Figure. Legionnaires Disease (LD) Cases and Rates for 2015 and 2016, by US Regions.

A, Numbers of LD cases reported to the Veterans Health Administration tracking system are shown, categorized by type of Veterans Affairs (VA) health care facility exposure, if any. B, Total LD rates were calculated for each region using the number of enrolled veterans in the regions who used the VHA system in the 2-year period as denominator. The results for each pairwise χ² test are provided in eAppendix 4 and eTable 5 in the Supplement to allow for assessment of the strength of the differences in the presence of multiple comparisons.

^aRate was significantly different (P < .01) compared with the rate for the Middle Atlantic region by pairwise χ² test.

^bRate was significantly different (P < .01) compared with the rates for the New England, South Atlantic, and Pacific regions by pairwise χ² test.

^cRate was significantly different (P < .01) compared with the rates for the South Atlantic and Pacific regions by pairwise χ² test.

^dRate was significantly different (P < .01) compared with the rates for the Middle Atlantic and East North Central regions by pairwise χ² test.