WHO Model Prescribing Information: Drugs Used in Skin Diseases
(1997; 132 pages) [French] [Spanish] View the PDF document
Table of Contents
View the documentPreface
View the documentIntroduction
Open this folder and view contentsParasitic infections
Open this folder and view contentsInsect and arachnid bites and stings
Open this folder and view contentsSuperficial fungal infections
Open this folder and view contentsSubcutaneous fungal infections
Close this folderBacterial infections
View the documentStaphylococcal and streptococcal infections
View the documentYaws and pinta
Open this folder and view contentsViral infections
Open this folder and view contentsEczematous diseases
Open this folder and view contentsScaling diseases
Open this folder and view contentsPapulosquamous diseases
View the documentCutaneous reactions to drugs
Open this folder and view contentsPigmentary disorders
Open this folder and view contentsPremalignant lesions and malignant tumours
Open this folder and view contentsPhotodermatoses
Open this folder and view contentsBullous dermatoses
View the documentAlopecia areata
View the documentUrticaria
Open this folder and view contentsConditions common in children
View the documentAcne vulgaris
View the documentPruritus
View the documentTropical ulcers
Open this folder and view contentsAntimicrobial drugs
Open this folder and view contentsAntifugal drugs
Open this folder and view contentsAntiseptic agents
Open this folder and view contentsKeratoplastic and keratolytic agents
Open this folder and view contentsScabicides and pediculicides
Open this folder and view contentsAnti-inflammatory and antipruritic drugs1
Open this folder and view contentsAntiallergics and drugs used in anaphylaxis
Open this folder and view contentsUltraviolet radiation-blocking agents (sunscreens)
Open this folder and view contentsMiscellaneous drugs
Open this folder and view contentsAnnex
View the documentSelected WHO Publications of Related Interest
View the documentBack cover

Yaws and pinta

Yaws and pinta are caused respectively by the spirochaetes Treponema pertenue and T. carateum (invalid). Although closely related to T. pallidum which causes syphilis, neither organism is transmitted by sexual contact. Intensive campaigns organized by WHO and UNICEF virtually eradicated these diseases in the 1950s, but yaws is now widely endemic in tropical areas, while pinta is confined to the American tropics. Both diseases are spread among children by direct contact. Exudate from infectious primary lesions gains access to deeper layers of the skin through minor skin abrasions or cheilitic lesions associated with vitamin B deficiency.

Yaws is heralded, after an incubation period of 3-5 weeks, by a small papule, usually on the lower leg or foot. Occasionally, however, night pain in the legs resulting from periosteal inflammation of the long bones is the first indication of the disease. The primary skin lesion rapidly enlarges into a fleshy, ulcerated papilloma, which exudes a serous fluid containing many treponemes. Secondary cutaneous papillomatous or papulosquamous lesions may appear anywhere, but are typically found in moist areas and at mucocutaneous junctions. Pain and swelling of the small joints of the hand is also typical of the early disseminated phase of the disease. The initial acute inflammatory lesions usually resolve completely within a few months, but subsequent relapses may leave extensive cutaneous scars. Prolonged periostitis results in “sabre tibia” and other characteristic bone deformities. For several years, however, episodes of hyperkeratosis with fissuring and ulceration of the soles of the feet often provide the only indication of continued activity of the disease. Later, gummatous lesions of the skin similar to those of syphilis and destructive lesions of the bone may occur. Gummatous cranial periostitis and destruction of the palatal and nasal cartilage are also typical and serious complications of the late stages of the disease.

Pinta is a comparatively benign condition in which only the skin is involved. The primary lesion is usually psoriasiform in appearance and often attains a diameter of several centimetres. This, and other lesions which may develop subsequently, gradually lose their initial violet colour to leave depigmented and atrophic scars.


A single dose of 2.4 million IU of benzathine benzylpenicillin (1.2 million IU for children) should be administered in two intramuscular injections to avert all risk of relapse. Patients who are sensitive to penicillin should receive tetracycline provided they are over 8 years of age, while younger patients should be given erythromycin.


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