By Gary M. White, MD
Yaws is an infection by the spirochete, Treponema pallidum subsp. pertenue, which is nearly identical (99.8%) to the cause of syphilis Treponema pallidum. Thus, the same tests to detect syphilis (e.g., VDRL, fluorescent treponemal antibody) are used to diagnose yaws.
The primary stage is the "mother yaw" which arises at the site of inoculation (e.g., bite, scratch, or abrasion), usually on the legs, feet, or buttocks. It begins as an erythematous papule and enlarges to form an ulcerating, crusted nodule. Fever, arthralgias, or local adenopathy may accompany the primary stage. It heals spontaneously over several weeks to months.
The secondary stage which occurs several weeks to months after the "mother yaw" consists of disseminated smaller "daughter yaws." They are moist, exudative, adjacent to body orifices (e.g., nose and mouth), and often attract flies. Palmoplantar hyperkeratosis is also common in this secondary stage as is pain and swelling of long bones and fingers (dactylitis).
The tertiary stage which occurs several years later in approximately 10% of cases consists of the palmoplantar keratoderma, destructive, nodular, plaque-like and ulcerating cutaneous lesions as well as bone and joint lesions.
The latest recommended treatment guidelines should be consulted. A single dose of oral azithromycin (30 mg/kg with a maximum of 2 g) is as effective as intramuscular benzathine penicillin (1.2 million Units for adults, and 0.6 million U in children younger than 10 years). Alternatives include tetracycline, e.g., 1-2 gm in divided doses per day for at least five days. For young children, erythromycin 8-10 mg/kg QID for 15 days has been used.
Primary and secondary Yaws and dactylitis. Br Med Bull. 2015 Mar; 113(1): 91–100.
Primary Yaws. PLoS Negl Trop Dis. 2012 Nov; 6(11): e1837.
Images of yaws lesions (papilloma) on the face and arm before and after treatment. PLoS Negl Trop Dis. 2014 Sep; 8(9): e3016
Multiple photos. www.who.int
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