Disease

According to The World Health Organization (WHO) health is "a state of complete physical, mental and social well-being, not merely the absence of disease" so although disease is often described as the opposite to health it is, in fact, an illness that can affect a human, plant or animal's body and/or mind. The condition is usually caused by an infection, inflammation, genetic defects or environmental factors. A disease is a medical condition associated with specific signs and symptoms.

The four main types of disease are; pathogenic, deficiency, hereditary, and physiological.