Concepts of causation of disease screen

Concept of causation of disease and their screening

1. GUESS WHAT?

2. BY DIPA CHAKRABORTY MSC(N),1ST YEAR SEMINAR ON: CONCEPTS OF CAUSATION OF DISEASE AND THEIR SCREENING

3. INTRODUCTION Health and disease have always been matters of concern of the society. This resulted in constant search for improvement in quality of living and maintenance of a healthy society .In that process various concept on health, disease and treatment emerged, thereby the practice of medicine got refined on scientific basis .The emergence of a biomedicine with the advent of germ theory completely changed the outlook towards the health and disease and effort in scientific investigation started finding correlation with material cause to every diseases. Understanding the causes of disease is the key to begin the process of finding remedies that could cure them .Every medical system has its own model of identifying the reason of disease. Based on those concept they develop models of treatment .Though all these model divergent in nature, the goal of every medical system has been to provide rational treatment to the diseases.

4. DEFINATION OF HEALTH AND DISEASE

5. HEALTH “Health is a state of complete physical, mental and social wellbeing and not merely an absence of disease or infirmity”. (WHO 1946) OR, “Health is a state dynamic balance of an individual’s ability to perform personally valued roles and responsibilities , to deal and cope with physical, biological psychological and social stresses and challenges throughout the life while continuing to maintain sense of wellbeing”(ICN)

6. DISEASE “Disease is a condition in which body health is impaired and performance of vital function in the body is interrupted”.(WEBSTER) OR A disease is a particular abnormal condition that negatively affects the structure or function of part or all of an organism, and that is not due to any external injury. OR According to Jennings (1986), “disease is demonstrable pathophysiology or pathochemistry and is diagnosed by the demonstration of pathologic features”.

7. CONCEPT OF DISEASE CAUSATION

8. OLD THEORIES: 1. Demonic/super natural theories: Religion, philosophy, medicine were integral part in the early part of civilization. It was believed that sun, moon, and stars are capable of influencing human beings. One concept prevalent was that the evil spirit entering the body directly and pursuing nefarious actions. Another concept was the evil spirit as a messenger of gods giving warning in the forms of diseases. Some other concept was a human enemy with supernatural powers, send evil spirits to harm others.

9. 2. Miasmatic theory Miasmatic theory is based on the inference that the air arising from certain kinds of ground, especially low, swampy areas, was a cause of disease. Certain places were thus given a very evil reputation, because the ground was said to exude some invisible, insensible vapour, called it miasm, which produced disease. People were searching for a material and natural causes, instead finding shelter on god or a devil. Rational thinking that something cannot come out of nothing was the basis of the concept.

10. 3. Humoral theory The Greeks rejected the super natural theories and looked upon a disease as a natural process. They advocated that the matter is made up of four elements, earth, air, fire and water and these elements have the qualities of being cold, dry, hot and moist. With this concept they hypothesized that these qualities are represented in the body by four humors - phlegm, yellow bile, black bile, and blood. According to this theory, the equilibrium among these humors characterizes health, and disequilibrium characterizes disease.

11. MODERN THEORIES: Biomedical model Biomedical model is based on the greek philosophy which describes the mind and body to be two separate entities with mind representing the godly aspect and the body as a separate machine, the malfunctioning of which can be recognised easily by observation. Invention of circulation by William Harvey and German pathologist sir. Rudolf Virchow reinforced the mechanistic philosophy. According to this model, disease is the pathological or mechanical alteration in body function. The pathological process needs to be contained or baited and body function has to be restored through medical measures to get cure.

12. GERM THEORY OF DISEASE Louis Pasteur (1860) demonstrate the presence of bacteria in the air. Robert Koch (1877) showed that anthrax was caused by bacteria. These theories of Pasture and Koch confirmed the germ theory of disease. Acc. to this theory there is one single specific micro-organism (causative agent) to every disease. This refers to one to one relationship between the causative agent and the disease. This is also called as a single cause theory. E.g. diphtheria due to Corynebacterium diphtheria, cholerae due to vibrio cholerae. AGENT MAN DISEASE

13. Epidemiological triad One of the most straightforward models of disease causation is the epidemiologic triad or triangle, the traditional model for infectious disease. The triad consists of an external agent, a susceptible host, and an environment that brings the agent and host together. In this model, disease results from the interaction between the agent and the susceptible host, in an environment that supports transmission of the agent from a source to that host. The epidemiologic triad model is helpful when considering association and causation. The triad consists of three factors - agent, host and environment. They interact in a variety of ways that result in various states of health in an individual or a community.

14. 4. THE MULTIFACTORIAL CAUSATION This theory of multifactorial causation was put forth by Pettenkofer Munich(1819-1901). This theory de-emphasizes the "Germ theory" (or single cause idea). It is now known that most of these factors are so much linked to life style and human behaviour that they are considered as 'risk factors', in the web of causation of the disease. Now it is recognized that a disease is not caused by an organism but also predisposed by many factors contributing to its occurrence, specially 'modern disease of civilization like lung cancer, diabetes, coronary heart disease, mental illness, etc. These predisposing factors are social, economic, cultural, genetic, psychological factors etc. (including poverty, illiteracy, ignorance and poor living conditions.

15. THE MULTIFACTORIAL CAUSATION This theory of multifactorial causation was put forth by Pettenkofer Munich(1819-1901). This theory de-emphasizes the "Germ theory" (or single cause idea). It is now known that most of these factors are so much linked to life style and human behaviour that they are considered as 'risk factors', in the web of causation of the disease. Now it is recognized that a disease is not caused by an organism but also predisposed by many factors contributing to its occurrence, specially 'modern disease of civilization like lung cancer, diabetes, coronary heart disease, mental illness, etc. These predisposing factors are social, economic, cultural, genetic, psychological factors etc. (including poverty, illiteracy, ignorance and poor living conditions.

16. T THE MULTIFACTORIAL CAUSATION As a result of advances in public health, it is now well recognized that many diseases are neither caused by an organism nor could they be prevented by the traditional methods of isolation, immunization, improvement in sanitation. These diseases are predisposed by many factors (social, economic, cultural, genetic, and psychological) contributing to its occurrence, especially in case of modern diseases of civilization like coronary heart disease, various type of cancer, many types of diabetes, COPD, mental illness etc. It is now known that most of these factors (excess of fat and salt intake, smoking, lack of physical exercise, junk foods, and obesity) are so much linked to lifestyle and human behaviour that they are considered as "risk factors", in the web of causation of disease.

17. RISK FACTORS: Modifiable Factors: smoking, hypertension, elevated serum cholesterol, physical activity, obesity, etc. Unmodified Factors: Age, sex, race, family history and genetic factors. The risk factor can be modified by intervention or eliminated, thereby reducing the possibility of occurrence of the disease, this is called 'primordial prevention'.

18. s.no Disease Risk factors 1. Coronary artery Smoking , cholesterol, obesity, lack of exercise,type A personality. 2. Lung cancer Smoking , ionizing radiation, asbestos drug, air pollution 3. Stroke High blood pressure, elevated cholesterol level smoking 4. Vehicular accident Alcohol , non-use of seat belts, excessive speed, roadway design 5. Diabetes Obesity , lack of exercise, excessive food consumption

19. RISK GROUPS: These are the groups of individuals who are exposed to, or associated with, the risk factors and, therefore, they are at high risk of mortality and morbidity, either because of the constitution or of the environment physically, biologically or sociocultural . The following are the risk-groups depending upon the situation Physical situation: poor living condition, overcrowding and lack of sanitation . Biological situation 1 . Age (LBW new born, infants, toddlers, elderly ). 2 . Sex (female in reproductive age ). 3.Physiological state (pregnancy and malnutrition) 4.Genetic factors (strong family history ) Sociocultural situation: socioeconomic class. Lifestyle, habits, beliefs, customs, traditions, etc