Hemorrhagic colitis is a rare illness involving Escherichia coli O157:H7. It causes abdominal pain and watery diarrhea. People can contract it in various ways, including by eating contaminated foods.

Escherichia coli (E. coli) O157:H7 is the most common form of infectious E. coli in the United States. It causes severe abdominal pain and watery diarrhea that often changes to bloody diarrhea. The infection usually lasts 5–7 days.

This article outlines hemorrhagic colitis symptoms, causes, links to COVID-19, diagnosis, and more.

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Hemorrhagic colitis can cause severe abdominal pain and watery diarrhea. Watery diarrhea may change to bloody diarrhea during the illness.

Other possible symptoms include:

  • fever
  • vomiting
  • nausea

Symptoms will occur within 3–4 days of exposure to the bacteria. They typically last 5–7 days.

A specific strain of E. coli causes hemorrhagic colitis.

Human and animal intestines contain several different strains of E. coli. Most are harmless and play an important role in overall health.

The strain responsible for this illness, O157:H7, produces a toxin that can damage the lining of the intestines and kidneys.

People can contract this strain of bacteria by:

  • eating produce, such as lettuce, that came in contact with cattle feces
  • eating undercooked, contaminated ground beef
  • drinking raw milk
  • swimming in or drinking contaminated water near farm animals such as cattle
  • having direct contact with a person who is carrying the bacteria, such as within families and child care centers

Risk factors can include:

  • consuming products made from unpasteurized milk
  • working in a day care or school setting where diaper changing occurs
  • eating food prepared by someone who did not wash their hands after using the bathroom
  • working directly with cattle or other animals
  • not washing hands at a petting zoo or farm
  • eating undercooked hamburgers

Nearly everyone has at least a small risk of contracting this strain of E. coli.

Some evidence suggests that COVID-19 can cause a type of hemorrhagic colitis.

A 2021 case study of three people reported that they experienced bloody diarrhea and abdominal pain but no other symptoms typical of COVID-19.

Another case study from 2020 noted that a person developed bloody diarrhea and abdominal pain due to a COVID-19 infection. The person showed no other symptoms of COVID-19.

In other words, a person with COVID-19 may experience symptoms similar to those of E. coli-related hemorrhagic colitis, with or without respiratory symptoms.

If a doctor suspects hemorrhagic colitis due to E. coli, they will typically send a stool sample to a lab for diagnosis and to check for toxins. They may order other tests to help rule out other possible causes of the symptoms, such as Salmonella.

If the lab results show signs of E. coli O157:H7, healthcare professionals will typically send the sample to a public health laboratory. This will allow officials to determine whether there is an outbreak.

Treatment typically involves giving the person plenty of fluids. A doctor may also recommend medications to help with symptoms but will generally avoid antibiotics and antidiarrheal medications.

These medications can increase the risk of hemolytic uremic syndrome, a rare condition that can destroy red blood cells and cause kidney failure.

A person can take steps to limit their chances of contracting hemorrhagic colitis, such as:

  • avoiding unpasteurized dairy products
  • always washing their hands after contact with farm animals
  • washing their hands after changing a diaper
  • washing their hands after using the bathroom
  • washing produce, such as lettuce, well before consuming it
  • avoiding eating undercooked hamburgers
  • avoiding drinking water from streams, rivers, or lakes

A person should also use caution around anyone whom they know has a confirmed case of E. coli. This may involve limiting contact, washing hands frequently, and sanitizing shared spaces.

The following are some frequently asked questions about hemorrhagic colitis:

What causes hemorrhagic colitis?

The O157:H7 strain of E. coli causes hemorrhagic colitis. It is the most common cause of E. coli in the United States. COVID-19 may cause symptoms similar to those of E. coli in some people.

What is the treatment for hemorrhagic colitis?

Treatment typically focuses on symptom relief and providing fluids. Experts do not recommend using antibiotics or antidiarrheal medications because they may increase the risk of hemolytic uremic syndrome.

What bacteria can cause hemorrhagic colitis?

The E. coli strain O157:H7 is typically responsible for hemorrhagic colitis. Other strains of E. coli can cause similar symptoms if they release toxins that damage the intestines.

What foods are associated with hemorrhagic colitis E. coli?

The most common forms of food-based transmission include:

  • contaminated water, often near cattle farms
  • raw milk products
  • lettuce and other produce grown near cattle
  • food prepared by people who did not wash their hands after using the bathroom

Hemorrhagic colitis is often the result of infection with the E. coli bacteria strain O157:H7. The infection can damage the intestines, leading to bloody diarrhea.

The infection is usually self-limiting, meaning it will resolve on its own within a few days. Treatment consists almost exclusively of rehydration.

Experts generally do not recommend using antibiotics or antidiarrheal medications to treat E. coli. These can increase the risk of potentially severe complications.