O-25 - 77% of vehicle-identified SE outbreaks in the 1985-87 US Northeast traced to Grade A shell eggs (65 outbreaks, 11 deaths)
The central attribution finding, with hard endpoints (11 deaths). The intact/refrigerated condition of the implicated eggs is what distinguishes this from classic cracked/soiled-egg salmonellosis.
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Why this is evidence
Discriminates both facets of the thesis from the residual H-58. The 77% attribution to Grade A shell eggs is strongly predicted by H-12 (eggs the principal vehicle) and contradicts the H-58 branch where eggs are not the principal vehicle. The implicated eggs being intact, uncracked and properly refrigerated is predicted by H-11 (internal/trans-ovarian route, uncontrollable by handling) and contradicts the H-58 branch where transmission is external/shell contamination controllable by handling — which requires cracked or soiled eggs.