Symptoms of Infectious Colitis and How to Treat It

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Infectious colitis is a contagious illness caused by an infection in the colon, or large intestine. It can be from a virus such as norovirus, a bacterium like Salmonella, or a parasite. It usually comes from contaminated food or water.

Infectious colitis is usually a short-term condition that just involves at-home symptom management. However, antibiotics are sometimes needed to clear up bacterial infections.

This article looks at types of infectious colitis, its symptoms, how it's diagnosed and treated, your outlook after infection, and how to prevent it.

Screening for infectious colitis
Phynart Studio / Getty Images

Types of Infectious Colitis

Infectious colitis can be caused by bacteria, viruses, or parasites. It differs from chronic forms of colitis like Crohn's disease and ulcerative colitis, which may be a result of genetics and immune system abnormalities.


A large number of cases of infectious colitis are caused by bacteria, specifically food-borne bacteria. Common causes of bacterial colitis include:


Infectious colitis can also be caused by viruses like the cytomegalovirus (CMV). This is a common virus that can be spread through bodily fluids like saliva, blood, urine, semen, and vaginal fluids. It can cause CMV colitis, resulting in inflammation of the stomach and intestines.

Aside from CMV, other viruses that can cause colitis include:

  • Adenovirus, which causes cold-like symptoms
  • Norovirus, which causes vomiting and diarrhea
  • Rotavirus, which causes severe, watery diarrhea in children and infants

Most forms of infectious colitis are contagious and are often transmitted through direct contact with fluids or matter. Infectious colitis could potentially be spread by touching surfaces or objects that are contaminated by these fluids and matter, like a toothbrush. If you start experiencing symptoms like vomiting or diarrhea, contact your healthcare provider.


One common example of a parasite that can cause colitis is Entamoeba histolytica. Another is the parasite Trypanosoma cruzi (T. cruzi), which leads to Chagas disease, most common in Central America and South America.

Many parasitic infections that cause colitis can be spread through water or food contaminated by infected stools, like Entamoeba histolytica, close personal contact through the rectal area or mouth, or contaminated fertilizer made from human waste.

In the case of T. cruzi, the parasite is most commonly spread through the bite and fecal matter of an insect, the triatomine bug.

Infectious colitis tied to sexually transmitted infections (STIs) disproportionately affects men who have sex with men (MSM), particularly people who are living with human immunodeficiency virus (HIV). These STIs include chlamydia, gonorrhea, and syphilis.

Symptoms of Infectious Colitis

Symptoms of infectious colitis can vary depending on what kind you have. They can include:

  • Bloating, abdominal pain, cramping
  • Bloody or mucus-filled bowel movements
  • Dehydration
  • Diarrhea
  • Headaches
  • Fever
  • Vomiting

When to See a Doctor

If you notice any sudden, drastic shifts in your overall health, you should notify your healthcare provider or seek emergency medical attention immediately. Some warning signs to look for include:

  • Sudden weight loss
  • Dizziness and confusion
  • Changes in urination
  • Presence of blood in your stool or excessive quantities of blood in your stool
  • Changes in your heartbeat
  • Difficulty breathing

How Infectious Colitis Is Diagnosed

Your healthcare provider will provide a routine screening, assessing your past history of infectious colitis. You may also be asked if you have been using any antibiotics and whether you have traveled recently, especially to areas that do not have a clean water supply. Additionally, you'll be questioned about whether you have been admitted to a hospital.

Beyond this, your provider will assess your level of dehydration and take a stool sample to see if you have any viruses, parasites, or bacteria in your system that may be causing your colitis symptoms.

People with sepsis (a life-threatening condition caused by an infection in your body), older adults, and individuals who are immunocompromised may need to go through imaging tests, such as an X-ray or CT (computed tomography) scan. Separately, a colonoscopy (a procedure using a long, flexible tube with a camera attached) may be performed to examine your colon.

What Is Colitis?

The word colitis means inflammation of the colon. Chronic types include Crohn's disease (affects the lining of the small and large intestines) and ulcerative colitis (irritation and ulcers in the colon).

These are forms of inflammatory bowel disease (IBD).

Treatment of Infectious Colitis

It's important that you focus on staying hydrated. You may also be prescribed an oral hydrating solution or one that is administered through an IV (an intravenous drip). There will be an emphasis on making sure you load up on electrolytes.

If you have a bacterial infection, you most likely will be prescribed antibiotics, but, again, the dosage, amount, and exact medication will vary depending on the infection and person being treated. Adhere to the recommended dosage, and do not go above or below what your provider prescribes.

Some bacterial infections, like Salmonella, don't require antibiotic treatments. Treatment for parasitic colitis will generally involve hydrating as well as a prescription. In more serious cases, a surgical procedure on the colon, rectum, or surrounding areas may be needed.

Consult with your provider to review the best course of treatment and care as you recover from a case of infectious colitis.

Prognosis of Infectious Colitis

Bacterial, viral, and parasitic cases of colitis can be cured when the appropriate measures are taken. Infectious colitis is not a chronic condition that needs to be managed like Crohn's disease.

How long infectious colitis lasts also differs from person to person. For instance, mild-to-moderate infectious bacterial colitis in children tends to last just one to three days and less than seven days in adults. More severe cases could last for as long as three to four weeks.

Viral colitis should resolve by one to two weeks if you adhere to the treatment prescribed and focus on rehydrating and resting.

There is no broad, uniform amount of time it takes for parasitic colitis to resolve, but Chagas disease generally resolves within eight weeks.

How to Prevent Infectious Colitis

There are several things you can do to reduce your risk of contracting infectious colitis:

  • Always clean utensils thoroughly before and after use.
  • Keep raw and cooked foods separate and avoid eating undercooked items.
  • Avoid swallowing water from swimming pools and bodies of waters like lakes. When you are traveling, rely on bottled water, but still make sure you know where the water is coming from and whether it's clean.
  • Wash your hands frequently to avoid the spread of germs.


Infectious colitis can be caused by a virus, bacteria, or a parasite. Symptoms include diarrhea, abdominal pain, and fever. It can lead to weight loss, digestive problems, bloating, fever, and more severe illness. Infectious colitis usually resolves within a matter of weeks with medications tailored to the specific cause.

As with any infection, it's important to prevent its spread. Be mindful of what you are eating and drinking when traveling, and always practice proper hygiene to prevent the spread of germs. If you notice any sudden changes in your health or are concerned that you may have been exposed to an infection, contact your healthcare provider.

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Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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By Brian Mastroianni
Brian Mastroianni is a health and science journalist based in New York. His work has been published by The Atlantic, The Paris Review, CBS News, The TODAY Show, Barron's PENTA, Engadget and Healthline, among others.