From Seattle/King County Department of Health:

The investigation team is continuing to figure out where the E. coli O157 came from. We expected to find additional people who were exposed to the E. coli O157 linked to Los Chilangos before we closed them. To this point, we are able to say that there are four more people impacted by this outbreak, bringing the total to ten. These are not people who are newly ill, but rather people who were unable to be reached during our initial interview process or people who did not recall eating at Los Chilangos at the time of their interview. None of these nine people became sick after August 21.