Questions and answers (Q and A) on the outbreaks in Germany and France

7  July 2011

What is causing these E. coli outbreaks?

The outbreaks are caused by infection with O104:H4, a rare strain of the enterohaemorrhagic Escherichia coli (EHEC) bacterium. It can cause haemorrhagic colitis (bloody diarrhoea), which sometimes develops into haemolytic uraemic syndrome (HUS). HUS can cause kidney failure and death. It is a severe complication of shigatoxin-producing E. coli (STEC), also called verocytotoxin-producing E. coli (VTEC). 

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

Yes, E. coli is a common and normally harmless bacterium that is found in the intestines of humans and warm-blooded animals. This particular serotype is severe, however, and has not been reported in an outbreak before.

This is a significant outbreak, with several unusual characteristics. Between 22 May and 30 June, over 4000 people in Germany fell sick and 49 people died, including 1 in Sweden. Unusually, it has mostly affected people who were previously healthy, female and over 20 years of age. Cases occurred in 15 countries outside Germany, mostly in people with travel links to Germany.

Has it spread to France?

Between 22 and 28 June, the French authorities reported eight people in hospital with HUS and eight with bloody diarrhoea. The sick people had no connection with and had not visited Germany, but four were confirmed as having the same rare serotype: E. coli O104:H4. (The one death that has been reported was not from E. coli O104:H4.) Analysis has shown that the two strains are genetically indistinguishable, suggesting that these outbreaks have a common source. There is also an isolated case in Sweden.

So what is the connection?

Intensive investigation revealed that sprouted seeds/beans were likely to be the vehicle for the infection in Germany. The French authorities reported that nine patients had eaten sprouted seeds/beans, scattered on a cold vegetable soup at a local school. This has raised concern about sprouted seeds, so food safety authorities are trying to trace their origin. A major part of the investigation now focuses on this task, although all options have to be investigated.

What kinds of investigation are involved?

The French authorities are carrying out epidemiological, food trace-back and risk communication activities, and are looking at all possible vehicles for the infection. The suspected sprouting seeds in France did not come from the implicated farm in Germany, but further data and investigation are needed to find out whether:

• the sprouts are indeed the culprit;
• the seeds of the implicated sprouts in the two countries are of the same type and origin;
• the seeds come from the same producer/country; and
• there are contaminated sprouts/seeds in other countries.

Who is doing this investigation?

The German authorities made extensive investigations, questioning thousands of people and doing research. Tracking down seeds – perhaps from countries outside the WHO European Region – is a major challenge. To support the French and German authorities in their task and at the request of the European Commission (EC), the European Food Safety Authority (EFSA) set up a task force to coordinate investigations seeking the source of any contaminated seeds used for sprouting. Along with experts from the EC, some European Union (EU) Member States and the European Centre for Disease Prevention and Control (ECDC), WHO provided technical expertise, with the support of relevant WHO collaborating centres, and facilitated information gathering, particularly outside the EU. The task force’s report and its conclusions can be found on the EFSA web site (http://www.efsa.europa.eu/en/press/news/110705.htm).

Why are bean sprouts a likely vehicle for infection?

Sprouted seeds/beans have been linked to many recent outbreaks of foodborne disease. Since 2000, there have been 28 outbreaks worldwide of either E. coli or Salmonella in sprouted seeds. In 1996, over 9000 people in Japan fell sick with E. coli (0157:H7) after eating radish sprouts. E. coli and Salmonella outbreaks have been associated with alfalfa, bean, clover and radish sprouts.

Sprouting seeds/beans have a high risk of contamination with bacteria because of the conditions required for germination. They are grown in steam drums; if bacteria are present, the process provides ideal conditions for the bacteria to thrive. Practices for seed processing, shipping and selling often involve mixing multiple seed lots of different origins, so trace-back is complicated and cross-contamination between the seeds is a real risk. This can make finding the exact source of an outbreak very difficult.

What is WHO doing about the outbreaks?

The International Health Regulations require all countries to inform WHO of any events that may constitute a public health emergency of international concern. WHO helps to coordinate information sharing and collaboration worldwide through international reporting mechanisms such as the International Food Safety Authorities Network (INFOSAN – a joint initiative of WHO and the Food and Agriculture Organization of the United Nations). WHO liaises with the WHO Collaborating Centre for Reference and Research on Escherichia and Klebsiella at the State Serum Institute in Denmark and is in touch with the health ministry and the Institut de veille sanitaire (InVS) in France. WHO also coordinates with the EC, ECDC and EFSA. Sharing information on such an outbreak enables unaffected countries to know what is happening and act accordingly.

What is WHO’s advice for the public?

In earlier outbreaks, caused by different strains, many health authorities advised particularly vulnerable people – such as young children, the elderly and people with weakened immune systems – to avoid eating sprouted seeds/beans. As the outbreak in France and Germany has mostly affected healthy adults, WHO extends this advice to everyone.

E. coli bacteria are killed at a cooking temperature of 70° C. While investigations continue into the source of the infection, WHO advises consumers in the European Region, as a precautionary measure, to eat bean sprouts or sprouted seeds, whether commercially or home grown, only after thorough cooking. Since measuring the temperature of sprouting beans and seeds is difficult, WHO recommends cooking them until steaming hot, not just warm. People should: wash sprouting seeds/beans thoroughly in clean water, cook them until piping hot before consumption, thoroughly clean any equipment used for handling them and wash hands after handling them. The latter procedures are also advisable when handling seeds intended for planting or sprouting.

In addition, people should always follow normal food-hygiene measures: washing fruit and vegetables thoroughly in clean running water, washing their hands after using the toilet and before and after handling food, keeping raw and cooked foods separate and using different equipment when handling them, and cooking food thoroughly.

How long is the incubation period of this infection?

It is usually about 48–72 hours, but can range from 1 to 10 days.

What are the symptoms?

They include abdominal cramps and diarrhoea, which may be bloody. Fever and vomiting may also occur. Most patients recover within 10 days; in a few cases (particularly in young children and elderly people, although these groups do not predominate in the current outbreak) the infection may lead to a life-threatening disease, such as HUS.

What if I get diarrhoea?

People who experience symptoms, particularly severe or bloody diarrhoea, should consult their general practitioners right away. They should maintain strict hand hygiene, especially if in contact with small children and people with weakened immune systems. They should not self-medicate for diarrhoea, or use antibiotics, as these could make it worse. Health professionals and authorities should ensure they know how to diagnose and treat such patients, and report any cases to national authorities.

What has been the source of past E. coli outbreaks?

The sources of past outbreaks included:

• processed meat from cattle in hamburgers, kebabs and salami;
• raw milk and cheeses;
• raw vegetables, such as cabbage, lettuce, spinach, and radish and alfalfa sprouts;
• fruits, including melons, and apple juice;
• contact with lakes, ponds, paddling and swimming pools (in waterborne outbreaks); and
• direct contact with goats, sheep or other ruminants in petting zoos.

Might other outbreaks of this rare infection occur in other countries?

Foodborne disease outbreaks happen all the time in many places in the world, and this particular bacterium could appear elsewhere. Without further information on the actual source of the contamination, predictions cannot be made. Once the source of the outbreak is made clearer (not a trivial task), reducing the risk of further outbreaks will be easier.

Every foodborne outbreak can spread if the vehicle or source is not identified rapidly and people keep eating contaminated food. This is why identifying the source of the contamination is so important.

Why do investigations into foodborne disease take so long?

Bacteria can be transmitted in so many ways: through water, food or material. Finding a particular source involves many different agencies, complex laboratory tests, research and tracing, and requires isolating the bacteria and investigating patients’ exposure in detail.

How are the bacteria transmitted to human beings?

Bacteria are transmitted through the faecal/oral route and eating contaminated food is a common vehicle of infection. Other sources of EHEC infection are contaminated water, and contact with animals and with affected people, if proper infection control is not practised. A person can pass the infection to someone else through poor hygiene, such as not washing hands after using the toilet and/or before handling food. Person-to-person spread has been seen in previous E. coli outbreaks, for example, in institutions.