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Definition.— Yaws is a contagious inoculable disease characterized by an indefinite incubation period followed usually by fever, by rheumatic-like pains, and by the appearance of papules which generally develop into a fungating, encrusted, granuloniatous eruption. It runs a chronic course; is mostly protective against a second attack; is believed to be caused by Treponema pertenue; is amenable to salvarsan, and, to a certain extent, is influenced by mercury and potassium iodide. Geographical distribution.— Yaws is widely diffused throughout the greater part of the tropical world. In certain places it is very common— as in tropical Africa, particularly on the west coast; in many of the West India Islands; in Ceylon, where it is one of perhaps several diseases included under the term parangi; in Fiji, where it is known as coko; in Java; in Samoa; and in many of the islands of the Pacific. It is difficult to say to what extent it exists in India; some deny its presence there altogether, but recent observations show that it does occur there to a limited extent; Powell has recognized and described it as occurring in Assam. Barker and Gimlette have shown that the skin disease described by Brown under the name of purru, and common in parts of the Malay Peninsula, is yaws. Yaws occurs in China, but is rare there— at all events on the coast. In some of the West India Islands, and Fiji, almost every child passes through an attack. In the latter, according to Daniels, those children who do not acquire the disease in the ordinary way are inoculated with it by their parents, who regard an attack of yaws as an occurrence more or less necessary and wholesome. Nicholls has made a