Figure 1.

Neighbor-joining tree of pairwise allele-sharing genetic distances calculated with the program MICROSAT. Tree construction was performed with programs in the PHYLIP package (36). The isolate marked with an asterisk signifies a patient who was diagnosed in Texas but was subsequently found to have acquired the infection in California (42). The tree is mid-point rooted, and the scale bar signifies 0.1 changes. CA, Californian; non-CA, non-Californian.