Appendix Figure 1. An unrooted neighbor-joining HKY85 phylogram with all MACS 1993 late infection and PIC 1993 early infection sequences shown in relation to each other and 100 CDC sequences. MACS 1993 are circled in gray ovals, PIC 1993 are boxed in black rectangles. Mean tip branch lengths are significantly longer in MACS 1993 than PIC 1993 lineages (P < 0.001, two-tailed Mann-Whitney U test). .
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