Prof. Saman Wimalasundera MBBS . Do . PhD, Professor in Community Medicine, Former Head, Department of Community Medicine, Incharge Ophthalmologist, Community Ophthalmology Center, Faculty of Medicine University of Ruhuna Sri Lanka

Concept of Health & disease

Dimension and Determinants of Health Health is difficult to define but easier to understand. To many of us it may mean absence of disease or infirmity and to many it may mean sound body and sound mind and sound function of the body.

To an anatomist Healthy body means it should confirm to normal anatomical structures. To a physiologist Health means normal body functions

To a biochemist It means normal biochemical levels / values To a pathologist It means normal cellular make up.

To a geneticist It means correct existence of genetic potential Similarly to a clinician it means no abnormality in structure and function of the body. When a clinician fails to detect anything abnormal by his clinical wisdom and laboratory tests he labels a person no abnormality detected (NAD).

To a psychiatrist It means well adjusted and a balanced personality

Definition “Health is a state of complete physical, mental and social well being and not merely the absence of disease or infirmity”. WHO’s 191 member states have endorsed this statement.

Physical Health It means adequate body weight, height and circumference as per age and sex with acceptable level of vision, hearing, locomotion or movements, acceptable levels of pulse rate, blood pressure, respiratory rate, chest circumference, head circumference, waist hip ratio.

It means The body structure and functions confirming to laid down standards within the range of normal development and functions of all the systems.

Mental health The positive dimension of mental health is stressed in WHO’s definition of health as contained in its constitution.

Mental health is defined “as a state of well being in which the individual realized his or her own abilities, can cope with normal stresses of life, can work productively and fruitfully and is able to make a contribution to his or her community”.

A mentally normal person has the ability to mix up with others, he/she makes friendship, behaves in a balanced manner, keeps himself tidy and observes adequate personal hygiene, well oriented to time, place and person and environments and he is unduly not suspicious of others.

He is cheerful and happy and enjoys life with a purpose and he thinks positively and has normal development and contributes fully and is useful and productive to society and nation.

Social wellbeing It is the third dimension of health. It means ability of a person to adjust with others in his social life, at home, at work place and with people. Men interact with men and they inter-relate and inter depend on each other and pay their effective role in accordance with a situation.

Essentially social wellbeing includes inter-relation and interaction of human beings. Social wellbeing is a composite function of income level, literacy, occupation and working conditions marital harmony, institution of a family, social groups and have good cultural and behavioral patterns of the society.

Social wellbeing can be measured on scale by taking in to consideration of indicators like income, literacy and occupation (as discussed under socio economic status of family).

Determinants of health Heredity Environment Physical, social, biological and man-made Health services Promotive, preventive, curative, rehabilitative Health Behavior Actions Habits Reactions Belief, attitudes Practices (Lifestyles)

Environment The environment is considered to be the most important determinant and input of health.

Man made environment Health is influenced in the man made environment or artificial environment too. It included items like housing, transport, industries and communication.

Health services Availability, accessibility, affordability and acceptability of health services are considered an important determinant / input to health.

Health indicators It is some what easier to defined health for an individual. But to define “community health” it is some what more difficult. “Community health” parameters are different from health parameters of an individual.

“Community health” can be measured through indicators of economics, (gross national product gross national income and per capita income), life expectancy, under five mortality, infant mortality, literacy level, composite index of human development, maternal mortality etc.

A community is healthy when it enjoys sound health where disease and death rate is acceptably low, it is not threatened with bad environments and its economy is sound and the health resources are available, practices are sound and based on scientific evidences.

Its literacy levels are high and demographically it has balanced sex ratio and people live long, quality of life is good and human development index is high.

A village is said to be healthy if it has: safe sources of improved water supply, safe method of waste water disposal, paved streets, disposal of garbage refuse and animal excreta by manure pits, people use sanitary latrines, female literacy is high, girls enrolment is universal, deliveries are conducted by trained persons, birth rate and death rate are within acceptable limits, immunization coverage is high and housing condition is good.

Health is a fundamental human right. The attainment of highest possible level of health is the most important world wide social goal.

What is Disease The meaning of “Disease” is “without ease” (uneasiness) Either a Physiological /Psychological dysfunction

Illness Not only presence of disease but involvement of individual's perceptions and behavior in response to disease are included. Disease is very subjective. Sickness includes a state of social dysfunction too. i.e. The role, an individual assumes when ill.

The environment related to disease This refers not only to the environment the man lives. Various environmental factors are categorized as follows.

Physical Environment Physical aspects of environment Air, water, light, heat, radiation, gravity, pressure, and chemical agents etc. man tries a great deal to control these factors.

2. Biological Environment Certain diseases do not occur in some areas because agents or vectors can not exist in that environment due to biological reasons.

Biological environment includes Infectious agents of diseases, reservoirs of infective agents, vectors that transmit diseases, plants and animals.

3. Social Environment The social factors relevant to health include socio-economic status, social customs, traditional believes, etc.

Natural History of Disease Refers to the course of a disease over a period of time, unaffected by treatment.

Disease occurrence is usually insidious. Chronic diseases evolve over a long period and have their own progression. The history and time period that it spread is different from disease to disease. Most of the diseases pass through the following pattern.

1. Stage of susceptibility Risk factors that favors the occurrence of a disease are operating in this stage. Host factors:- Age, sex, race, family history, nutritional status Environmental Exposure to infectious factors:- agents, (infections) obesity, (HT, DM, coronary artery diseases) During this stage the person remains free of clinical diseases

2. Stage of pre-symptomatic disease Three important factors i.e.. Host, agent and environment interact to initiate pathogenic changes that is adequate to cause a disease. Still the disease does not clinically manifest.

3. Stage of clinical disease In this stage, the particular signs and symptoms develop. During this stage a disease can be sub classified in to its own severity grades.

E.g. Cancers Stage Localized Local Lymph nodes are involved Involvement of other organs within the same region Distant metastases

4. Stage of terminations Disease terminates and follow the following trend Spontaneous resolution –No sequels Settles down but with some sequels. Result in death of the patient.

5. Stage of sequels Disability Handicap Disease may extinct but aftermath remains may be an impairment is left. Disability Handicap

Sequence of events Disease Impairment Disability Handicap Impairment “Any loss or abnormality of psychological, physiological or anatomical structure or function”. e.g. Loss of foot, defective vision, mental retardation.

Impairment will be  visible or invisible  temporary or permanent  progressive or regressive

Disability “Any restriction or lack of ability to perform an activity in the manner or within or within the range considered normal for a human being”.

Handicap Definite disadvantages for a given individual resulting from an impairment or a disability that limits or prevents the fulfillment of a role that is normal for him/her depending on his/her age, sex, social and cultural factors or for that individual. e.g. Accident Disease Loss of foot Impairment Cannot walk Disability Unemployed Handicap