Figure 4.

Local (non-spatially disseminated) infection hypotheses. The 12 farms that contributed with ≥ 6 isolates were assessed in terms of intrafarm isolates/EP (percentage of isolates of a given farm reporting the same EP). Numbers identify farms (the same as reported in Table 5). Because the farm displayed in the upper right quadrant showed a high intrafarm isolates/EP index (67% of all isolates collected in farm 14 pertained to the same EP) but no spatial diffusion (zero EPspeed, see Tables 4 and 5), a "problem farm" hypothesis was supported. In contrast, no EP predominated in the 3 farms identified in the lower left quadrant (6, 8, 2): EPs collected in those farms explained < 13% of all isolates and displayed no spatial diffusion, profile that supported an "animal-problem" hypothesis.