A disease is an abnormal condition affecting the body of an organism. It is often construed to be a medical condition associated with specific symptoms and signs. It may be caused by external factors, such as infectious disease, or it may be caused by internal dysfunctions, such as autoimmune diseases. In humans, "disease" is often used more broadly to refer to any condition that causes pain, dysfunction, distress, social problems, or death to the person afflicted, or similar problems for those in contact with the person. In this broader sense, it sometimes includes injuries, disabilities, disorders, syndromes, infections, isolated symptoms, deviant behaviors, and atypical variations of structure and function, while in other contexts and for other purposes these may be considered distinguishable categories. Diseases usually affect people not only physically, but also emotionally, as contracting and living with many diseases can alter one's perspective on life, and their personality.
Death due to disease is called death by natural causes. There are four main types of disease: pathogenic disease, deficiency disease, hereditary disease, and physiological disease.
Diseases can also be classified as communicable and non-communicable disease.
Famous quotes containing the word disease:
“And this disease that was Swanns love had so multiplied, it was so intimately tied to all of Swanns habits, to all his acts, to his thoughts, to his health, to his sleep, to his life, even to what he desired for his afterlife, his love was so much a part of him that it could not be extracted from him without destroying him entirely: as is said in surgery, his love was inoperable.”
—Marcel Proust (18711922)
“Perfect Scepticisme ... is a disease incurable, and a thing rather to be pitied or laughed at, then seriously opposed. For when a man is so fugitive and unsettled that he will not stand to the verdict of his own Faculties, one can no more fasten any thing upon him, than he can write in the water, or tye knots in the wind.”
—Henry More (16141687)