is intense itching that can affect the whole body, apart from the head and neck, and that is especially annoying at night. Occasionally a rash develops on the head and neck.

It is common to see scratch marks, especially in the folds of the skin such as the elbows, the groin, between the fingers, the palms of the hands and soles of the feet. These may develop into crusty sores and become infected and require antibiotics to treat the skin infection. The rash can spread across the whole body and resemble eczema.

There is also a pimple-like rash with tiny red spots and silvery lines where the mites have burrowed under the skin to lay their eggs. The mites can be seen with a magnifying glass at the ends of the burrows as tiny black dots.

It’s usually obvious to a doctor or nurse from looking at the rash if it is scabies, but it can be confirmed by taking scrapings and checking for the mites under a microscope.

TREATMENT | How is scabies treated?

There is a topical treatment to eradicate the mite but it should be noted that often the itching carries on for a few weeks before settling. All household members, close friends and sexual contacts within one month should be treated at the same time or they will end up re-infesting each other. This is similar to treating head lice!

  • The first-line topical treatment for scabies is permethrin 5% cream. There is no contraindication for women who are pregnant or breast-feeding, but specialist paediatric dermatologist advice should be sought for babies under two years old.
  • The treatment must be applied to all areas of skin below the neck in adults, but ALL areas of skin and scalp in children. The treatment should be applied to cool dry skin.
  • Leave to dry before applying clothes and for eight to 12 hours before washing off.
  • Two treatments must be applied, separated by seven days.
  • All bedding, towels and clothing should be washed on one normal high temperature cycle of at least 60°C and dried in a hot dryer.
  • Any items that can’t be washed should be placed in a sealed zip-lock bag for 72 hours or placed in the freezer.
  • All rooms should be thoroughly cleaned and vacuumed.

Malathion aqueous 0.5% liquid is commonly used as an alternative when permethrin cannot be used, for whatever reason such as allergy. Malathion should be left on the skin for 24 hours rather than 12 hours.

It is common for the itching to persist for up to two weeks after successful treatment – this can be treated with topical antihistamine or steroid cream. However, if the itching persists longer than this, and new burrows appear, you need further medical review and may need re-treatment.

PREVENTION | What precautions can I take to prevent getting scabies?

There are various precautions you can take to prevent scabies:

  • Avoid prolonged skin-to-skin contact- remember it is contagious up to six weeks before someone knows they’ve got it!
  • Make sure that if someone in the household or a sexual partner (within the last month) is diagnosed with scabies, that all contacts start treatment at the same time
  • Avoid contact with clothing, bedding, towels etc. used by an infested person. Wash all such items on a regular cycle at least 60°C and dry in a hot dryer
  • Rooms used by a person with scabies should be thoroughly cleaned and vacuumed after use. Environmental disinfestation using pesticide sprays or fogs generally is unnecessary and is discouraged.

RECOVERY | How soon can I return to work?

Since scabies is usually spread by prolonged skin-to-skin contact with a person who has scabies, it is not likely to spread to a casual passer-by. Consideration should be given to the nature of the work and the extent of close contact with colleagues or other people.

It is highly unlikely that a colleague will get scabies from an office chair or cubicle that has been used by a person with scabies. Avoidance of prolonged skin-to-skin contact with the infested person and simple vacuuming of the infested person’s desk, surrounding rugs and carpeting should prevent any spread.

As a general rule, a person diagnosed with scabies could return to work once treatment has begun after the first application of permethrin cream.

There may be local regulations that need to be taken into consideration, as well as the nature of the work.

Scabies mites do not survive more than two to three days away from human skin and therefore spraying or fumigating an office or living area is NOT necessary.

Prophylactic treatment of workers without symptoms could be considered in a situation such as a nursing home or care facility in order to reduce the risk of further transmission.

An uncommon form of scabies: “Crusted scabies”

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

Persons with crusted scabies have thick crusts of skin that contain large numbers of scabies mites and eggs. Persons with crusted scabies are very contagious to other persons and can spread the infestation easily both by direct skin-to-skin contact and by contamination of items such as their clothing, bedding, and furniture.

Persons with crusted scabies may not show the usual signs and symptoms of scabies such as the characteristic rash or itching. Persons with crusted scabies should receive quick and aggressive medical treatment for their infestation to prevent outbreaks of scabies