A communicable disease is one that can be transmitted from one person to another in a multitude of ways, including contact with blood and bodily fluids, inhaling an airborne virus, or being bitten by an insect. Planning and evaluating disease prevention and control initiatives, as well as ensuring appropriate medical therapy and detecting common-source outbreaks, all require knowledge of communicable disease. When a pathogen enters a person's body, it begins to replicate. After that, the person may start to experience symptoms. Some symptoms are caused by the infection causing damage to the body's cells. Others are caused by the immune system's reaction to the infection. Symptoms of communicable infections are usually mild and disappear after a few days. Some, on the other hand, can be dangerous and even life-threatening.
A non-communicable disease (NCD) is a condition that cannot be passed from one person to another. Parkinson's disease, autoimmune disorders, strokes, the majority of cardiac diseases, the most of tumours and cancers, diabetes, chronic renal disease, osteoarthritis, osteoporosis, Alzheimer's disease, cataracts, and other NCDs are among them. NCDs can be chronic or acute in nature. Although there are some non-communicable infectious diseases, such as parasitic disorders where the parasite's life cycle does not entail direct host-to-host transmission, the majority are non-infectious. NCDs are the world's leading cause of mortality.