E. coli, more specifically Shiga Toxin-Producing E. coli, are among the most dangerous of the food poisoning pathogens – causing approximately 73,000 cases of foodborne illnesses each year in the United States. E. coli sources can be found in undercooked or raw hamburger meat, produce, raw milk, and unpasteurized juices and ciders, to name just a few.
What is E. coli?
Escherichia coli, or E. coli are rapidly-growing bacteria that are present in all environments. Most E. coli strains are harmless and can even live in the bodies of people. Some are even beneficial. Non-pathogenic E. coli (the type that do not cause humans illness) are found among the natural gut flora in healthy adults, where they aid metabolism by producing Vitamin K.
But some types of E. coli can cause bloody diarrhea and severe food poisoning. Other types of E. coli can cause urinary tract infections, respiratory illness, pneumonia, and other illnesses. Whole genome sequencing testing and live culture testing of stool cultures are two of the ways in which investigators can identify a link between an E. coli infection and a specific food source.
Some E. coli strains are pathogenic and harmful. Contact with pathogenic E. coli (the type that make humans sick) can result in infection and serious illness. The most severe E. coli infections are life-threatening and may require hospitalization.
What is O157 and O157:H7?
The E. coli O157:H7 strain, often referred to as just O157, is a strain of Shiga toxin-producing E. coli that is particularly dangerous. It is among the most common type of E. coli to cause serious infections in humans and cause long-term health problems.
O157:H7 is a particularly virulent E. coli strain, and results in a far higher incidence of hospitalization and fatality than non-STEC pathogenic E. coli strains.
What is STEC? Is STEC the same thing as O157?
The initials of “STEC” stand for Shiga toxin-producing Escherichia coli. The term is used to describe different strains of E. coli that produce Shiga-toxins when nested in the human colon. Exposure to Shiga-toxins can result in severe illness and long-term complications that may require hospitalization and can even cause death.
STEC E. coli O157:H7 is the most common (and among the most severe) strain of Shiga toxin-producing E. coli. According to the CDC, E. coli O157:H7 is the most prevalent pathogenic STEC strain and accounts for approximately half of all diagnosed STEC-infections in the United States. While O157 is the widest known and most frequently seen STEC strain, there are other strains that can cause severe illness as well. These can include, E. coli O26, E. coli O111, E. coli O121, and E. coli O103.
Science is still catching up with research about the non-O157 STEC E. coli, as older laboratory tests did not identify these bacteria. However, with new lab methods, new information about these types will be forthcoming.
Where does E. coli Come From?
Everywhere. E. coli lives in the gut of humans and animals. It is in the soil and natural water sources. However, it is important to note that not all E. coli make people sick. And the types that make people sick may not make the animals that are their hosts sick.
For typical E. coli infections, the major source of human illnesses is linked to cattle. The STEC E. coli that cause human illness, like E. coli O157, generally do not make animals sick. Other kinds of animals, including pigs and birds, sometimes pick up STEC from the environment and may spread it. This is why drinking raw milk can be a big concern.
How Does Someone Become Sick with an E. coli Infection?
E. coli most commonly follows a transmission route known as the “fecal-oral” route. In short, E. coli bacteria live in the digestive systems of humans (or other animals) are shed in their waste. Small (even microscopic) particles of waste contaminate food, water, or anything else that would be put in the mouth, and enters the digestive system. It is in the digestive system, namely the colon, where E. coli begins to nest and grow.
Most people become ill with E. coli infections by ingesting food that was mishandled (stored at the wrong temperature, not cooked or washed properly, or contaminated). For example, past outbreaks of E. coli infections have stemmed from undercooked hamburgers or leafy greens.
Other ways someone can become ill with E. coli infections include:
- working with or around livestock
- direct contact with bodily fluids from other infected individuals
- eating undercooked meats
- drinking raw milk or unpasteurized fruit juices
It is fairly common for adults to contract pathogenic E. coli infections by handling bodily fluids from infected children.
Who is at the Greatest Risk of E. coli Infection?
E. coli does not discriminate. Severe food poisoning is a risk that everyone faces. Virulent strains of E. coli like O157:H7 can cause serious and long lasting symptoms, even in healthy adults.
Some individuals are at a particularly high risk for foodborne illness¾for purposes of this, they are termed the “high risk group.” As with most other infections, foodborne illnesses are very dangerous for young children, the elderly, and anyone with a compromised immune system, like those with cancer, HIV/ AIDS, organ transplant patients, or other immune issues.
What are the Symptoms of E. coli Infections?
It is important to note that symptoms of Shiga toxin-producing E. coli (STEC) infections may vary for each person. The typical symptoms of these types of inflections include:
- Severe stomach cramps
- Watery diarrhea (often bloody)
- Sometimes a fever, which usually is not very high (less than 101˚Fahrenheit)
The majority of people infected with E. coli will exhibit symptoms of diarrhea and abdominal cramps within 2 to 8 days after ingestion of the bacteria. These persons will usually recover from illness within a week.
However, those with more severe food poisoning may develop a concerning long-term complication, called Hemolytic Uremic Syndrome, within 5 to 10 days of the infection.
How Do Doctors Diagnose and Treat E. coli?
Only a licensed healthcare provider can diagnose an E. coli infection. A medical provider will typically order a stool sample to be tested. A stool sample test can tell your doctor whether it is E. coli or some other organism that is causing your illness. Once the doctor knows what type of organism is making you ill, the doctor can prescribe the most effective course of treatment for you.
Treatment of foodborne E. coli infections is typically done through supportive care, including ample rest and hydration.
If you have severe symptoms consistent with an E. coli infection, or if you have eaten at a restaurant or consumed food that was the source of a recent outbreak, you should consult a physician or another licensed healthcare provider for medical advice. Early medical intervention could reduce the risk of long-term complications.
Are There Long-Term Complications of E. coli Infections?
There could be. About 5-10% of those with STEC E. coli infections can develop Hemolytic Uremic Syndrome (HUS), which is a type of kidney failure that could have long-term consequences and can even lead to death. It can develop anywhere within 5-10 days after the initial E. coli infection. Children under the age of five are at the highest risk for developing HUS. However, anyone could develop the affliction.
The symptoms of HUS include:
- abdominal pain
- bloody diarrhea
- decreased urination
- pale skin
- unexplained bruises and bleeding.
Those who have developed HUS require hospitalization because their kidneys may begin to fail. Most people with HUS recover within a few weeks, but some could suffer permanent damage, require blood transfusions or kidney transplants, or may even die.
E. coli infections can also cause central nervous system complications, like seizures or strokes. These stem from the brain or spinal cord not getting enough healthy red blood cells to function, causing damage to tissues and blood vessels.
How Can Someone Prevent an E. coli Infection?
The best way to avoid an E. coli infection is to wash your hands regularly, clean all produce thoroughly, and make sure that you cook any raw meat to their optimum cooking temperature – usually 165° Fahrenheit. As ready-to-eat foods often become contaminated through cross-contamination from raw meats, it is a good idea to separate raw foods from ready-to-eat ones – while prepping, in your shopping cart, and in your refrigerator at home.
Those who have come into contact with livestock, through work or a petting zoo, can also take care to wash their hands, shoes, and clothing to prevent transmission of the bacteria onto food or food preparation surfaces.
Finally, it is a good idea to pay close attention to the restaurants, noting their health grades.
What Are Some Ways Food Producers Are Trying to Reduce the Spread of E. coli?
There are many different practices food producers can do to reduce the spread of E. coli.
Those who process animal meats can take care to remove the digestive tracts of animals prior to processing. Those who make milk and dairy products can pasteurize their milk base prior to making the final product, to kill any dangerous E. coli that may have come into contact with the milk.
Some producers are turning to hydroponics to reduce the contamination of E. coli in leafy greens. As soil can be contaminated by a multitude of exposures – animal feces blended with water irrigation for example, hydroponics is a way to completely separate food from soil.