Frequently asked questions on the EHEC infection outbreak in Germany


6 June 2011

1. What are EHEC and HUS?

Enterohaemorrhagic Escherichia coli (EHEC) is a human pathogenic E. coli bacterium that is able to cause haemorrhagic colitis (bloody diarrhoea), which sometimes develops into haemolytic uraemic syndrome (HUS). HUS is a life-threatening disease that causes kidney damage and is a severe complication of EHEC infection. EHEC is so-called Shigatoxin-producing E. coli (STEC), also known as verocytotoxin-producing E. coli (VTEC). Animals can carry other types of STEC/VTEC in their intestines that are not necessarily pathogenic for humans.

2. Surely E. coli is very common, so why the concern?

Yes, E. coli is a common bacterium that is found in the intestines of humans and warm-blooded animals. Nevertheless, this particular strain, a rare serotype of EHEC (E. coli O104:H4), is severe, and has caused much illness and some deaths in Germany. Cases have also occurred in 12 other countries, all of whom had travel links to, or residence in, Germany, except for one case still under investigation. This is a significant outbreak of HUS. It is affecting mostly women and people over 20 years of age, which is unusual. As the source of the outbreak has not been found, it is difficult to say how long it will last.

3. Is this unique?

The serotype of EHEC, O104:H4, isolated from cases in the EHEC infection outbreak in Germany, is a rare one, seen in humans before but never in an EHEC outbreak. This has been confirmed by the WHO Collaborating Centre for Reference and Research on Escherichia and Klebsiella, the Statens Serum Institut in Denmark. Authorities report that the outbreak strain is EHEC serotype O104:H4, or more precisely a strain of enteroaggregative verocytotoxin-producing E. coli (EAggEC VTEC) O104:H4.

4. How would you describe the current EHEC outbreak in Germany?

Germany is experiencing a significant outbreak of EHEC, a highly pathogenic bacterium subgroup of STEC. A minority of cases are presenting complications with HUS, a life-threatening disease characterized by acute kidney failure (uraemia), haemolytic anaemia, and a low platelet count (thrombocytopenia).

5. When was the last EHEC outbreak?

Every year there are EHEC outbreaks in different parts of the world including Europe, sometimes involving HUS and even deaths, but the number of affected people is very much lower than what Germany is now experiencing. In 1996, the world’s biggest recorded outbreak was registered in Japan and included over 10 000 infected cases.

6. How many countries are involved in the current outbreak?

Cases have now been notified from 12 countries in addition to Germany: Austria, the Czech Republic, Denmark, France, the Netherlands, Norway, Poland, Spain, Sweden, Switzerland, the United Kingdom and the United States of America. These are typically people who have recently visited northern Germany or, in one case, had contact with a visitor from northern Germany who was an EHEC case.

7. Do people outside Germany need to worry?

Most of the cases are linked to the northern part of Germany, and investigations are taking place to define the exact geographical areas where transmission is occurring. There is no indication so far of confirmed domestic or secondary infection in other countries.