Gastritis, peptic ulcer disease, inflammatory bowel disease, and stomach and colon cancers- are they all caused by viral infections?

It is hypothesized that chronic gastritis and ulcerative colitis both are induced by viral infection, and that such chronic infection of the mucosa may lead to ulceration and occasionally cancer. Duodenal ulcer disease and Crohn's disease may on the other hand, be due to activation of latent viral infection of the corresponding neural ganglions, with subsequent migration of virus along the nerves to the gut wall. The gastric acid hypersecretion often occurring in patients with duodenal ulcer disease might be a consequence of viral interference with the efferent nerve function of vagal ganglions. Correspondingly, non-ulcer dyspepsia as well as irritable colon may reflect viral infection of afferent nerve function leading to pain and discomfort.