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11 August 2017

Causative agent

Scabies is a skin disease caused by a mite called Sarcoptes scabiei, which is a parasite that burrows into, resides and reproduces in human skin. It can affect people of all ages, but people with weakened immunity or the elderly are more susceptible. Scabies can spread rapidly in crowded conditions, hence, outbreaks of scabies have been reported in hospitals, child-care facilities, hostels and elderly homes.

Clinical features

Scabies manifests in two main ways:

People infested with classical scabies will present with intense itchiness which is more severe at night or after a bath. The common affected areas are finger webs, and skin folds of wrists, elbows, armpits, nipples, lower abdomen, external genitalia, buttocks and groins. Rashes, thread-like lesions or vesicles may be seen on the skin. The face and scalp are usually spared, except in infants, young children and immunocompromised persons.

A rare but severe type of scabies known as Norwegian or crusted scabies can occur in institutionalised people, particularly in those who are weak or mentally retarded. The skin lesions appear as marked scales and crusts. The nails may thicken, with debris in the nail bed. Face and scalp can also be affected. This type of scabies is highly contagious because an infested person may harbour thousands of mites, compared with 10 – 15 mites present in classical scabies.

Mode of transmission

Scabies usually spreads through direct skin contact with the infested people. Their clothing and bedding may also carry the mites/ eggs and transmit the disease. Transmission within household and institutional settings is common.

Incubation period

Incubation period is about 2 – 6 weeks for people with new infestation. For people who have previously been infested with scabies, symptoms develop earlier, usually within 1 – 4 days after re-exposure.


  • If you suspect scabies, seek medical advice immediately.
  • Apply topical medicated lotions and take drugs according to the doctor's advice to kill the mites and control itchiness respectively.
  • Family member(s), sexual partner(s) and close personal contacts of the infested persons should also seek medical advice and receive treatment if necessary.
  • When caring for and coming into contact with the infested persons, wear appropriate personal protective gear such as gloves and gown.
  • Wash hands thoroughly before and after contact with the infested person.
  • Wash the clothing, towels and bed linen of the infested persons separately. These items should be washed in hot water at 60°C or above, for not less than 10 minutes so as to kill the mites and its eggs. Place non-washable items in a plastic bag and seal up for at least 14 days before reuse.
  • Dedicated use of equipment is recommended.
  • Clean shared use equipment/ devices with detergent before using on other persons.
  • Discard shared use or suspected contaminated creams and lotions.


  • Keep good personal hygiene, perform hand hygiene frequently and daily bathing.
  • Regularly change into clean clothing, towels and bed linen.
  • Avoid sharing clothing and personal items with others.
  • Perform skin inspection for institutionalised residents regularly for early identification of infestation.