A fourth person has tested positive for E. coli in Boone County, Missouri, and tests on a fifth is pending.  The Boone County/Columbia, Missouri Health Department says:

This a higher-than-average number of cases for our county. Our staff is working with state officials to determine the cause of the illnesses and whether or not they are at all related to the current outbreak in St. Louis. At this point, our disease investigators have not identified a commonality among the cases.

One of the Boone County E. coli cases matches the strain of E. coli O157:H7 involved in the St. Louis E. coli outbreak linked to Schnucks stores.  That Boone County case is not being considered a confirmed case in the St. Louis E. coli outbreak, however, because the person has not had any recent travel to St. Louis.  Reports have also indicated that an Illinois resident also tested positive for the same strain of E. coli O157:H7 as is involved in the St. Louis outbreak.  No word on whether this person had any recent travel to the St. Louis area. 

These outlying illnesses could be explained in a number of ways, but one is that they may not be “outlying illnesses” at all.  The epicenter of the St. Louis outbreak is clearly St. Louis, but given the distribution of cases and that this seems to be a produce outbreak, it’s certainly possible that a regionally distributed produce product has caused illness in more areas than just St. Louis.  Time will tell.