This is the fifth of 6 guest posts on infectious causes of chronic disease.
By Rachel Kirby
There are about 500,000 (or approx 1 in 544 people) in the United States who suffer from Crohn’s disease, and is most prevalent in both men and women between the ages of 20-30. Crohn’s Disease is an autoimmune disease which causes a chronic inflammation of the digestive tract. It can affect the entire digestive tract but is most prevalent in the lower small intestine and in the ileum. It will cause swelling, causing pain and diarrhea.
More after the jump…
Though a lot is known about the disease; little is known about what actually causes the disease or where it comes from. There is a lot of speculation spanning a vast spectrum of topics. The most popular theory is that the body’s immune system reacts to a virus or a bacterium by causing ongoing inflammation in the intestine. One of the first I came across and strangest but most relevant to an infectious cause was that the bacteria enters your body through contaminated milk (dairy) or water products. The bacteria are a mycobacterium that is abbreviated MAP (Mycobacterium avium subsp. Paratuberculosis).There seems to be some correlation between culturing MAP in patients with Crohn’s. The idea that there is a bacterial cause may come from the idea that there is a similar bovine disease called Johne’s disease. It has many of the same symptoms. Because of the similarities with Johne’s disease, a mycobacterial cause of Crohn’s disease has been sought for many years. It has been disproved that they have any real connection. In one study it suggests that once the bovine strain enters a human host it becomes less virulent. Another reason there is a problem making the correlation of MAP and Crohn’s is because MAP is often hard to culture. Why they do they still suggest that there is an infectious agent that causes Crohn’s? This could be because they still continue to culture MAP in Crohn’s patients but there is not strong enough evidence to fully support the theory. It may be that MAP is present even before the onset of Crohn’s.
The reason that this is so disputed is because the other main theory for the cause of Crohn’s is that there is a strong genetic aspect of the disease which would mean that an infectious cause would be completely irrelevant. This is also what a friend gave me as the cause of her onset of Crohn’s. She said there are several auto immune diseases in her family so this would be the most logical reason for her disease.
If there is a genetic link why then is there so much research on finding a bacterial cause. Finding a genetic cause seems like a more logical and easier approach than trying to find some sort of infection, when there could be so many causes of infection. Where did it come from? Does it come from food or is it zoonotic, meaning does it come from animals? It is closely related to the bovine bacterium? There are still so many questions to answer. Seeing how Crohn’s affects people first hand we need to find out where the condition is coming from in order to provide a cure to this chronic condition that that affects so many people’s lives. If in fact more research is done to prove that the disease does indeed come from an infectious agent it is much more realistic to find a cure!
Rachel works at the hospital in the Pediatric Hematology/Oncology department as a research assistant, assisting with a Cord Blood Stem Cell study. She is planning to apply to the College of Public Health to obtain a degree in Environmental and Occupational Health. She ultimately would like to work in or with the CDC.
Saleh A Naser, George Ghobrial, Claudia Romero, John F Valentine. 2004. Culture of Mycobacterium avium subspecies paratuberculosis from the blood of patients with Crohn’s disease. The Lancet. 364:1039-44. PubMed link.
R Balfour Sartor. 2005. Does Mycobacterium avium subspecies paratuberculosis cause Crohn’s disease? Gut. 54:896-898. Link.
Warwick S Selby. 2004. Mycobacterium avium subspecies paratuberculosis bacteraemia in patients with inflammatory bowel disease. The Lancet. 364:1013-14. Link.