Health : The World Health Organization (WHO) defines health as a state of complete physical, mental, and social well¬being, not merely the absence of disease or infirmity. By that defi¬nition, we all are ill to some extent. Likewise, we all can improve our health to live happier, longer, more productive, and more satis¬fying lives if we think about what we do.
Disease : A disease is an abnormal change in the body's condition that impairs important physical or psychological functions. Diet and nutrition, infectious agents, toxic substances, genetics, trauma, and stress all play roles in morbidity (illness) and mortality (death). Environmental health focuses on external factors that cause disease, including elements of the natural, social, cultural, and technological worlds in which we live.
In the past, health organizations have focused on the leading causes of death as the best summary of world health. Mortality data, how¬ever, fail to capture the impacts of nonfatal outcomes of disease and injury, such as dementia or blindness, on human well-being.
When people are ill, work isn't done, crops aren't planted or har¬vested, meals aren't cooked, and children can't study and learn. Health agencies now calculate disability-adjusted life years (DALYs) as a measure of disease burden. DALYs combine prema¬ture deaths and loss of a healthy life resulting from illness or dis¬ability. This is an attempt to evaluate the total cost of disease, not simply how many people die.
A full understanding of health requires that humanity be seen as part of an ecosystem. The human ecosystem includes in addition to the - natural environment, all the dimensions of the man-made environment - physical, chemical, biological, psychological: in short, our culture and all its products. Disease is embedded in the ecosystem of man. Health, according to ecological concepts, is visualized as a state of dynamic equilibrium...