Like pinta, bejel and syphilis, the culprit is a spirochaete. Those ulcers are caused by treponema pertenue and the disease – yaws – is most common in younger children in tropical countries. Unlike syphilis, spread of yaws is by direct contact and the treatment is a single dose of imi benzathine penicillin or oral azithromycin. The response is rapid. Untreated however, secondary bone involvement can lead to nasty disfigurement.
Since mass treatment and public health measures were introduced in India that country, once a yaws capital, has not seen a new case for 5 years. This disease is venerable – examination of the 1.5 million year old remains of Homo erectus in Kenya has revealed signs typical of yaws.