pertenue

Treponema pertenue is a spirochete bacterium that belongs to the genus Treponema and is closely related to Treponema pallidum, the agent of syphilis. It is the causative agent of yaws, a chronic infectious disease of the skin and bones that is endemic to tropical regions and primarily affects children. Transmission occurs mainly through non-sexual skin-to-skin contact with infectious lesions.

Clinical features: Yaws typically begins with a primary lesion at sites such as the legs or trunk; the lesion, sometimes called a mother yaw, starts as a papule that enlarges and ulcerates before healing. Weeks to months later, secondary lesions may appear as widespread papules and plaques, sometimes with mucosal involvement. Bone and joint involvement (osteoperiostitis) can occur, leading to pain and, in chronic cases, deformities. Without treatment, infection can persist in a latent form and occasionally progress to later damage.

Diagnosis: In endemic settings, diagnosis relies on clinical suspicion supported by serology. Non-treponemal tests (RPR or VDRL) and treponemal tests (TPHA, FTA-ABS) are used; however, serology cannot reliably distinguish yaws from other treponematoses. Direct detection by dark-field microscopy is not widely available; PCR on lesion material can confirm Treponema pertenue infection.

Treatment and control: A single dose of benzathine penicillin G (for example, 50 mg/kg up to 2.4 million units in adults) is highly effective. Alternatives such as single-dose oral azithromycin are used in some settings, though macrolide resistance has emerged in parts of the world. Public health strategies include case finding, treatment of contacts, and, where feasible, mass drug administration, along with surveillance.

Prognosis and history: With timely treatment, lesions heal and transmission is interrupted. Yaws has a long-standing presence in the tropics, and eradication efforts have aimed for global elimination.