In the past health has been thought of as just the absence of disease, however today it is thought of more as the state of physical and mental wellbeing. Factors can work together to affect physical and mental health. A disease is a disorder that affects health by affecting an organism's body, organs, tissues or cells.
Diseases can be grouped into two types:
Communicable diseases are illnesses which result from infections by microorganisms called pathogens and are contagious among individuals. Bacteria, viruses, protozoa and fungi all cause disease which may be spread between organisms.
Non-communicable diseases are illnesses which are not transferred between people or other organisms. These are often the result of unhealthy lifestyles or a predisposition to a disorder caused by inherited factors.
Some lifestyle factors that can have major affects on physical and mental health include:
An example of non-communicable disease is cardiovascular disease (CVD). Many lifestyle factors contribute to the development of this disease of the heart and related blood vessels. Smoking, a diet high in saturated fat, and a sedentary lifestyle (lacking regular exercise) may contribute to the development of CVD.
Historically it is communicable disease that has contributed to most deaths. However, more recently it is non-communicable disease that has caused most severe illnesses.