CDC is following a large outbreak of Shiga toxin-producing E. coli O104, or STEC O104, infections currently going on in Germany. As of May 31, 2011, the Robert Koch Institute (RKI), Germany’s disease control and prevention agency, has confirmed six deaths and 373 patients with hemolytic uremic syndrome, or (HUS) (kidney failure), a life-threatening complication of E. coli infections.

To date, no confirmed cases of STEC O104 infections have been reported in U.S. travelers to Europe. Two cases of HUS in the United States have been reported in persons with recent travel to Hamburg, Germany. CDC is working with state health departments to learn more about these two cases and to identify others. CDC has been in contact with the German public health authorities at RKI. We have alerted state health departments in the United States of the ongoing outbreak. We have also requested that they report to CDC any cases in which people have either HUS or Shiga toxin-positive diarrheal illness, with illness onset during or after travel to Germany since April 1, 2011.

The strain of STEC causing illness, STEC O104:H4, is very rare. CDC is not aware of any cases of STEC O104:H4 infection ever being reported in United States. Any person with recent travel to Germany with signs or symptoms of STEC infection or HUS, should seek medical care and let the medical provider know about the outbreak of STEC infections in Germany and the importance of being tested. Symptoms of STEC infection include severe 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 to skin and membranes due to anemia.

CDC is not aware that a specific food has been confirmed as the source of the infections. Travelers to Germany should be aware that the German public health authorities have recommended against eating raw lettuce, tomatoes or cucumbers, particularly in the northern states of Germany (Hamburg, Bremen, Lower Saxony, Schleswig Holstein). We have no information that any of these suspected foods have been shipped from Europe to the United States at this time. The US Department of Defense has been notified of this outbreak because of the presence of U.S. military bases in Germany. We are not aware of any cases among U.S. military personnel.

Here are answers to frequently asked questions:

Would this be the largest E. coli outbreak ever in the world?

We are still learning more about the overall size of this outbreak. The number of HUS cases involved indicates that the outbreak is very large.

Tell us about this rare strain and are we testing for it here?

A very rare strain of Shiga toxin-producing E. coli, or STEC has been reported from some patients in the outbreak. This strain, E. coli O104:H4 has never been seen in the United States, and CDC is only aware of few reports of this strain from other countries. Although it is rare, the United States’ public health surveillance systems are designed to be able to identify this, and other rare STEC strains, in ill people. However, the ability to detect STEC infections through surveillance depends on proper diagnostic testing of patients presenting with symptoms suggestive of STEC. In 2009, CDC published recommendations for the diagnosis of STEC infections by clinical laboratories. The illness that it causes is similar to that caused by E. coli O157:H7 which is also a Shiga toxin-producing E. coli and the one most commonly identified in the United States.

Could people travel from Germany and spread it here?

STEC infections can be spread from person to person. The best defense is careful, thorough hand washing. Persons returning from Germany who have diarrhea should be sure to wash hands well with soap and warm water after using the bathroom, and should not prepare food for others while they are ill. People who are in contact with ill people who recently visited Germany should also follow basic hygiene practices carefully, including washing their hands thoroughly before eating or drinking and after caring for an ill person.

Why so many sick people?

It is too early to know why this is such a large outbreak. The large size may have to do with contamination of a popular food item. However, to our knowledge a specific food vehicle has yet to be confirmed. It is also possible that the unusual strain is particularly likely to cause HUS.