Yaws, a chronic bacterial infection caused by Treponema pertenue, typically presents in darker-skinned individuals with skin lesions that start as painless sores, progressing to ulcerations and thickened, scarred tissue. The disease primarily affects the skin, bones, and cartilage, and is most common in tropical areas where sanitation is poor. Treatment is usually effective with a single dose of penicillin or, in some cases, tetracycline, which cures the infection and prevents further complications.