E. Coli Epidemic

June 13, 2011

Scanning electron micrograph of Escherichia coli, grown in culture and adhered to a coverslip

Scanning electron micrograph of Escherichia coli, grown in culture and adhered to a coverslip.

After more than a month of epidemiological studies and false conclusions, German public health investigators confirmed late last week that bean sprouts were responsible for the most lethal E. coli outbreak in modern history.

At least 33 people have died and almost 3,000 have been sickened by the bacteria that can spread rapidly through the food system.

E. coli is a type of bacteria that lives in the intestines of all humans and animals to help the body break down and digest food. E. coli can cause disease when certain strains infect meat or vegetables that are then eaten by humans.

“When you’re seeing E. coli outbreaks, it’s a result of some cross-contamination event,” said Jessica Leibler, a research scientist in the Department of Environmental and Occupational Health in GW’s School of Public Health and Health Services. “And when it’s this widespread, it means there was cross contamination at the farm.

E. coli can be ingested from meat that isn’t fully cooked or from vegetables that have been contaminated by unclean cutting boards, knives or hands. The contamination can also occur on the farm if water used for irrigation is infected through contact with feces or if manure isn’t properly composted for use in fertilizer.

German public health investigators traced the outbreak to an organic bean sprout farm in northern Germany.

In 1993, four children died and hundreds of others became sick in the western United States after ingesting E. coli in contaminated meat from the fast food chain Jack in the Box. More recently, three deaths and 276 illnesses across the country were attributed to tainted spinach and lettuce in 2006.

E. coli infection can result in severe diarrhea, dehydration or hemolytic-uremic syndrome (HUS), a disorder that can cause kidney failure and neurological damage. HUS typically affects people with lower immunity -- children, the elderly and people with compromised immune systems. But the strain of E. coli in Germany is also causing HUS in healthy adults.

“It’s a really, really severe illness. Even if you’re in the hospital, you may not make it. It’s very hard to support someone who has lost almost all of their kidney function,” said Lynn Goldman, SPHHS dean and a professor of environmental and occupational health.

Dr. Goldman said parts of this strain had been documented previously, but scientists had never seen this particular combination of genes.

“The attack rate is very high, and it’s attacking populations that are typically more resistant to this type of infection,” said Dr. Leibler, an epidemiologist in the area of infectious diseases and food systems.

German public health officials initially blamed cucumbers, tomatoes and lettuce from Spain for the infection before turning their attention to sprouts grown in Germany. The German authorities have faced criticism for being slow in their response to the outbreak.

Epidemiologists trace the source of an outbreak by questioning those who got sick – and others who were with them but were not sickened – about what they ate, how it was prepared and other factors.Once they suspect a particular food as the cause, they can trace it back to its point of production and take samples for testing.

“How these things can happen is so multifold,” said Dr. Goldman, a pediatrician and epidemiologist. “You have to move very quickly. This is something you want to know within a couple of days what it might be.”

But it’s difficult to pinpoint the source of an outbreak, especially when that food may be an herb or other complementary ingredient. In Germany, sprouts are often put on sandwiches as a condiment.

“It’s very hard to do. It can be very hard to backtrack the cause of an outbreak when you don’t have a whole lot to go on,” Dr. Leibler said.

Dr. Leibler said epidemiologists have to strike a balance between protecting the public and preventing the release of incorrect information that could do serious damage to the food industry.

“The goal is to prevent people from getting sick,” Dr. Leibler said. “If you have a scientifically driven hunch, you want to get that message out as soon as possible. But at the same time there are enormous economic consequences to these industries. So you need to be sure.”

The outbreak in Germany showed the danger of rushing to judgment. Although it appears that cucumbers had nothing to do with the outbreak, the industry has already been affected, and the European Union is weighing compensatory payments to Spanish farmers.

“Every single cucumber grower in Europe has been affected by this,” Dr. Goldman said. “It really hits the entire industry.”

And the effects could be lasting as a nervous public stays away from a food they associate with the infection.

“There are people in Germany who will probably never eat another cucumber in their life although it looks like cucumbers had nothing to do with it,” said Dr. Goldman.

Dr. Leibler said the worst of the German outbreak seems to be over, but many questions remain.

“The attack rate is slowing and that’s consistent with an outbreak related to fresh produce. There was a batch of produce contaminated somewhere and it’s either been consumed or disposed of,” Dr. Leibler said. “What remains to be seen is if this particular type of E. coli is here to stay and will present itself again and produce outbreaks around the world. With the amount of food importation we have, pathogens can be transported globally. Global disease is common due to the global nature of our food supply.”

Dr. Goldman said it’s difficult to predict if and when this strain of E. coli might reach the U.S.

“It could come here in the near future, or it could take decades to get here,” Dr. Goldman said. “There’s a lot we don’t know about the dynamics of these things.”

She said she hopes the Food and Drug Administration will be able to get the appropriate funding and regulatory oversight after the passage of the Food Safety Modernization Act earlier this year to better monitor domestic and imported produce -- both on the farm and in processing and shipping facilities.

“There are so many places in the growing and production and processing of food where E. coli can be introduced,” Dr. Goldman said. “The only way to be absolutely certain that people are kept safe is that we never introduce the pathogens and toxins into the food in the first place.”

In the meantime, consumers can take some basic steps to protect themselves against infection: Practice good hygiene, especially in the kitchen; use a meat thermometer to cook foods to a safe temperature; disinfect countertops and cutting boards with hot water and soap or chlorine bleach solution; put sponges in the dishwasher or replace them frequently; be careful about taking food outside that should be refrigerated; and go to the doctor if experiencing signs and symptoms of a bacterial pathogen, especially bloody diarrhea.

“There are core issues in food safety that we all know,” Dr. Leibler said. “Let’s go back to the basics and keep ourselves as healthy as possible.”