A disease may be a particular abnormality that negatively affects the structure or function of all or a part of an organism, which isn't thanks to any immediate external injury. Diseases are often known to be medical conditions that are related to specific symptoms and signs. A disease could also be caused by external factors like pathogens or by internal dysfunctions. for instance , internal dysfunctions of the system can produce a spread of various diseases, including various sorts of immunodeficiency, hypersensitivity, allergies and autoimmune disorders. In humans, disease is usually used more broadly to ask any condition that causes pain, dysfunction, distress, social problems, or death to the person afflicted, or similar problems for those in touch with the person. during this broader sense, it sometimes includes injuries, disabilities, disorders, syndromes, infections, isolated symptoms, deviant behaviors, and atypical variations of structure and performance, while in other contexts and for other purposes these could also be considered distinguishable categories. Diseases can affect people not only physically, but also mentally, as contracting and living with a disease can alter the affected person's perspective on life.