An 8-year-old boy from a remote tribal settlement in central India presents with a raspberry-like papillomatous lesion on the sole of the foot. There is no history of genital ulceration or sexual contact. VDRL and TPHA are both reactive. The most likely causative organism is:

• A Treponema pallidum subspecies pallidum
• B Treponema pallidum subspecies endemicum
• C Treponema pallidum subspecies pertenue ✓
• D Treponema carateum

Explanation

Yaws, caused by Treponema pallidum subspecies pertenue, is an endemic nonvenereal treponematosis of children in warm rural areas, spread by direct skin contact. It begins as a papillomatous granulomatous lesion, classically on the lower limbs, and later stages involve bones and palms and soles. Bejel, caused by subspecies endemicum, affects mucosa of the mouth, while Treponema carateum causes pinta with dyschromic skin patches in Central and South America. Standard serological tests cannot separate these organisms, so differentiation is clinical and geographic.

Reference: Harrison's Principles of Internal Medicine, 21st ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.