What is scabies?

Scabies is a highly contagious, intensely itchy skin disease caused by a tiny mite called the Sarcoptes scabiei or human itch mite.

Sarcoptes scabiei spend their entire life cycle on humans. The fertilised female  burrows into the person's skin, forming small tunnels where she lays her eggs. These hatch into six legged larvae approximately 4 days later. After feeding, the skin is shed and the eight-legged, sexually mature nymph appears. Following several skin molts, the mature adult male is formed.

Scabies is spread via close skin contact, this includes direct contact, sexual contact, bedding, sharing clothing and towels . The mite can only survive 24-36 hours away from humans.

Scabies symptoms:

Symptoms of scabies usually occur around 4 weeks after exposure. If you have had scabies before, symptoms may become apparent sooner. Although any part of the body can be affected, areas commonly include the hands & between the fingers, the feet, and between the toes, inside the wrists, behind the elbows, genital area, waist, penis & breasts.

• Intense itching which is commonly worse at night or after a hot  bath/shower.

• Signs of pimple like irritations, small, red burrows under the skin.

Immunocompromised individuals or elderly people may develop a severe form of scabies known as Norwegian scabies or crusted scabies. Large numbers of mites are found, in the millions, compared to a healthy individual who will only have a small number of mites (around 10-15). Symptoms of Norwegian scabies include extensive areas of thickened, crusted, scaly rash. Itching is often less severe with Norwegian scabies.

How is scabies diagnosed?

Your doctor may be able to diagnose scabies based on signs & symptoms. He may perform a skin scraping which is then studied under a microscope for the presence of mites and/or their eggs.

Scabies treatment:

All members of the household should be treated, even if they display no symptoms of mites.

• Permethrin creams (Quellada or Lyclear) are usually recommended. These are applied before going to bed & need to be rubbed all over the body except the head. The cream is left on at least 8 hours before washing. Particular attention should be paid to commonly affected areas (listed above). This treatment may need to be re-applied 7 days later to catch any eggs that have hatched in the meantime.

Children under two, the elderly, people with sensitive skin, pregnant or lactating women should not use this ointment. Their doctor can advise on suitable alternatives.

Clothing & bedding should be washed in hot water.

Acknowledgments:

Norwegian scabies photo courtesy of Wikipedia.