In its natural habitat -- the digestive tracts of humans and other animals -- Escherichia coli is just another bacterium in a sea of mostly harmless germs. There are actually hundreds of strains of this bacterium, and the vast majority are not dangerous. But when the disease-causing version O157:H7 shows up in our food supply, E. coli becomes a huge threat.
According to the Centers for Disease Control and Prevention, about 73,000 Americans become infected with this strain of E. coli each year, and about 60 people die as a result. In 2008, at least 49 cases of E. coli were confirmed in 7 states, due to contamination of ground beef. The year before at least 21 people in 10 different states fell ill after eating frozen pepperoni pizza tainted with E. coli; four suffered kidney failure. In 2006, at least 199 people were sickened by E. coli that had found its way into bags of fresh spinach.
How does E. coli spread?
As the above cases show, E. coli can turn up in many different places. One of the most common sources of illness is undercooked ground beef. (Unsanitary conditions at slaughterhouses and processing plants can also be a source of contamination.) E. coli is found more often in ground beef than in other types of meat because the germs are typically localized on the surface of the meat, but can be spread throughout after it is ground up. Then, if the meat is not thoroughly cooked, some bacteria may survive and could cause an infection.
Contaminated water used to irrigate crops can spread the bacteria to fruits and vegetables, including spinach, sprouts, and lettuce. The germ has also been found in salami, sausage, and unpasteurized milk and juice.
Food isn't the only source of E. coli infections. Because the germ thrives in the digestive systems of goats, sheep, and cows, it's possible to pick it up from animals at a petting zoo, especially if there is no facility for washing your hands after a visit. You can also catch the germ from someone who is already infected, especially if you don't wash your hands thoroughly. That's why children are at increased risk, as are daycare workers who change a lot of diapers.
What are the symptoms of E. coli infection?
Within two to eight days of being infected, you may suffer severe stomach cramps followed quickly by watery, bloody diarrhea. It's not uncommon to have more than 10 bowel movements in a single day, and some may seem to contain almost nothing but blood. You may also have a mild fever and some nausea and vomiting. The symptoms will usually fade within five to 10 days.
It's also possible to develop other complications: About 5 to 10 percent of people diagnosed with severe E. coli infections develop a potentially life-threatening complication called hemolytic uremic syndrome (HUS). A person with HUS may seem pale, tired, and irritable. Urine output may slow down, and they may lose the pink color from their cheeks and the inside of their lower eyelids. These symptoms usually show up about a week after the first symptoms of E. coli, when the diarrhea is improving. A person with HUS is at serious risk of kidney failure and should be hospitalized. The elderly and young children are especially vulnerable to this complication; in fact, E. coli is the leading cause of sudden kidney failure in children.
How is a routine intestinal E. coli infection treated?
In the vast majority of cases, time is the best treatment for an E. coli infection. Antibiotics won't help, and neither will anti-diarrheal medications. In this case, diarrhea actually does you a favor by ridding the germ from your system. If you drink plenty of fluids and get some rest, the germ should eventually disappear completely, and you'll be back to normal. Be vigilant, however: If you become severely dehydrated or start showing signs of kidney failure, get to a hospital right away.
When people recover, are there long-term consequences of an E. coli infection?
Even if the infection was bad enough to land you in the hospital, usually you will suffer no long-term consequences.
However, scientists suspect that some people who survive a severe E. coli infection later develop high blood pressure or kidney problems. In one study, these long-term effects occurred only if the initial infection had caused kidney problems, and they showed up in only a tiny percentage of the food poisoning cases. However, it is difficult to link a medical problem to a food poisoning event 20 years earlier. To help researchers studying the issue, a consumer advocacy group, Safe Tables Our Priority (STOP), has begun a registry of food poisoning survivors with long-term health problems.
How can I avoid an E. coli infection?
- Taking a few extra precautions in the kitchen is the best way to protect yourself and your family from E. coli infections. For example, always cook hamburger meat or sausage until every hint of pink disappears. If you're using a cooking thermometer (which is always a good idea), the internal temperature should be at least 160 degrees Fahrenheit.
- Keep raw meat and poultry separate from all other foods. If a cutting board, dish, or utensil comes in contact with raw meat, wash it thoroughly with hot, soapy water.
- Also, thoroughly rinse all vegetables, especially if you'll be eating them raw. Don't drink unpasteurized milk and juices, and never give them to children. (Any juices sold in cartons and bottles at room temperature have been pasteurized, although it may not say so on the label.)
- If you hear about any food products that have been recalled because of E. coli contamination, take the news seriously and make sure you don't have that product in your house.
- Washing your hands thoroughly and regularly is always a good way to avoid catching or spreading harmful germs. Wash before cooking and after handling raw meat. And, of course, everyone should wash up after changing diapers or using the bathroom. Children might need an extra reminder or even a little help, especially if they have diarrhea. One missed opportunity at the sink could spread an illness to the entire family.
Centers for Disease Control and Prevention. Escherichia coli 0157:H7. July 2010.
American Academy of Family Physicians. E. coli infection. 2006.
Centers for Disease Control and Prevention. Multistate outbreak of E. coli 0157 infection linked to Topps brand ground beef patties. 2007.
Centers for Disease Control and Prevention. Investigation of outbreak of human infections caused by E. coli 0157:H7.
Centers for Disease Control and Prevention. Questions and answers about E. coli 0157:H7 outbreak from fresh spinach. 2006.
Centers for Disease Control and Prevention. E. coli: FAQs. March 27, 2008.
Mayo Clinic. E. coli. July 2009.
Siegler, R.L. et al. A 20-year population-based study of postdiarrheal hemolytic uremic syndrome in Utah. Pediatrics. 1994;94;35-40.
Mayo Clinic. Hemolytic uremic syndrome (HUS). December 2010.
Associated Press. Food poisoning can be long-term problem. Lauran Neergaard. January 22, 2008.