Figure 1. After reaching plateau in bacillary numbers, M. ulcerans-infected mouse footpads continue to increase in swelling.

Swelling first became apparent at day 20 after infection. For the first 3 weeks, the number of cultivable organisms increased from 3.29±0.33 log₁₀ on day 3 to 4.26±0.08 log₁₀ on day 7, 4.73±0.42 log₁₀ on day 13, 5.05±0.19 log₁₀ on day 20, and 6.02±0.13 log₁₀ on day 24, the first day of treatment. CFU remained at approximately this level for the remainder of the experiment in untreated mice. Swelling averaged ∼grade 1 at day 27 after infection, nearly grade 2 at day 34, grade 2.67 at day 40, 3.42 at day 48, 3.75 at day 55, 3.58 at day 63, and 3.75 again at day 78. Data based on 3 mice per group per time point. Red lines emphasize the period between the onset and augmentation of swelling and the plateau in CFU.