SCABIES

SCABIES-Explained briefly

Edited by, JOHN FELIX

Scabies is a contagious itchy skin condition caused by the infestation of tiny human itch mite called the SARCOPTES SCABIEI which is less than 0.5 mm in size. The word scabies is originated from the Latin term Scabere meaning 'to scratch'.

EPIDEMIOLOGY:

• Scabies is found all over the world and the mite is transmitted by direct and prolonged skin to skin contact with a person who has scabies.

• Around 2.8% of the world's population is affected with scabies. It is equally common in men and women.

• Both young and old people can get scabies. Scabies is one of the three common skin disorders in children, along with ringworm and bacterial skin infections.

TRANSMISSION:

• Scabies is caused by infection with the female mite Sarcoptes Scabiei. It can be transmitted by prolonged contact with infested person. Sexual contact is the most common transmission way.

• Exposure is most common in clinical settings, Institutions and daycare settings. Sharing clothes or towels can also transmit scabies.

• The mite can survive only for 48-72 hours without human contact at warm temperature.

PATHOPHYSIOLOGY:

Once the mite gets bound to the host, they mate on the surface of the skin. After mating, the male mites die. The female mites burrows into the epidermis of the host. They use their jaws and front legs for burrowing. These mites lays up to three eggs per day for duration of her 30-60 day lifetime. The eggs hatch within 3-4 days.

The larvae migrate to skin surface and forms short burrows called molting pouches. The larvae usually has 3 pairs of legs and later they turn into nymphs, having 4 pairs of legs. Mating occurs with male mates in the short burrows. Further they lay egg after making deep burrows.

A delayed type, Hypersensitivity IV reactions to mites, their eggs and packets of feces (scybala) occurs after 30 days of infestation. This reaction causes intense itching and inflammation.

SIGNS AND SYMPTOMS:

The symptoms may occur within 2-6 weeks.

        • Intense itching

        • Superficial burrows

        • Erythematous skin (redness)

        • Papular rashes occur in finger webs, feet, wrist, elbow and even genitals.

WHAT IS CRUSTED SCABIES(Norwegian scabies)?

The elderly, disabled people with impaired immunity such as those people with HIV, cancer and people taking immunosuppressive drugs may get crusted scabies. Eradication of mites is difficult as the crust protects the inner mites from topical medications.

DIAGNOSIS:

• History and physical examination

• Skin scrapping

• Dermoscopy

• Adhesive tape test

TREATMENT:

Scabies can be treated using several creams and lotions. The medication should be applied from neck to feet all over the body and should be left for at least 8 hours. In some cases second application after weeks may be prescribed. It is better to go for second application after weeks to prevent further spread. If an individual get infested with scabies, the entire family or people around are advised to apply the medication in their bodies, even if they show no signs of scabies infestation.

The following are the commonly used medications

• Permethrin 5%

• Ivermectin- Oral anti-parasitic medication used in patients who fails to respond to topical medications. It is found effective in treating crusted scabies.

• Sulphur

• Lindane 1% (gamma benzene hexachloride)

• Malathion

• Calamine lotion can help relieve itching and pain

• Crotamiton

• Antihistamines relieve allergic symptoms

PREVENTION:

When someone around you gets infested with scabies, do not share their clothes, towels, bedsheets and other things. Wash their clothes in hot and soapy water.