The Centers for Disease Control and Prevention (CDC) has declared the outbreak of Shiga toxin-producing Escherichia coli linked to onions served on McDonald's hamburgers over.
The outbreak of E coli O157:H7, which began in September, sickened 104 people in 14 states, resulting in 34 hospitalizations, 4 cases of hemolytic uremic syndrome, and 1 death. The source of the outbreak is believed to be slivered onions served primarily on McDonald's Quarter Pounder hamburgers. Of the 81 case-patients who were interviewed 80 reported eating at McDonald's, and 63 reported eating a menu item containing fresh slivered onions.
E coli O157:H7 causes severe stomach cramps, bloody diarrhea, and vomiting. Symptoms typically start 3 to 4 days after ingesting the bacteria, and most people recover without needing medical treatment. The CDC says the true number of people affected in the outbreak is likely much higher, and the outbreak may not have been limited to the states. with known illnesses.
Taylor Farms, the company that supplies yellow onions to McDonald's restaurants in several of the affected states, voluntarily recalled the product on October 22, and restaurants in those states temporarily stopped using slivered onions. McDonald's also temporarily stopped serving Quarter Pounder hamburgers in the affected states.
Investigations by the CDC, the Food and Drug Administration (FDA), the US Department of Agriculture's Food Safety and Inspection Service, and state partners did not find the strain of E coli linked to illnesses in the outbreak in samples of recalled onions or an environmental sample from a grower that supplies Taylor Farms. But the FDA said epidemiologic and traceback evidence indicates the onions were the likely source of the outbreak. Testing of beef samples by the Colorado Department of Agriculture were negative for E coli.
The FDA said in an update yesterday that there does not appear to be a continued food safety concern related to the outbreak, and that their investigation is closed. McDonald's said in a statement that it has identified an alternative slivered onion supplier for approximately 900 restaurants.
Other E coli outbreaks
The McDonald's outbreak is one of two major E coli outbreaks the CDC has investigated in recent months. On November 17, the agency reported an outbreak of E coli O121 linked to organic whole and baby carrots sold by Grimmway Farms. That outbreak has sickened 39 people in 18 states, with 15 hospitalizations and 1 death.
In related news, Food Safety News reports that an E coli outbreak thought to be limited to St. Louis, Missouri, has now spread across six other states. The outbreak, which has affected 115 people in St. Louis, is suspected to be linked to leafy greens. Genetic testing has found additional patients in Illinois, Indiana, Kansas, North Dakota, Ohio, and South Dakota.
