Stage 1 yaws typically occurs in early childhood, with peak incidence at about six years of age. A single itchy, strawberry-like growth appears on the skin over which a thin yellow crust forms (papillomatous lesion). This growth, the “mother yaw”, appears at the spot where the organism entered the body (inoculation site), typically on the leg or foot.

Stage 2 yaws typically follows several weeks or months after the initial symptoms. Similar skin sores appear on the face, legs, arms, and/or around the rectum and genitals. These sores usually heal slowly and may recur. Lesions on the bottom of the feet may produce painful cracks and ulcerations (keratosis), resulting in an awkward “crab-like” walk or “crab yaws.”

At this stage, swollen glands (swollen lymph nodes) are not uncommon and the rash may develop a brown crust.

The symptoms of stage 3 yaws occur in only about 10% of the people who are infected and may follow a dormant period of several years. Painful ulcers or nodules may develop on the skin (cutaneous) and cause facial disfigurement. Painful, granular sores (gummatous lesions) may also develop on the bones, especially the long bones of the legs (tibia). Painful skin and bone nodules may impair joint function and mobility.

Stage 3 yaws may also produce different and distinct syndromes. One, known as goundou syndrome, is characterized by inflammation and swelling of the tissues surrounding the nose (paranasal swelling), as well as overgrowth of the bones in the same region of the face (hypertrophic osteitis). Another, known as gangosa syndrome (also known as rhinopharyngitis mutilans), is characterized by degenerative changes of the nose, throat (pharynx), and the roof of the mouth (hard palate).