Escherichia coli (E. coli)
Escherichia coli (E. coli) is a common bacterium that is found in the intestines of humans and warm-blooded animals. Most E. coli strains are harmless, but some serotypes can cause serious food poisoning in humans. Enterohaemorrhagic Escherichia coli (EHEC), virulent strains of E. coli, were first identified as human pathogens in 1982 when strains of a previously uncommon serotype, O157:H7, were implicated in two outbreaks of haemorrhagic colitis in the United States. Since then, outbreaks of EHEC O157:H7 infection have occurred, and continue to occur throughout many regions of the world, as have outbreaks of infections from many other non-O157 serotypes of E. coli.
Human response from EHEC ingestion ranges from asymptomatic infection to death, with the incubation period ranging from 1 to 8 days. Illness typically begins with abdominal cramps and non-bloody diarrhoea that can progress to bloody diarrhoea within 2 to 3 days. Infection with EHEC may lead to further complications, most notably haemolytic uremic syndrome (HUS), a life-threatening disease characterized by acute renal failure (uraemia), haemolytic anaemia, and a low platelet count (thrombocytopenia). HUS is the most common cause of acute renal failure in young children; and it is estimated that up to 10% of EHEC-affected patients may develop HUS, with a mortality rate ranging up to 5%.
Germany notified WHO of the outbreak under the International Health Regulations (IHR), as a potential public health event of international concern, and WHO is sharing information with health authorities in other countries. The current severe outbreak in Europe is caused by a rare serotype of EHEC (namely E. coli O104:H4). EHEC serotype O104:H4 or, more precisely, a strain of enteroaggregative verocytotoxin-producing E. coli (EAggEC VTEC), has been seen in humans before but never in an EHEC outbreak.
As of 5 June 2011, Germany had reported 1536 cases of EHEC and 627 cases of HUS, including 15 deaths; other EU countries had reported 721 cases of EHEC, 31 HUS cases and one death respectively. Two cases of HUS were reported from the United States. The current outbreak is unusual in that it has developed very rapidly, and an unusually high number of cases affect adults. Cases are predominantly among adult females aged 20 years or older, with the highest attack rates in the age group 20–49 years, particularly women, rather than in the usual high-risk groups, which are young children and the elderly. Nevertheless, cases have also been reported in school-aged children. Many people have been hospitalized, several requiring intensive care, and new cases continue to be identified. Cases have now been notified from eleven countries in addition to Germany: Austria, Czech Republic, Denmark, France, Netherlands, Norway, Spain, Sweden, Switzerland, United Kingdom and United States of America. Almost all reported cases of serotype O104:H4 were among people who had recently visited northern Germany. There is no indication so far of confirmed domestic or secondary infection in other countries. All of the affected countries are reporting their cases to the German authorities and to WHO. The European Union (EU) countries are also sharing information through the secure Early Warning and Response System (EWRS).
Data from previous outbreaks and sporadic infections indicated consumption of beef, including ground beef and processed beef products, as the most important source of foodborne EHEC infection. However, while epidemiological and laboratory investigations continue, the source of the outbreak still remains unknown.
WHO does not recommend any restrictions in travel to or trade with Germany. WHO is not making any new recommendations for treatment. WHO has offered technical assistance and stands ready to facilitate collaboration between laboratories to support countries without the capacity to detect the unusual E. coli serogroup O104. WHO will maintain in close contact with the relevant authorities. WHO will provide information or assistance on laboratory testing or potential reference laboratories. The International Health Regulations (IHR 2005) national focal points within the WHO Eastern Mediterranean Region are encouraged to share this outbreak alert information with relevant public health authorities and clinicians. This will enable timely recognition of potential cases of EHEC and HUS which could be related to this outbreak, especially potential cases with a history of travel to Germany in May.
Normal hygiene measures should be observed. Regular hand washing, particularly before food preparation or consumption and after toilet contact, is highly recommended, particularly for people who care for small children or are immunocompromised, as the bacterium can be passed through food, water and direct contact with animals. Anyone who develops bloody diarrhoea and abdominal pain, and who has had contact recently with northern Germany, should seek medical advice urgently.
