Yaws is a chronic, bacterial infection that affects the skin, bones and cartilage of an infected person, typically children up to 15 years old. It is spread by person to person contact. In the first stages Yaws appears on the skin as a papilloma (benign tumour/lump) and without treatment it will ulcerate. These ulcers are infectious and spread quickly to others. Secondary Yaws (weeks to months after the original infection) will appear as several raised yellow lesions or as swelling in long bones and fingers. If Yaws is not treated it can lead to disfigurement and disability.
For full information please refer to the WHO fact sheets: