Distribution of Buruli ulcer lesions over body surface area in a large case series in Ghana: uncovering clues for mode of transmission.

We studied hospital records of 750 consecutive Buruli ulcer patients in a highly endemic area in Amansie West, Ghana. Although more Buruli ulcer lesions were found on the right side of the body, comparison of lesions on arms and legs showed a bilaterally symmetrical distribution. Upper and lower extremities were affected equally by Buruli ulcers, if correction was made for differences in body surface area. Patients from outside the Amansie West district presented significantly more often with ulcerated lesions, which were more often located on a joint, than patients who lived in Amansie West, suggesting that longer travel distance might have caused delay. Our observations of a bilaterally symmetrical distribution of lesions on extremities and equal upper and lower extremity involvement are compatible with a mode of transmission that involves passive exposure of exposed body parts. An asymmetrical distribution of lesions was found in an earlier study, suggesting transmission by vegetation near the ground, through activities like farming or play. Perhaps, transmission in or near water, e.g. by bites of infected aquatic insects, might favour the pattern of distribution of lesions that we found.