E. coli is a type of bacteria that normally live in the intestines of people and animals. However, some types of E. coli, particularly E. coli O157:H7, can cause intestinal infection. E. coli O157:H7 and other strains that cause intestinal sickness are called Shiga toxin–producing E. coli (STEC) after the toxin that they produce.
People with weakened immune systems, pregnant women, young children, and older adults are at increased risk for developing these complications.
Most intestinal infections are caused by contaminated food or water. Proper food preparation and good hygiene can greatly decrease your chances of developing an intestinal infection.
Most cases of intestinal E. coli infection can be treated at home. Symptoms generally resolve within a few days to a week.
Symptoms of intestinal infection generally begin between 1 and 10 days after you’ve been infected with E. coli. This is known as the incubation period. Once symptoms appear, they usually last around 5 to 10 days.
Symptoms can include:
- abdominal cramping
- sudden, severe watery diarrhea that may change to bloody stools
- loss of appetite or nausea
- vomiting (uncommon)
Symptoms can last anywhere from a few days to more than a week.
Symptoms of a severe E. coli infection may include:
Call your doctor if you experience any of these severe symptoms.
According to the Centers for Disease Control and Prevention, about 5 to 10 percent of those who are infected develop hemolytic uremic syndrome (HUS), a condition in which the red blood cells are damaged. This can lead to kidney failure, which can be life-threatening, especially for children and the elderly. HUS generally begins about 5 to 10 days after the onset of diarrhea.
People and animals normally have some E. coli in their intestines, but some strains cause infection. The bacteria that cause infection can enter into your body in a number of ways.
Improper food handling
Whether food is prepared at home, in a restaurant, or in a grocery store, unsafe handling and preparation can cause contamination. Common causes of food poisoning include:
- failing to wash hands completely before preparing or eating food
- using utensils, cutting boards, or serving dishes that aren’t clean, causing cross-contamination
- consuming dairy products or food containing mayonnaise that have been left out too long
- consuming foods that haven’t been stored at the right temperature
- consuming foods that aren’t cooked to the right temperature or duration of time, especially meats and poultry
- consuming raw seafood products
- drinking unpasteurized milk
- consuming raw produce that hasn’t been properly washed
During the slaughtering process, poultry and meat products can acquire bacteria from the animals’ intestines.
Poor sanitation can cause water to contain bacteria from human or animal waste. You can get the infection from drinking contaminated water or from swimming in it.
Person to person
E. coli can spread when an infected person doesn’t wash their hands after having a bowel movement. The bacteria are then spread when that person touches someone or something else, like food. Nursing homes, schools, and child care facilities are particularly vulnerable to person-to-person spreading.
People who work with animals, especially cows, goats, and sheep, are at increased risk for infection. Anyone who touches animals or who works in an environment with animals should wash their hands regularly and thoroughly.
While anyone can experience an E. coli infection, some people are more at risk than others. Some risk factors include:
- Age: Older adults and young children are more likely to experience serious complications from E. coli.
- A weakened immune system: People with weakened immune systems are more susceptible to E. coli infections.
- Season: E. coli infections are more likely to occur during the summer months, June to September, for unknown reasons.
- Low stomach acid levels: Medications used to decrease stomach acid levels can increase your risk of E. coli infection.
- Certain foods: Drinking unpasteurized milk or juices and eating undercooked meat can increase your risk of E. coli.
When to see a doctor
Intestinal infection can lead to dehydration and serious complications, such as kidney failure and sometimes death, if it’s not treated. You should see your doctor if:
- You have diarrhea that isn’t getting better after four days, or two days for an infant or child.
- You have a fever with diarrhea.
- Abdominal pain doesn’t get better after a bowel movement.
- There is pus or blood in your stool.
- You have trouble keeping liquids down.
- Vomiting has continued for more than 12 hours. For a baby under 3 months old, contact your pediatrician as soon as symptoms begin.
- You have symptoms of intestinal infection and have recently traveled to a foreign country.
- You have symptoms of dehydration, such as a lack of urine, extreme thirst, or dizziness.
A doctor can confirm an E. coli infection with a simple stool sample.
Find a doctor
In most cases, home care is all that’s required to treat an E. coli infection. Drink plenty of water, get lots of rest, and keep an eye out for more severe symptoms that require a call to your doctor.
If you have bloody diarrhea or fever, check with your doctor before taking over-the-counter antidiarrheal medications. You should always check with your pediatrician before giving medications to infants or children.
If dehydration is a concern, your doctor may order hospitalization and intravenous fluids.
Most people show improvement within five to seven days after the onset of an infection, and make a full recovery.
Practicing safe food behaviors can decrease your chances of developing an intestinal infection due to E. coli. These include:
- washing fruits and vegetables thoroughly
- avoiding cross-contamination by using clean utensils, pans, and serving platters
- keeping raw meats away from other foods and away from other clean items
- not defrosting meat on the counter
- always defrosting meat in the refrigerator or microwave
- refrigerating leftovers immediately
- drinking only pasteurized milk products (avoiding raw milk)
- not preparing food if you have diarrhea
You should also make sure that all meat is cooked properly. The U.S. Department of Agriculture provides guidelines for cooking meat and poultry to proper temperatures to make sure all bacteria are killed. You can use a meat thermometer to check that meat is cooked to these temperatures:
- poultry: 165˚F (74˚C)
- ground meat, eggs: 160˚F (71˚C)
- steaks, pork chops, roasts, fish, shellfish: 145˚F (63˚C)
One of the easiest things you can do to prevent an E. coli infection is to regularly wash your hands. You should wash your hands before handling, serving, or eating food, and especially after touching animals, working in animal environments, or using the bathroom. Practicing good hygiene and following food safety guidelines can go a long way to decreasing your risk of infection.