Investigation Update: Outbreak of Shiga toxin-producing E. coli O104 (STEC O104:H4) Infections Associated with Travel to Germany

Updated June 15, 2011

Introduction

CDC is monitoring a large outbreak of Shiga toxin-producing Escherichia coli O104:H4 (STEC O104:H4) infections ongoing in Germany. The responsible strain shares virulence characteristics with enteroaggregative E. coli (EAEC).  As of June 14, 2011, case counts confirmed by Germany’s Robert Koch Institute* include 784 patients with hemolytic uremic syndrome (HUS)–a type of kidney failure that is associated with Shiga toxin-producing E. coli or STEC infections–and 23 HUS-associated deaths.

In the United States, four confirmed cases and one suspect case of STEC O104:H4 infections have been identified. Of these five cases, four recently traveled to Hamburg, Germany, where they were likely exposed. The bacterial isolates from the three HUS cases reported in Massachusetts, Michigan, and Wisconsin and one case with Shiga toxin-positive diarrheal illness in Michigan have been confirmed as matching the outbreak strain. The Michigan case with Shiga toxin-positive diarrheal illness did not travel to Germany, but is a close contact of the Michigan case with HUS.  Their diarrheal illness developed later and was likely acquired through contact with the HUS case.  The suspect case is currently under investigation.

Among U.S. military personnel and their dependents that are stationed in Germany, there are no confirmed cases at this time. Continuous monitoring has shown no increase in visits due to gastrointestinal illness at U.S. military medical treatment facilities in Europe.

CDC has alerted state health departments of the ongoing outbreak and requested information about any persons with either HUS or Shiga toxin-positive diarrheal illness, with illness onset during or after travel to Germany and since April 1, 2011. Additionally, CDC is working with state health departments to learn more about suspect cases and obtain bacterial isolates for further characterization. When a report of STEC infection is investigated, every effort is made to identify ill family members or other close contacts to determine if person-to-person spread has occurred. With this outbreak, only one instance of person-to-person spread has been documented.

Investigation of the Outbreak

RKI, the Federal Institute for Risk Assessment and the Federal Office of Consumer Protection and Food Safety have announced there is substantial epidemiologic and traceback evidence indicating that fresh sprouts produced by a farm in Lower Saxony are responsible for the current outbreak in Germany. German public health authorities currently recommend that people in Germany not eat raw sprouts of any origin. Trace back investigations of the food chain indicate that no sprouts or other food items from the implicated farm in Lower Saxony have been exported outside Germany. Travelers to Germany should be aware that the recommendation not to eat cucumbers, tomatoes and leafy salads in northern Germany has been lifted as of June 10.

Although rare, E. coli O104:H4 has been identified before. For example, in 2009 in the Republic of Georgia, culture of specimens from two patients who were part of a cluster of diarrheal illness yielded an E. coli O104:H4 strain that was similar to the current outbreak strain. That strain produced Shiga toxin, but had a different molecular fingerprint and was less resistant to antibiotics than the current outbreak strain in Germany. No clear outbreak was identified in the Republic of Georgia, and no food was identified as a source of infections.

Clinical Features/Signs and Symptoms

Any person who has recently traveled to Germany or has been in recent contact with an ill person who has recently traveled to Germany and has signs or symptoms of STEC infection or HUS, should seek medical care. He or she should tell the medical provider about the outbreak in Germany and the importance of asking the laboratory to test a stool specimen for STEC. Symptoms of STEC infection include stomach cramps, diarrhea (which is often bloody), and vomiting. If there is fever, it usually is not very high. Most people get better within 5-7 days, but some patients go on to develop HUS—usually about a week after the diarrhea starts. Symptoms of HUS include decreased frequency of urination, feeling very tired, and losing pink color of skin and membranes due to anemia.

Key Resources

• Escherichia coli O157:H7 and other Shiga toxin-producing Escherichia coli (STEC)
• CDC E. coli Resources for Clinicians
• CDC Travelers' Health Website - "Outbreak Notice"
• Presentation -“Shiga Toxin-Producing Escherichia Coli Infections: What Clinicians Need to Know”
• MMWR - “Recommendations for Diagnosis of Shiga Toxin–Producing Escherichia coli Infections by Clinical Laboratories” [PDF - 287 KB]
• E. coli: Key publications [PDF - 227 KB]
• Description of the Steps In a Foodborne Outbreak Investigation
• FoodSafety.gov*
• Robert Koch Institute (Germany)*

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 the Food and Drug Administration of the U.S. Department of Health and Human Services and the Food Safety and Inspection Service of the U.S. Department of Agriculture. 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.