The relationship between intestinal parasites and some immune-mediated intestinal conditions

Over the last decades, the incidence of infestation by minor parasites has decreased in developed countries. Infectious agents can also suppress autoimmune and allergic disorders. Some investigations show that various protozoa and helminthes are connected with the main immune-mediated intestinal conditions including celiac disease (CD), inflammatory bowel diseases (IBD) and irritable bowel syndrome (IBS). Celiac disease is a digestive and autoimmune disorder that can damage the small intestine and characterized by a multitude gastrointestinal (GI) and extra GI symptoms. IBD (including ulcerative colitis and Crohn's disease) is a group of inflammatory conditions of the small intestine and colon. The etiology of IBD is unknown, but it may be related to instability in the intestinal microflora that leading to an immoderate inflammatory response to commensal microbiota. Irritable bowel syndrome (IBS) is a common, long-term condition of the digestive system. Bloating, diarrhoea and/or constipation are nonspecific symptoms of IBS. Various studies have shown that some intestinal parasites can effect on immune system of infected hosts and in some cases, they are able to modify and change the host's immune responses, particularly in autoimmune disorders like celiac disease and IBD. The main objective of this review is to investigate the relationship between intestinal parasites and different inflammatory bowel disorders.