A disease is deemed rare if it affects fewer than one in every 2,000 people in the European Union (EU), however having one of these diseases is far from uncommon. A rare disease affects up to 36 million people in the EU, with more than half of them being children. Rare digestive disorders can be debilitating, and those who suffer from them frequently require lifelong treatment to manage their persistent and often unpredictable symptoms. Both patients and physicians face unique challenges when it comes to bowel problems.
Infections of the gastrointestinal tract are a leading cause of morbidity and mortality around the world. The surgical pathologist must be familiar with infectious diseases that were once limited to tropical regions of the world or the realm of esoterica as the number of transplant patients and those with other immunocompromising conditions rises, and as global urbanisation and transcontinental travel become more common. Gastrointestinal infections cause a significant amount of chronic disease, with diarrhoea being the most prevalent symptom. The majority of cases are caused by viruses, with norovirus being the most prevalent, although bacteria and parasites also play a role in acute and chronic gastrointestinal illnesses and their complications.