Concepts of health and disease

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Concepts of health and disease

  1. 1. CONCEPTS OF HEALTH AND DISEASE www.drjayeshpatidar.blogspot.com
  2. 2. INTRODUCTION a) Importance b) Taken for granted and value not understood c) Fundamental human right and social goal d) Integrated to Socio-economic growth e) “Health for all concept” www.drjayeshpatidar.blogspot.in
  3. 3. DEFINITIONS • HEALTH • DISEASE • PREVENTIVE MEDICINE • POSITIVE HEALTH www.drjayeshpatidar.blogspot.in
  4. 4. PHILOSOPHY OF HEALTH a) Fundamental right b) Essence of productive life c) Intersectoral d) Integral part of development e) Central to PQLI f) Combined responsibility g) Major social investment h) Social goal www.drjayeshpatidar.blogspot.in
  5. 5. DIMENSIONS OF HEALTH a) Physical b) Mental c) Social d) Spiritual e) Emotional f) Others :- vocational, cultural, socio- economic, educational, environmental, nutritional www.drjayeshpatidar.blogspot.in
  6. 6. SPECTRUM OF HEALTH POSITIVE HEALTH BETTER HEALTH FREEDOM FROM SICKNESS UNRECOGNISED SICKNESS MILD SICKNESS SEVERE SICKNESS DEATH www.drjayeshpatidar.blogspot.in
  7. 7. DETERMINANTS OF HEALTH a) Biological b) Behavioral and Socio-cultural conditions c) Environment d) Socio-economic conditions e) Health services f) Ageing g) Gender h) Other factors www.drjayeshpatidar.blogspot.in
  8. 8. PRINCIPLES OF EPIDEMIOLOGY 1) DEFINITION :- BASIC SCIENCE OF COMMUNITY MEDICINE “Study of distribution and determinants of disease frequency in man” 2) SCOPE AND HISTORY  Began with study of epidemics  Now studies communicable and non communicable diseases as well  Emphasis on prevention of diseases and also promotion of positive health www.drjayeshpatidar.blogspot.in
  9. 9. PRINCIPLES OF EPIDEMIOLOGY (CONTD) 3) In clinical medicine focus is on one case. Here it is on group of persons 4) Study cases, search causes, modes of transmission, prevent and control, help administration to reform health care facilities and strategy www.drjayeshpatidar.blogspot.in
  10. 10. WEB OF CAUSATION FOR MYOCARDIAL INFARCTION www.drjayeshpatidar.blogspot.in
  11. 11. NATURAL HISTORY OF DISEASE www.drjayeshpatidar.blogspot.in
  12. 12. www.drjayeshpatidar.blogspot.in
  13. 13. EPIDEMIOLOGY
  14. 14.  1. INTRODUCTION  2. CONCEPTS OF DISEASE  a) DEFINITION  b) SPECTRUM OF DISEASE 3. CAUSES OF DISEASE a) ANCIENT BELIEFS b) GERM THEORY :-AGENT MAN DISEASE www.drjayeshpatidar.blogspot.in
  15. 15.  4) DEFINITION OF EPIDEMIOLOGY  5) EPIDEMIOLOGICAL TRIAD (& MULTIFACTORIAL CAUSATION)  6) NATURAL HISTORY OF DISEASE  a) PRE-PATHOGENIC PHASE  b) PATHOGENIC PHASE AGENT HOST ENVIRONMENT www.drjayeshpatidar.blogspot.in
  16. 16.  7) AGENT FACTORS  a) BIOLOGICAL  i) VARIOUS ORGANISMS  ii) INFECTIVITY  iii) PATHOGENICITY  iv) VIRULENCE b) NUTRIENTS c) PHYSICAL d) CHEMICAL d) MECHANICAL e) SOCIAL www.drjayeshpatidar.blogspot.in
  17. 17. 8) HOST FACTORS  a) AGE, SEX, ETHNICITY  b) GENETIC  c) SOCIO-ECONOMIC :- Socio-economic status, occupation, education, stress, marital status, housing  d) LIFE STYLE :- HABITS www.drjayeshpatidar.blogspot.in
  18. 18. 9) ENVIRONMENT FACTORS  a) PHYSICAL  b) BIOLOGICAL  c) PSYCHOSOCIAL www.drjayeshpatidar.blogspot.in
  19. 19. 10) ICEBERG PHENOMENON www.drjayeshpatidar.blogspot.in
  20. 20. 11) LEVELS OF PREVENTION  a) PRIMORDIAL  b) PRIMARY  c) SECONDARY  d) TERTIARY www.drjayeshpatidar.blogspot.in
  21. 21. GENERAL USES OF EPIDEMIOLOGY 1) Study history of health of population and rise and fall of diseases and their character. 2) Diagnose health of the community. 3) Plan and evaluate health services 4) Estimate individual risks and chances www.drjayeshpatidar.blogspot.in
  22. 22. GENERAL USES ….CONTD  5) Identify syndromes  6) Complete the natural history of the disease  7) Search for causes  8) Help prevention, control and further research. www.drjayeshpatidar.blogspot.in
  23. 23. 12) MODES OF INTERVENTION  a) HEALTH PROMOTION i) HEALTH EDUCATION ii) ENVIRONMENTAL MODIFICATION iii) NUTRITIONAL INTERVENTION iv) LIFESTYLE / BEHAVIOUR CHANGE b) SPECIFIC PROTECTION c) EARLY DIAGNOSIS AND TREATMENT d) DISABILITY LIMITATION e) REHABILITATION 13) CONCLUSION www.drjayeshpatidar.blogspot.in
  24. 24. THANX www.drjayeshpatidar.blogspot.in
  25. 25. EPIDEMIOLOGICAL APPROACH www.drjayeshpatidar.blogspot.in
  26. 26.  1) DEFINITION  2) TYPES OF EPIDEMIOLOGY  a) DESCRIPTIVE  b) ANALYTICAL  3) BASIC QUESTIONS STUDIED  a) When does the disease occur?  b) Where does the disease occur?  c) Who are the people affected?  d) Why has the disease occurred?  e) What should be done to prevent or control the disease? www.drjayeshpatidar.blogspot.in
  27. 27. 4) DESCRIPTIVE EPIDEMIOLOGY  a) TIME DISTRIBUTION  i) SEASON  ii)CYCLIC TREND  iii) SECULAR TREND  b) PLACE DISTRIBUTION  i) AREA  ii) FACTORY  iii) DEPARTMENT  iv) SHOP FLOOR www.drjayeshpatidar.blogspot.in
  28. 28.  c) PERSON DISTRIBUTION  i) AGE  ii) SEX  iii) MARITAL STATUS  iv) ETHNIC GROUP  v) OCCUPATION  vi) SOCIO-ECONOMIC STATUS  vii) EDUCATION  viii) DIET  ix) HABITS  5) ANALYSE RATES AND FORMULATE HYPOTHESIS www.drjayeshpatidar.blogspot.in
  29. 29. 6) USES OF DESCRIPTIVE EPIDEMIOLOGY  a) Provides occurrence data in an occupational setting.  b) Provides clues to etiology.  c) Help formulate hypothesis  d) Provides data for planning, organization and evaluate medical and health services.  e) Helps further research. www.drjayeshpatidar.blogspot.in
  30. 30. 8) SOURCES OF DATA  a) MORTALITY DATA  b) MEDICAL COMPENSATION RECORDS  c) FACTORY MORBIDITY DATA  d) E S I COMPENSATION RECORDS  e) HOSPITAL DATA  f) SICKNESS ABSENTEEISM  g) PERIODIC MEDICAL EXAM RECORDS  h) FIELD SURVEYS www.drjayeshpatidar.blogspot.in
  31. 31. 8) ANALYTICAL EPIDEMIOLOGY  a) CASE CONTROL STUDY  b) COHORT STUDY  i) RETROSPECTIVE  ii) PROSPECTIVE 9) CONCLUSION www.drjayeshpatidar.blogspot.in
  32. 32. EPIDEMIOLOGICAL METHODS www.drjayeshpatidar.blogspot.in
  33. 33. 1) INTRODUCTION a) Primary role is to study disease occurrence in people b) Study factors which may have disease etiology by studying exposures c) Community based. www.drjayeshpatidar.blogspot.in
  34. 34. 2) CLASSIFICATION  A) OBSERVATIONAL STUDIES :-  1) DESCRIPTIVE  2) ANALYTICAL :- a) ECOLOGICAL b) CROSS-SECTIONAL c) CASE CONTROL d) COHORT www.drjayeshpatidar.blogspot.in
  35. 35.  B) EXPERIMENTAL / INTERVENTIONAL STUDIES  1) RANDOMIZED CONTROLLED TRIALS  2) FIELD TRIALS – COMMUNITY INTERVENTION TRIALS  - Above are not watertight compartments  - They are flexible and complementary www.drjayeshpatidar.blogspot.in
  36. 36. DESCRIPTIVE EPIDEMIOLOGY  1. KEY TO SUCCESS - METICULOUS OBSERVATIONS  2. EXAMPLES – Burkitts lymphoma- epstein barr virus, Scurvy – J Lind, Small pox – Edward Jenner.  3. BASIC QUESTIONS – When, Where and Who www.drjayeshpatidar.blogspot.in
  37. 37. 4) EPIDEMIOLOGICAL TRIAD  BALANCING ACT AGENT ENVIRONMENTHOST www.drjayeshpatidar.blogspot.in
  38. 38. 5) PROCEDURES  a) Defining population  b) Defining disease  c) Describing disease :- Time, Place, Person  d) Measurement of disease  e) Comparing known indices  f) Formulation of hypothesis www.drjayeshpatidar.blogspot.in
  39. 39.  6.a) DEFINING THE POPULATION i) TOTAL NUMBER  ii) AGE  iii) SEX  iv) OCCUPATION  v) CULTURAL / SOCIAL CHARECTERISTICS  vi) EITHER WHOLE OR SAMPLE/ SPECIAL SELECTED GROUPS  vii) NO MIGRANTS / OUTSIDERS / OVERTLY DIFFERENT GROUPS  viii) GIVES DENOMINATOR ( IMPORTANT) www.drjayeshpatidar.blogspot.in
  40. 40.  6.b) DEFINING THE DISEASE  i) PRECISE AND VALID DEFINITION REQUIRED  ii) IDENTIFY THOSE HAVING / NOT HAVING DISEASE  iii) DIAGNOSTIC METHODS ACCEPTABLE BY POPULATION AND APPLICABLE TO LARGE COMMUNITIES ( e.g Tonsillitis ) www.drjayeshpatidar.blogspot.in
  41. 41.  6.c) DESCRIBING THE DISEASE  i) PRIMARY OBJECTIVE – Describe occurrence and distribution. Systematic collection of data (epidemiological triad) and analysis of data  ii) TIME DISTRIBUTION a) Short – term fluctuations i) whether there is epidemic? ii) Type of epidemic * Common source – single source/ multiple source * Propogated epidemic – person- person, arthropod borne, animal reservoir * Slow / modern epidemics www.drjayeshpatidar.blogspot.in
  42. 42. II) TIME DISTRIBUTION…..CONTD  b) PERIODIC FLUCTUATIONS  i) SEASONAL  ii) CYCLIC  c) LONG TERM ( SECULAR TREND) e.g IHD, DIABETES, CANCER, ADDICTION TYPHOID, TB, POLIO d) INTERPRETATION OF TIME TRENDS www.drjayeshpatidar.blogspot.in
  43. 43.  iii) PLACE DISTRIBUTION  a) INTERNATIONAL VARIATIOINS  b) NATIONAL VARIATIONS  c) URBAN – RURAL VARIATIONS  d) LOCAL DISTRIBUTION  e) MIGRATION STUDIES  iv) PERSON DISTRIBUTION  a) AGE  b) SEX  c) ETHNICITY  d) MARITAL STATUS  e) SOCIAL CLASS  f) OCCUPATION  g) BEHAVIOUR / HABITS  h) STRESS  j) MIGRATIONS www.drjayeshpatidar.blogspot.in
  44. 44.  v) MEASUREMENT OF DISEASE  a) CROSS-SECTIONAL STUDIES  b) LONGITUDINAL STUDIES  vi) COMPARING WITH KNOWN INDICES www.drjayeshpatidar.blogspot.in
  45. 45.  vii) FORMULATION OF HYPOTHESIS. SPECIFY-  a) POPULATION  b) SPECIFIC CAUSE CONSIDERED  c) EXPECTED OUTCOME i.e DISEASE  d) DOSE – RESPONSE RELATIONSHIP  e) TIME – RESPONSE RELATIONSHIP e.g 1) “Cigarette smoking causes cancer” 2) “ 30 – 40 cigarettes per day for 20yrs causes cancer in 10% smokers” www.drjayeshpatidar.blogspot.in
  46. 46. ADVANTAGES  a) Decides magnitude, load, type of disease.  b) Gives clues to etiology  c) Helps planning, organizing and evaluating control measures  d) Contribute to research. www.drjayeshpatidar.blogspot.in
  47. 47. ANALYTICAL STUDIES  1) INTRODUCTION  a) Second major type of study  b) Focus on individual but results applied to population  c) Object is not to formulate but to test hypothesis  2) TYPES  a) CASE CONTROL STUDY  b) COHORT STUDY In them we determine :- a) Statistical association exists or not b) If yes, then strength of association www.drjayeshpatidar.blogspot.in
  48. 48. 3) CASE CONTROL STUDIES  (Often retrospective)  a) Both exposure and outcome have occurred before starting the study.  b) Study backward. Effect Cause  c) Uses control to support / refute inference.  4) DESIGN  a) Comparison studies.  b) Cases and Controls must be comparable.  c) Neutralise effect of confounding factors. www.drjayeshpatidar.blogspot.in
  49. 49.  d)Example – Smoking and Lung cancer If (a/a+c) ↑ in cases than (b/b+d ) in control .·. Association exists . RISK FACTOR ( SMOKING) CASES (CANCER) CONTROL (NO CANCER) PRESENT a b ABSENT c d a + c b + d www.drjayeshpatidar.blogspot.in
  50. 50.  5) BASIC STEPS  a) Selection of Cases and Controls  b) Matching  c) Measurement of exposure  d) Analysis and interpretation  a) SELECTION OF CASES  i) Diagnostic criteria  ii) Eligibility criteria  iii) Sources - Hospital - Population www.drjayeshpatidar.blogspot.in
  51. 51.  b) SELECTION OF CONTROLS  i) Free from disease  ii) Identified before study  iii) Not exposed to disease under study  iv) Source - Hospital - Relatives - Neighbours - Population c) MATCHING d) MEASUREMENT OF EXPOSURE i) Precise information ii) Interviews, questionnaires, records iii) No “BIAS” www.drjayeshpatidar.blogspot.in
  52. 52.  e) ANALYSIS  i) Exposure rates Cases = (a/a+c) = 33/35 = 94.2% Controls = (b/b+d) = 55/82 = 67% CASES CONTROLS SMOKERS 33 (a) 55 (b) NON - SMOKERS 2 (c) 27 (d) TOTAL 35 (a + c) 82 (b + d) p < 0.00 www.drjayeshpatidar.blogspot.in
  53. 53.  ii) ESTIMATION OF RISK  a) Relative Risk (RR) RR = Incidence among exposed . Incidence among non-exposed b) Odds Ratio = ad / bc = 33×27 ÷ 55×2 = 8.1 i.e. Risk is 8.1 times more in smokers e) ELIMINATE BIAS i) Confounding ii) Memory/ recall iii) Selection iv) Berkesonian bias – Hospital admission bias v) Interviewers bias www.drjayeshpatidar.blogspot.in
  54. 54. ADVANTAGES  1. Relatively easy to carry out  2. Rapid and inexpensive ( compared to Cohort studies)  3. Require comparatively few subjects  4. Particularly suitable to investigate rare diseases or diseases about which little is known. But a disease which is rare in the general population ( e.g. leukemia in adolescents) may not be rare in special exposure group (e.g. prenatal X-Rays)  5. No risk to subjects www.drjayeshpatidar.blogspot.in
  55. 55. ADVANTAGES ……CONTD  6. Allows the study of several different etiological factors (e.g. smoking, physical activity and personality characteristics in myocardial infarction)  7. Risk factors can be identified. Rational prevention and control programmes can be established  8. No attrition problems, because case control studies do not require follow-up of individuals into the future  9. Ethical problems minimal. www.drjayeshpatidar.blogspot.in
  56. 56. DISADVANTAGES  1. Problems of bias relies on memory or past records, the accuracy of which may be uncertain; validation of information obtained is difficult or sometimes impossible  2. Selection of an appropriate control group may be difficult  3. We cannot measure incidence, and can only estimate relative risk  4. Do not distinguish between causes and associated factors  5. Not suited for the evaluation of therapy or prophylaxis of disease  6. Another major concern is the representativeness of cases and controls  CONCLUSION www.drjayeshpatidar.blogspot.in
  57. 57. COHORT STUDY  1. INTRODUCTION  a) Descriptive epidemiology produces suspected cause and effect (disease) relationship  b) Cohort study is (obs.) analytical study undertaken to obtain additional evidence to support/ refute association  ( also called Prospective, Longitudinal, Forward Looking Studies) www.drjayeshpatidar.blogspot.in
  58. 58.  2. FEATURES  a) Cohorts identified prior to study  b) Groups observed over a period of time  c) Proceeds forward from CAUSE to EFFECT  3. CONCEPT OF COHORT – Group who share common characteristics and experience/exposure within a defined period (e.g. Age, Sex, etc.) :- Birth Cohort, Exposure Cohort, Marriage Cohort, Disease Cohort and so on (Test/ Control Cohort) www.drjayeshpatidar.blogspot.in
  59. 59.  4. INDICATION  a) Good evidence present from clinical observation/ Descriptive/ Case – Control Studies  b) Exposure rare but incidence high e.g. X-Rays/Radiation  c) Follow up easy, Cohort is stable, co-operative and easily accessible  d) Funds available www.drjayeshpatidar.blogspot.in
  60. 60.  5.FRAME WORK  a) Cause to effect  b) Basic design :- COHORT DISEASE TOTAL YES NO EXPOSED (STUDY COHORT) a b (a + b) NOT EXPOSED ( CONTROL COHORT) c d (c + d) TOTAL (a + c) (b + d) www.drjayeshpatidar.blogspot.in
  61. 61. C) CONSIDERATIONS FOR MAKING A COHORT  i) Examine and exclude persons with disease under study  ii) Both groups should be equally susceptible to disease under study  iii) Both groups should be comparable  iv) Diagnostic and eligibility criteria defined beforehand  v) Groups followed under similar conditions/time  vi) Well designed cohort study is most reliable  vii) If a/a + b is higher than c/c + d association is suspected www.drjayeshpatidar.blogspot.in
  62. 62.  6) TYPES  a) Prospective  b) Retrospective  c) Combined  a) PROSPECTIVE COHORT STUDY :- (also called “CURRENT”) – Cause to effect e.g. Smoking and Ca Lung  b) RETROSPECTIVE COHORT STUDY :- (also called “HISTORICAL”) – Effect to cause, records are studied e.g. Lung Cancer uranium miners, Life span of radiologists and exposure. www.drjayeshpatidar.blogspot.in
  63. 63. Radiotherapy records  c) COMBINED Leukemia :- Rx for Ankylosing spondylitis followed in future also for occurrence subsequently www.drjayeshpatidar.blogspot.in
  64. 64.  7) ELEMENTS OF COHORT STUDY  a) Selection of study subjects  b) Data collection of exposure  c) Selection of comparison groups  d) Follow up  e) Analysis www.drjayeshpatidar.blogspot.in
  65. 65.  a) SELECTION OF STUDY SUBJECTS  i) General population – when exposure is frequent; should be residing in defined geographical/ administrative areas. Appropriate / Representative sample taken.  ii) Select groups – If exposure is rare i.e. Doctors/Govt employees / obstetric cases  iii) Exposure groups – Only exposed ( X-Ray exposures) www.drjayeshpatidar.blogspot.in
  66. 66.  b) OBTAINING DATA  i) Interview  ii) Records  iii) Questionnaire  iv) Medical exams  v) Environmental surveys DATA www.drjayeshpatidar.blogspot.in
  67. 67.  c) SELECTION OF COMPARISON GROUPS  i) INTERNAL – Select first cohort and then divide them in comparison groups as per exposure( ½ pack, 1 pack, 2 packs smoked)  ii) EXTERNAL – Smokers Vs Non-smokers ( comparable cohorts included)  iii) GENERAL POPULATION – If above not applicable only then used, e.g. Uranium vis-à- vis Ca Lung in workers Vs General population  d) PROPER FOLLOW-UP www.drjayeshpatidar.blogspot.in
  68. 68.  e) ANALYSIS  i) Incidence Rates - Ca Lung  Incidence in smokers = 70/7000 = 10/1000  Incidence in Non-Smokers = 3/3000 = 1/1000  p < 0.001 CIGARETTE SMOKING YES NO TOTAL YES 70 (a) 6930 (b) 7000 (a+b) NO 3 (c) 2997 (d) 3000 (c+d) www.drjayeshpatidar.blogspot.in
  69. 69.  ii) RELATIVE RISK  RR = Incidence amongst exposed _ Incidence amongst non-exposed = 10/1 = 10 (i.e. 10 times more) iii) ATTRIBUTABLE RISK AR = Incidence in exposed – Incidence among non-exposed Incidence among exposed .· .(10-1/10) × 100 = 90% www.drjayeshpatidar.blogspot.in
  70. 70. 8) ADVANTAGES  a) Incidence can be calculated  b) Several exposures can be studied simultaneously  c) Provide direct estimate of Relative Risk  d) Dose and response ratios can be calculated  e) Decreased bias  9) DISADVANTAGES  a) Large number of people are involved  b) More time, men, money, material  c) Difficult in chronic diseases  d) Extensive record keeping needed  e) Matching difficult  f) Study knowledge of risk may itself modify the cohort behaviour. www.drjayeshpatidar.blogspot.in
  71. 71. 10) DIFFERENCES S No CASE CONTROL STUDY COHORT STUDY 1 Proceed from “effect to cause” Proceeds from “cause to effect” 2 Starts with disease Starts with people exposed to risk factor or suspected cause 3 Tests whether the suspected cause occurs more frequently in those with disease than among those without the disease Tests whether disease occurs more frequently in those exposed, than in those not similarly exposed 4 Usually the first approach to the testing of a hypothesis, but also useful for exploratory studies Reserved for testing precisely formulated hypothesis 5 Involves fewer number of subjects Involves large number of subjects 6 Yields relatively quick results Long follow-up period often needed, involving delayed results www.drjayeshpatidar.blogspot.in
  72. 72. DIFFERENCES…….CONTD S No CASE CONTROL STUDY COHORT STUDY 7 Suitable for study of rare diseases Inappropriate when the disease exposure under investigation is rare 8 Generally yields only estimate of RR(Odds Ratio) Yields Incidence rates, RR as well as AR 9 Cannot yield information about diseases other than that selected for study. Can yield information about more than one disease outcome 10 Relatively inexpensive Expensive CONCLUSION THANX www.drjayeshpatidar.blogspot.in
  73. 73. EXPERIMENTAL EPIDEMIOLOGY  1) INTRODUCTION – Historically (1920) meant experiments in animals(rats, mice etc)  Now – Clinical trials. Conditions are under control (Action / Intervention / manipulation) with trial and control groups  2) AIMS –  a) Scientific proof  b) Measure efficacy and effectiveness of Rx, prevention and control  3) ADDITIONAL PROBLEMS – Cost, Feasibility and ethics. www.drjayeshpatidar.blogspot.in
  74. 74.  4) ANIMAL STUDIES :- Helped us in the past by lab experiments of epidemics / herd immunity in animals. Also gave knowledge about basic medical sciences / drug trials / Rx etc.  a) APPLICATIONS  i) Experimental reproduction of human diseases  ii) Study of etiology  iii) Study pathogenesis  iv) Test efficacy of Rx and Prevention ( vaccines / drugs)  v) Complete natural history of Disease www.drjayeshpatidar.blogspot.in
  75. 75.  b) ADVANTAGES  i) Easy breeding of Animals  ii) Easy manipulation  iii) Fast results  iv) Genetic studies possible  v) Cheaper  C) LIMITATIONS  i) All human diseases cannot be tested  ii) Conclusion not juxtaposable, extrapolatable  iii) Ethical issues ( SPCA) www.drjayeshpatidar.blogspot.in
  76. 76. 5) HUMAN EXPERIMENTS  a) Always needed  b) Essential when animal studies not possible  c) Studies by James Lind and Edward Jenner  d) Ethical and logistics issues  e) USA found 23% of 16000 drugs really effective  f) Thalidomide disaster  g) Leubek epidemic  6) TYPES :-  a) Randomized controlled clinical trials  b) Non-Randomized (i.e. not strictly randomized) www.drjayeshpatidar.blogspot.in
  77. 77. STUDY DESIGNS OF CONTROLLED TRIALS  1) CONCURRENT PARALLEL DESIGN – Compare two random samples of patients exposed and non-exposed to specific treatment for duration of time.  2) CROSS-OVER DESIGN – Patient as his own control. Groups given test and control drug or placebo. Observed for a duration. Stopped both for a “wash-out” period and then switched and repeat crossover Rx.  ADVANTAGES  i) Patient as own control  ii) Less number of patients needed  iii) Less time needed. www.drjayeshpatidar.blogspot.in
  78. 78. TYPES OF RANDOMIZED CONTROL TRIALS  1) CLINICAL TRIALS – Mainly drug trials. All are not possible to be blinded( Tonsils – op and non op Rx) Many ethical, administrative and technical problems, but still are powerful tools Therefore Necessary.  2) PREVENTIVE TRIALS Done for primary prevention. Trials to eliminate / prevent diseases  e.g. Vaccine trials ( viz pertussis vaccine trial in UK 1946) Attack rates decide efficacy www.drjayeshpatidar.blogspot.in
  79. 79.  a) Benefit by community must be clearly known beforehand  b) Risks must be explained  c) Cost of 3M’s to health services must be estimated.  3) RISK FACTOR TRIALS – e.g. IHD – modify risk factors and conduct trials ( single / multiple)  4) CESSATION EXPERIMENTS – Evaluate stopping of a habit i.e. Smoking Vs Ca Lung/ IHD www.drjayeshpatidar.blogspot.in
  80. 80. 5) TRIAL OF ETIOLOGICAL AGENT  Retrolental Fibroplasia causing blindness in premature babies who received O2 therapy.  Trial group = 50% O2 therapy × 28 days ; Control = 02. RLF ↑ in trial group. ( Difficult to plan these trials, only in emergency)  6) EVALUATION OF HEALTH SERVICES – They are planned to assess efficiency and effectiveness of health services e.g. Domiciliary Rx of TB Vs Hospital/ Sanatorium Rx. They are also called “ Health Services Research” studies www.drjayeshpatidar.blogspot.in
  81. 81. NON-RANDOMIZED TRIALS  1) INTRODUCTION – Randomized trials are always better, more scientific and to be preferred. But sometimes due to ethical, administrative, logistic and feasibility problems on human subjects make these difficult. Moreover long follow-up on large number have limitations. Therefore we do non-randomized trials. Here approach is crude, comparability less and chances of spurious results more (may be extra- statistical judgment). However they are acceptable when planned reasonably correct. www.drjayeshpatidar.blogspot.in
  82. 82.  2) EXAMPLES  a) UNCONTROLLED TRIALS – No control group. However “historical controls” are used from records e.g. Pap test for screening of Ca Cervix cases  b) NATURAL EXPERIMENTS – Natural circumstances mimic an experiment e.g. Smokers / Non-smokers are naturally separated into test and control group. Observe incidence of Ca Lung in them and draw hypothesis www.drjayeshpatidar.blogspot.in
  83. 83.  Other examples  a) Migrants  b) Religions  c) Social groups  d) Atomic bombing in Japan  e) Famines  f) Earthquakes  g) John Snow’s cholera investigation  C) BEFORE AND AFTER COMPARISON STUDIES  i) Without control  ii) With control www.drjayeshpatidar.blogspot.in
  84. 84.  i) WITHOUT CONTROL – Comparison before and after introducing preventive measures e.g. John Snow’s Cholera investigation in 1854.  Needs for such trial :-  a) Incidence before and after intervention essential  b) Manipulate only one factor  c) Diagnostic criteria clear and same  d) Adopt preventive measures over wide area  e) Several trials needed. e.g. compulsory seat belts & ↓ of accidents www.drjayeshpatidar.blogspot.in
  85. 85.  ii) WITH CONTROL – e.g. Seat belt Vs accidents in states where it is compulsory Vs not.  Considerations  a) How much benefit ? Effectiveness, acceptance compared.  b) What are the risks to recipients ? Immediate and long term risks estimated.  c) Cost in money and manpower. Check economics, practicability and feasibility.  CONCLUSION  THANX www.drjayeshpatidar.blogspot.in
  86. 86. ASSOCIATION AND CAUSATION  1) INTRODUCTION – Descriptive studies help indicate a hypothesis by studying time, place person, agent, host and environment. Suggest possible etiological hypothesis. Analytical and experimental studies test it i.e. confirm/ refute association  2) DEFINITION  a) ASSOCIATION – When events occur together frequently not by chance.  b) CO-RELATION -1.0 to +1.0 , however co- relation does not imply causation www.drjayeshpatidar.blogspot.in
  87. 87.  3) TYPES OF ASSOCIATION  a) SPURIOUS  b) INDIRECT  c) DIRECT i) One to one causal ii) Multifactorial www.drjayeshpatidar.blogspot.in
  88. 88.  a) SPURIOUS – Sometimes association between disease and suspected factor is not real. E.g. In perinatal mortality study, hospital delivery rates were 27.8/1000 and home delivery rates were 5.4/1000 . But this association may be spurious because of high risk pregnancy in hospital and other confounding variables. i.e. “like” not compared with “like” – Selection bias www.drjayeshpatidar.blogspot.in
  89. 89.  b) INDIRECT ASSOCIATION – May appear causal but further study may show indirect association. There may be presence of 3rd factor common to disease and charecteristic and may show statistical association ( confounding)  E.g. a) Iodine deficiency → Altitude  → Endemic goitre ( Statistical association does not necessarily mean causation) b) Consumption of Sucrose and CHD ↑ Sugar – more MI, but later studies showed cigarette smoking → high frequency tea Therefore ↑ Sugar – more MI ( later studies showed no association between ↑ Sugar and MI) However indirect association is also useful e.g John Snow’s study of polluted water and Cholera www.drjayeshpatidar.blogspot.in
  90. 90.  c) DIRECT ASSOCIATION ( CAUSAL)  i) One to One causal relationship – Change in A is followed by change in B i.e. when cause present – disease results and vice versa  Eg. Koch’s postulates  However other problems –  a) Cause may not be manipulable ( as direct experiment may not be possible)  b) One cause may lead to many diseases  E.g. Haemolytic streptococcus – tonsillitis  - Scarlet fever  - Erysipelas www.drjayeshpatidar.blogspot.in
  91. 91.  ii) MULTIFACTORAL CAUSATION Factor 1 (Smoking) Factor 2 ( Air pollution) Disease (Ca Lung) Factor 3 ( Asbestos) Synergistic Factor 1 (Obesity) Factor 2 (Stress) Cumulative Disease Factor 3 (LDL↑ ) effect ( IHD) www.drjayeshpatidar.blogspot.in
  92. 92. ADDITIONAL CRITERIA FOR CAUSALITY  1) Temporal association  2) Strength of Association  3) Specificity  4) Consistency  5) Biological plausibility  6) Coherence of association  CONCLUSION –  i) Many factors to be studied  ii) Cause “necessary” and “sufficient” but not always reached  iii) Additional criteria important THANX www.drjayeshpatidar.blogspot.in
  93. 93. ADDITIONAL CRITERIA FOR CAUSALITY  1) INTRODUCTION – When controlled experimental evidence absent, additional criteria have been devised to ascertain causal association.  2)CLASSICAL EXAMPLE – “Smoking and Health” Report of PH Service of US ( 1964) Bradford Hill & many others have shown causal association by presence of following factors :-  1) Temporal association  2) Strength of Association  3) Specificity  4) Consistency  5) Biological plausibility  6) Coherence of association www.drjayeshpatidar.blogspot.in
  94. 94.  3) PHILOSOPHY – Causal significance of any association is matter of judgment beyond statistical probability. All above criteria must be utilized. No one by itself is self-sufficient. All add up to quantum of evidence and put together contribute to the probability of causal association. www.drjayeshpatidar.blogspot.in
  95. 95. ASSOCIATION BETWEEN CIGARETTE SMOKING AND LUNG CANCER  1) Provides excellent example for above criteria.  a) Temporal Association – Does the suspected cause precede observed effect? This is essential for causal association. In acute diseases to establish this is not difficult as latency is less, but in chronic disease it has to be present for long time e.g. Smoking – temporal association. Observations are compatible to long latent period required for carcinogenesis. www.drjayeshpatidar.blogspot.in
  96. 96.  b) Strength of Association – Depends on :-  i) Relative Risk (RR) – Is it large ?  ii) Dose – response and duration response relation ?  a) Larger the RR, ↑ causal relationship.  b) ↑ dose – response, ↑ causal relation.  c) ↑ duration – response, ↑ causal relation If absent, argument against causal effect  Decrease on stopping exposure, ↑ relation All above are noticed in smoking and Ca Lung www.drjayeshpatidar.blogspot.in
  97. 97.  c) SPECIFICITY OF ASSOCIATION – Decides one – to – one cause and effect relationship.  Problems  i) Single cause can produce many diseases e.g. Smoking.  ii) Multifactorial etiology makes it difficult to show one – to – one relation.  iii) Specify one single cause responsible is difficult e.g. Tobacco has CO, Nicotine, Hydrocarbons. Even then causal association exists. Specificity supports causal relation but lack of it does not negate it ! Paradox :- Everyone who smokes does not get Ca Lung and vice versa, still causal association accepted on available evidence www.drjayeshpatidar.blogspot.in
  98. 98.  d) Consistency of Association– More than one (many) studies should consistently show association (done by different workers in different settings e.g. Smoking – Ca Lung)  e) Biological Plausibility e.g. Smoke and Lung tissue, Nutritional diet and GI Tract (supported by animal studies). Carcinogens isolated from smoke prove credibility of hypothesis.  f) Coherence of Association ↑ quantity of tobacco & ↑ Ca Lung. ↑ smoking in women & ↑ Ca Lung in women. ↑ death rates with ↑ smoking, ↓ when stopped. www.drjayeshpatidar.blogspot.in
  99. 99. CONCLUSION  - Direct experimental proof in Humans difficult.  - Inferences drawn on collective and convincing evidence in favour and against by long term studies in epidemiology. THANX www.drjayeshpatidar.blogspot.in
  100. 100. CONFOUNDING AND BIAS  1) INTRODUCTION - These are to be avoided and taken care of in any experiment and epidemiological investigation and analysis, failing which faulty deductions get drawn.  2) Confounding – They are variables which are present, which may influence the outcome of cause and effect relationship. www.drjayeshpatidar.blogspot.in
  101. 101.  Example – Article in “International Journal of Quackery” – “ Metronidazole causes Jaundice”  Abstract – We gave this drug ( Metronidazole 400mg with permitted colour, “ Amaranth” to 100 patients of Giardiasis. 80 developed deep yellow urine.  Conclusion – Medicine causes Jaundice in 80% of patients.  This research is outright unscientific.  Defects :- Incorrect investigations, No scientific criteria used.  You protest  Reply :- Sorry . Revised conclusion – “ metronidazole causes yellow urine” AGAIN WRONG.  After controlled trial we know it is dye and not drug. www.drjayeshpatidar.blogspot.in
  102. 102.  3) Properties of a Confounder –  a) Associated with exposure of interest.  b) Independent of exposure and confuse outcome  c) Association indirect.  4) Difference between Confounding and Bias  Bias – To be identified and avoided in planning / designing.  Confounding – Identify, control by randomization, matching, testing dummy tables. If found at later stage adjust during analysis.  E.g. Alcohol & IHD ( confounding are smoking, obesity, sex, lack of exercise and nutrition. www.drjayeshpatidar.blogspot.in
  103. 103.  5) Controlling for Confounding  a) Randomization  b) Restriction – Do not include suspected Potential Confounding Factors (PCF) in the study  c) Matching  Ex – Tobacco user in trial and control groups.  6) Adjustment during Analysis – By using appropriate statistical measures like standardization, stratified analysis, multiple regression analysis, logistic regressions and so on.  CONCLUSION  THANX www.drjayeshpatidar.blogspot.in
  104. 104. USES OF EPIDEMIOLOGY a) Study of history of health of populations and study rise/ fall/ change in character of disease b) Diagnose health of community c) Study working of health services d) Estimate individuals risk e) Describe natural history of disease f) Identify syndromes g) Search for causes of health and disease www.drjayeshpatidar.blogspot.in
  105. 105. MODES OF TRANSMISSION 1) DIRECT CONTACT – Skin to skin or mucosa to mucosa – touching, kissing and sexual intercourse 2) DROPLET – Coughing, sneezing etc. increased by overcrowding/ ↓ ventillation 3) CONTACT WITH SOIL 4) INDIRECT – Flies, Fingers, Fomites, Food and Fluids 5) VEHICLE BORNE – Water, food, blood, organ transplant. ( Explosive, severe, over long distance, isolation of agent possible, common source infection) www.drjayeshpatidar.blogspot.in
  106. 106. 6) VECTOR BORNE a) Mechanical b) Biological i. Propogative ii. Cyclopropagative iii. Cyclodevelopmental iv. Transovarian v. Trans-stadial 7)AIR BORNE a) Droplet nuclei b) Dust 8) TRANSPLACENTAL(VERTICAL) www.drjayeshpatidar.blogspot.in
  107. 107. 9) VACCINES a) Live b) Killed c) Toxoids d) Immunoglobulins e) Antisera 10) DISEASE PREVENTION AND CONTROL a) Control source/ reservoir b) Control transmission c) Protect host www.drjayeshpatidar.blogspot.in
  108. 108. a) Reservoir i. Early diagnosis and treatment ii. Notification iii. Epidemiological investigation iv. Isolation v. Treatment vi. Quarantine b) Control transmission c) Protect susceptible host (UIP) 11) CONCLUSION www.drjayeshpatidar.blogspot.in
  109. 109. 7) INDICATORS OF HEALTH a) Mortality 1. CDR 2. Life expectancy 3. IMR 4. MMR b) Morbidity c) Disability d) Nutritional e) Health care delivery f) Utilization g) Social / mental health h) Environmental j) Socio-economic k) Quality of life 8) CONCLUSION www.drjayeshpatidar.blogspot.in
  110. 110. DISEASE DYNAMICS 1) 2) SOURCE a) Human cases – Clinical - Sub – clinical b) Animal c) Inanimate d) Human carriers i. Incubatory ii. Convalescent iii. Healthy a) Temporary b) Chronic SOURCE OR RESERVOIR SUSCEPTIBLE HOST MODE OF TRANSMISSION www.drjayeshpatidar.blogspot.in
  111. 111. 3) a) Primary case b) Index case c) Secondary cases 4) Secondary attack rate No. developing disease during incubation period × 100 No. of susceptible exposed to index case www.drjayeshpatidar.blogspot.in
  112. 112. Solving Community Health Problem a) Definition of the problem b) Appraisal of existing facts c) Formulation of hypothesis d) Testing the hypothesis e) Conclusions / Recommendations www.drjayeshpatidar.blogspot.in
  113. 113. DEFINITIONS 1) INFECTION 2) CONTAMINATION 3) INFESTATION 4) INFECTIOUS DISEASE 5) CONTAGIOUS DISEASE 6) COMMUNICABLE DISEASE 7) NON- COMMUNICABLE DISEASE 8) EPIDEMIC 9) ENDEMIC 10)SPORADIC 11)PANDEMIC 12) EXOTIC DISEASE 13) ZOONOSES 14) EPIZOOTIC 15) ENZOOTIC 16) NOSOCOMIAL INFECTION 17) OPPORTUNISTIC INFECTION 18) IATROGENIC 19) SURVEILLANCE 20) ERADICATION www.drjayeshpatidar.blogspot.in
  114. 114. MODES OF TRANSMISSION 1) CONTACT – DIRECT - INDIRECT 2) VEHICLE BORNE 3) VECTOR BORNE 4) AIR BORNE 5) TRANSPLACENTAL www.drjayeshpatidar.blogspot.in
  115. 115. IMMUNITY IMMUNITY INNATE (BASIC) ACQUIRED ACTIVE NATURAL ARTIFICIAL PASSIVE NATURAL ARTIFICIAL HERD IMMUNITY www.drjayeshpatidar.blogspot.in
  116. 116. INVESTIGATION OF AN EPIDEMIC
  117. 117. INVESTIGATION OF AN EPIDEMIC  Outbreak of any disease is due to shift in balance between agent, host & environment.  Usually causes a lot of concern & attention and needs a well practiced, deliberate response by the medical teams.  Epidemiological principles must be correctly used. www.drjayeshpatidar.blogspot.in
  118. 118. OBJECTIVES  Define magnitude in terms of person, place & time distribution.  Determine conditions, factors responsible for the outbreak.  Identify cause, source of infection, modes of transmission & plan control measures.  Make recommendations to prevent recurrence. www.drjayeshpatidar.blogspot.in
  119. 119. INVESTIGATION STEPS  Verify Diagnosis  Confirm existence of outbreak  Define population at risk  Rapid search for ALL cases  Data Analysis www.drjayeshpatidar.blogspot.in
  120. 120. INVESTIGATION STEPS  Formulation of Hypothesis  Testing of Hypothesis  Evaluation of ecological factors  Further investigation of population at risk  Writing the report www.drjayeshpatidar.blogspot.in
  121. 121. 1.VERIFICATION OF DIAGNOSIS  Spurious reports are quite common.  Not necessary to examine all the cases.  Confirm by clinical evaluation of a sample no. of patients.  Lab investigations if required. www.drjayeshpatidar.blogspot.in
  122. 122. 2. CONFIRM EXISTENCE OF EPIDEMIC  Compare disease frequencies ( incidence/ prevalence )  Epidemic if MORE than “ Normal Expectancy”.  Usually more than 2 standard errors from mean.  Often common source outbreaks – food poisoning, Cholera etc. need no such comparison.  Modern epidemics – IHD, Cancer less easily discernible. www.drjayeshpatidar.blogspot.in
  123. 123. 3.DEFINING POPULATION AT RISK  Obtain a map of area – with all dwelling units, water sources, natural landmarks, population numbers.  Population has to be counted for - “population at risk”  It maybe entire population of an area – census with age, sex distribution – necessary to decide the “attack rate” www.drjayeshpatidar.blogspot.in
  124. 124. 4.RAPID SEARCH FOR ALL CASES  Medical Survey - of all undiagnosed cases in the population who may not have reported/ self- medicated/ got treated elsewhere.  Epidemiological case sheet – All relevant data is collected by the trained health workers – details of age, sex, occupation, social class, travel history, past history, history of onset, details of signs & symptoms, contacts at home, workplace, school etc. History of intake of food items, consumption of water, receipt of blood products. Incase a large no. – Sample survey. www.drjayeshpatidar.blogspot.in
  125. 125. 4.RAPID SEARCH FOR ALL CASES  Searching for more cases - Search for secondary cases to be carried out everyday at all hospitals, nursing homes, clinics as well as from informants in the community. Continue till no more cases are found and area is free of epidemic – usually TWICE the MAXIMUM incubation period of the disease since the last case. www.drjayeshpatidar.blogspot.in
  126. 126. 5.DATA ANALYSIS Time distribution – Chronological distribution of dates of onset; construct an “epidemic curve”  Time relation with exposure to suspected source  Common source/ Propagated source  Seasonal/cyclical pattern Place distribution – Make a “spot map” denoting location of cases – geographical clustering of cases near common source of exposure – water, air, food etc. www.drjayeshpatidar.blogspot.in
  127. 127. www.drjayeshpatidar.blogspot.in
  128. 128. 5.DATA ANALYSIS Person distribution - Age/ sex/ occupation etc. analysed for risk factor ; attack rate ; CFR for those exposed with respect to those not exposed to the risk factor. In Food poisoning, attack rate is taken for specific food items. Purpose of data analysis is to determine any common event /experience, and to delineate the groups at risk due to this common experience. www.drjayeshpatidar.blogspot.in
  129. 129. 6.FORMULATION OF HYPOTHESIS Based on person-place-time distribution or the Agent, Host, Environment model, formulate a hypothesis explaining the epidemic in terms of –  Possible source  Causative agent  Possible modes of spread  Environmental factors which enabled spread www.drjayeshpatidar.blogspot.in
  130. 130. 7.TESTING OF HYPOTHESIS All reasonable hypothesis are considered and evaluated – comparisons of attack rates for each group of exposed with suspected exposure is analysed ; the most reasonable hypothesis has to be accepted by the epidemiologist. www.drjayeshpatidar.blogspot.in
  131. 131. 8.ECOLOGICAL FACTORS WHICH MAY HAVE CONTRIBUTED  Sanitary condition – eating establishments  Water & milk supply  Breakdown in water supply system  Human movements – disasters, wars  Population dynamics of vectors – insects, animals. Correlation with source of infection, reservoir & modes of transmission. www.drjayeshpatidar.blogspot.in
  132. 132. 9.FURTHER INVESTIGATION OF POPULATION-AT-RISK  Further tests for more specific diagnosis  Tests of food / water samples  Serological studies for clinically inapparent cases  Classification of exposure and those at risk www.drjayeshpatidar.blogspot.in
  133. 133. 10.WRITING THE REPORT Background –  Geographic location  Climatic condition  Demography  Organisation of health services  Existence of early warning systems  Normal diseases prevalence www.drjayeshpatidar.blogspot.in
  134. 134. 10.WRITING THE REPORT Historical data –  Epidemics in same / nearby area  Same disease / related disease  First case discovered in present outbreak Methodology of investigation –  Case definition  Questionnaire used – epidemiological inv.  Survey teams – household/ retrospective/ prospective/ lab specimens & procedures www.drjayeshpatidar.blogspot.in
  135. 135. 10.WRITING THE REPORT Analysis of data – 1. Clinical data -  Frequency of signs & symptoms  Course of disease  Differential diagnosis  Death / sequelae rates 2. Epidemiological data –  Mode of occurrence – time/ place/ person distribution www.drjayeshpatidar.blogspot.in
  136. 136. 10.WRITING THE REPORT  Modes of transmission –  Source of infection  Route of excretion/ portal of entry  Factors influencing transmission 3. Laboratory data –  Isolation of agent  Serological confirmation  Significance of result www.drjayeshpatidar.blogspot.in
  137. 137. 10.WRITING THE REPORT 4. Interpretation of data –  Comprehensive picture of outbreak  Hypothesis of cause  Formulation & testing of hypothesis – statistical analysis www.drjayeshpatidar.blogspot.in
  138. 138. 10.WRITING THE REPORT Control measures –  Define strategies / methodology of implementation – constraints, results  Evaluation of these measures – efficacy of results, cost effectiveness  Any other preventive measures suggested. www.drjayeshpatidar.blogspot.in
  139. 139. SUSCEPTIBLE HOST  1) Successful Parasitism – four stages  a) Portal of entry – respiratory, ailmentary, genito-urinary or skin ( can be more than one e.g. viral hepatitis)  b) Site of choice / election for optimum conditions  c) Portal of exit ( otherwise dead end infection )  d) Survival externally till new host found.  Note :- Produce low grade immunity and no death. www.drjayeshpatidar.blogspot.in
  140. 140.  2) Incubation period –  a) Define  b) Multiplies till sufficient density, equilibrium lost, disease signs appear  c) “Median incubation period” – Time taken by 50% to occur after exposure  3) Factors determining incubation period  a) Generation time :- Receipt – Mass infectivity  b) infective dose  c) Portal of entry  d) Individual susceptibility  Note – It is minimum / maximum / different www.drjayeshpatidar.blogspot.in
  141. 141.  4) Latent period – Non-infectious disease :- Initiation to detection ( not well understood)  5) Importance  a) Tracing source/contacts  b) Period of surveillance  c) Immunization  d) Point source or propagated epidemics  e) Prognosis  6) Serial Interval – Gap between primary and secondary case.  7) Communicable period.  8) Secondary Attack Rate – No. developing disease × 100 Susceptible www.drjayeshpatidar.blogspot.in
  142. 142.  9) Host Defences –  a) Local  b) Systemic  c) Non-Specific  d) Specific  e) Humoral  f) Cell Mediated  g) They are overlapping  h) Vertical immunity ( IgG, IgM + Breast milk) www.drjayeshpatidar.blogspot.in
  143. 143.  10) Specific Defences – Recognize, destroy and eliminate antigens  a) Active Immunity  i) Humoral  ii) Cellular  iii) Combined  b) Passive Immunity  i) Normal Human IgG  ii) Specific Human IgG  iii) Animal anti-toxins and anti-sera www.drjayeshpatidar.blogspot.in
  144. 144.  a) Active Immunity  i) Specific for a disease.  ii) Following sub-clinical / clinical infection  iii) Immunization – Live/Killed/Toxoids  iv) Primary response  v) Secondary/Booster response  vi) Factors determining extent of response -  a) Dose of Antigen  b) Nature  c) Route of Administration  d) Adjuvants  e) Nutrition / Health of the host  f)IgG response requires × 50 dose than IgM  g) Immunological memory developed PRIMARY www.drjayeshpatidar.blogspot.in
  145. 145.  Booster –  a) Short latent period  b) Antibodies ↑ and rapid  c) Maintained for long  d) Capacity ↑  e) Basis for vaccination and re-vaccination  vii) Humoral Immunity – B-cells ( bone marrow lymphocytes)  - IgG, IgM, IgA, IgD & IgE – Circulate, neutralise and are specific.  viii) Cellular Immunity – T-cells, ↑ resistance (mainly TB, Leprosy)  ix) Combined - Synergestic SECONDARY www.drjayeshpatidar.blogspot.in
  146. 146.  x) Factors affecting maintenance of Immunity –  a) Threshold of resistance  b) Susceptibility  c) Physiological state  d) Fatigue  e) Age  f) Drugs  g) Diet  h) Emotional shock  b) Passive Immunity  i) Antisera  ii) Immune human globulins  iii) Maternal – Placenta, Milk www.drjayeshpatidar.blogspot.in
  147. 147.  Attributes –  1) Ready-made  2) Temporary  3) No immune memory  4) Less effective  C) Herd Immunity www.drjayeshpatidar.blogspot.in
  148. 148. IMMUNIZING AGENTS  a) Vaccines –  i) Live vaccines – more potent, multiplying organisms, have all major + minor antigenic components, engage tissues locally (oral polio), persistence.  ii) Inactivated or Killed vaccines – By heat or chemicals – Less efficiency, boosters required.  iii) Toxoids – From exotoxins ( Diptheria, Tetanus)  iv) Combinations. www.drjayeshpatidar.blogspot.in
  149. 149.  b) Immunoglobulins – IgG, IgM, IgA, IgD, IgE  c) Antisera  i) Animal origin  ii) ATS, ADS, AGS, Anti - snake venom  iii) Testing essential  12) COLD CHAIN ATTENUATED VACCINES KILLED VACCINES VACCINE DOSE LOW (REPLICATES) HIGH ANTIBODY PERSISTENCE LONG SHORT BOOSTER NEEDED INFREQUENTLY FREQUENTLY REVACCINATION POSSIBLE NONE LATENCY POSSIBLE NONE ONCOGENICITY ? NONE www.drjayeshpatidar.blogspot.in
  150. 150. IMMUNIZING AGENTS BCG TYPHOID ORAL PLAGUE ORAL POLIO YELLOW FEVER MEASLES RUBELLA MUMPS INFLUENZA EPI. TYPHUS  LIVE ATTENUATED VACCINE BACTERIAL VIRAL RICKETTSIAL www.drjayeshpatidar.blogspot.in
  151. 151. TYPHOID CHOLERA PERTUSSIS C.S.MENINGITIS PLAGUE SALK (POLIO) RABIES INFLUENZA HEPATITIS B JAPANESE – ENCEPHALITIS KFD INACTIVATED KILLED VACCINE BACTERIAL VIRAL TOXOIDS DIPHTHERIA TETANUS BACTERIAL www.drjayeshpatidar.blogspot.in
  152. 152. IMMUNOGLOBULINS  HUMAN IMMUNO - GLOBULINS HUMAN NORMAL Ig HUMAN SPECIFIC Ig  HEPATITIS A  MEASLES  RABIES  TETANUS  MUMPS  HEPATITIS B  VARICELLA  DIPHTHERIA NON – HUMAN (ANTISERA)  DIPHTHERIA  TETANUS  GAS GANGRENE  BOTULISM  RABIES  BACTERIAL  VIRAL www.drjayeshpatidar.blogspot.in
  153. 153. NATIONAL IMMUNIZATION SCHEDULE Vaccine Age Birth 6 weeks 10 weeks 14 weeks 9-12 months Primary vaccination BCG X Oral polio X X X X DPT X X X Hepatitis B* X X X Measles X Booster Doses DPT + Oral polio 16 to 24 months DT 5 years Tetanus toxoid (TT) At 10 years and again at 16 years Vitamin A 9, 18, 24, 30 and 36 months Pregnant women Tetanus toxoid (PW): 1st dose 2nd dose Booster As early as possible during pregnancy (first contact) 1 month after 1st dose If previously vaccinated, within 3 years www.drjayeshpatidar.blogspot.in
  154. 154. HAZARDS OF IMMUNIZATION  a) Local reactions + General symptoms  b) Reaction due to faulty technique  c) Hypersensitivity reactions  d) Neurological  e) Provocative reaction. www.drjayeshpatidar.blogspot.in
  155. 155. DISINFECTION 1) INTRODUCTION – SEMMELWEIS (1818 1865) demonstrated hand washing with antiseptics reduced puerperal fevers. LISTER (1897 – 1912) used prophylactic antiseptics for wounds. 2) ADVANTAGES – i) Controls sepsis ii) ↓ disease transmission / spread iii) Rx of local infections iv) Cost ↓ - effective v) Cleanliness vi) Easy www.drjayeshpatidar.blogspot.in
  156. 156. 3) DEFINITIONS a) Disinfectant – Substance which destroys pathogenic microbes but not necessarily spores b) Antiseptic – Destroys or inhibits growth of microbes c) Deodorant d) Sterilization e) Disinfection 4) TYPES – a) Concurrent b) Terminal c) Prophylactic www.drjayeshpatidar.blogspot.in
  157. 157. 5) AGENTS i. Natural ii. Sunlight iii. Air b) Physical i) Burning ii) Hot air iii) Boiling iv) Autoclaving v) Radiation c) Chemical – Done for articles which cannot be boiled or autoclaved. Used for faeces & urine/ contaminated water. www.drjayeshpatidar.blogspot.in
  158. 158. Chemical agents – Wide range available with advantages / disadvantages Phenol and related compounds a) Phenol ( Carbolic acid) – Best known. Also reference standard i.e. R W co-efficient. Used as 10%, 5% for mopping floors b) Cresol – Excellent, 3 to 10 times more powerful yet not toxic. 5 – 10% for faeces / urine. For 5% - add 50ml to one litre of water. It is all purpose disinfectant. c) Saponified cresol emulsions – Lysol, Cyllin – used as 2% solution for faeces (powerful disinfectant) d) Chlorhexidine (Hibitane) - Very good skin antiseptic. 0.5% alcohol solution as hand lotion. 1% cream for burns e) Dettol – 5% for instruments, plastics and wounds. Minimum 15 min contact www.drjayeshpatidar.blogspot.in
  159. 159. 2) Quarternary Ammonia compounds a) Cetrimide (cetavlon) – 1 – 2% strength b) Savlon (cetavlon + hibitane) 1:6 spirit 3) Halogens a) Bleaching powder – Disinfect water, urine, faeces and as deodorant. b) Sod. Hypochlorite – Stronger (feeding bottles) c) Halazone tablets – 4mg tablet/litre for ½ to 1hr d) Iodine – 1 – 2% in alcohol 4) Alcohol – 70% spirit 5) Formaldehyde – rooms, blankets, beds, books 6) Miscellaneous – Lime (quick) 10-20% (2hrs period) www.drjayeshpatidar.blogspot.in
  160. 160. DISINFECTION PROCEDURES 1)Faeces & Urine a) Collect in impervious vessel + equal quantity of bleaching powder (5%), crude phenol(10%), Cresol 5%, Formalin 10% (contact 2 hrs) b) Boiling water c) Bedpans – Steam, 2.5% cresol 2) Sputum – Burning, boiling or 5% cresol 3) Room – Clean; air, sunlight, bleaching powder, 2.5% Cresol, 1% Formaldehyde (4hrs) Formaldehyde – 1:2 ratio with water. CONCLUSION THANX DISINFECTION TESTS www.drjayeshpatidar.blogspot.in
  161. 161. NUTITIONAL SURVEILANCE 1) INTRODUCTION - It is same as disease surveillance. “Keeping watch over nutrition in order to make decisions to improve population nutrition” 2) OBJECTIVES a) Aid long term planning in health and development b) Provide programme management and evaluation c) Timely warning and intervention to prevent short-term food consumption crisis. www.drjayeshpatidar.blogspot.in
  162. 162. 3) Difference in Surveillance Vs Growth monitoring a) Growth Monitoring – Oriented to individual child b) Nutritional surveillance – Sample children from community and compare overall nutrition condition www.drjayeshpatidar.blogspot.in
  163. 163. FACTOR GROWTH MONITORING NUTRITIONAL ASSESSMENT STRATEGY Preservation of normal growth Detection of undernutritioin APPROACH Educational – motivational Diagnostic – interventional ENROLMENT All infants Representative sample AGE Start before 6 months and continue monthly Representative ages at longer levels NUMBER Small groups, preferably between 10 & 20 Any size group, 50 to 100 most efficient WEIGHER /RECORDER Mothers guided by worker Trained worker WEIGHT CARD Simple, emphasis growth Precise, nutritional status COMPARISON OF GROWTH MONITORING AND NUTRITIONAL SURVEILLANCE www.drjayeshpatidar.blogspot.in
  164. 164. FACTOR GROWTH MONITORING NUTRITIONAL ASSESSMENT NUTRITIONAL EMPHASIS Maintaining good nutrition Detect malnutrition RESPONSE Early home intervention based on local knowledge Nutritional rehabilitation often with supplements RESPONSE TIME Brief, resumption of normal growth Long, regain of good nutrition in community INTERVENTIONS Primary health care; oral rehydration therapy; vaccines; Vit A; deworming; contraceptives; chloroquine; other treatment Food supplements of community – wide response, such as food subsidy REFERRAL Health system for checkup and possible brief food supplements Malnutrition rehabilitation, often in special centre www.drjayeshpatidar.blogspot.in
  165. 165. NUTRITIONAL INDICATORS MATERNAL NUTRITION INFANT & PRESCHOOL CHILDREN SCHOOL CHILD NUTRITION Birth weight Height for age and weight for height at 7yrs or school admission clinical signs Proportion being breastfed and proportion on weaning foods, by age in months, mortality rates in children aged 1,2,3&4yrs with emphasis on 2yr olds If age known – height for age, weight for age If age unknown – weight for height, arm circumference, clinical signs and syndromes www.drjayeshpatidar.blogspot.in
  166. 166. SOCIAL ASPECTS OF NUTRITION 1) INTRODUCTION – Malnutrition a global and serious social problem of international concern 2) PROBLEM OF MALNUTRITION – Pathological state due to relative or absolute deficiency or excess of one or more essential nutrients a) Under nutrition b) Over nutrition c) Imbalance d) Specific deficiency www.drjayeshpatidar.blogspot.in
  167. 167. FAO :- 15% are malnourished, majority in SE Asia (300 million), mainly children < 5 and pregnant women. Malnutrition has direct and indirect effects on community (Diseases & retarded mental / physical growth) Therefore ↑ morbidity & mortality, ↓ vitality & productivity Health hazards of over nutrition are equally bad and harmful e.g. IHD, Diabetes, High BP etc. www.drjayeshpatidar.blogspot.in
  168. 168. ECOLOGY OF MALNUTRITION 1) INTRODUCTION – Man-made disease. “Begins in womb and ends in grave” BD Jelliffe(1966) WHO monograph No. 29 is a masterpiece on this subject. Various ecological factors responsible are :- a) Conditioning influences b) Cultural influences c) Socio-economic factors d) Food production e) Health and other services www.drjayeshpatidar.blogspot.in
  169. 169. a) CONDITIONING INFLUENCES – Infectious diseases (children) – Diarrhoea, Intestinal parasites, Measles, Whooping cough, Malaria & TB (vicious cycle ). Further complicated by bad environmental sanitation/ health b) CULTURAL INFLUENCES – i. Choose poor diets ii. Food habits, customs, beliefs, traditions and attitudes – Family plays important role, effects passed on for generations. Staple diet fads, hot/cold-light/heavy foods, forbidden foods iii. Religion iv. Cooking practices v. Child rearing – breast feeding, top feed, products vi. Miscellaneous – Men first, alcoholism etc www.drjayeshpatidar.blogspot.in
  170. 170. c) SOCIO-ECONOMIC FACTORS – Poverty ignorance, illiteracy, lack of knowledge, overpopulation “very nature and culture and structure of society” d) FOOD PRODUCTION – Uneven, ↓ technologies, ↓ facilities for 4M’s, weather, ?distribution. e) HEALTH & OTHER SERVICES i. Surveillance ii. Nutritional rehabilitation iii. Nutrition supplementation iv. Health education www.drjayeshpatidar.blogspot.in
  171. 171. PREVENTIVE AND SOCIAL MEASURES 1) INTRODUCTIOIN – Outcome of many factors, therefore action at different levels i.e. family, community, national & international. Coordinated action by many :- nutrition food, health, education, transport, agriculture, marketing, planning, deliver etc 2) FAMILY LEVEL - a) Nutrition education b) Housewife as manager c) × taboos and fads d) Breast feed e) Baby foods f) Vulnerable groups care g) Kitchen garden / poultry h) Locally available/ acceptable food i) FP, ANC, child health and immunization services j) Role of HWS www.drjayeshpatidar.blogspot.in
  172. 172. 3) COMMUNITY LEVEL a) Survey b) Risk approach c) Feeding and nutritional programmes d) ↑ production e) ICDS f) RH Mission g) ↑ sanitation h) ↓ infectious disease i) ↑ SE Conditions 4) NATIONAL LEVEL a) Rural development b) ↑ agricultural production c) Stabilize population d) Nutrition intervention programmes e) Health programmes f) Seek help FAO/WHO/ UNICEF www.drjayeshpatidar.blogspot.in
  173. 173. 5) INTERNATIONAL LEVEL a) World Food Programme b) International agencies :- WHO/ FAO/ ILO/ World Bank/ UNICEF/ UNDP/ CARE 6) FOOD SURVEILLANCE :- Food, Milk, Meat, Fish, Eggs hygiene, PFA Act 1954 CONCLUSION ?CORRUPTION ? MALPRACTICES ?↓ CHARACTER Can we forget them ? Cure? THANX www.drjayeshpatidar.blogspot.in

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