Definition: Yaws is a chronic, debilitating, non-venereal infectious disease caused by the bacterium Treponema pallidum pertenue, primarily affecting the skin, bones, and joints. It is transmitted through direct skin-to-skin contact, predominantly among children in warm, humid tropical regions.
The disease progresses through distinct stages, beginning with an initial ‘mother yaw’ lesion, typically a papule that enlarges and ulcerates. This is followed by secondary lesions, which are often widespread, framboesiform (raspberry-like) papules or plaques on the skin, and can include painful bone lesions (periostitis). Without treatment, yaws can advance to a late stage characterized by destructive lesions of the skin, bones, and cartilage, leading to severe disfigurement, chronic pain, and disability, particularly affecting the limbs and face. Historically widespread across tropical and subtropical areas globally, yaws was nearly eradicated in the mid-20th century due to successful mass treatment campaigns using penicillin, but has seen a resurgence in recent decades in a limited number of endemic countries.
From a public health perspective, yaws represents a significant burden in affected communities, causing severe morbidity, social stigma, and economic hardship, especially among marginalized populations. Diagnosis is typically based on clinical presentation in endemic areas, supported by serological tests such as rapid plasma reagin (RPR) and Treponema pallidum particle agglutination (TPPA) assays. Crucially, yaws is highly curable with a single oral dose of azithromycin, or historically, a single intramuscular injection of long-acting penicillin. This simple and effective treatment strategy has made yaws a prime candidate for global eradication, with the World Health Organization (WHO) launching renewed efforts to eliminate the disease by 2030 through active case finding, mass drug administration, and enhanced surveillance.
Key Context:
- Treponema pallidum pertenue: The specific bacterial subspecies responsible for yaws, closely related to the causative agents of syphilis, pinta, and bejel.
- Single-dose Azithromycin: A highly effective and easily administered oral antibiotic that revolutionized yaws treatment and made its global eradication a feasible public health goal.
- Neglected Tropical Disease (NTD): Yaws is classified as an NTD, disproportionately affecting impoverished communities in tropical and subtropical regions, highlighting health inequalities.