Yaws disease is a chronic infection caused by the bacterium *Treponema pertenue*, which primarily affects the skin, bones, and cartilage. It is most common in warm, humid tropical regions and mainly affects children. The symptoms of yaws develop in stages, each with distinct signs that reflect the progression of the disease.
In the **first stage**, often called *early yaws*, the initial symptom is a small bump or papule on the skin. This bump usually appears at the site where the bacterium entered the body, often on the legs, arms, or face. Over days to weeks, this bump transforms into a painless sore or ulcer. The sore may look yellowish, wet, or crusty but does not cause pain, which can make it easy to overlook. Despite the lack of pain, this sore is highly infectious and can spread the bacteria to others through direct skin contact. After several weeks, the sore typically heals on its own, but the infection remains in the body, silently progressing if untreated.
If the disease is not treated, it enters the **second stage**, or *late yaws*, which can occur weeks to months after the initial sore heals. During this stage, new skin lesions appear, often multiple and scattered across the body. These sores can be more widespread and may sometimes bleed. Alongside the skin symptoms, the person may start to feel general fatigue and experience pain in the bones and joints. Swelling can develop in the fingers, toes, and nose, causing discomfort and visible deformities. The skin lesions in this stage are more persistent and can cause significant discomfort, although they may still be painless.
Without treatment, yaws can progress to a **third and very late stage**, which is much rarer but more severe. This stage can occur months to years after the initial infection and is characterized by destructive changes to the skin, bones, and cartilage. The skin may become thickened and hardened, and deformities can develop, especially in the legs and nose. These deformities result from chronic inflammation and damage caused by the persistent infection. The bones may become misshapen, leading to permanent disability and disfigurement. This late stage reflects the destructive potential of untreated yaws and highlights the importance of early diagnosis and treatment.
Throughout all stages, the symptoms of yaws are primarily dermatological and musculoskeletal. The initial painless ulcer is a hallmark sign, followed by recurrent skin lesions and bone pain. The disease does not typically cause fever or systemic illness in its early phases, which can delay recognition. However, the visible skin changes and bone deformities in later stages are unmistakable signs of advanced infection.
Diagnosis of yaws is often clinical, based on the characteristic skin lesions and patient history, especially in endemic areas. Simple blood tests can confirm the infection, and microscopic examination of skin samples may be used in some cases. Early recognition is crucial because yaws is highly contagious in its early stages but can be effectively treated with antibiotics, preventing progression to the destructive late stage.
In summary, the symptoms of yaws disease evolve from a small, painless skin bump that becomes an infectious sore, to widespread skin ulcers, bone and joint pain, swelling of extremities, and eventually to severe deformities of skin and bones if left untreated. The painless nature of the initial sore and the chronic progression make awareness and early treatment essential to avoid long-term complications.
