$MCD - MCDONALD'S CUSTOMER VISITS FALL AFTER E. COLI OUTBREAK McDonald's suffered a slowdown in business in the wake of the E. coli outbreak tied to onions served on Quarter Pounders. Customer foot traffic to the chain's U.S. stores declined more than 6% over the three days following the outbreak's announcement on Oct. 22, compared with the same period a year earlier, according to Gordon Haskett Research Advisors. A day earlier, the Centers for Disease Control and Prevention flagged that at least one person had died and 49 were sickened in connection with the outbreak.