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:
“The inconveniences and horrors of the pox are perfectly well known to every one; but still the disease flourishes and spreads. Several million people were killed in a recent war and half the world ruined; but we all busily go on in courses that make another event of the same sort inevitable. Experientia docet? Experientia doesnt.”
—Aldous Huxley (18941963)
“Health is a state of complete physical, mental and social well-being, and not merely the absence of disease or infirmity.”
—Constitution of the World Health Organization.
“Anti-Semitism is a horrible disease from which nobody is immune, and it has a kind of evil fascination that makes an enlightened person draw near the source of infection, supposedly in a scientific spirit, but really to sniff the vapors and dally with the possibility.”
—Mary McCarthy (19121989)