Tag Archives: Epidemiology

I forgot I ate sprouts threw disease trackers off trail

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People who forgot to mention they had eaten sprouts may have thrown disease trackers off the trail as they sought to trace the source of the deadly strain of E. coli that sickened more than 4,300 people and killed at least 50 in Europe this year, according to a study published in the New England Journal of Medicine.

While a definitive genetic link remains elusive, three separate lines of investigation point to sprouts as the means by which the deadly O1O4:H4 strain of the bacteria was spread, researchers led by Udo Buchholz at the Robert Koch Institute in Berlin, Germany’s disease-control agency.

Buchholz and colleagues wrote, “The one dish that frequently exposed guests to sprouts was the side salad, which contained tomatoes, cucumbers, three sorts of leaf salads, and sprouts. Sprouts may have been the ingredient that visitors recalled least in such a mixed salad.”

Buchholz and colleagues conducted three studies in parallel. The first involved asking patients hospitalized with E. coli infection about their recent food consumption, and comparing that with food eaten by uninfected people. It found that “the only significant variable was sprouts.”

The second study identified 10 groups of diners who ate at a restaurant in Luebeck between May 12 and 16. It found that among 115 people who had been served sprouts, 31 fell ill, compared with none of those who had not eaten sprouts.

The third investigation traced 41 clusters of infections to a producer in Lower Saxony, who grew sprouts from seeds that came from a “supplier X,” Buchholz and colleagues wrote, without identifying either the producer or the supplier. A European Commission task force said in July that the sprouts were probably grown from fenugreek seeds imported from Egypt in 2009. The researchers still don’t know whether the seeds were contaminated before, during or after export from Egypt.

In an accompanying editorial, Martin J. Blaser, M.D. from the Departments of Medicine and Microbiology, New York University, writes the chain of transmission appears to have begun in Egypt, with fecal contamination of fenugreek seeds by either humans or farm animals during storage or transportation, perhaps as long ago as 2009. The seeds then went to a European distributor and from there to farms in several countries. During sprout germination, bacteria multiplied and moved from farm to restaurants and consumers, as Buchholz et al. extensively detail in their study. The evidence for such a series of events is compelling, even though the organism was not identified at the earliest steps, since the trail often is cold in point-source outbreaks by the time investigators are able to conduct trace-back investigations.

German outbreak of Escherichia coli O104:H4 associated with sprouts
26.oct.11
The New England Journal of Medicine
Udo Buchholz, M.D., M.P.H., Helen Bernard, M.D., Dirk Werber, D.V.M., Merle M. Böhmer, Cornelius Remschmidt, M.D., Hendrik Wilking, D.V.M., Yvonne Deleré, M.D., Matthias an der Heiden, Ph.D., Cornelia Adlhoch, D.V.M., Johannes Dreesman, Ph.D., Joachim Ehlers, D.V.M., Steen Ethelberg, Ph.D., Mirko Faber, M.D., Christina Frank, Ph.D., Gerd Fricke, Ph.D., Matthias Greiner, D.V.M., Ph.D., Michael Höhle, Ph.D., Sofie Ivarsson, M.Sc., Uwe Jark, D.V.M., Markus Kirchner, M.D., M.P.H., Judith Koch, M.D., Gérard Krause, M.D., Ph.D., Petra Luber, Ph.D., Bettina Rosner, Ph.D., M.P.H., Klaus Stark, M.D., Ph.D., and Michael Kühne, D.V.M., Ph.D.
http://www.nejm.org/doi/full/10.1056/NEJMoa1106482?query=featured_home
Human infection with Shiga-toxin–producing Escherichia coli is a major cause of postdiarrheal hemolytic–uremic syndrome. This life-threatening disorder, which is characterized by acute renal failure, hemolytic anemia, and thrombocytopenia, typically affects children under the age of 5 years. Shiga-toxin–producing E. coli O157 is the serogroup that is most frequently isolated from patients with the hemolytic–uremic syndrome worldwide.1
In May 2011, a large outbreak of the hemolytic–uremic syndrome associated with the rare E. coliserotype O104:H4 occurred in Germany.2-5 The main epidemiologic features were that the peak of the epidemic was reached on May 21 and May 224,5 and that the vast majority of case subjects either resided or had traveled in northern Germany. Almost all patients from other European countries or from North America had recently returned from northern Germany.2,6,7 Of the affected case subjects, 90% were adults, and more than two thirds of case subjects with the hemolytic–uremic syndrome were female.4
Early studies in Hamburg suggested that infections were probably community-acquired and were not related to food consumption in a particular restaurant. A first case–control study that was conducted on May 23 and 24 suggested that raw food items, such as tomatoes, cucumbers, or leaf salad,3 were the source of infection. The consumption of sprouts, which was previously implicated in outbreaks of Shiga-toxin–producing E. coli in the United States8 and Japan,9 was mentioned by only 25% of case subjects in exploratory interviews, so consumption of sprouts was not tested analytically.
This report describes the investigations that were conducted by the federal agencies under the auspices of the German Ministry of Health and the Ministry of Food, Agriculture, and Consumer Protection, as well as by the respective state agencies, to identify the vehicle of infection of this international outbreak.

Salmonella in Del-Monte cantaloupes: epidemiology is faster, more powerful than laboratory confirmation

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As part of continuing coverage of the yes-it-was-salmonella-in-Del-Monte-cantalopues-that-made-people-sick-no-it-wasn’t lawsuit, Kirk Smith, epidemiology supervisor for the Minnesota Department of Health, told the Washington Post it’s rare for scientists investigating foodborne illness outbreaks to test the exact food suspected of carrying pathogens. By the time symptoms occur and a foodborne illness is reported and confirmed, the product in question has likely been consumed or has exceeded its shelf-life and been thrown away.

Instead, scientists, like detectives, interview victims, collect data, analyze patterns and match food “fingerprints” to determine the likely source of an outbreak.

“The majority of outbreaks, we don’t have the food to test,” Smith said. “Laboratory confirmation of the food should never be a requisite to implicating a food item as the vehicle of an outbreak. Epidemiology is actually a much faster and more powerful tool than is laboratory confirmation.”

The Post also uncovered some e-mail exchanges between Oregon state epidemiologist William E. Keene and Del Monte execs.

Keene wrote in an e-mail to the company on March 19 that evidence the company’s cantaloupe was the source of contamination was “overwhelming. … I think we need to move ahead with the common understanding that your cantaloupes caused this outbreak.”

Keene included in the e-mail an epidemiological analysis of cantaloupe consumption in the United States and how it relates to the U.S. share of cantaloupe from a farm in Guatemala that supplies Del Monte Fresh Produce. He used this analysis to explain the high probability that the contaminated cantaloupe originated from the farm, located in AsuncionMita.

“In our world, these numbers are considered pretty good evidence, however circumstantial,” he wrote.

Thomas Young, Del Monte Fresh Produce’s vice president of research and agricultural services, wrote in one e-mail, “I cannot imagine how [salmonella] could be coming from our Mita operation, but I am available to assist you in your investigation.”

Young also argues that none of Del Monte Fresh Produce cantaloupes tested positive for Salmonella Panama. Keene responded that a positive test “is a pretty tough standard to meet,” given the fact that the implicated cantaloupe had already been consumed and whatever remained had likely been thrown away.

Fridge raids help track listeria-in-cantaloupe outbreak; biosolids being investigated as possible source

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The hunt by Colorado scientists’ to identify the source of a national listeria outbreak that has been linked to eight deaths involved two weeks of brainstorming, studying blood samples and confiscating half-eaten food from patients’ refrigerators.

Health officials also shopped for grocery-store cantaloupe before pinpointing a single farm in Holly as the source.

State epidemiologist Alicia Cronquist thought it slightly odd when she learned two people were sickened by listeria bacteria within days.

When two more reports arrived at the state health department in late August, Cronquist figured she was dealing with an outbreak.

In the early stages of Colorado’s investigation, county health authorities used 15-page questionnaires to interview patients and their families about what they ate and where they bought it.

"The vast majority of people are elderly," Cronquist said. "The average age is in the 80s and they are quite ill. Their family members are at their bedside, and we are asking them to remember food that they ate a month ago. They are actually very difficult interviews."

Meanwhile, the bacteria in patients’ blood was isolated, and state microbiologist Hugh Maguire’s labs deconstructed the DNA profiles to see whether they had listeria strains in common.

Those profiles were uploaded into a CDC database of data from across the nation.

Scientists pulled food from patients’ homes, including typical listeria suspects like deli meats, hot dogs and dairy products.

By Sept. 2, the state food lab determined that two patients had matching strains and two other patients matched in a separate strain. With hundreds of strains of listeria, two or more can be on the same food.

Epidemiologists in patients’ home counties interviewed the patients to look for patterns while the state health department faxed and emailed a listeria alert to doctors, hospitals and labs.

When Cronquist checked a CDC database tracking foods that listeria victims reported eating, she found that all the patients she was tracking had eaten cantaloupe.

Health authorities purchased 15 cantaloupes at three grocery stores and tested the rind and flesh for listeria bacteria. They also were testing patients’ leftover melon. Maguire’s lab fast-tracked the genetic matching, setting aside some of the lab’s other, more routine work.

A week after the first public warning, health authorities announced they had linked the source of the poisoning to cantaloupe.

As more patient blood samples arrived at the state lab, they fell into three distinct strains. Cantaloupe taken from patients’ refrigerators had the same strains but no sticker naming the farm. In interviews, though, patients volunteered that the cantaloupe said ‘Rocky Ford’ on it or was extra sweet.

By tracking the melon purchases of patients back to the distribution trucks, investigators from the state and the Food and Drug Administration narrowed the focus to two farms and sampled soil and machinery.

Two days after warning people not to eat Rocky Ford cantaloupe, health officials announced they had pinpointed the farm.

Jensen Farms in Holly recalled its cantaloupes Sept. 14, while farmers in the Rocky Ford region miles away lamented how their produce was swept into early warnings about cantaloupe.

Meanwhile, 7NEWS in Denver has confirmed the investigation is expanding beyond Jensen Farms and that a company that sprays treated human waste – biosolids — confirmed to 7NEWS it has been contacted by investigators. State investigators confirmed they want to know if biosolids may have caused the contamination.

Parker Ag Services vice president Mike Shearp told 7NEWS that government investigators have questioned him in recent days as to where those biosolids were applied. He said the substance was applied to a field directly across from a Jensen Farms field years ago.

Shearp maintained that the contamination will not be traced back to his operation.

Colorado State University animal science professor Lawrence Goodridge said, "If processed properly, there should not be pathogens. If they are not processed properly, if the wastewater treatment process breaks down, they could be (a) source of pathogenic bacteria such as salmonella, listeria and other pathogens."

A spokeswoman with Jensen Farms said the company does not use biosolids in its operation.

Our melons are salmonella-safe: Del Monte-FDA agreement expected before lawsuit reaches court?

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Continuing with all things melon, did Del Monte cantaloupes, imported from a farm in Guatemala, sicken at least 20 people in 10 states with Salmonella Panama beginning in Feb. 2011?

Or was the link a result of zealous health types in Oregon and at the U.S. Food and Drug Administration?

William Neuman of the N.Y. Times writes a lawsuit filed by Del Monte Fresh Produce against FDA is being cheered by many in the produce industry, who often complain about what they call overreaching by regulators and welcome a company with resources pushing back.

Aside from suing the F.D.A., the company has threatened legal action against a leading state food-borne disease investigator in Oregon, where the Del Monte cantaloupes were identified as the cause of the salmonella outbreak. And it has challenged some of the basic techniques of food safety investigations, like relying on ill people’s memories of what they ate when microbiological testing does not find pathogens on food.

Dennis Christou, vice president of marketing for Del Monte Fresh Produce, which is based in Coral Gables, Fla., said, “It’s got to be a comprehensive and reliable investigation, and in our opinion this was neither. There’s absolutely no basis in the claim that this was done intentionally to intimidate or bully anyone.”

The company said Wednesday that it was in talks with the F.D.A. to resolve the dispute and expected an agreement soon.

When the outbreak was emerging, epidemiologists used data from Costco membership cards and found that the melons came from one farm in Guatemala, called Asunción Mita, owned by Del Monte Fresh Produce.

The investigators, working with the federal Centers for Disease Control and Prevention and the FDA asked Del Monte Fresh Produce for a recall, following the usual procedure. The company at first resisted but, according to its lawsuit, eventually agreed to a limited recall to prevent the FDA from issuing a broad warning about contaminated melons that could have affected the entire cantaloupe market. The recall was announced on March 22.

But in mid-July the FDA issued an import alert, saying that the conditions that caused the contamination might still exist on the Asunción Mita farm. The alert allowed inspectors to stop cantaloupes grown on the farm from entering this country.

Del Monte Fresh Produce fired back, filing its lawsuit and accusing federal and state inspectors of conducting a slipshod investigation. And it questioned the validity of the results because investigators had not found a cantaloupe contaminated with the bacteria that had made people sick.

The company’s filings include an audit report of the Guatemala farm, submitted to the FDA last month, which raises questions about the company’s practices.

The audit, done by a company hired by Del Monte Fresh Produce, found that a pipe containing raw sewage and wastewater emptied into an open ditch about 110 yards from the farm’s packing house. The ditch led into a lagoon containing additional sewage, more than 220 yards from the packing house. The audit recommended that the ditch be eliminated.

Mr. Christou said the ditch was protected by barbed wire to keep large animals from tracking the waste into fields. He said the lagoon contained chemicals to speed decomposition of the waste and was away from fields and wells. After the audit, he said, the company extended the pipe all the way to the lagoon and discontinued use of the open ditch.

Asked if having raw sewage in an open ditch near its packing house was consistent with high food safety standards, Mr. Christou said that tests on melons had found no pathogens.

Dr. Michael T. Osterholm, director of the Center for Infectious Disease Research and Policy at the University of Minnesota, said, “There’s no doubt the data are very tight. Del Monte caused that outbreak.”

And he said that many investigations involving sickness from produce did not find contaminated food because by the time officials became aware of the outbreak, the tainted produce had been eaten or discarded.

A table of cantaloupe- (or rock melon) related outbreaks is available at http://bites.ksu.edu/cantaloupe-related-outbreaks.

The byzantine world of government speak; E. coli O157 again in walnuts in Canada

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In CFIA-speak, ‘no confirmed illnesses’ means there are sick people, but we can’t say so until we’re super-duper sure through testing, no matter how many more people get sick. It’s part of a disturbing trend where government agencies are pressured to downgrade the findings of epidemiology and rely only on positive test results. It’s on display in the Del Monte vs. Oregon lawsuit, and was on full display in the Maple Leaf listeria outbreak of 2008 that saw 23 people die and 53 others sickened; CFIA led with a press statement then “There have been no confirmed illnesses associated with the consumption of these products.”

So no one should be comforted after the Canadian Food Inspection Agency reported this morning that certain prepackaged raw shelled walnut products described below are being voluntarily recalled because they may be contaminated with E. coli O157:H7.

“There have been no confirmed illnesses associated with the consumption of these products.”

Uh-oh.

When no one is sick, CFIA says, “there have been no illnesses associated with the consumption of these products.”

It’s the kind of wiggle-room bureaucrats thrive on – and shows the overall importance of public health.

The following raw shelled walnut products, imported from USA and packaged in Canada, are affected by this alert.

President’s Choice
Raw California Walnut Halves Unsalted 250 g 0 60383 87185 7 Best Before 2012 OC 07
Reddi Snack Hand Selected
California Walnuts 350 g 0 64777 28695 1 16581

Earlier this year, 14 people were sickened after eating E. coli-contaminated walnuts distributed by Montreal-based Amira Enterprises.

One patient in Quebec with an underlying medical condition died during the outbreak, which also affected people in Ontario and New Brunswick.
 

Will Del Monte’s lawsuit against Oregon health succeed in setting poisonous tone for outbreak investigations?

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Del Monte Fresh Produce, a company that recalled its cantaloupes in March after health investigators in several states linked them to a Salmonella Panama outbreak, said yesterday that is plans to sue Oregon Health Authority and, Dr William Keene, one of the nation’s most well-known disease outbreak investigators (right, exactly as shown), claiming that the company’s products were wrongly singled out.

Lisa Schnirring of CIDRAP news at the University of Minnesota interviewed several public health types, who say the company’s suit is unprecedented, and some worry that it may inhibit future foodborne illness investigations.

Lon Kightlinger, MPH, PhD, state epidemiologist with the South Dakota Department of Health, said some of his department’s disease investigations have involved legal tug-of-wars. "Although we do have some worries of legal threats, that does not drive our investigation, but causes us to do a better job," he said.

In Iowa, laws require public health officials to treat the names of entities such as restaurants or companies the same as people, said Patricia Quinlisk, MD, MPH, medical director and state epidemiologist for the Iowa Department of Public Health.

She said that, before going public with names, health officials must discuss the issue with the state attorney general’s office to make sure the action complies with a "necessary for public health" clause. "Thus something like this might have more scrutiny here than other places," she said, adding that she’s never seen a legal threat like Del Monte’s.

Tim Jones, MD, MPH, state epidemiologist for the Tennessee Department of Health, said he’s been bullied and subjected to implied threats in the course of epidemiologic investigations. "I’ve never taken them seriously, and legally I’ve never been worried," he said.

Though Del Monte’s legal threat could create an inhibitory effect, epidemiologists take pride in being able to respond to outbreaks faster and freer than federal agencies, which are often bound by legal restrictions, Jones said.

"Our job is to protect people."

Some measure of immunity is needed for investigators, Jones said. "If anyone in public health is nervous about getting sued, it could be dangerously inhibitory."

Clues that sprouts caused Germany’s E. coli O104 outbreak

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At a news conference on Friday, Reinhard Burger, president of the Robert Koch Institute said an investigation into the pattern of the E. coli O104 outbreak that has killed at least 31, had produced enough evidence to draw a conclusion.

“In this way, it was possible to narrow down epidemiologically the cause of the outbreak of the illness to the consumption of sprouts,” Mr. Burger said, accompanied by the heads of Germany’s Federal Institute for Risk Assessment and Federal Office for Consumer Protection. “It is the sprouts.”

The breakthrough in the investigation came after a task force from the three institutes linked separate clusters of patients who had fallen sick to 26 restaurants and cafeterias that had received produce from the organic farm.

“It was like a crime thriller where you have to find the bad guy,” said Helmut Tschiersky-Schoeneburg from the consumer protection agency.

“They even studied the menus, the ingredients, looked at bills and took pictures of the different meals, which they then showed to those who had fallen ill,” said Andreas Hensel, head of the Risk Assessment agency.

Those interviews with patients and even the chefs at restaurants where they had eaten showed that people who had consumed bean sprouts were nine times more likely to become infected than those who had not.

Gert Lindemann, the state agriculture minister, said the owners of the farm had already pledged not to sell any produce after their facility came under suspicion last Sunday.

In an interview to be published in next week’s edition of Focus magazine, Mr Lindemann said 60 of the people contaminated had eaten sprouts from the small farm in Bienenbuettel.

Contamination might have been caused by infected seeds or "poor hygiene", he added.
He said three of the farm’s employees also fell ill last month, suffering from diarrhea.

The farm is located about 35 miles (56 kilometers) southeast of Hamburg. Its products include radish, red-cabbage, alfalfa, broccoli, onion and garlic sprouts, as well as sunflower seedlings, according to information on its website. Gaertnerhof has about 18 employees.

An updated table of international sprout-related outbreaks is available at:
http://bites.ksu.edu/sprouts-associated-outbreaks
 

Amateur epi-time in Germany; how many foods can be fingered? Health types say sprouts now cleared? 22 dead, 627 HUS, 1,526 sick

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German officials said today initial tests provided no evidence that sprouts from an organic farm in northern Germany were the cause of the country’s deadly E. coli outbreak.

The Lower-Saxony state agriculture ministry said 23 of 40 samples from the sprout farm suspected of being behind the outbreak have tested negative for the highly agressive, "super-toxic" strain of E. coli bacteria. It said tests were still under way on the other 17 sprout samples.

"The search for the outbreak’s cause is very difficult as several weeks have passed since its suspected start," the ministry said in a statement, cautioning that further testing of the sprouts and their seeds was necessary to achieve full certainty.

Negative test results on sprout batches now, however, do not mean that previous sprout batches weren’t contaminated.

Osterholm gets it right when he tells msnbc, "All this wishy-washy back-and-forth, it’s just incompetence. Where’s the epidemiology?"

Dr. Michael Osterholm, director of the Center for Infectious Disease Research and Policy at the University of Minnesota says that continuing failure to identify the source of the deadly German outbreak of E. coli poisoning points to a flawed investigation that could shake faith in the global public health system.

European food safety officials appear to rely far more on bacterial cultures than on tracing back what people involved in the outbreak actually ate — and where it came from. But a microbiological approach has repeatedly been shown to fall short of a detailed study of the epidemiology, or health patterns, that characterize foodborne illness outbreaks, Osterholm said.

And why does no one seem to care that a bunch of Spanish cucumbers were E. coli positive, just not the outbreak strain? Are they grown in sewage?
 

Was it walnuts? E. coli O157:H7 update in Canada

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Some were wondering yesterday if Amira-imported walnuts from California was the source of an E. coli O157:H7 outbreak in Canada that has sickened 13 and linked to one death.

Keith Warriner of the University of Guelph said there appear to be some unanswered questions in the federal government’s food-safety investigation, so he wouldn’t be surprised if it turns out walnuts aren’t to blame for an outbreak of E. coli in three provinces.

"I’ve got a feeling it’s going to be more like the tomato recall we had," he said Friday.

This is how a single food agency apparently works in Canada:

The Canadian Food Inspection Agency on Sunday announced a voluntary recall of shelled walnut products imported from California by Montreal-based Amira Enterprises Inc., because they may be contaminated with E. coli bacteria. The agency took action based on information provided by the Canadian Public Health Agency and a risk assessment by Health Canada.

In fact, a senior public health official said Friday there is "no evidence" the Quebecer who died of E. coli illness actually ate any of the walnuts thought to be behind the outbreak. "When we bring information from different people together, they share something in common, and in this particular case, we were looking at food consumption, and this individual did not fit the same pattern," said Dr. Mark Raizenne of the Public Health Agency of Canada.

Of the 12 people who were able to provide information about their food consumption history to the Canadian Public Health Agency as part of the investigation, four people reported they hadn’t consumed walnuts.
Those hit by the outbreak consumed foods typically associated with E. coli, such as ground beef, but there was no overlapping brand -meaning the "likely source based on the information that we have" is walnuts, said Raizenne.

To date, no Amira walnut product has tested positive for E. coli, according to CFIA.

Meanwhile, CFIA last night announced the fingered raw shelled walnuts were also available in Vancouver (that’s in Canada) and should be avoided.

Not that it matters, because CBC reported yesterday that those same walnuts are still on store shelves in Montreal.

University of Manitoba food sciences professor Rick Holley said the CFIA does not have the resources to do a proper followup.

"It’s one thing to make a recall, it’s another thing to make sure it happens.”
 

Kansas church dinner toll climbs

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There are now at least 159 individuals have reported becoming ill, with one hospitalization, following a Kansas church dinner earlier this month.

The Sacred Heart Turkey Dinner that was held on the evening of November 8, 2010, in Arkansas City, KS, had over 1,800 people in attendance.

The Kansas Department of Health and Environment (KDHE) and City-Cowley County Health Department, with assistance from the Kansas Department of Agriculture and the cooperation of the Sacred Heart Catholic Church in Arkansas City, are continuing to conduct an investigation of a possible foodborne illness outbreak, and are asking for the public’s help in completing a survey to identify the source of the outbreak.

“It’s really important that everyone who attended the dinner or consumed food prepared for the event complete this survey or contact the health department,” said Dr. Jason Eberhart-Phillips, Kansas State Health Officer and Director of KDHE’s Division of Health. “Regardless of whether you’ve become sick, the information you provide will help us better understand what may have caused this gastrointestinal outbreak.”

The KDHE survey is available at: https://www.surveymonkey.com/s/SacredHeartDinner.