The Big Itch

Clement Hanson DO, MPH (COL, Ret)

 Scratching yourself? Hmm… . This afternoon, my back yard thermometer shows ninety seven degrees. That prickliness in your back, arms, and legs might not be due to sticky sweat. Brace yourself. We’re going to talk about a critter that will make your hair stand on end.

Background: Scabies is an itchy skin condition caused by a tiny mite. It has tortured humans through two thousand five hundred years. There are about three hundred million worldwide cases every year. The mite, Sarcoptes scabei, can be seen with high power magnification. It causes fierce itching and is transmitted by skin-to-skin contact, clothing, sexual contact, and bedding. However, there’s good news. Early diagnosis and effective treatment cure the condition

Symptoms and findings: Pruritus (itchiness) at night is the hallmark symptom. Diagnostic findings include small bumps (papules), nodules, as well as burrows between the fingers, on the wrists, elbows, underarms, buttocks, and genitals. In “crusted” scabies, there are thickened skin patches (hyperkeratotic plaques) on the palms of the hands, chest, and the soles of the feet.

Diagnosis: Skin scrapings examined by microscope show the mites and eggs. However, inability to find the mite doesn’t rule out the condition. Newer methods, such as dermoscopy or adhesive tape testing, increase likelihood of finding the mite. However, there is no standard criterion comparing test accuracy. 

Treatment: People with scabies, their close physical contacts, affected household members, and sex partners should be treated at the same time. Otherwise, the condition can recur. Skin creams, such as permethrin lindane, benzyl benzoate bioalethrin, crotamiton, and sulfur, are helpful. An oral medicine, invermectin, is an option for people who can’t tolerate the creams. Invermectin is recommended for people confined in institutional settings, such as prisons.

Topical permethrin is reasonable first-line treatment. Scabies is sexually transmitted, therefore, affected people should examined for sexually transmitted infections. After treatment, all clothes and bedding should be washed at high temperature (greater than fifty degrees Celsius, or at least one hundred twenty two degrees Fahrenheit).

 Insecticidal powders and aerosols are useful for contaminated materials or objects that can’t be washed.

Treatment can be repeated, according to the infection severity. If the itching persists more than a few weeks, then a re-evaluation is needed. Failure of treatment is usually due to not following treatment instructions. 

Source: Medscape, Skin Therapy Letter; Mosel and Closedown.

Scabies quotes: What does one person who has scabies say to another?
 “Life's an itch, isn't it?” Author unknown.

“It is not so important to be serious as it is to be serious about the important things. The monkey wears an expression of seriousness which would do credit to any college student, but the monkey is serious because he itches.” Robert Hutchins, American Educator and Writer, 1946.

 Have you checked out “Doctor Clem’s blogsite? (clement.hanson@blospot.com.) It’s crawling with all sorts of medical information that will make your hair stand on end.