BERLIN- German scientists are scrambling to find the source of an outbreak of enterohemorrhagic Escherichia coli (EHEC), a dangerous intestinal pathogen That hAS Hundreds of people sent to the hospital with bloody diarrhea and killed at least one. The investigation is complicated by the fact que la outbreak HAS beens Apparently Caused by a very rare EHEC serotype O104 called Expired.
"I Hope that more patient samples will be APPROBATION today, aim it Certainly looks as if an E. Coli O104 is the case of These infections," says Klaus Stark, head of the division of gastrointestinal infections, zoonoses, and tropical infections at Robert Koch Institute (RKI) here, the German center for disease prevention and control.
RKI Researchers first Took notice last Thursday, When a clinic in Hamburg em Enable notifications of a host of Patients Suffering from hemolytic uremic-syndrome (HUS). The syndrome-caractérisé by a destruction of red blood cells and severe kidney problems-is The Most severe complication of EHEC infection year.
Selon RKI, Nearly 140 patients in Germany-have HUS Developed since the second week of May, Compared with only about 60 cases in an average year. "This is one of the biggest EHEC outbreaks in the world, the biggest one Certainly we-have ever had in Germany," says Stark.
Scientists-have-been baffled not only by the outbreak's size and rapid spread in northern Germany aussi goal by the fact That It affects mostly adults and females, an odd pattern Because EHEC usually sickens children. Of the 65 HUS cases in Germany in 2010, only six patients Were more than 18 years old.
While E. coli bacteria are hand of the human gut flora and usually not pathogenic, strains classed together as the EHEC Produce a dangerous Shiga toxin That Enters the cells in the gut and Inhibits protein synthesis by cleaving ribosomal RNA. The destruction of cells lining the gut leads to abdominal cramping, watery diarrhea, and bloody diarrhea Eventually. In about 10% of cases, the toxin attacks the kidneys aussi, leading to the Potentially fatal HUS. EHEC has-been confirmed as the causes of death in year 83-year-old woman Who HAD beens admis to a hospital in Bremen on 15 May and Who died on Saturday; Reviews another potential EHEC fatality is still under investigation.
Most EHEC infections are Caused by a notorious called Expired serotype O157: H7; Researchers Refer To That serotype and four others frequently found in Europe as the "gang of five." Aim the German reference laboratory for EHEC in Wernigerode HAS so far APPROBATION the serotype of EHEC in stool samples from five patients as O104.
That Makes the highly unusual outbreak, says Helge Karch, head of the National Consulting Laboratory on Hemolytic Uremic Syndrome in Münster. Among Karch's E. coli 588 isolates from HUS patients file Managed over the past 20 years, only two are O104. In Reviews another unusual twist, Karch HAS found the strain to be eae-negative. The gene eae codes for the protein intimin, qui the bacteria uses to attach to the intestinal wall. Most pathogenic EHEC serogroups are eae-positive.
It is still unclear whether the serotype might explain the strange pattern of infections. E. coli O104 first Emerged as a pathogen in a small outbreak in Helena in early 1994. Four people Developed abdominal cramps and bloody diarrhea. Experts at the U.S. Centers for Disease Control and Prevention (CDC) in Atlanta has APPROBATION serotype called Expired O104: H21 as the culprit. A CDC investigation later found up to 18 patients; MOST of Them Were women and the median age Was 36 years.
The source of infection in Germany is still unclear, and the uncommon serotype Could make it harder for autorités to find it. "O104 is very hard to Distinguish from normal, non-pathogenic E. Coli ," says Lothar Beutin, head of the National Reference Laboratory for E. coli at the Federal Institute for Risk Assessment here. He and --other Researchers are now try trying to Develop a more rapid and specific test for the unusual serotype.
The natural tank of EHEC bacteria are ruminants Such as cows and sheep, qui carry the pathogens In Their guts and spread Them With Their feces. It is Transmitted to humans through consumption of contaminated Primarily foods.
"When we first Interviewed patients, a lot of 'em MENTIONED eating raw vegetables, purpose That Does not mean That vegetables are the source," Stark says. RKI is using a detailed questionnaires to ask patients what They Have eaten in the days before falling ill and Comparing Their answers with Those Who of healthy controls match the characteristics in patients Such as age and sex, a common method in epidemiology.
In order to save time, HOWEVER, the Epidemiologists are not searching public records to find the matching controls. Instead, a team of 15 experts Went door to door yesterday in the areas in Hamburg Where Some patients live, looking for matching Roughly controls. "If we get a clear signal, something That 0% of the boxes purpose only 10% of the controls ate, Then We Can Be very sour That We-have found the source," says Stark.
But a first statistical analysis this morning Did not yield clear results Any. Indeed, because of the smaller MOST of the EHEC outbreaks in recent years HAS never beens Established definitely. Scientists are Hopping que le current outbreak will turn out to be unusual fait que respect as well.
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