Investigation Update: Multistate Outbreak of E. coli O157:H7 Infections Associated with In-shell Hazelnuts
March 10, 2011
- Laboratory testing conducted by the Minnesota Department of Agriculture on in-shell hazelnuts recovered from a patient's home has identified Escherichia coli O157:H7 matching patient isolates by DNA analysis.
- No new cases of persons infected with the outbreak strain of E. coli serotype O157:H7 have been reported since the web announcement on March 5, 2011.
CDC is collaborating with public health officials in California, Michigan, Minnesota, Wisconsin, and the U.S. Food and Drug Administration (FDA) to investigate a multistate outbreak of E. coli O157:H7 infections. Investigators are using DNA analysis of E. coli O157:H7 bacteria obtained through diagnostic testing to identify cases of illness that may be part of this outbreak.
As of March 9, 2011, seven persons infected with the outbreak strain of E. coli serotype O157:H7 have been reported from Michigan (1 case), Minnesota (3 cases), and Wisconsin (3 cases). Reported dates of illness onset range from December 20, 2010 to January 28, 2011. Ill persons range in age from 15 to 78 years, with a median age of 62 years; 86% are male. Among ill persons, 43% reported being hospitalized, and none have reported hemolytic uremic syndrome, a type of kidney failure that is associated with E. coli O157:H7 infections. No deaths have been reported.
The outbreak can be visually described with a chart showing the number of people who became ill each day. This chart is called an epidemic curve or epi curve. Illnesses that occurred after February 22, 2011, might not be reported yet due to the time it takes between when a person becomes ill and when the illness is reported. This takes an average of 2 to 3 weeks. Please see the Timeline for Reporting of E. coli Cases for more details.
Investigation of the Outbreak
Collaborative investigative efforts of local, state, and federal public health and regulatory agencies have associated this outbreak with eating in-shell hazelnuts (also known as filberts). Most of the in-shell hazelnuts were purchased from bulk bins at retail food stores. Source tracing has identified a common distributor for the hazelnuts consumed by ill persons: DeFranco & Sonss in Los Angeles, California. Laboratory testing conducted by the Minnesota Department of Agriculture on in-shell hazelnuts recovered from a patient's home has identified E. coli O157:H7 matching patient isolates by DNA analysis.
DeFranco & Sons of Los Angeles, CA is voluntarily recalling bulk and consumer-packaged in-shell hazelnuts and mixed-nut products containing hazelnuts. These nuts may have been sold by retailers nationwide. The in-shell nuts may have been sold in two-pound and four-pound packages of mixed nuts, one-pound packages containing only hazelnuts, or in open bins of nuts in grocery stores. Consumers are advised to review the DeFranco press release for a list of recalled products.
Clinical Features/Signs and Symptoms
Most people infected with E. coli O157:H7 develop diarrhea (often bloody) and abdominal cramps 2-8 days (3-4 days, on average) after swallowing the organism, but some illnesses last longer and are more severe. Infection is usually diagnosed by stool sample culture. While most people recover within a week, some develop a severe infection. A type of kidney failure called hemolytic uremic syndrome (HUS) can begin as the diarrhea is improving; this condition can occur among persons of any age but is most common in children under 5 years old and the elderly. Signs and symptoms of HUS may include fever, abdominal pain, pale skin tone, fatigue and irritability, small, unexplained bruises or bleeding from the nose and mouth, decreased urination and swelling of the face, hands, feet, or entire body. Persons who experience these symptoms and believe they are at risk for HUS should seek emergency medical care immediately.
Advice to Consumers, Retailers and Others
Consumers should not eat any of the recalled products, and restaurants and food service operators should not serve them. Consumers, retailers, and others who have any of the recalled products should dispose of them in a closed plastic bag placed in a sealed trash can. This will prevent people or animals from eating them.
- FDA press release
- California Department of Public Health press release
- Minnesota State Department of Health press release
- Wisconsin Department of Health Services press release
- DeFranco press release
- E. coli O157:H7 Frequently Asked Questions
- E. coli Resources for Clinicians
- Description of the Steps In a Foodborne Outbreak Investigation
CDC's Role in Food Safety
CDC leads federal efforts to gather data on foodborne illnesses, investigate foodborne illnesses and outbreaks, and monitor the effectiveness of prevention and control efforts. CDC is not a food safety regulatory agency but works closely with the food safety regulatory agencies, in particular, with FDA and U.S. Department of Agriculture’s Food Safety and Inspection Service. CDC also plays a key role in building state and local health department epidemiology, laboratory, and environmental health capacity to support foodborne disease surveillance and outbreak response. Notably, CDC data can be used to help document the effectiveness of regulatory interventions.
Page last modified: March 10, 2011
Content source: Centers for Disease Control and Prevention
National Center for Emerging and Zoonotic Infectious Diseases (NCEZID)
Division of Foodborne, Waterborne, and Environmental Diseases (DFWED)