Escherichia coli (E. coli) is a group of bacteria found in the intestines of people and animals, and that can also be found in the environment. Most strains of E. coli are harmless and serve an important role in the digestive system. However, some strains of E. coli are pathogenic, meaning they can cause illness in humans. Many of these pathogenic E. coli cause diarrhea and are referred to as diarrheagenic E. coli. Other E. coli can leave the intestines and cause infections in other sites of the body such as urinary tract infections, blood stream infections, and respiratory illnesses.
There are six pathotypes of E. coli that cause diarrhea in people. In Wisconsin, four of the six pathotypes are reportable:
- Shiga toxin-producing E. coli (STEC), which includes E. coli O157:H7—STEC, and may also be referred to as Verocytotoxin-producing E. coli (VTEC) or enterohemorrhagic E. coli (EHEC). This pathotype is the one most commonly reported in the news, in association with foodborne outbreaks.
- Enterotoxigenic E. coli (ETEC)
- Enteropathogenic E. coli (EPEC)
- Enteroinvasive E. coli (EIEC)
More information can be found on the Food Poisoning home page.
E. coli 101
How do people get sick from E. coli?
People of any age can become infected. Very young children and the elderly are more likely to develop severe illness and hemolytic uremic syndrome (HUS) than others, but even healthy older children and young adults can become seriously ill.
Infections start when you swallow STEC—in other words, when you get tiny (usually invisible) amounts of human or animal feces in your mouth.
Unfortunately, this happens more often than we would like to think about. Exposures that result in illness include eating contaminated food, drinking unpasteurized (raw) milk, drinking water that has not been disinfected, contact with cattle, or contact with the feces of infected people.
Some foods are considered to carry such a high risk of infection with E. coli O157 or another germ that health officials recommend that people avoid them completely. These foods include unpasteurized (raw) milk, unpasteurized apple cider, and soft cheeses made from raw milk. Sometimes the contact is pretty obvious (working with cows at a dairy or changing diapers, for example), but sometimes it is not (like eating an undercooked hamburger or a contaminated piece of lettuce).
People have gotten infected by swallowing lake water while swimming, touching the environment in petting zoos and other animal exhibits, and by eating food prepared by people who did not wash their hands well after using the toilet. Almost everyone has some risk of infection.
Signs and Symptoms
Symptoms of Shiga toxin-producing E. coli (STEC) infection vary for each person, but often include severe stomach cramps, diarrhea (often bloody), and vomiting. Some people may have a fever, which usually is not very high (less than 101˚F/38.5˚C). Most people get better within five to seven days. Some infections are very mild, but others are severe or even life-threatening.
Most people with a STEC infection start feeling sick three to four days after eating or drinking something that contains the bacteria. However, illnesses can start anywhere from one to 10 days after exposure. Contact your healthcare provider if you have diarrhea that lasts for more than three days or diarrhea that is accompanied by a fever higher than 102˚F, bloody diarrhea, or so much vomiting that you cannot keep liquids down and you pass very little urine.
Hemolytic Uremic Syndrome (HUS)
About 5 to 10% of people who are diagnosed with STEC infection develop a potentially life-threatening complication known as HUS. HUS develops about seven days after symptoms first appear, when diarrhea is improving. Clues that someone is developing HUS include decreased frequency of urination, feeling very tired, and losing pink color in cheeks and inside the lower eyelids. People with HUS should be hospitalized because their kidneys may stop working and they may develop other serious problems. Most people with HUS recover within a few weeks, but some suffer permanent damage or die.
Diagnosis and Treatment
STEC infections are usually diagnosed through laboratory testing of stool specimens (feces). Identifying the specific strain of STEC is essential for public health purposes, such as finding outbreaks. Many labs can determine if STEC are present, and most can identify E. coli O157. Labs that test for the presence of Shiga toxins in stool can detect non-O157 STEC infections. However, for the O group (serogroup) and other characteristics of non-O157 STEC to be identified, Shiga toxin-positive specimens must be sent to a state public health laboratory.
Contact your healthcare provider if you have diarrhea that lasts for more than three days, or it is accompanied by high fever, blood in the stool, or so much vomiting that you cannot keep liquids down and you pass very little urine.
Non-specific supportive therapy, including hydration, is important. Antibiotics should not be used to treat this infection. There is no evidence that treatment with antibiotics is helpful, and taking antibiotics may increase the risk of HUS. Antidiarrheal medications like Imodium® may also increase that risk.
Know your chances of getting food poisoning.
People with higher chances for foodborne illness are pregnant women, newborns, children, older adults, and those with weak immune systems, such as people with cancer, diabetes, or HIV/AIDS.
Practice proper hygiene, especially good handwashing.
- Wash your hands thoroughly after using the bathroom and changing diapers.
- Wash your hands thoroughly before and after preparing or eating food.
- Wash your hands thoroughly after contact with animals or their environments (at farms, petting zoos, fairs, even your own backyard).
- Wash your hands thoroughly before preparing and feeding bottles or foods to an infant or toddler, before touching an infant or toddler’s mouth, and before touching pacifiers or other things that go into an infant or toddler’s mouth.
- Keep all objects that enter infants’ and toddlers’ mouths (such as pacifiers and teethers) clean.
- If soap and water aren’t available, use an alcohol-based hand sanitizer with at least 60% alcohol (check the product label to be sure). These alcohol-based products can quickly reduce the number of germs on hands in some situations, but they are not a substitute for washing with soap and running water.
Follow four steps to food safety when preparing food.
Wash fruits and vegetables well under running water.
The only exception to this when the package says the contents have already been washed.
Cook meats thoroughly.
- To kill harmful germs, cook beef steaks and roasts to an internal temperature of at least 145°F (62.6˚C) and allow to rest for 3 minutes after you remove meat from the grill or stove.
- Cook ground beef and pork to a minimum internal temperature of 160°F (70˚C).
- Always use a food thermometer to check that the meat has reached a safe internal temperature because you can’t tell whether meat is safely cooked by looking at its color.
Don’t cause cross-contamination in food preparation areas.
Thoroughly wash hands, counters, cutting boards, and utensils after they touch raw meat.
Avoid raw milk, unpasteurized dairy products, and unpasteurized juices
An example an unpasteurized juice includes fresh apple cider.
Don’t swallow water when swimming and when playing in lakes, ponds, streams, swimming pools, and backyard “kiddie” pools.
- Shiga toxin-producing E. coli (STEC) fact sheet, P-42158 (Multiple Languages)
- Enterotoxigenic E. coli (ETEC) fact sheet, P-01820 (Multiple Languages)
- Enteropathogenic E. coli (EPEC) fact sheet, P-02094 (Multiple Languages)
- E. coli O157:H7 fact sheet, P-42044 (Multiple Languages)
These are Wisconsin disease surveillance category II diseases:
- Report to the patient's local public health department electronically, through the Wisconsin Electronic Disease Surveillance System (WEDSS), by mail or fax using an Acute and Communicable Disease case report, F-44151 (Word) or by other means within 72 hours upon recognition of a case.
- Information on communicable disease reporting
Wisconsin case reporting and public health follow-up guidelines:
- Case Reporting and Investigation Protocol (EpiNet):
- Foodborne and Waterborne Disease Outbreak Investigation Manual, P-44722 (PDF)
- Wisconsin routine Enteric follow-up worksheet (PDF)
- Wisconsin State Laboratory of Hygiene Clinical testing reference manual
Questions about E. coli? Contact us!
Phone: 608-267-9003 | Fax: 608-261-4976