---

THEORIES OF DISEASE CAUSATION, EPIDEMIOLOGICAL TRIAD, WEB OF CAUSATION & NATURAL HISTORY OF DISEASE

---

OVERVIEW FLOWCHART - EVOLUTION OF DISEASE CAUSATION CONCEPTS

ANCIENT BELIEFS (Supernatural / Humors / Miasma)
        ↓
GERM THEORY OF DISEASE (Pasteur, Koch - 1860-1880s)
  (Single Agent → Man → Disease)
        ↓
  LIMITATIONS RECOGNIZED
  (Not all exposed persons develop disease)
        ↓
EPIDEMIOLOGICAL TRIAD (Agent + Host + Environment)
        ↓
BIOMEDICAL MODEL
        ↓
WEB OF CAUSATION (MacMahon & Pugh - multifactorial)
        ↓
BEINGS MODEL / MULTIFACTORIAL AETIOLOGY (Modern Concept)

---

SECTION 1: PRIMITIVE & EARLY THEORIES OF DISEASE CAUSATION

---

SECTION 2: GERM THEORY OF DISEASE

Key Milestones:

• 1860 - Louis Pasteur (French bacteriologist, 1822-1895) demonstrated bacteria in air; disproved spontaneous generation
• 1873 - Pasteur advanced the "Germ Theory of Disease"
• 1877 - Robert Koch (1843-1910) proved anthrax was caused by a bacterium
• This was the "Golden Age of Bacteriology" - microbes discovered in rapid succession:
  • Gonococcus (1847)
  • Typhoid bacillus, Pneumococcus (1880)
  • Tubercle bacillus (1882)
  • Cholera vibrio (1883)
  • Diphtheria bacillus (1884)

Disease Model:

Disease Agent -----→ Man -----→ Disease
   (Germ)         (Host)

Limitations of Germ Theory:

1. One-to-one relationship is an over-simplification
2. Not everyone exposed to TB develops tuberculosis
3. Not everyone exposed to streptococci develops rheumatic fever
4. Cannot explain chronic diseases (where agent is often unknown)
5. Cannot account for host resistance, nutrition, immunity, environment
6. Conclusion: Modern medicine has moved away from strict adherence to the germ theory

---

SECTION 3: EPIDEMIOLOGICAL TRIAD

Definition:

Diagram - The Epidemiological Triad:

The Triangle of Epidemiology:

"The agent is the cause of disease; the host is an organism that harbours the disease; the environment is those surroundings and conditions external to the human that cause or allow disease transmission; and time accounts for incubation periods, life expectancy of the host or pathogen, and duration of the illness." - Park's PSM

---

A. AGENT FACTORS

Classification of Disease Agents:

                    DISEASE AGENTS
                         |
    ┌────────┬────────┬────────┬────────┬────────┬────────┐
    ↓        ↓        ↓        ↓        ↓        ↓        ↓
Biological Nutrient Physical Chemical Mechanical Social  Absence/
Agents    Agents   Agents  Agents    Agents    Agents  Excess of
                                                        factors

• Key properties:
  • Infectivity - Ability to invade and multiply in host
  • Pathogenicity - Ability to induce clinically apparent illness
  • Virulence - Proportion of clinical cases with severe manifestations

• Excess OR deficiency causes disease
• Examples: PEM (Protein Energy Malnutrition), anaemia, goitre, obesity

• Endogenous: Produced inside body - urea (uraemia), bilirubin (jaundice), ketones, uric acid (gout)
• Exogenous: Allergens, metals, fumes, dust, gases, insecticides - acquired by inhalation, ingestion, or inoculation

• Chemical: hormones (insulin, oestrogens, enzymes)
• Nutrient factors
• Lack of structure (e.g., thymus)
• Chromosomal factors (mongolism, Turner's syndrome)
• Immunological factors (agammaglobulinaemia)

---

B. HOST FACTORS (Intrinsic)

"In epidemiological terminology, the human host is referred to as 'soil' and the disease agent as 'seed'." - Park's PSM

Classification of Host Factors:

---

C. ENVIRONMENTAL FACTORS (Extrinsic)

Three categories:

---

Dynamic Interaction of the Triad:

      ENVIRONMENT
     (Extrinsic factors)
           ↑
           |
   AGENT ←---→ HOST
(Disease    (Intrinsic
 cause)      factors)
           ↓
         DISEASE

• If AGENT is strong + HOST is susceptible + ENVIRONMENT is favourable → DISEASE occurs
• If HOST immunity is high → No disease (even with agent present)
• If ENVIRONMENT is unfavourable for agent → Disease does not spread

---

SECTION 4: WEB OF CAUSATION

Definition:

Key Features:

1. Proposed by Brian MacMahon and Thomas Pugh in their book "Epidemiologic Principles and Methods"
2. Ideally suited for chronic disease where the disease agent is often NOT known
3. Disease is an outcome of interaction of multiple factors
4. Does NOT imply all causes must be removed to control disease
5. Sometimes elimination of just one important link may be sufficient to control disease
6. Relative importance of factors expressed as "relative risk"

Classic Example - Web of Causation for Myocardial Infarction:

Reading the Web:

Changes in Lifestyle + Stress
      ↓                 ↓
Abundance of food   Emotional disturbances
Lack of exercise    Smoking
      ↓                 ↓
   Obesity --------→ Hypertension ←-- Ageing
      ↓                    ↓
Hyperlipidaemia    Changes in artery walls
      ↓                    ↓
Coronary atherosclerosis + Increased catecholamines
              ↓
        Coronary Occlusion
              ↓
       Myocardial Ischaemia
              ↓
       MYOCARDIAL INFARCTION

Significance of Web of Causation:

• Provides a model showing a variety of possible interventions
• Breaking even ONE link in the web can prevent disease
• Forms the basis of multifactorial causation in modern epidemiology
• Explains why chronic diseases cannot be attributed to a single agent

---

SECTION 5: BEINGS MODEL (Multifactorial Aetiology)

What is the BEINGS Model?

BEINGS = Biological, Environmental, Immunological, Nutritional, Genetic, Social/Services

BEINGS Model - Flowchart:

                    DISEASE CAUSATION
                         ↑
    ┌──────┬──────┬──────┼──────┬──────┬──────┐
    ↓      ↓      ↓      ↓      ↓      ↓      ↓
  Bio-   Envi-  Immun- Nutri- Genet-  Social/
logical  ronm'l  olog'l  ional   ic    Services
factors factors factors factors factors factors

Types of Causal Factors in Disease:

---

SECTION 6: NATURAL HISTORY OF DISEASE

Definition:

Diagram - Natural History of Disease (Leavell & Clark Model):

---

TWO PHASES OF NATURAL HISTORY OF DISEASE:

NATURAL HISTORY OF DISEASE
           |
     ┌─────┴─────┐
     ↓           ↓
PHASE 1:     PHASE 2:
Pre-         Pathogenesis
pathogenesis Phase
Phase        (Process in Man)
(Process in
Environment)

---

PHASE 1: PREPATHOGENESIS PHASE

• Also called: "Man in the midst of disease" or "Man exposed to risk of disease"
• Potentially, all humans are in the prepathogenesis phase of many diseases (both communicable and non-communicable)
• The Epidemiological Triad (Agent + Host + Environment) operates during this phase

---

PHASE 2: PATHOGENESIS PHASE

Sub-phases:

Entry of Agent into Host
        ↓
Early Pathogenesis
(Agent multiplies, tissue/physiological changes begin)
        ↓
Discernible Early Lesions
(Pathological changes below "clinical horizon")
        ↓
CLINICAL HORIZON
(Signs and symptoms appear)
        ↓
Advanced Disease / Illness
        ↓
Convalescence
        ↓
   ┌────┴────┐
   ↓         ↓
RECOVERY   DEATH / DISABILITY / CHRONIC STATE

Clinical Horizon:

• The threshold below which disease is not detectable clinically
• Above this horizon = signs and symptoms appear
• In chronic diseases (e.g., hypertension, cancer), the presymptomatic phase is silent and prolonged

Host's Reaction to Infection - Not Predictable:

• May be clinical or subclinical
• May be typical or atypical
• Host may become a carrier (e.g., diphtheria, Hepatitis B)

---

SECTION 7: LEVELS OF PREVENTION (Based on Natural History)

PRIMARY PREVENTION:

1. Health Promotion - Health education, adequate nutrition, improved housing, regular exercise
2. Specific Protection - Immunization, chemoprophylaxis, protection from carcinogens, use of protective equipment

SECONDARY PREVENTION:

• Early Diagnosis - Screening programs, case finding
• Prompt Treatment - Preventing complications, limiting disability

TERTIARY PREVENTION:

• Disability Limitation - Treatment to prevent further complications
• Rehabilitation - Physical, social, psychological rehabilitation to restore maximum function

---

SECTION 8: BIOMEDICAL MODEL vs SOCIAL MODEL (Comparison)

---

QUICK SUMMARY MIND MAP

                  DISEASE CAUSATION
                       |
     ┌─────────────────┼─────────────────┐
     ↓                 ↓                 ↓
HISTORICAL          MODERN           NATURAL
THEORIES           MODELS            HISTORY
     |                 |                 |
 Supernatural    Epidemiol.        Pre-patho-
 Humors          Triad             genesis
 Miasma          (AHE)             phase
 Germ Theory         |                 |
                 Web of           Pathogenesis
                 Causation        phase
                     |                 |
                 BEINGS           Levels of
                 Model            Prevention
                                  (1°, 2°, 3°)

---

KEY DEFINITIONS (For Viva/MCQ):

• Disease Agent - A substance, living or non-living, or force, the excessive presence or relative lack of which may initiate or perpetuate a disease process (Park's PSM)
• Host - "Soil" in which the disease "seed" grows; harbours the disease
• Epidemiological Triad - Agent + Host + Environment operating in combination to determine disease occurrence
• Web of Causation - Model showing complex interrelationship of all predisposing factors (MacMahon & Pugh)
• Natural History of Disease - Evolution of disease from prepathogenesis to recovery/death in absence of treatment
• Clinical Horizon - The threshold above which disease becomes clinically detectable
• Prepathogenesis Phase - Period before disease agent enters the host; "man exposed to risk"
• Pathogenesis Phase - Begins with entry of agent into susceptible host

---

---

SECTION A: FUNDAMENTAL CONCEPTS OF COMMUNITY MEDICINE & PUBLIC HEALTH

---

LAQ 1: DEFINE AND DIFFERENTIATE COMMUNITY MEDICINE, PREVENTIVE MEDICINE, SOCIAL MEDICINE AND PUBLIC HEALTH

Flowchart - Evolution of Terms:

PUBLIC HEALTH (1840s)
      ↓
PREVENTIVE MEDICINE (18th-19th century)
      ↓
SOCIAL MEDICINE (1940s - Virchow, Sand)
      ↓
COMMUNITY MEDICINE (1960s-70s - modern successor)
      ↓
All share common ground: Prevention of Disease + Promotion of Health

---

1. PREVENTIVE MEDICINE

"Preventive medicine is the science and art of health, dealing with individuals, families and groups, is oriented towards the whole person, and is concerned with the promotion of health and the prevention of disease."

• Focuses on individuals and families
• Applied by the practicing physician in clinical settings
• Deals with primary, secondary and tertiary prevention
• Closely linked with clinical medicine
• Applied to specific individuals (not populations)

Primary Prevention → Preventing disease before it occurs
Secondary Prevention → Early detection and treatment
Tertiary Prevention → Rehabilitation, limiting disability

---

2. SOCIAL MEDICINE

"Social medicine investigates conditions of life and work that affect the state of health and endeavours to ensure the citizen good means of maintaining health or recovering it when it is impaired."

• Studies the relationship between health and social conditions
• Focuses on the social determinants of disease (poverty, unemployment, housing)
• Introduced by Rudolf Virchow: "Medicine is nothing but politics on a large scale"
• Concerned with the social causes of ill-health

---

3. COMMUNITY MEDICINE

"That speciality which deals with populations...and comprises those doctors who try to measure the needs of the population, both sick and well, who plan and administer services to meet those needs, and those who are engaged in research and teaching in the field." (Park's PSM, p. 23)

• Deals with populations (not just individuals)
• Successor of Public Health, Preventive and Social Medicine
• Studies health needs, plans services, conducts research
• Uses epidemiology as its primary tool
• Applicable to both sick and well populations

---

4. PUBLIC HEALTH

"The science and art of preventing disease, prolonging life, and promoting health and efficiency through organized community efforts for the sanitation of the environment, the control of communicable infections, the education of the individual in personal hygiene, the organization of medical and nursing services for early diagnosis and preventive treatment of disease, and the development of social machinery to ensure for every individual a standard of living adequate for the maintenance of health." (Park's PSM, p. 1)

• Arose from the need to protect "the public" from communicable diseases (~1840)
• Organized, community-based effort
• Involves sanitation, immunization, health education, disease control
• A social institution created and maintained by society
• Modern public health also includes organization of medical care

---

COMPARISON TABLE: Preventive Medicine vs Public Health vs Community Medicine

---

LAQ 2: FUNCTIONS OF PUBLIC HEALTH

Core Functions (WHO / Institute of Medicine):

         FUNCTIONS OF PUBLIC HEALTH
                    |
     ┌──────────────┼──────────────┐
     ↓              ↓              ↓
 ASSESSMENT     POLICY          ASSURANCE
(Monitoring)  DEVELOPMENT    (Service Delivery)

Detailed Functions:

• Monitor health status of communities
• Investigate and diagnose health problems and hazards
• Collect, manage, analyze health data (vital statistics)

• Inform, educate and empower people about health issues
• Mobilize community partnerships
• Develop policies and plans that support health efforts

• Link people to needed health services
• Ensure a competent public health workforce
• Evaluate effectiveness, accessibility of health services
• Research new insights and innovative solutions

• Sanitation of the environment
• Control of communicable infections
• Education of individuals in personal hygiene
• Organization of medical/nursing services for early diagnosis
• Development of social machinery for adequate standard of living
• Organize medical care as a means of protecting health

---

LAQ 3: HISTORY OF PUBLIC HEALTH - GLOBALLY AND IN INDIA

GLOBAL HISTORY:

PHASE 1: Disease Era / Miasmatic Period (before 1850)
         Sanitary reforms; John Snow (Cholera, 1854)
                    ↓
PHASE 2: Bacteriological / Germ Theory Era (1850-1900)
         Pasteur, Koch; vaccines, antiseptics
                    ↓
PHASE 3: Health Promotion Era (1900-1950)
         Maternal & child health, nutrition, housing
                    ↓
PHASE 4: Social Engineering Era (1950-1980)
         WHO (1948), Health For All, Primary Health Care
                    ↓
PHASE 5: Health Promotion & Sustainable Development (1980-present)
         Ottawa Charter (1986), MDGs, SDGs

• 1796 - Jenner: Smallpox vaccination
• 1842 - Chadwick Report (sanitary conditions of labouring population)
• 1848 - Public Health Act, England
• 1854 - John Snow: Cholera epidemic map (Broad Street pump)
• 1860 - Florence Nightingale: Nursing and hospital hygiene
• 1860-1890 - Pasteur, Koch: Golden Age of Bacteriology
• 1948 - WHO established; WHO definition of health
• 1978 - Alma-Ata Declaration: "Health for All by 2000", Primary Health Care
• 1986 - Ottawa Charter: Health Promotion

PUBLIC HEALTH IN INDIA:

PRE-INDEPENDENCE:
1859 - First Sanitary Commissioner appointed
1864 - Sanitary Commission established
1897 - Epidemic Diseases Act
1912 - Indian Red Cross Society

POST-INDEPENDENCE:
1946 - Bhore Committee Report (comprehensive health services plan)
1952 - First Five Year Plan: Community Development Programme
1952 - National Family Planning Programme (first in the world)
1977 - Community Health Workers (CHW) programme
1978 - Alma-Ata Declaration endorsed
1983 - National Health Policy (NHP)
2002 - NHP 2002 (focus on decentralization)
2005 - NRHM (National Rural Health Mission)
2013 - NUHM (National Urban Health Mission)
2017 - NHP 2017
2018 - Ayushman Bharat: Health & Wellness Centres + PM-JAY

---

---

SECTION B: CONCEPT OF HEALTH

---

LAQ 4: DEFINE HEALTH. DISCUSS THE DIMENSIONS AND BIOMEDICAL MODEL OF HEALTH

Definition of Health (WHO, 1948):

"Health is a state of complete physical, mental and social well-being and not merely an absence of disease or infirmity." (Park's PSM, p. 19)

• Amplified later to include: ability to lead a "socially and economically productive life"
• The WHO definition is broad, positive, and sets a standard of "positive health"
• Criticized as being too ideal / not easily measurable

Operational Definition (WHO Study Group):

• Broad sense: "A condition or quality of the human organism expressing the adequate functioning of the organism in given conditions, genetic or environmental"
• Narrow sense (measurable): No obvious evidence of disease + person functioning normally within normal limits for age, sex, community, geography

---

DIMENSIONS OF HEALTH:

               DIMENSIONS OF HEALTH
                        |
     ┌──────┬───────┬───────┬────────┬─────────┬──────────┐
     ↓      ↓       ↓       ↓        ↓         ↓          ↓
 Physical Mental  Social Spiritual Emotional Vocational Political

• "Perfect functioning" of the body
• Every cell and organ functioning at optimum capacity
• Signs: good complexion, clean skin, bright eyes, normal pulse/BP, normal weight
• Evaluated by: self-assessment, inquiry into symptoms, inquiry into medications, laboratory tests

• Ability to think clearly and coherently
• Absence of mental disorder
• Not just absence of mental illness but positive mental well-being
• Includes: ability to respond to challenges, manage stress, maintain self-esteem

• Ability to make and maintain relationships
• Social harmony and adjustment
• Ability to participate in social activities
• Quantified by: social adjustment, social functioning scales

• Relates to personal beliefs, values, morals
• Provides a sense of purpose and direction
• Not necessarily linked to religion; involves living according to one's values
• Important especially in palliative care

• Ability to express emotions appropriately
• Emotional maturity and control
• Ability to handle stress and adversity

• Ability to engage in productive work
• Occupational health and satisfaction
• "Health is the essence of productive life" (WHO philosophy)

---

BIOMEDICAL MODEL OF HEALTH:

• Based on the Germ Theory of Disease
• Focuses on pathological, biochemical and physiological changes
• Treats disease as a deviation from normal biological function
• Single cause → single disease model
• Ignores social, psychological, environmental factors

Disease Agent → Biological Defect → Disease → Treatment → Cure

1. Cannot explain chronic non-communicable diseases
2. Ignores social determinants of health
3. Ignores psychological factors (mind-body connection)
4. Does not explain why some exposed individuals do not get disease
5. Leads to over-medicalization
6. Not applicable to health promotion

---

COMPARISON OF MODELS OF HEALTH:

---

---

SECTION C: NUTRITION FOR COMMUNITY

---

LAQ 5: DISCUSS THE TYPES OF MALNUTRITION. METHODS TO MEASURE AND PREVENTION/CONTROL

Definition of Malnutrition:

"Malnutrition is a pathological state resulting from a relative or absolute deficiency or excess of one or more essential nutrients." - WHO / Park's PSM

Flowchart - Classification of Malnutrition:

                    MALNUTRITION
                         |
           ┌─────────────┴─────────────┐
           ↓                           ↓
  UNDERNUTRITION                OVERNUTRITION
  (Deficiency)                  (Excess)
           |                           |
  ┌────────┴────────┐              Obesity, Metabolic
  ↓                 ↓              Syndrome, CVD
Protein Energy  Micronutrient
Malnutrition    Deficiency
(PEM)                |
                ┌────┴────┐
                ↓         ↓
           Vitamins    Minerals
           (A, D, B1,  (Iron, Iodine,
           B2, C, etc) Calcium, Zinc)

TYPES OF MALNUTRITION:

• Obesity (BMI >30), metabolic syndrome, type 2 DM, CVD, NAFLD

---

METHODS TO MEASURE MALNUTRITION (Nutritional Assessment):

NUTRITIONAL ASSESSMENT
         |
┌────────┼────────┬─────────┐
↓        ↓        ↓         ↓
Anthro-  Clinical Dietary  Biochem-
pometric Signs   Methods   ical/Lab

• Stunting = Low Height-for-Age (chronic, long-standing malnutrition)
• Wasting = Low Weight-for-Height (acute, recent malnutrition)
• Underweight = Low Weight-for-Age (composite indicator)

• Hair: flag sign, easily pluckable, dyspigmentation
• Skin: dermatosis, oedema, pallor
• Eyes: Bitot's spots, corneal ulceration
• Mouth: angular stomatitis, glossitis, bleeding gums
• Bones: rickets, bowing of legs
• Abdomen: hepatomegaly, pot belly

• Serum albumin, total protein, transferrin (protein status)
• Haemoglobin, serum ferritin (iron status)
• Serum retinol (Vitamin A)
• Urinary iodine excretion (iodine status)
• Serum 25-OH Vitamin D (Vit D status)

---

PREVENTION AND CONTROL OF MALNUTRITION:

PREVENTION OF MALNUTRITION
          |
┌─────────┼─────────┐
↓         ↓         ↓
Primary  Secondary  Tertiary
(Before  (Early     (Treatment
 disease) detection) & Rehab)

1. Promotion of breastfeeding (exclusive for 6 months)
2. Appropriate complementary feeding after 6 months
3. Food fortification (iodized salt, iron-fortified flour)
4. Dietary diversification
5. Growth monitoring and promotion
6. Nutrition education
7. Food security programs (ICDS, PDS, Mid-Day Meal)

1. Screening for malnutrition (growth monitoring)
2. Treatment of micronutrient deficiencies (Vitamin A supplementation, iron-folic acid tablets)
3. Management of acute malnutrition at community level

1. Nutritional Rehabilitation Centres (NRC)
2. Therapeutic feeding (F75 and F100 formula feeds for SAM)
3. Community-based Management of Acute Malnutrition (CMAM)

---

LAQ 6: NATIONAL NUTRITIONAL PROGRAMMES OF INDIA (POSHAN ABHIYAN, ICDS, MID-DAY MEAL)

Overview Flowchart:

NATIONAL NUTRITIONAL PROGRAMMES
              |
┌─────────────┼──────────────┐
↓             ↓              ↓
ICDS        Poshan        Mid-Day
(1975)     Abhiyan        Meal
           (2018)        Programme

• Launched: 2 October 1975
• Target group: Children (0-6 years), pregnant women, lactating mothers, adolescent girls
• Delivered through: Anganwadi Centres (AWCs)
• Services provided (6 services):
  1. Supplementary nutrition
  2. Immunization
  3. Health check-up
  4. Referral services
  5. Non-formal pre-school education
  6. Nutrition and health education

• Launched: 8 March 2018 (International Women's Day), Rajasthan
• Aims to reduce stunting, undernutrition, anaemia, and low birth weight
• Targets:
  • Reduce stunting by 2% per year
  • Reduce underweight by 2% per year
  • Reduce anaemia by 3% per year
• Technology-driven: Real-time monitoring through ICDS-CAS (Common Application Software)
• Focus: Convergence of multiple schemes

• Started: 1995 (National Programme of Nutritional Support to Primary Education)
• Renamed: PM POSHAN Shakti Nirman in 2021
• Target: Children in Classes 1-8 in government/government-aided schools
• Provides: Hot cooked meals
• Calorie norms: 450 kcal + 12g protein (primary); 700 kcal + 20g protein (upper primary)
• Benefits: Increases school enrolment and attendance, reduces hunger, improves nutrition

• Diet-based approach
• Food fortification
• Popularize low-cost nutritious foods
• Minimum Nutritional Status monitoring
• Prophylaxis against micronutrient deficiencies
• Promotes research in nutrition

---

LAQ 7: FOOD SAFETY, FOOD PROCESSING, FOOD FORTIFICATION, FOOD ADDITIVES AND FOOD ADULTERATION

KEY DEFINITIONS:

---

WHO'S FIVE KEYS FOR FOOD SAFETY:

1. Keep CLEAN - Wash hands, clean utensils
2. Separate RAW and COOKED - Avoid cross-contamination
3. COOK thoroughly - Heat kills pathogens
4. Keep food at SAFE temperatures - Below 5°C or above 60°C
5. Use SAFE water and raw materials

---

FOOD PROCESSING:

1. Preserve food from spoilage
2. Improve palatability and digestibility
3. Extend shelf life
4. Improve safety
5. Create convenience foods

• Extends shelf life, reduces wastage
• Destroys pathogens (safety)
• Improves digestibility
• Makes food available in off-season

• Loss of nutrients (especially Vitamins B, C)
• Addition of preservatives/additives may be harmful
• Processed foods often high in salt, sugar, fats

---

FOOD FORTIFICATION:

• Widespread micronutrient deficiency ("hidden hunger")
• Not everyone can afford/access diverse diets
• Cost-effective public health intervention

• Iodized salt (prevents iodine deficiency / goitre)
• Iron and folic acid fortified wheat flour (prevents anaemia)
• Vitamin A fortified vanaspati and sugar
• Vitamin D fortified milk

• FSSAI (Food Safety and Standards Authority of India) mandates fortification of staple foods
• Large-scale wheat flour, rice, edible oil, milk fortification
• Logo: "+F" symbol on fortified food packages

---

FOOD ADDITIVES:

• Prevention of Food Adulteration Act, 1954 (PFA) - now superseded
• Food Safety and Standards Act, 2006 (FSSA) - current legislation
• FSSAI (Food Safety and Standards Authority of India) - regulatory body
• Lays down standards for permitted additives, their maximum permissible limits

---

FSSAI (Food Safety and Standards Authority of India):

• Established under FSSA 2006
• Autonomous body under Ministry of Health & Family Welfare
• Functions:
  1. Lay down food safety standards
  2. Regulate and supervise food safety
  3. Grant licenses to food businesses
  4. Conduct surveillance, monitoring, and inspection
  5. Promote general awareness about food safety

---

PASTEURIZATION OF MILK:

1. Phosphatase Test - Tests adequacy of pasteurization (enzyme destroyed at pasteurization temp)
2. Methylene Blue Reduction Test (MBRT) - Bacterial count estimation
3. Standard Plate Count (SPC) - Colony counting
4. Coliform test - Faecal contamination
5. Fat content - Gerber test / Babcock test

---

---

SECTION D: ENVIRONMENT AND HEALTH

---

LAQ 8: WATER AND HEALTH - DEFINE, SOURCES, PURIFICATION, QUALITY STANDARDS

KEY DEFINITIONS:

---

WATER-RELATED DISEASE CLASSIFICATION (Bradley Classification):

WATER-RELATED DISEASES
          |
┌─────────┼──────────┬──────────┐
↓         ↓          ↓          ↓
Water-   Water-    Water-    Water-
borne    washed    based     related
diseases diseases  diseases  (vector)
    |         |         |         |
Typhoid,  Diarrhoea, Guinea  Malaria,
Cholera,  Trachoma,  worm,  Dengue,
Hepatitis Scabies   Schisto- Filariasis
A, E               somiasis

---

SOURCES OF WATER:

---

DAILY WATER REQUIREMENTS:

---

METHODS OF WATER PURIFICATION:

1. Storage - Allows sedimentation and natural die-off of bacteria (ineffective alone)
2. Sunlight (SODIS) - Solar water disinfection in PET bottles; 6 hours in sunlight
3. Boiling - Most reliable household method; kills all pathogens; 100°C for 3-5 minutes

RAW WATER
    ↓
Sedimentation (allow particles to settle - 24 hrs)
    ↓
Filtration (Candle filter / Slow sand filter)
    ↓
Disinfection (Chlorine tablets / Boiling / UV)
    ↓
SAFE STORAGE (covered container)

SOURCE WATER
    ↓
COAGULATION (Alum added; floc forms)
    ↓
FLOCCULATION (Slow mixing; floc particles aggregate)
    ↓
SEDIMENTATION (Floc settles; removes turbidity, 70-80% bacteria)
    ↓
FILTRATION (Rapid sand filter / Slow sand filter)
    ↓
DISINFECTION (Chlorination: 0.5 ppm residual chlorine)
    ↓
STORAGE & DISTRIBUTION
    ↓
FLUORIDATION (optional; 0.7-1.0 ppm)

• Most widely used disinfectant
• Residual chlorine: 0.2-0.5 mg/L at point of use
• BLEACHING POWDER: 30% available chlorine; 2-4 kg/million liters for clear water
• Breakpoint chlorination: Enough chlorine to satisfy demand + residual 0.2 ppm

---

WATER QUALITY STANDARDS (BIS/WHO):

---

FLUORIDATION OF WATER:

• Optimal level: 0.7-1.0 mg/L (WHO recommends 1.5 mg/L maximum)
• Prevents dental caries
• Excess fluoride (>1.5 mg/L): Fluorosis (dental mottling, skeletal fluorosis)
• Deficient fluoride: Increased dental caries

---

JAL JEEVAN MISSION (National Rural Drinking Water Programme):

• Launched: 15 August 2019
• Goal: Provide Functional Household Tap Connection (FHTC) to every rural household by 2024
• "Har Ghar Jal" - water in every home
• Potable water: 55 litres per person per day
• Focus: Water quality testing, women participation

---

LAQ 9: AIR POLLUTION - CAUSES, EFFECTS, COMPONENTS, AQI AND PREVENTION

Definition:

"Environmental pollution is the presence of a substance in the environment at a concentration which is harmful to human beings, plants, animals or which interferes with well-being of the ecosystem." - Park's PSM

SOURCES / CAUSES OF AIR POLLUTION:

AIR POLLUTION SOURCES
         |
┌────────┴────────┐
↓                 ↓
NATURAL        MAN-MADE (Anthropogenic)
SOURCES        SOURCES
     |                  |
Volcanoes,    ┌─────────┼──────────┐
Dust storms,  ↓         ↓          ↓
Forest fires  Industry  Transport  Domestic
              (factories, vehicles, (cooking,
              power plants) aircraft) burning)

COMPONENTS OF AIR POLLUTANTS:

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HEALTH EFFECTS OF AIR POLLUTION:

• Eye irritation, burning
• Coughing, sneezing
• Exacerbation of asthma/COPD
• CO poisoning: headache, nausea, death

• Chronic bronchitis, emphysema, COPD
• Lung cancer (PM2.5, PAH, benzene)
• Cardiovascular disease (PM2.5, NO₂)
• Neurological damage (lead, mercury)
• Developmental effects in children (lead)
• Increased mortality

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AIR QUALITY INDEX (AQI):

---

PREVENTION AND CONTROL OF AIR POLLUTION:

1. Use of cleaner fuels (CNG, LPG, electric vehicles)
2. Electrostatic precipitators, scrubbers in industry
3. Catalytic converters in vehicles
4. Transition to renewable energy (solar, wind)

1. Air (Prevention and Control of Pollution) Act, 1981
2. Environment Protection Act, 1986
3. National Ambient Air Quality Standards (NAAQS)
4. Bharat Stage Emission Standards (BS-VI)

1. Promoting public transport, cycling
2. Reducing open burning (crop stubble, waste)
3. Tree planting / Green corridors
4. Construction dust control measures
5. AQI alerts to public

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LAQ 10: HOUSING AND HEALTH - HEALTHFUL HOUSING, STANDARDS, HAZARDS OF OVERCROWDING

Definition of Healthful Housing:

"Healthful housing means construction of a house so as to create and maintain healthy conditions for the occupants and their neighbors." - Park's PSM

CHARACTERISTICS OF HEALTHFUL HOUSING:

• High, well-drained land
• Free from flooding
• Away from swamps, nuisance industries
• Near school, market, health centre

• Adequate floor space (min 9 sq m per person)
• Adequate ventilation (windows on opposite walls)
• Adequate natural lighting
• Smooth, cleanable walls and floors
• Proof against insects and rodents

• Safe water supply
• Sanitary disposal of excreta and refuse
• Electricity

HOUSING STANDARDS (India - CPWD/BIS):

• Floor area: 9.5 sq m per person minimum
• Ventilation: Windows = 1/10 of floor area (minimum)
• Ceiling height: 2.75 m minimum
• Cubic air space: 14.2 m³ per person minimum

FACTORS AFFECTING HEALTHFUL HOUSING:

1. Socioeconomic status (poverty)
2. Land availability and cost
3. Cultural practices (joint families)
4. Government housing policies
5. Urbanization and migration
6. Building regulations enforcement

HAZARDS OF OVERCROWDING:

OVERCROWDING
     |
┌────┴─────┐
↓          ↓
DIRECT     INDIRECT
EFFECTS    EFFECTS
     |           |
Facilitates  Mental
disease      health
spread       stress
     |
Airborne: TB, measles,
          meningitis,
          influenza
Faecal-oral: diarrhea,
             typhoid
Skin: scabies,
      ringworm
     |
Sleep deprivation
Domestic accidents
Domestic violence
Sexual abuse

1. Tuberculosis (most important)
2. Meningococcal meningitis
3. Influenza, COVID-19
4. Measles, chickenpox
5. Typhus (louse-borne)
6. Scabies, tinea

1. Dampness - mould growth, respiratory disease
2. Lack of ventilation - CO poisoning, respiratory infections
3. Inadequate lighting - eye strain, accidents
4. Pest infestation (rats, mosquitoes) - rodent-borne diseases
5. No safe water - waterborne diseases
6. No sanitation - fecal-oral diseases

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LAQ 11: RADIATION AND HEALTH - TYPES, SOURCES, EFFECTS AND PREVENTION

Types of Radiation:

RADIATION
    |
┌───┴───┐
↓       ↓
IONIZING    NON-IONIZING
    |              |
Alpha,  X-rays  UV, Infrared,
Beta,           Radio waves,
Gamma           Microwaves

SOURCES OF RADIATION EXPOSURE:

HEALTH EFFECTS OF RADIATION:

• High doses (>1 Gy): nausea, vomiting, bone marrow suppression, death
• Hematopoietic syndrome: bone marrow failure
• GI syndrome: intestinal epithelium destruction
• CNS syndrome: most severe; cerebral oedema, rapid death

• Cancers: leukemia (most common), thyroid, breast, lung
• Cataracts (eye lens)
• Genetic mutations in offspring
• Aplastic anaemia

• Sunburn, premature aging of skin
• Skin cancer (melanoma, non-melanoma)
• Cataracts
• Immune suppression

PREVENTION AND PROTECTION AGAINST RADIATION:

1. Time - Minimize time of exposure
2. Distance - Maximize distance from source (inverse square law)
3. Shielding - Use appropriate shielding material

• Lead aprons, thyroid shields in X-ray departments
• Dosimetry badges for radiation workers
• ALARA principle: As Low As Reasonably Achievable
• Iodine tablets (KI) for nuclear accidents (protects thyroid from I-131)
• Limiting medical radiation (justify each investigation)
• Sunscreen, protective clothing for UV

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LAQ 12: NOISE AND HEALTH - EFFECTS, PREVENTION

Definition:

Health Effects of Noise:

• Noise-Induced Hearing Loss (NIHL) - most important
• Tinnitus (ringing in ears)
• Temporary Threshold Shift (TTS) - reversible
• Permanent Threshold Shift (PTS) - irreversible

• Cardiovascular: hypertension, increased heart rate
• Psychological: anxiety, irritability, decreased concentration
• Sleep disturbance, fatigue
• Interference with communication
• Reduced work efficiency

Prevention:

1. Engineering controls: noise barriers, mufflers, sound-absorbing materials
2. Administrative controls: rotate workers, limit exposure hours
3. Personal protection: earplugs (25 dB attenuation), earmuffs
4. Legislative: Noise Pollution (Regulation and Control) Rules, 2000
5. Standards: Industrial noise <90 dB for 8 hours/day; residential area: day 55 dB, night 45 dB

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LAQ 13: VENTILATION AND HEALTH

Definition:

"Ventilation is the process of supplying and removing air by natural or mechanical means to and from any space in a building."

Types of Ventilation:

Standards for Adequate Ventilation:

• Air changes per hour: 6-10 changes in living rooms; 15-20 in hospitals
• CO₂ level: should not exceed 0.1% (1000 ppm)
• Temperature: 18-24°C (comfortable range)
• Relative humidity: 40-60%
• Air velocity: 0.1-0.2 m/s (draught-free)

Effects of Inadequate Ventilation:

1. Accumulation of CO₂ → headache, drowsiness, suffocation
2. Build-up of CO (if combustion indoors) → poisoning, death
3. Increased humidity → mould growth → asthma, allergies
4. Spread of airborne infections (TB, measles, COVID-19)
5. Radon accumulation → lung cancer
6. Sick Building Syndrome

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SECTION E: SOCIAL AND BEHAVIOURAL HEALTH

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LAQ 14: HEALTH BEHAVIOUR, ILLNESS BEHAVIOUR, SICK ROLE BEHAVIOUR AND HEALTH-SEEKING BEHAVIOUR

KEY DEFINITIONS:

"Any activity undertaken by a person believing themselves to be healthy, for the purpose of preventing disease or detecting it at an asymptomatic stage."

"Any activity undertaken by a person who feels ill, to define the state of his health and to discover a suitable remedy." - Mechanic (1961)

1. Person is exempt from normal social responsibilities
2. Person cannot recover by willpower alone; needs help
3. Person must try to get well
4. Person must seek technically competent help

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HEALTH-SEEKING BEHAVIOUR:

HEALTH-SEEKING BEHAVIOUR
          |
┌─────────┼────────┬─────────┐
↓         ↓        ↓         ↓
Patient  Provider Health   Community
Factors  Factors  System   Factors
    |         |   Factors        |
Age, sex, Cost, Availability, Culture,
education competence distance   stigma
perception quality  waiting    social
of illness          time       support

1. Financial: cost of consultation, medicines, transport
2. Geographical: distance from health facility
3. Social/Cultural: stigma, traditional healers preferred
4. Educational: low health literacy
5. System barriers: long waiting times, poor quality, unfriendly staff
6. Fear of diagnosis, denial

1. Community health workers (ASHA, ANM) to improve access
2. Health education and awareness programmes
3. Telemedicine and mobile health clinics
4. Free essential drugs and diagnostics (Jan Aushadhi)
5. Community engagement and trust building
6. Cultural sensitivity in health services

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LAQ 15: SOCIAL DETERMINANTS OF HEALTH

Definition (WHO Commission on Social Determinants of Health):

"The conditions in which people are born, grow, live, work and age. These circumstances are shaped by the distribution of money, power and resources at global, national and local levels."

SOCIAL DETERMINANTS (BEINGS framework applied socially):

SOCIAL DETERMINANTS OF HEALTH
              |
┌─────────────┼──────────────┐
↓             ↓              ↓
SOCIOECONOMIC PHYSICAL     SOCIAL &
CONDITIONS    ENVIRONMENT  COMMUNITY
     |              |      CONTEXT
Income,        Housing,        |
Education,     Transport,   Social support,
Employment,    Clean water,  Discrimination,
Occupation     Safe food     Community
                             cohesion

1. Income and social protection - poverty is the biggest determinant
2. Education - health literacy, behaviour change
3. Employment and working conditions - occupational health
4. Housing - overcrowding, sanitation
5. Food security - nutritional status
6. Social support networks - mental health, resilience
7. Gender - inequalities in health access for women
8. Culture and ethnicity - traditional beliefs, discrimination
9. Health systems - access, quality, affordability

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LAQ 16: COMMUNITY - DEFINITION, TYPES (BRINT), COMMUNITY BEHAVIOUR AND ENGAGEMENT

Definition of Community:

"A group of people who share a common place, common interests, common problems and have developed a capacity to act collectively." - Park's PSM

Brint's Definition: A community is a group of people who share a sense of identity, culture, history, or location and who have social bonds with each other.

TYPES OF COMMUNITY (Brint, 2001):

COMMUNITY BEHAVIOUR:

The norms, values, traditions, and collective actions of a community that influence health

1. Shapes health practices (diet, hygiene, immunization acceptance)
2. Determines social support during illness
3. Affects healthcare-seeking behaviour
4. Community mobilization is essential for disease control programs
5. Community behaviour discipline = study of collective behaviours affecting health

COMMUNITY ENGAGEMENT / COMMUNITY RELATIONSHIP:

"The process of working collaboratively with groups of people affiliated by geographic proximity, special interests, or similar situations, to address issues affecting their well-being." - CDC

1. Builds trust between health services and community
2. Improves acceptance of health programs
3. Identifies locally relevant health problems
4. Sustains health interventions beyond program periods
5. Promotes health equity and social justice
6. Essential for the Homoeopath practicing at community level

1. Respect for community values and culture
2. Transparency and honesty
3. Two-way communication
4. Shared decision-making
5. Building on community strengths and assets

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SECTION F: SANITATION AND EXCRETA DISPOSAL

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LAQ 17: EXCRETA DISPOSAL - METHODS, SANITARY BARRIERS AND SEWAGE SYSTEM

Sanitation Definition:

"The provision of facilities and services for the safe disposal of human urine and faeces." - WHO

TYPES OF EXCRETA DISPOSAL METHODS:

1. Open defecation in fields, bushes, water bodies
2. Wrap and throw method
3. Shallow pit (non-lined)

SANITARY EXCRETA DISPOSAL
           |
┌──────────┼──────────┐
↓          ↓          ↓
Non-water  Water-     Sewerage
carriage   carriage   Systems
methods    methods
     |          |          |
Pit latrine, Pour-flush WC + sewer
Compost     latrine,    network
latrine,    Septic tank
SULABH

TYPES OF LATRINES:

PRINCIPLES OF SANITARY LATRINE:

1. Prevent access of flies, rodents, insects to excreta
2. Prevent contamination of soil, water
3. No objectionable odour
4. No aesthetic nuisance
5. Easy to construct and maintain
6. Affordable

SEWERAGE SYSTEM:

1. House connections - from WC to main sewer
2. Lateral sewers - small pipes collecting from houses
3. Main sewers / Trunk sewers - large pipes carrying to treatment
4. Lift stations - pumps to raise sewage where gravity is insufficient
5. Sewage Treatment Plant (STP)

RAW SEWAGE
    ↓ Preliminary Treatment
Screen (removes large objects) + Grit chamber
    ↓ Primary Treatment
Sedimentation (removes 50-60% SS, 25-35% BOD)
    ↓ Secondary Treatment
Biological treatment (removes 90% BOD)
- Activated sludge process / Trickling filter
    ↓ Tertiary Treatment
Chlorination, filtration (removes remaining pathogens)
    ↓
TREATED EFFLUENT (discharged to water body)

• Amount of oxygen needed by microorganisms to decompose organic matter in water
• Raw sewage BOD: 200-400 mg/L
• Treated effluent: <30 mg/L (standard)
• High BOD = high organic pollution

• Oxygen needed to oxidize all chemical substances in water
• Includes both biodegradable and non-biodegradable organic matter

SWACHH BHARAT ABHIYAN / MISSION:

• Launched: 2 October 2014 (Mahatma Gandhi's birth anniversary)
• Goal: Open Defecation Free (ODF) India
• Achievements: Construction of millions of household toilets; India declared ODF in 2019 (rural)
• Phase 2: Solid waste management, greywater management, ODF+

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LAQ 18: BIOMEDICAL WASTE MANAGEMENT

Definitions:

"Any waste which is generated during the diagnosis, treatment or immunization of human beings or animals, or in research activities pertaining thereto, or in the production or testing of biologicals." - Biomedical Waste (Management and Handling) Rules, 1998 (amended 2016)

CLASSIFICATION OF BIOMEDICAL WASTE (BMW Rules 2016):

MANAGEMENT STEPS (Flowchart):

GENERATION of BMW at source
          ↓
SEGREGATION (at point of generation)
(Colour-coded bins: Yellow/Red/White/Blue)
          ↓
COLLECTION & TRANSPORTATION
(Labelled, leak-proof containers; closed trolleys)
          ↓
STORAGE (max 48 hours at facility)
          ↓
TREATMENT
     ↓              ↓               ↓
INCINERATION    AUTOCLAVING     CHEMICAL
(Yellow waste)  (Red waste)    DISINFECTION
     ↓
FINAL DISPOSAL

TREATMENT TECHNOLOGIES:

BMW RULES IN INDIA:

• Biomedical Waste Management Rules, 2016 (replaced 1998 rules)
• Key provisions:
  • Hospitals must have an Authorization from State Pollution Control Board
  • Bar-coded bags and containers mandatory
  • Annual report to State PCB
  • Training to all staff
  • Common Biomedical Waste Treatment Facilities (CBWTFs) for smaller units

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SECTION G: TEMPERATURE AND SPECIAL ENVIRONMENTS

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LAQ 19: EFFECTS OF HOT ENVIRONMENT, HEAT STROKE, HEAT EXHAUSTION AND PREVENTION

Heat-Related Illness Classification:

HOT ENVIRONMENT HEALTH EFFECTS
             |
┌────────────┼─────────────┐
↓            ↓             ↓
MILD      MODERATE       SEVERE
     |          |              |
Heat      Heat             HEAT
cramps  exhaustion         STROKE
(muscle)  (fatigue,    (Medical emergency)
          sweating)

COMPARISON: Heat Exhaustion vs Heat Stroke:

FIRST AID for Heat Stroke:

1. Call emergency services immediately
2. Move to cool shaded area
3. Remove excess clothing
4. Rapid cooling: ice packs to neck, axilla, groin; cool water spraying
5. IV fluids (if available)
6. Monitor and transfer to hospital

PREVENTION:

1. Avoid outdoor activity 11am-4pm in summer
2. Wear light, loose, light-coloured clothing
3. Stay hydrated (ORS, water, lemon water)
4. Avoid alcohol and caffeinated beverages
5. Use shade, fans, AC
6. Buddy system for outdoor workers
7. Heat health action plans (HHAP) - India has National Action Plan for Heat

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LAQ 20: EFFECTS OF COLD ENVIRONMENT - HYPOTHERMIA, FROSTBITE AND PREVENTION

Definitions:

• Hypothermia: Core body temperature <35°C
• Frostbite: Freezing of skin and underlying tissues

HYPOTHERMIA - Stages:

FROSTBITE - Degrees:

FIRST AID FOR COLD INJURIES:

• Remove from cold environment
• Remove wet clothing
• Gradual rewarming (warm room, warm drinks, warm water 38-42°C for frostbite)
• Do NOT rub frostbitten tissue
• Do NOT rewarm if refreezing is possible
• Homoeopathic: Agaricus muscarius (frostbite), Camphora (hypothermia)

PREVENTION OF COLD ILLNESS:

1. Layered clothing (wool/synthetic, not cotton)
2. Cover extremities: gloves, socks, hat
3. High calorie diet (generates heat)
4. Avoid alcohol (causes vasodilation, increases heat loss)
5. Shelter from wind
6. Buddy system in extreme cold environments

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LAQ 21: HIGH ALTITUDE ILLNESS - ADVERSE EFFECTS, PREVENTION AND FIRST AID

High Altitude Definition:

• High altitude: 2500-3500 m
• Very high: 3500-5500 m
• Extreme altitude: >5500 m

TYPES OF HIGH ALTITUDE ILLNESS:

HIGH ALTITUDE ILLNESS
          |
┌─────────┼──────────┐
↓         ↓          ↓
AMS      HACE       HAPE
(Acute  (High Alt  (High Alt
Mountain Cerebral   Pulmonary
Sickness  Oedema)    Oedema)

PREVENTION:

1. Gradual ascent (not more than 300-500 m/day above 3000 m)
2. Acclimatization (rest day every 1000 m gain)
3. Acetazolamide 250 mg BD starting 24 hours before ascent (prophylaxis)
4. Stay hydrated
5. Avoid alcohol
6. Know the rule: "Climb high, sleep low"

FIRST AID:

1. DESCEND IMMEDIATELY for HACE or HAPE (most important)
2. Supplemental oxygen
3. Portable hyperbaric chamber (Gamow bag) if descent not immediately possible
4. Dexamethasone (HACE), Nifedipine (HAPE)
5. Homoeopathic: Coca (altitude sickness)

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QUICK REVISION TABLES

Comparison: Community Medicine vs Public Health vs Preventive Medicine

WHO Definition Summary:

• Health (1948): Complete physical, mental and social well-being
• Public Health (Winslow): Science and art of preventing disease...through organized community efforts
• Environment: All that is external to the individual human host (physical, biological, social)
• Malnutrition: Pathological state from relative/absolute deficiency or excess of nutrients

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• Park's Textbook of Preventive and Social Medicine (Park's PSM), 26th Edition
• Leavell & Clark, Preventive Medicine for the Doctor in His Community
• WHO Technical Reports and Guidelines
• FSSAI, GoI Guidelines; BMW Rules 2016; Jal Jeevan Mission documents
• MacMahon B & Pugh TF - Epidemiologic Principles and Methods