Scab²

A disease characterized by small papules the size of a pinhead that are associated with insufferable penetrating itching and that, when scratched, may suppurate or crust without producing any exudate. Scab commonly occurs between the fingers and may also be observed on the inside of the elbow, in the armpits, on the lower abdomen, in the groin, and on the buttocks and thighs, and, in severe cases, over the whole body. It is attributed to damp-heat depressed in the skin and is transmitted by contact. In The Origin and Indicators of Disease (诸病源候论 zhū bìng yuán hòu lùn) of the Sui Dynasty, the author, Chao Yuan-fang, attributed it to worms, which he said were small and very difficult to see.

Biomedical correspondence: Scabies.

NB: Scabies is caused by the common itch mite, Sarcoptes scabiei, which is 0.3–0.5 mm long and 0.2–0.4 mm wide.

Medicinal therapy: Wash with a decoction of 9g of zanthoxylum (Zanthoxyli Pericarpium, 花椒 huā jiāo) and 30g of kochia (Kochiae Fructus, 地肤子 dì fū zǐ); then apply Cnidium Seed Powder (蛇床子散 shé chuáng zǐ sǎn). This disease is less commonly seen nowadays because of improved hygiene. See sore³.

Etymology

Chin The character 疥 is composed of 介 jiè, a shell or crust with the illness signifier 疒. Eng scab akin to Old Swedish skabbr and Latin scabies mange, scabere to scratch. The meaning of crust (a protective coating that forms over a wound) developed from scab as a disease name. Thus scab and 疥 are almost identical in their linguistic meaning.