First of all if we want to explain what health is and how to approach it we have to define some key terms.
What is health?
As defined by World Health Organization (WHO), it is a “State of complete physical, mental, and social well being, and not merely the absence of disease or infirmity.” Health is a dynamic condition resulting from a body’s constant adaptation in response to stresses and chnages in the environment for maintaining an inner equilibrium that we know as homeostasis.
What is disease?
Disease is a dynamic process and it is just opposite to health. Health denotes perfect harmony and normal functioning of all the body system or state of complete wellness, whereas disease denotes disharmony and deviation from normal functioning of various bodies functioning system.
What’s the difference between infectious and non communicable diseases?
Basically communicable disease also known as infectious refers to diseases that can pass from one person to another whereas non-communicable diseases referred to as chronic occur in one person and cannot be passed on to another. 
NON COMMUNICABLE DISEASES
PLAY A ROLE IN THE CAUSATION OF THESE DISEASES.
THEORIES OF DISEASE CAUSATION
Before the rise of modern medicine, disease was attributed to a variety of spiritual or mechanical forces. It was interpreted as a punishment by God for sinful behavior or the result of an imbalance in body elements. Greeks related disease to the natural environment or the way in which human populations lived and worked. Then the idea that disease could be passed from person to person arose in the Middle Ages and convincing evidence proved that the disease was spread by water contaminated by the excretions of cholera victims.
In those times, the body was viewed as a machine to be corrected when things go wrong, by procedures designed to neutralize specific agents or modify the physical processes causing disease.
Before the discovery of micro-organism several theories explaining the cause of disease were put forward time to time. These are the principal: germ theory, epidemiological triangle, multifactorial causation theory, web of causation and divers epidemiological model. 
According to this theory, there is one single specific cause of every disease. This refers to one to one relationship between the causative agent and disease. This theory explains the origin of infectious-communicable diseases
Theory of epidemiological triangle:
According to this theory, every one exposed to disease agent did not contract the disease. This means it is not only the causative agent that is responsible for disease but there are another factors also, related to man and environment which contribute to disease.
Multifactorial causation theory
Epidemiological theory is not applicable for non infectious and chronic diseases like coronary artery diseases etc. because it has many causes or multiple factors. This theory helps to understand the various associated causative factors, which suggests preventive and plan measures to control the disease.
Web of causation theory
According to its creators disease never depends upon single isolated cause rather it develops from a chain of causation in which each link itself is a result of complex interaction of preceding events these chain of causation which may be the fraction of the whole complex is known as web of causation.
The socio-environmental model
The socio-environmental approach is not so much concerned with the causes of disease, rather it focuses to identify the main factors that make and keep people healthy. This model is composed of four major categories of factors: human biology, lifestyle, environment and health system. All these factors influence health status positively or negatively.
- Human biology include genetic inheritance, complex physiological systems, factors related to maturation and ageing.
- Life style factors include daily living activities, customs, traditions, health habits etc.
- Environmental factors include physical, biological, social and spiritual components.
- Health care system factors include availability, accessibility, adequacy and use of health care services at all levels. 
With all the scientific research, the studies that have been made and the theories developed in the last century, we are increasingly close to finding the formula for health. Certainly we have much to learn, but there are certain things we have for granted. Because the diseases are caused by agents they can be prevented by having good hygiene, getting away from people infected with vaccines, strengthening our immune system, etc.
On the other hand, it is clear that chronic diseases are a problem caused by bad habits and improper lifestyle. The environment and the social condition that surrounds a society play a key role in the development of both cases of disease, so they are factors we must balance to maintain people healthy.
To improve the levels of health in our society, government and people must work together in an effort to change our lifestyle and adopt a new operatin system for for 21st century medicine. Re-shaping health professions and adopting new clinical models is a must.
 WHO. “definition of health. “Bussiness Dictionary. 2005. WebFinance. 02/02/2013 <http://www.businessdictionary.com/definition/health.html>
 Wise Geek. “What Is the Difference Between Communicable and Non-Communicable Disease?. “WiseGeek. 2008. ConjectureCorporation. 02/02/2013 <http://www.wisegeek.com/what-is-the-difference-between-communicable-and-non-communicable-disease.htm. >
 David Locker. “Social determinants of health and disease. “Servier Health. 2009. Scambler. 02/02/2013 <http://www.elsevierhealth.com/media/us/samplechapters/9780702029011/9780702029011.pdf.>
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