The McDonald’s E. Coli Outbreak Was Worse Than We Thought

The scope of the McDonald’s E. coli outbreak has gotten larger. Health officials have reported a substantial increase in cases this week, with many more cases likely having gone unnoticed.

The U.S. Centers for Disease Control and Prevention first reported the outbreak in late October, which had initially affected at least 49 people in 10 states. As of the CDC’s latest update released Wednesday, there have now been 104 cases across 14 states, while 34 people have been hospitalized and one person has died.

Though more cases may yet emerge, the probable source of the outbreak has been identified—fresh slivered onions—and officials have said that the danger from these tainted onions has likely passed. But while this episode is largely over, it highlights that such outbreaks can quickly spin out of control, perhaps aided by the complexities of manufacturing and distribution practices within fast food chains. Insufficient or shoddy quality control could be another factor.

Health officials initially found a link between these cases and McDonald’s Quarter Pounder menu item. But suspicion soon turned to the fresh slivered onions that are exclusively used on the sandwich. The CDC eventually confirmed that the outbreak was caused by onions supplied by the company Taylor Farms. Some fast food chains temporarily pulled their own onion items in response and Taylor Farms issued a larger recall of its onion products, though no further cases outside of McDonald’s appeared to have occurred.

Many strains of harmful E. coli can cause unpleasant, if short-lasting, gastrointestinal symptoms. But the strain behind this outbreak, O157:H7, produces toxins that can raise the risk of more severe, life-threatening complications like hemolytic–uremic syndrome (HUS), which can cause major organ damage, particularly to the kidneys. Four cases of HUS have been identified, though the one death reported to date was not among them.

It’s certainly possible that more cases will be reported. In general, foodborne outbreaks are often much larger than they look, since only a small percentage of people become sick enough to seek outside medical attention. It can also take three to four weeks on average for health officials to determine if someone’s foodborne illness is tied to an existing outbreak. But most of the cases in this outbreak occurred prior to the CDC’s reporting and the subsequent removal of onions from the McDonald’s menu. And because the tainted lots were either recalled and/or have now gone past their expiration date, the current risk of further E. coli from this particular contamination is likely nil.

Within a week of the outbreak first being publicized, McDonald’s returned the Quarter Pounder to its menu, sans onions. More recently, after having obtained a new supplier, the chain bought back fresh slivered onions as well—a move that seems to have the blessing of health officials.

“At this time, there does not appear to be a continued food safety concern related to this outbreak at McDonald’s restaurants,” the Food and Drug Administration said in the newly released statement.

While things might have settled down for Quarter Pounder fans, the fallout for McDonald’s isn’t necessarily over. Several alleged victims of the outbreak have either retained legal representation or already begun to sue the restaurant chain over their food poisoning.