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.
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 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.