34-05: Yaws

Yaws (also known as frambesia or pain), the most prevalent of the endemic treponematoses, is largely limited to tropical regions, most commonly Ghana, the Solomon Islands, and Papua New Guinea, and is caused by T pallidum subspecies pertenue. It is characterized by granulomatous lesions of the skin, mucous membranes, and bone and is rarely fatal, though if untreated it may lead to chronic disability and disfigurement. Yaws is acquired by direct nonsexual contact, usually in childhood, although it may occur at any age. The “mother yaw,” a painless papule that later ulcerates, appears 3–4 weeks after exposure, usually with associated regional lymphadenopathy. Six to 12 weeks later, secondary raised papillomas and papules that weep highly infectious material appear and last for several months or years. Painful ulcerated lesions on the soles are called “crab yaws” because of the resulting gait. Late gummatous lesions may occur, with associated tissue destruction involving large areas of skin and subcutaneous tissues. The late effects of yaws, with bone change, shortening of digits, and contractions, may be confused with similar changes occurring in leprosy. CNS, cardiac, or other visceral involvement is rare. The WHO has set a goal of eliminating yaws using mass treatment with azithromycin in endemic regions. Emergence of macrolide resistance has complicated this approach.