E. Coli: From Cows to Cookie Dough

The E. coli O157:H7 bacteria made headlines again last month when Nestle USA recalled 300,000 cases of Toll House cookie dough, enough dough to make 86.4 million cookies.  While public health officials welcome any excuse to remove a few million calorie-laden cookies from the American food supply, this recall was particularly urgent.  According to the Center for Disease Control (C.D.C.), 70 people in 30 states were diagnosed with illness linked to eating raw cookie dough, including seven cases of a life-threatening disease called hemolytic-uremic syndrome (HUS).  This recall demonstrates the growing importance of E. coli in our food chain — in fact, since the cookie dough recall, two separate meat companies have also recalled ground beef due to E. coli contamination.

The O157:H7 strain of E. coli was first linked to food-borne illness in 1982, when a few victims developed bloody diarrhea after eating McDonald’s hamburgers.  In 1993 another outbreak due to improperly cooked hamburgers from Jack-in-the-Box led to several deaths, and the bacteria gained the public’s attention.  Fast food restaurants aren’t the only culprits — in 2006, an organic spinach farm supplied contaminated spinach which resulted in 205 illnesses and three deaths.  The CDC estimates O157:H7 causes 73,000 cases of illness per year in the United States.

So, where does this menacing bacteria come from anyway?  All warm-blooded animals naturally have E. coli living in their intestines.  Most strains usually cause no harm and might even benefit their hosts by fighting off nastier invaders such as Salmonella.  The O157:H7 strain has been found in two to three percent of cattle, and does not appear to result in any ill effects in cows, unlike humans.  After slaughtering the cows, bacteria from their feces can contaminate the meat.  Usually the bacteria inhabit only the outer surface of the beef, so when a steak is grilled medium rare, all the micro-organisms living on the surface of the meat are killed.  In the case of ground beef, however, the bacteria are mixed into the inside of the meat patty. A hamburger grilled medium-rare will still have infectious micro-organisms in its center, ready and willing to set up shop in your gut.  This is why most cases of E. coli infection are linked to hamburger joints instead of steak houses. 

E. coli from cow patties can jump to more than just hamburger patties.  The FDA thinks the spinach from the 2006 recall was likely contaminated by cattle and pigs in nearby fields.  In fact, O157:H7 has been found in apple juice, dairy products, leafy green vegetables, grapes, sprouts, coleslaw, and melons.  It has also been found in lakes, swimming pools, and drinking water, presumably due to fecal contamination from cattle.  Additionally, cases can occur from direct person-to-person transmission, especially in day care centers.

After eating contaminated food, victims will develop symptoms in about three days.  Bloody diarrhea is the most striking symptom, along with severe stomach cramps.  About a third of patients require hospitalization, often for hemolytic-uremic syndrome (HUS) — a kidney disease caused by a toxin secreted by the bacteria.  The toxin attacks kidney cells, leading to bloody urine and kidney failure.  HUS occurs in about five to ten percent of cases of O157:H7 infection, and children are particularly vulnerable.  In fact, this is the most common cause of acute kidney failure in children.  About 50 percent of children who develop HUS will require hemodialysis, and five percent will die.

Surprisingly, antibiotics are thought to be ineffective against O157:H7, and though controversial, some doctors believe antibiotics actually increase the risk of HUS.  They contend that when the antibiotics kill the bacteria, a large amount of toxin is released into the body, causing further kidney damage.  Anti-diarrhea medicines, such as Lomotil or Pepto Bismol, are also not recommended.  By preventing diarrhea, these medicines increase the amount of time the bacteria remain in the intestines, thereby prolonging the illness.

Since there is little modern medicine can do to treat this disease, the emphasis needs to be on prevention.  After the 1993 outbreak, several measures were taken to clean up our food supply.  The Food Safety and Inspection Service (FSIS), a branch of the USDA, is responsible for inspecting meat, poultry and eggs.  The agency implemented a major overhaul in its food inspections in 1997.  Regulations were tightened, testing was increased, and manufacturers were required be more vigilant.  Since then, the FSIS has detected O157:H7 in about 0.3% of samples of beef.  When it finds contaminated meat, the agency recommends a voluntary recall, and it has the power to seize infected beef.

As a result of increasing vigilance by both the FSIS and FDA, the incidence of food-borne illness has decreased since 1996.  However, since 2004, that progress has stalled.  For the past five years, we have seen no further decreases in the overall rate of food-borne illnesses, and in the specific case of O157:H7, have actually seen an increase.  The cookie dough contamination, followed by two further episodes of ground beef contamination, remind us that further improvements need to be made to ensure the safety of our food supply.

To that end, the Food Safety Enhancement Act is currently working its way through Congress.  This bill will strengthen the FDA, but not the FSIS.  While the bill is a good start, its focus on the FDA means it will not directly impact the agency inspecting meat for O157:H7.  Both government and food suppliers will need to make further efforts to ensure the safety of our food.

Improving our food safety will be a complex process, but fortunately, we still have chocolate chip cookie dough ice cream to enjoy along the way.  According to a Nestle spokesperson, the Nestle cookie dough used in Dreyer’s and Edy’s ice cream is cooked beforehand, so it should be safe to eat.  Raise your pints and rejoice!