Crohn’s disease is not contagious. It is a type of inflammatory bowel condition that may occur due to a person’s immune system mistakenly attacking their body’s cells.

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Crohn’s disease is a type of inflammatory bowel disease (IBD). Doctors consider it an autoimmune condition, as they believe the condition has links with an inflammatory immune response.

The Centers for Disease Control and Prevention (CDC) states that there are approximately 3 million people with IBD in the United States.

Symptoms of Crohn’s disease include:

In this article, we examine whether Crohn’s disease is contagious. We also list causes of Crohn’s disease, look at possible contagious causes, and outline how to help ease symptoms during a flare.

Anecdotal evidence shows that Crohn’s disease is not contagious. This means a person cannot catch it from someone else.

The condition can occur as a result of several causes. These may include:

  • autoimmune deficiency
  • genetics
  • some environmental factors, such as smoking

The exact causes of Crohn’s disease remain unclear. However, below are some factors that may lead to a person developing the condition.

Autoimmune deficiency

Experts suggest that Crohn’s disease is an autoimmune disorder. Autoimmune disorders occur due to an abnormal immune system reaction in which the immune system attacks a person’s healthy cells.

The CDC states that IBD occurs when the immune system responds incorrectly to certain environmental triggers. The trigger can be a virus or bacteria that causes inflammation of the gastrointestinal (GI) tract.

There are several harmless bacteria already present in the GI tract. In typical circumstances, the immune system does not attack these bacteria.

If a person has Crohn’s disease, their immune system can mistake these harmless bacteria for dangerous invaders. The immune system may then attack these cells, causing inflammation. Eventually, this inflammation can cause symptoms of Crohn’s disease.

The inflammation may not go away and can lead to the following:

  • chronic (long-term) inflammation
  • formation of ulcers
  • thickening of the intestinal wall

Genetics

Crohn’s disease may also be genetic. It often runs in families. The Crohn’s and Colitis Foundation (CCF) notes that 5–20% of people with IBD have a parent, child, or sibling who also has IBD.

A person’s risk of developing Crohn’s disease is substantially higher if both parents have IBD.

The CCF also states that Crohn’s disease is most common among people with Eastern European backgrounds, including Jewish people of European descent.

However, the number of people diagnosed with the condition in African American populations has risen in recent years.

Environmental factors

Some environmental factors may increase a person’s risk of developing Crohn’s disease. These include:

  • Smoking: Smoking dramatically increases a person’s risk of developing Crohn’s disease. It can also worsen the symptoms in a person who already has the disease.
  • Medications: Certain medications may slightly increase a person’s risk of developing Crohn’s disease. These medications include:
  • Diet: Eating a diet high in fat may slightly increase a person’s risk of developing Crohn’s disease.

Crohn’s disease is not contagious. However, some bacterial or viral infections may affect the colon and could contribute to the condition’s onset. And these infections may transmit to other people.

Escherichia coli (E. coli)

E. coli bacteria may be present in:

  • the environment
  • certain foods
  • the intestines of people and animals

E. coli is the name for a large and diverse group of bacteria, most of which do not cause harm to humans. However, some types of E. coli can cause:

Research suggests that there may be a link between the E. coli bacteria and Crohn’s disease. However, researchers have not yet proven this link.

Mycobacterium avium subspecies paratuberculosis (MAP)

MAP is a bacterium in the Mycobacteriaceae family. It causes Johne’s disease in cattle and other ruminant animals. Johne’s disease is a type of chronic enteritis.

Due to the similarities between Johne’s disease and Crohn’s disease, some scientists believe there is a link between MAP and Crohn’s disease.

A 2015 review shows increasing evidence to support a link between MAP and Crohn’s disease in humans. The review states that MAP and its DNA are present in high percentages of blood and tissues from people who have Crohn’s disease.

The review also adds that Crohn’s disease may occur in clusters or epidemics in areas where MAP is present in the environment. It further adds that the genes that people associate with susceptibility to Crohn’s disease and MAP infections overlap significantly.

However, experts must conduct more research to determine whether MAP can cause Crohn’s disease.

If a person has Crohn’s disease, there are several dietary changes they can make to try to reduce their symptoms. These include:

  • avoiding carbonated drinks
  • avoiding high fiber foods, such as popcorn, vegetable skins, and nuts
  • drinking more fluids
  • eating smaller meals more regularly

A person may wish to keep a food diary to help them identify foods that cause them problems.

If applicable, a person with Crohn’s disease should stop smoking, as cigarettes can worsen Crohn’s disease symptoms.

Medications

Although there is no cure for Crohn’s disease, many medications can help relieve symptoms.

  • Aminosalicylates: These medications contain 5-aminosalicylic acid, which helps manage inflammation.
  • Corticosteroids: These reduce immune system activity and decrease inflammation.
  • Immunomodulators: These medications slow down immune system activity, resulting in less inflammation.
  • Biologics: These medications neutralize proteins in the immune system, which decreases inflammation in the intestines.

Crohn’s disease is a form of IBD. It causes inflammation inside the GI tract, which can cause several symptoms. Common symptoms of Crohn’s disease include abdominal pain, diarrhea, and rectal bleeding.

Crohn’s disease is not contagious. Experts believe it occurs because a person’s immune system mistakenly attacks their body’s healthy cells. Genetics may also play a role.

Some scientists also link certain bacterial infections with the onset of Crohn’s disease. Such bacteria include E. coli and MAP. However, experts need to conduct more research to determine whether these bacteria can cause the disease to develop.