Figure 2.

NeighborNet (16) trees showing population differentiation of Shiga toxin–producing Escherichia coli O157:H7 isolates from humans and cattle from different regions in the North Island (red) and the South Island (blue), New Zealand. A) Isolates from human case-patients (n = 355, 8 isolates excluded). B) Isolates from bovine meat samples (n = 233, 2 isolates excluded). C) Map of New Zealand showing different regions from which samples were collected. The distances indicate population differentiation measured as pairwise F_ST values.