Health and disease.pptx who health concept

WHO Health concept

1. Health and Disease Concept of Health WHO Definition Disease Causation Theories and Models

2. The most ambitious definition of health is that proposed by WHO in 1948: “health is a state of complete physical, mental, and social well-being and not merely the absence of disease or infirmity.” The WHO ‘ health for all’ strategy was renewed in 1998 and again in 2003. Key Aspects of the WHO definition- - Holistic approach encourages a comprehensive perspective on health that addresses physical, mental, and social factors.  Health is viewed as a multidimensional state, not limited to just the absence of disease. Well Being- Includes complete well-being in three key areas, Physical well-being- The body’s normal functioning Mental well-being- The ability to cope with stress, realize one’s potential, and work productively. Social well-being- The ability to contribute to one’s community and engage in social interactions. Beyond absence of disease: Health is more than just the opposite of illness or physical weakness. It is a positive state of complete well-being.

3. The four main concepts of health are:   the Biomedical concept (health is the absence of disease), the Ecological concept (health is an adaptation to the environment), the Psychosocial concept (health is physical, mental, and social well-being), the Holistic concept (a balance of mind, body, and spirit)

4. Components of health Health is a multidimensional concept, and its components encompass various aspects of well-being. The components of health can be broadly categorized into the following dimensions. Physical health Mental health Social health Emotional health Spiritual health Intellectual health Environmental health Occupational health Financial health These components of health are interconnected and influence each other. Achieving a state of complete well-being involves balancing and nurturing all dimensions of health. It is essential to address each aspect to lead a healthy and fulfilling life

5. Webster defined disease as “a condition in which body health is impaired, a departure from a state of health, and alteration of the human body interrupting the performance of vital functions”. Explanation of disease causation is based on the following theories: i . Theories of the pre-modern era ii. Germ theory of disease iii. Biomedical model iv. Epidemiological triad v. Dever’s epidemiological model vi. Theory of multifactorial causation vii. Web of Causation viii. Wheel of disease causation ix. Other theories - Wolf’s theory of stress, organ maladaptation, and disease - Holmes and Rahe’s theory of life change and the onset of illness.

6. Theories of the pre-modern era These theories were in play before the concept of microorganisms was established till the end of the 18 th century. The demonic theory- considered disease as a result of being possessed by demons or evil spirits. The Punitive theory- thought the disease to be caused as a punishment for any bad deed done, as an outrage of God. The Maismatics theory- Breathing in certain areas was proposed to cause disease, such as air around swamps, marshes, and air at night was thought to cause an array of diseases. The Theory of Four Humors- It proposes that the body is composed of four humors: blood, phlegm, yellow bile, and black bile. any imbalance in these resulted in disease. - Bloodletting was considered the most common method of treating diseases

7. The Germ Theory of Disease The demonstration of bacterial presence in the air by Louis Pasteur and Anthrax is caused by a bacteria created a drastic shift in the understanding of disease causation. The germ theory applies the causal effect to one-to-one, ie , a single microorganism is responsible for a specific disease, e.g , Mycobacterium tuberculosis and the occurrence of Tuberculosis. The Biomedical Model Envisions the healthy human body as an efficiently functioning machine and any resulting anomaly as a dysfunction of engaged organs. E.g., Hypothyroidism caused by improper functioning of the thyroid gland. The theory overlooks the complex and summative role of psychological and social components.

8. Epidemiological Triad P roposes that the disease is an outcome of an imbalance of interactions between three essential components: Host, Agent, and Environment. Disease is caused when a susceptible host is exposed to the causative agent in a compatible environment . It’s a broader concept and overcomes the limitations of germ theory. Intercepting any of the three links provides a means of halting the disease process, also opening a window for preventive measures.

9. Dever’s epidemiological model Highlights the interplay of four factors: Human biology, Lifestyle, Environment, and Health system. Each can have a positive or a negative effect. Human biology includes genetics along with complex physiological systems, factors that are related to maturation and aging. Lifestyle factors include daily habits, customs, and traditions; Environmental factors are all the living and non-living factors that surround us. The health care system comprises accessibility and availability of health services. This model is used to explain those diseases where, rather than a causative organism, harmful living conditions and lifestyle are to be blamed.

10. Multifactorial causation Pettenkofer proposed that disease is a result of many factors, as opposed to germ theory, where the idea of a single cause was used. These factors can include genetic, environmental, lifestyle, and social determinants, all interacting to influence a person's health and susceptibility to disease.  Having multiple causes for a disease meant numerous methods of preventing that disease. But it was essential to know the sequence of events to tackle the disease causation .

11. Web of causation P roposed by MacMahon , Pugh, and Ipsen (1960), who argued that multiple factors causing a disease cannot be explained using a linear causal relation, as there is a complex network of interactions between various risk factors and their contributing roles in the development of disease.  It highlights that disease rarely has a single cause but emerges from a web of interconnected elements.  Gives equal prominence in recognizing determinants and helps in planning interventions.

12. Wheel of Disease Causation This was proposed by Mausner and Kramer in 1985. It eliminates microorganisms as the sole cause of disease, but emphasizes the complex network of interactions of physical, biological, and social environments . It also introduces genetics into the mix Epidemiological wheel

13. Rothman’s Component Causes and Causal Pies Model: It proposes that the causation of disease is by a collection of factors, which are represented by a pie. It discriminates the factors into sufficient and necessary factors. Sufficient cause : is a set of minimum conditions, events, or factors that are required to produce a given outcome These factors that form the sufficient cause are called component causes . A d isease can have more than one sufficient cause. Necessary cause : is a causal factor whose presence is imperative for the emergence of the effect. If a disease cannot occur without the presence of a factor, then the factor is known as Necessary . A component that appears in every pie or pathway is a necessary cause. The disease can be controlled by removing one component from the pies or removing the factor that is common to all pies.

14. Eg : Mycobacterium Tuberculosis bacteria is necessary to cause tuberculosis but cannot cause the disease in isolation, i.e. is not sufficient to cause the disease. A host of other factors are required such as impaired nutrition or immunity which can be deemed as sufficient cause. . Rothman’s Causal Pies

15. Postulates of Disease Causation: Postulates explaining the process of disease causation have been given by Henle and Koch in 1877 and then by Hill and Evans in 1965.

16. Hill-Evans Postulates Each criterion contributes to the strength of the causal relationship between a factor and disease. Strength- Stronger the association between the factor and the disease, the more likely it is that the factor is the causative agent. Consistency-Consistent observations seen across different scenarios and different populations strengthen the likelihood of the causal effect. Specificity- The More specific an association between a factor and effect, the greater the probability of effect. Temporality- Exposure to the cause should precede the effect. Biological ingredient- Greater exposure should cause a greater incidence of disease. Plausibility- A valid scientific explanation of the causal relationship, though limited by current knowledge, is essential. Coherence- The findings should be coherent with the causal argument. Experimental evidence- Analogy- Similar effects should be caused by similar factors