A. Phylogenetic tree of H. ducreyi CU and GU strains based on whole-genome sequences. B. Phylogenetic tree of H. ducreyi CU and GU strains based on dsrA-hgbA-ncaA sequences. The evolutionary relationship was inferred by using the Maximum Likelihood method based on the Hasegawa-Kishino-Yano model. The reliability of the tree was tested using 500 bootstrap replicates; the bootstrap support values are indicated next to the branches in percentage. Asterisks, GU strains. Strain designations for the CU strains included their country of origin as follows: Vanuatu, VAN, NZV; Samoa, NZS; Papua New Guinea, AUSPNG and Ghana, GHA. As reported previously [7], the GU strains have a worldwide distribution.