Concepts of health and disease

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Concepts of health and disease

  1. 1. CONCEPTS OF HEALTH ANDDISEASEwww.drjayeshpatidar.blogspot.com
  2. 2. INTRODUCTIONa) Importanceb) Taken for granted and valuenot understoodc) Fundamental human right andsocial goald) Integrated to Socio-economicgrowthe) “Health for all concept”www.drjayeshpatidar.blogspot.in
  3. 3. DEFINITIONS• HEALTH• DISEASE• PREVENTIVE MEDICINE• POSITIVE HEALTHwww.drjayeshpatidar.blogspot.in
  4. 4. PHILOSOPHY OF HEALTHa) Fundamental rightb) Essence of productive lifec) Intersectorald) Integral part of developmente) Central to PQLIf) Combined responsibilityg) Major social investmenth) Social goalwww.drjayeshpatidar.blogspot.in
  5. 5. DIMENSIONS OF HEALTHa) Physicalb) Mentalc) Sociald) Spirituale) Emotionalf) Others :- vocational, cultural, socio-economic, educational,environmental, nutritionalwww.drjayeshpatidar.blogspot.in
  6. 6. SPECTRUM OF HEALTHPOSITIVE HEALTHBETTER HEALTHFREEDOM FROMSICKNESSUNRECOGNISEDSICKNESSMILD SICKNESSSEVERE SICKNESSDEATHwww.drjayeshpatidar.blogspot.in
  7. 7. DETERMINANTS OF HEALTHa) Biologicalb) Behavioral and Socio-culturalconditionsc) Environmentd) Socio-economic conditionse) Health servicesf) Ageingg) Genderh) Other factorswww.drjayeshpatidar.blogspot.in
  8. 8. PRINCIPLES OF EPIDEMIOLOGY1) DEFINITION :- BASIC SCIENCE OFCOMMUNITY MEDICINE“Study of distribution and determinants ofdisease frequency in man”2) SCOPE AND HISTORY Began with study of epidemics Now studies communicable and noncommunicable diseases as well Emphasis on prevention of diseases and alsopromotion of positive healthwww.drjayeshpatidar.blogspot.in
  9. 9. PRINCIPLES OF EPIDEMIOLOGY(CONTD)3) In clinical medicine focus is on one case.Here it is on group of persons4) Study cases, search causes, modes oftransmission, prevent and control, helpadministration to reform health carefacilities and strategywww.drjayeshpatidar.blogspot.in
  10. 10. WEB OF CAUSATION FORMYOCARDIAL INFARCTIONwww.drjayeshpatidar.blogspot.in
  11. 11. NATURAL HISTORY OF DISEASEwww.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 DISEASE3. CAUSES OF DISEASEa) ANCIENT BELIEFSb) GERM THEORY :-AGENT MAN DISEASEwww.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 PHASEAGENTHOST ENVIRONMENTwww.drjayeshpatidar.blogspot.in
  16. 16.  7) AGENT FACTORS a) BIOLOGICAL i) VARIOUS ORGANISMS ii) INFECTIVITY iii) PATHOGENICITY iv) VIRULENCEb) NUTRIENTSc) PHYSICALd) CHEMICALd) MECHANICALe) SOCIALwww.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 :- HABITSwww.drjayeshpatidar.blogspot.in
  18. 18. 9) ENVIRONMENT FACTORS a) PHYSICAL b) BIOLOGICAL c) PSYCHOSOCIALwww.drjayeshpatidar.blogspot.in
  19. 19. 10) ICEBERG PHENOMENONwww.drjayeshpatidar.blogspot.in
  20. 20. 11) LEVELS OF PREVENTION a) PRIMORDIAL b) PRIMARY c) SECONDARY d) TERTIARYwww.drjayeshpatidar.blogspot.in
  21. 21. GENERAL USES OF EPIDEMIOLOGY1) Study history of health ofpopulation and rise and fall ofdiseases and their character.2) Diagnose health of the community.3) Plan and evaluate health services4) Estimate individual risks andchanceswww.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 PROMOTIONi) HEALTH EDUCATIONii) ENVIRONMENTAL MODIFICATIONiii) NUTRITIONAL INTERVENTIONiv) LIFESTYLE / BEHAVIOUR CHANGEb) SPECIFIC PROTECTIONc) EARLY DIAGNOSIS AND TREATMENTd) DISABILITY LIMITATIONe) REHABILITATION13) CONCLUSIONwww.drjayeshpatidar.blogspot.in
  24. 24. THANXwww.drjayeshpatidar.blogspot.in
  25. 25. EPIDEMIOLOGICAL APPROACHwww.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 controlthe 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 FLOORwww.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 FORMULATEHYPOTHESISwww.drjayeshpatidar.blogspot.in
  29. 29. 6) USES OF DESCRIPTIVEEPIDEMIOLOGY a) Provides occurrence data in an occupationalsetting. b) Provides clues to etiology. c) Help formulate hypothesis d) Provides data for planning, organization andevaluate medical and health services. e) Helps further research.www.drjayeshpatidar.blogspot.in
  30. 30. 8) SOURCES OF DATA a) MORTALITY DATA b) MEDICAL COMPENSATIONRECORDS c) FACTORY MORBIDITY DATA d) E S I COMPENSATION RECORDS e) HOSPITAL DATA f) SICKNESS ABSENTEEISM g) PERIODIC MEDICAL EXAMRECORDS h) FIELD SURVEYSwww.drjayeshpatidar.blogspot.in
  31. 31. 8) ANALYTICAL EPIDEMIOLOGY a) CASE CONTROL STUDY b) COHORT STUDY i) RETROSPECTIVE ii) PROSPECTIVE9) CONCLUSIONwww.drjayeshpatidar.blogspot.in
  32. 32. EPIDEMIOLOGICAL METHODSwww.drjayeshpatidar.blogspot.in
  33. 33. 1) INTRODUCTIONa) Primary role is to study diseaseoccurrence in peopleb) Study factors which may havedisease etiology by studyingexposures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) COHORTwww.drjayeshpatidar.blogspot.in
  35. 35.  B) EXPERIMENTAL / INTERVENTIONALSTUDIES 1) RANDOMIZED CONTROLLED TRIALS 2) FIELD TRIALS – COMMUNITYINTERVENTION TRIALS - Above are not watertight compartments - They are flexible and complementarywww.drjayeshpatidar.blogspot.in
  36. 36. DESCRIPTIVE EPIDEMIOLOGY 1. KEY TO SUCCESS - METICULOUSOBSERVATIONS 2. EXAMPLES – Burkitts lymphoma- epsteinbarr virus, Scurvy – J Lind, Small pox – EdwardJenner. 3. BASIC QUESTIONS – When, Where and Whowww.drjayeshpatidar.blogspot.in
  37. 37. 4) EPIDEMIOLOGICAL TRIAD BALANCING ACTAGENTENVIRONMENTHOSTwww.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 hypothesiswww.drjayeshpatidar.blogspot.in
  39. 39.  6.a) DEFINING THE POPULATIONi) TOTAL NUMBER ii) AGE iii) SEX iv) OCCUPATION v) CULTURAL / SOCIALCHARECTERISTICS vi) EITHER WHOLE OR SAMPLE/ SPECIALSELECTED 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 HAVINGDISEASE iii) DIAGNOSTIC METHODS ACCEPTABLE BYPOPULATION AND APPLICABLE TO LARGECOMMUNITIES ( e.g Tonsillitis )www.drjayeshpatidar.blogspot.in
  41. 41.  6.c) DESCRIBING THE DISEASE i) PRIMARY OBJECTIVE – Describeoccurrence and distribution. Systematiccollection of data (epidemiological triad) andanalysis of data ii) TIME DISTRIBUTIONa) Short – term fluctuationsi) whether there is epidemic?ii) Type of epidemic * Common source –single source/ multiple source* Propogatedepidemic – person- person, arthropod borne,animal reservoir* Slow / modern epidemicswww.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, ADDICTIONTYPHOID, TB, POLIOd) INTERPRETATION OF TIME TRENDSwww.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) MIGRATIONSwww.drjayeshpatidar.blogspot.in
  44. 44.  v) MEASUREMENT OF DISEASE a) CROSS-SECTIONAL STUDIES b) LONGITUDINAL STUDIES vi) COMPARING WITH KNOWN INDICESwww.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 RELATIONSHIPe.g 1) “Cigarette smoking causes cancer”2) “ 30 – 40 cigarettes per day for20yrs 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 evaluatingcontrol 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 topopulation c) Object is not to formulate but to testhypothesis 2) TYPES a) CASE CONTROL STUDY b) COHORT STUDYIn them we determine :-a) Statistical association exists or notb) If yes, then strength of associationwww.drjayeshpatidar.blogspot.in
  48. 48. 3) CASE CONTROL STUDIES (Often retrospective) a) Both exposure and outcome have occurredbefore 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 cancerIf (a/a+c) ↑ in cases than (b/b+d ) in control.·. Association exists .RISK FACTOR( SMOKING)CASES(CANCER)CONTROL(NO CANCER)PRESENT a bABSENT c da + c b + dwww.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- Populationwww.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- Populationc) MATCHINGd) MEASUREMENT OF EXPOSUREi) Precise informationii) Interviews, questionnaires, recordsiii) No “BIAS”www.drjayeshpatidar.blogspot.in
  52. 52.  e) ANALYSIS i) Exposure ratesCases = (a/a+c) = 33/35 = 94.2%Controls = (b/b+d) = 55/82 = 67%CASES CONTROLSSMOKERS 33(a)55(b)NON -SMOKERS2(c)27(d)TOTAL 35(a + c)82(b + d)p < 0.00www.drjayeshpatidar.blogspot.in
  53. 53.  ii) ESTIMATION OF RISK a) Relative Risk (RR)RR = Incidence among exposed .Incidence among non-exposedb) Odds Ratio = ad / bc = 33×27 ÷ 55×2 = 8.1i.e. Risk is 8.1 times more in smokerse) ELIMINATE BIASi) Confoundingii) Memory/ recalliii) Selectioniv) Berkesonian bias – Hospital admission biasv) Interviewers biaswww.drjayeshpatidar.blogspot.in
  54. 54. ADVANTAGES 1. Relatively easy to carry out 2. Rapid and inexpensive ( compared to Cohortstudies) 3. Require comparatively few subjects 4. Particularly suitable to investigate rarediseases or diseases about which little is known.But a disease which is rare in the generalpopulation ( e.g. leukemia in adolescents) maynot be rare in special exposure group (e.g.prenatal X-Rays) 5. No risk to subjectswww.drjayeshpatidar.blogspot.in
  55. 55. ADVANTAGES ……CONTD 6. Allows the study of several different etiologicalfactors (e.g. smoking, physical activity andpersonality characteristics in myocardialinfarction) 7. Risk factors can be identified. Rationalprevention and control programmes can beestablished 8. No attrition problems, because case controlstudies do not require follow-up of individualsinto 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 ofinformation obtained is difficult or sometimesimpossible 2. Selection of an appropriate control group may bedifficult 3. We cannot measure incidence, and can onlyestimate relative risk 4. Do not distinguish between causes and associatedfactors 5. Not suited for the evaluation of therapy orprophylaxis of disease 6. Another major concern is the representativeness ofcases and controls CONCLUSIONwww.drjayeshpatidar.blogspot.in
  57. 57. COHORT STUDY 1. INTRODUCTION a) Descriptive epidemiology producessuspected cause and effect (disease)relationship b) Cohort study is (obs.) analytical studyundertaken to obtain additional evidence tosupport/ refute association ( also called Prospective, Longitudinal, ForwardLooking 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 sharecommon characteristics and experience/exposurewithin 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 clinicalobservation/ Descriptive/ Case – Control Studies b) Exposure rare but incidence highe.g. X-Rays/Radiation c) Follow up easy, Cohort is stable, co-operativeand easily accessible d) Funds availablewww.drjayeshpatidar.blogspot.in
  60. 60.  5.FRAME WORK a) Cause to effect b) Basic design :-COHORT DISEASE TOTALYES NOEXPOSED(STUDYCOHORT)a b (a + b)NOTEXPOSED(CONTROLCOHORT)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 diseaseunder study ii) Both groups should be equally susceptible todisease under study iii) Both groups should be comparable iv) Diagnostic and eligibility criteria definedbeforehand 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 issuspectedwww.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 :- (alsocalled “HISTORICAL”) – Effect to cause, recordsare studied e.g. Lung Cancer uraniumminers, Life span of radiologists and exposure.www.drjayeshpatidar.blogspot.in
  63. 63. Radiotherapyrecords c) COMBINEDLeukemia :- Rx for Ankylosingspondylitisfollowed in future also for occurrencesubsequentlywww.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) Analysiswww.drjayeshpatidar.blogspot.in
  65. 65.  a) SELECTION OF STUDY SUBJECTS i) General population – when exposure isfrequent; should be residing in definedgeographical/ 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-Rayexposures)www.drjayeshpatidar.blogspot.in
  66. 66.  b) OBTAINING DATA i) Interview ii) Records iii) Questionnaire iv) Medical exams v) Environmental surveysDATAwww.drjayeshpatidar.blogspot.in
  67. 67.  c) SELECTION OF COMPARISON GROUPS i) INTERNAL – Select first cohort and thendivide them in comparison groups as perexposure( ½ pack, 1 pack, 2 packs smoked) ii) EXTERNAL – Smokers Vs Non-smokers( comparable cohorts included) iii) GENERAL POPULATION – If above notapplicable only then used, e.g. Uranium vis-à-vis Ca Lung in workers Vs General population d) PROPER FOLLOW-UPwww.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 < 0.001CIGARETTESMOKINGYES NO TOTALYES 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 RISKAR = Incidence in exposed – Incidence among non-exposedIncidence 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 cohortbehaviour.www.drjayeshpatidar.blogspot.in
  71. 71. 10) DIFFERENCESS No CASE CONTROL STUDY COHORT STUDY1 Proceed from “effect to cause” Proceeds from “cause to effect”2 Starts with disease Starts with people exposed torisk factor or suspected cause3 Tests whether the suspectedcause occurs more frequentlyin those with disease thanamong those without thediseaseTests whether disease occursmore frequently in thoseexposed, than in those notsimilarly exposed4 Usually the first approach tothe testing of a hypothesis,but also useful forexploratory studiesReserved for testing preciselyformulated hypothesis5 Involves fewer number ofsubjectsInvolves large number ofsubjects6 Yields relatively quick results Long follow-up period oftenneeded, involving delayedresultswww.drjayeshpatidar.blogspot.in
  72. 72. DIFFERENCES…….CONTDS No CASE CONTROL STUDY COHORT STUDY7 Suitable for study of rarediseasesInappropriate when the diseaseexposure under investigation israre8 Generally yields onlyestimate of RR(Odds Ratio)Yields Incidence rates, RR aswell as AR9 Cannot yield informationabout diseases other thanthat selected for study.Can yield information aboutmore than one disease outcome10 Relatively inexpensive ExpensiveCONCLUSIONTHANXwww.drjayeshpatidar.blogspot.in
  73. 73. EXPERIMENTAL EPIDEMIOLOGY 1) INTRODUCTION – Historically (1920) meantexperiments in animals(rats, mice etc) Now – Clinical trials. Conditions are undercontrol (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, Feasibilityand ethics.www.drjayeshpatidar.blogspot.in
  74. 74.  4) ANIMAL STUDIES :- Helped us in the past bylab experiments of epidemics / herd immunity inanimals. Also gave knowledge about basicmedical 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 Diseasewww.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 patientsexposed and non-exposed to specific treatment forduration of time. 2) CROSS-OVER DESIGN – Patient as his owncontrol. Groups given test and control drug orplacebo. Observed for a duration. Stopped bothfor a “wash-out” period and then switched andrepeat 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. Allare not possible to be blinded( Tonsils – op andnon op Rx) Many ethical, administrative andtechnical problems, but still are powerful toolsTherefore Necessary. 2) PREVENTIVE TRIALS Done for primaryprevention. Trials to eliminate / prevent diseases e.g. Vaccine trials ( viz pertussis vaccine trial inUK 1946) Attack rates decide efficacywww.drjayeshpatidar.blogspot.in
  79. 79.  a) Benefit by community must be clearly knownbeforehand b) Risks must be explained c) Cost of 3M’s to health services must beestimated. 3) RISK FACTOR TRIALS – e.g. IHD – modifyrisk factors and conduct trials ( single / multiple) 4) CESSATION EXPERIMENTS – Evaluatestopping of a habit i.e. Smoking Vs Ca Lung/ IHDwww.drjayeshpatidar.blogspot.in
  80. 80. 5) TRIAL OF ETIOLOGICAL AGENT Retrolental Fibroplasia causing blindness inpremature babies who received O2 therapy. Trial group = 50% O2 therapy × 28 days ;Control = 02. RLF ↑ in trial group. ( Difficult toplan these trials, only in emergency) 6) EVALUATION OF HEALTH SERVICES –They are planned to assess efficiency andeffectiveness of health services e.g. DomiciliaryRx of TB Vs Hospital/ Sanatorium Rx. They arealso called “ Health Services Research” studieswww.drjayeshpatidar.blogspot.in
  81. 81. NON-RANDOMIZED TRIALS 1) INTRODUCTION – Randomized trials arealways better, more scientific and to be preferred.But sometimes due to ethical, administrative,logistic and feasibility problems on humansubjects make these difficult. Moreover longfollow-up on large number have limitations.Therefore we do non-randomized trials. Hereapproach is crude, comparability less andchances of spurious results more (may be extra-statistical judgment). However they areacceptable when planned reasonably correct.www.drjayeshpatidar.blogspot.in
  82. 82.  2) EXAMPLES a) UNCONTROLLED TRIALS – No controlgroup. However “historical controls” are usedfrom records e.g. Pap test for screening of CaCervix cases b) NATURAL EXPERIMENTS – Naturalcircumstances mimic an experiment e.g. Smokers/ Non-smokers are naturally separated into testand control group. Observe incidence of Ca Lungin them and draw hypothesiswww.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 COMPARISONSTUDIES i) Without control ii) With controlwww.drjayeshpatidar.blogspot.in
  84. 84.  i) WITHOUT CONTROL – Comparison beforeand after introducing preventive measures e.g.John Snow’s Cholera investigation in 1854. Needs for such trial :- a) Incidence before and after interventionessential 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 accidentswww.drjayeshpatidar.blogspot.in
  85. 85.  ii) WITH CONTROL – e.g. Seat belt Vs accidentsin states where it is compulsory Vs not. Considerations a) How much benefit ? Effectiveness, acceptancecompared. b) What are the risks to recipients ? Immediateand long term risks estimated. c) Cost in money and manpower. Checkeconomics, practicability and feasibility. CONCLUSION THANXwww.drjayeshpatidar.blogspot.in
  86. 86. ASSOCIATION AND CAUSATION 1) INTRODUCTION – Descriptive studies helpindicate a hypothesis by studying time, placeperson, agent, host and environment. Suggestpossible etiological hypothesis. Analytical andexperimental studies test it i.e. confirm/ refuteassociation 2) DEFINITION a) ASSOCIATION – When events occur togetherfrequently not by chance. b) CO-RELATION -1.0 to +1.0 , however co-relation does not imply causationwww.drjayeshpatidar.blogspot.in
  87. 87.  3) TYPES OF ASSOCIATION a) SPURIOUS b) INDIRECT c) DIRECTi) One to one causalii) Multifactorialwww.drjayeshpatidar.blogspot.in
  88. 88.  a) SPURIOUS – Sometimes association betweendisease and suspected factor is not real.E.g. In perinatal mortality study, hospital deliveryrates were 27.8/1000 and home delivery rateswere 5.4/1000 . But this association may bespurious because of high risk pregnancy inhospital and other confounding variables. i.e.“like” not compared with “like” – Selection biaswww.drjayeshpatidar.blogspot.in
  89. 89.  b) INDIRECT ASSOCIATION – May appearcausal but further study may show indirectassociation. There may be presence of 3rd factorcommon to disease and charecteristic and mayshow statistical association ( confounding) E.g. a) Iodine deficiency → Altitude → Endemic goitre( Statistical association does not necessarily meancausation)b) Consumption of Sucrose and CHD↑ Sugar – more MI, but later studies showedcigarette smoking → high frequency teaTherefore ↑ Sugar – more MI ( later studies showedno association between ↑ Sugar and MI)However indirect association is also useful e.g JohnSnow’s study of polluted water and Cholerawww.drjayeshpatidar.blogspot.in
  90. 90.  c) DIRECT ASSOCIATION ( CAUSAL) i) One to One causal relationship – Change inA is followed by change in B i.e. when causepresent – disease results and vice versa Eg. Koch’s postulates However other problems – a) Cause may not be manipulable ( as directexperiment may not be possible) b) One cause may lead to many diseases E.g. Haemolytic streptococcus – tonsillitis - Scarlet fever - Erysipelaswww.drjayeshpatidar.blogspot.in
  91. 91.  ii) MULTIFACTORAL CAUSATIONFactor 1 (Smoking)Factor 2 ( Air pollution) Disease (Ca Lung)Factor 3 ( Asbestos)SynergisticFactor 1 (Obesity)Factor 2 (Stress) Cumulative DiseaseFactor 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 notalways reached iii) Additional criteria importantTHANXwww.drjayeshpatidar.blogspot.in
  93. 93. ADDITIONAL CRITERIA FOR CAUSALITY 1) INTRODUCTION – When controlledexperimental evidence absent, additional criteriahave 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 bypresence of following factors :- 1) Temporal association 2) Strength of Association 3) Specificity 4) Consistency 5) Biological plausibility 6) Coherence of associationwww.drjayeshpatidar.blogspot.in
  94. 94.  3) PHILOSOPHY – Causal significance ofany association is matter of judgmentbeyond statistical probability. All abovecriteria must be utilized. No one by itself isself-sufficient. All add up to quantum ofevidence and put together contribute to theprobability of causal association.www.drjayeshpatidar.blogspot.in
  95. 95. ASSOCIATION BETWEEN CIGARETTESMOKING AND LUNG CANCER 1) Provides excellent example for above criteria. a) Temporal Association – Does the suspectedcause precede observed effect?This is essential for causal association. Inacute diseases to establish this is not difficult aslatency is less, but in chronic disease it has to bepresent for long time e.g. Smoking – temporalassociation. Observations are compatible to longlatent 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 relationIf absent, argument against causal effect Decrease on stopping exposure, ↑ relationAll above are noticed in smoking and Ca Lungwww.drjayeshpatidar.blogspot.in
  97. 97.  c) SPECIFICITY OF ASSOCIATION – Decidesone – to – one cause and effect relationship. Problems i) Single cause can produce many diseases e.g.Smoking. ii) Multifactorial etiology makes it difficult toshow one – to – one relation. iii) Specify one single cause responsible isdifficult e.g. Tobacco has CO, Nicotine,Hydrocarbons. Even then causal associationexists. Specificity supports causal relation butlack of it does not negate it ! Paradox :- Everyonewho smokes does not get Ca Lung and vice versa,still causal association accepted on availableevidencewww.drjayeshpatidar.blogspot.in
  98. 98.  d) Consistency of Association– More than one(many) studies should consistently showassociation (done by different workers indifferent settings e.g. Smoking – Ca Lung) e) Biological Plausibility e.g. Smoke and Lungtissue, Nutritional diet and GI Tract (supportedby animal studies). Carcinogens isolated fromsmoke prove credibility of hypothesis. f) Coherence of Association ↑ quantity oftobacco & ↑ Ca Lung. ↑ smoking in women & ↑ CaLung 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 convincingevidence in favour and against by long termstudies in epidemiology.THANXwww.drjayeshpatidar.blogspot.in
  100. 100. CONFOUNDING AND BIAS 1) INTRODUCTION - These are to be avoidedand taken care of in any experiment andepidemiological investigation and analysis,failing which faulty deductions get drawn. 2) Confounding – They are variables which arepresent, which may influence the outcome ofcause and effect relationship.www.drjayeshpatidar.blogspot.in
  101. 101.  Example – Article in “International Journal ofQuackery” – “ Metronidazole causes Jaundice” Abstract – We gave this drug ( Metronidazole 400mgwith permitted colour, “ Amaranth” to 100 patients ofGiardiasis. 80 developed deep yellow urine. Conclusion – Medicine causes Jaundice in 80% ofpatients. This research is outright unscientific. Defects :- Incorrect investigations, No scientificcriteria used. You protest Reply :- Sorry . Revised conclusion – “ metronidazolecauses 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 andBias Bias – To be identified and avoided in planning /designing. Confounding – Identify, control byrandomization, 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 PotentialConfounding Factors (PCF) in the study c) Matching Ex – Tobacco user in trial and control groups. 6) Adjustment during Analysis – By usingappropriate statistical measures likestandardization, stratified analysis, multipleregression analysis, logistic regressions and soon. CONCLUSION THANXwww.drjayeshpatidar.blogspot.in
  104. 104. USES OF EPIDEMIOLOGYa) Study of history of health of populations andstudy rise/ fall/ change in character of diseaseb) Diagnose health of communityc) Study working of health servicesd) Estimate individuals riske) Describe natural history of diseasef) Identify syndromesg) Search for causes of health and diseasewww.drjayeshpatidar.blogspot.in
  105. 105. MODES OF TRANSMISSION1) DIRECT CONTACT – Skin to skin or mucosa tomucosa – touching, kissing and sexualintercourse2) DROPLET – Coughing, sneezing etc. increasedby overcrowding/ ↓ ventillation3) CONTACT WITH SOIL4) INDIRECT – Flies, Fingers, Fomites, Food andFluids5) VEHICLE BORNE – Water, food, blood, organtransplant. ( Explosive, severe, over longdistance, isolation of agent possible, commonsource infection)www.drjayeshpatidar.blogspot.in
  106. 106. 6) VECTOR BORNEa) Mechanicalb) Biologicali. Propogativeii. Cyclopropagativeiii. Cyclodevelopmentaliv. Transovarianv. Trans-stadial7)AIR BORNEa) Droplet nucleib) Dust8) TRANSPLACENTAL(VERTICAL)www.drjayeshpatidar.blogspot.in
  107. 107. 9) VACCINESa) Liveb) Killedc) Toxoidsd) Immunoglobulinse) Antisera10) DISEASE PREVENTION AND CONTROLa) Control source/ reservoirb) Control transmissionc) Protect hostwww.drjayeshpatidar.blogspot.in
  108. 108. a) Reservoiri. Early diagnosis and treatmentii. Notificationiii. Epidemiological investigationiv. Isolationv. Treatmentvi. Quarantineb) Control transmissionc) Protect susceptible host (UIP)11) CONCLUSIONwww.drjayeshpatidar.blogspot.in
  109. 109. 7) INDICATORS OF HEALTHa) Mortality1. CDR2. Life expectancy3. IMR4. MMRb) Morbidityc) Disabilityd) Nutritionale) Health care deliveryf) Utilizationg) Social / mental healthh) Environmentalj) Socio-economick) Quality of life8) CONCLUSIONwww.drjayeshpatidar.blogspot.in
  110. 110. DISEASE DYNAMICS1)2) SOURCEa) Human cases – Clinical- Sub – clinicalb) Animalc) Inanimated) Human carriersi. Incubatoryii. Convalescentiii. Healthya) Temporaryb) ChronicSOURCEORRESERVOIRSUSCEPTIBLEHOSTMODE OFTRANSMISSIONwww.drjayeshpatidar.blogspot.in
  111. 111. 3)a) Primary caseb) Index casec) Secondary cases4) Secondary attack rateNo. developing disease during incubation period × 100No. of susceptible exposed to index casewww.drjayeshpatidar.blogspot.in
  112. 112. Solving Community Health Problema) Definition of the problemb) Appraisal of existing factsc) Formulation of hypothesisd) Testing the hypothesise) Conclusions / Recommendationswww.drjayeshpatidar.blogspot.in
  113. 113. DEFINITIONS1) INFECTION2) CONTAMINATION3) INFESTATION4) INFECTIOUSDISEASE5) CONTAGIOUSDISEASE6) COMMUNICABLEDISEASE7) NON-COMMUNICABLEDISEASE8) EPIDEMIC9) ENDEMIC10)SPORADIC11)PANDEMIC12) EXOTIC DISEASE13) ZOONOSES14) EPIZOOTIC15) ENZOOTIC16) NOSOCOMIALINFECTION17) OPPORTUNISTICINFECTION18) IATROGENIC19) SURVEILLANCE20) ERADICATIONwww.drjayeshpatidar.blogspot.in
  114. 114. MODES OF TRANSMISSION1) CONTACT – DIRECT- INDIRECT2) VEHICLE BORNE3) VECTOR BORNE4) AIR BORNE5) TRANSPLACENTALwww.drjayeshpatidar.blogspot.in
  115. 115. IMMUNITYIMMUNITYINNATE(BASIC)ACQUIREDACTIVENATURAL ARTIFICIALPASSIVENATURAL ARTIFICIALHERD IMMUNITYwww.drjayeshpatidar.blogspot.in
  116. 116. INVESTIGATIONOF ANEPIDEMIC
  117. 117. INVESTIGATION OF AN EPIDEMIC Outbreak of any disease is due to shift in balancebetween agent, host & environment. Usually causes a lot of concern & attention andneeds a well practiced, deliberate response by themedical teams. Epidemiological principles must be correctlyused.www.drjayeshpatidar.blogspot.in
  118. 118. OBJECTIVES Define magnitude in terms of person, place &time distribution. Determine conditions, factors responsible for theoutbreak. Identify cause, source of infection, modes oftransmission & 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 Analysiswww.drjayeshpatidar.blogspot.in
  120. 120. INVESTIGATION STEPS Formulation of Hypothesis Testing of Hypothesis Evaluation of ecological factors Further investigation of population atrisk Writing the reportwww.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 asample 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 – foodpoisoning, Cholera etc. need no such comparison. Modern epidemics – IHD, Cancer less easilydiscernible.www.drjayeshpatidar.blogspot.in
  123. 123. 3.DEFINING POPULATION AT RISK Obtain a map of area – with alldwelling units, water sources, naturallandmarks, 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 inthe population who may not have reported/ self-medicated/ got treated elsewhere. Epidemiological case sheet – All relevantdata is collected by the trained health workers –details of age, sex, occupation, social class, travelhistory, past history, history of onset, details ofsigns & 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 forsecondary cases to be carried outeveryday at all hospitals, nursing homes,clinics as well as from informants in thecommunity.Continue till no more cases are foundand area is free of epidemic – usuallyTWICE the MAXIMUM incubationperiod of the disease since the last case.www.drjayeshpatidar.blogspot.in
  126. 126. 5.DATA ANALYSISTime distribution – Chronologicaldistribution of dates of onset; construct an“epidemic curve” Time relation with exposure to suspectedsource Common source/ Propagated source Seasonal/cyclical patternPlace distribution – Make a “spot map”denoting location of cases – geographicalclustering of cases near common source ofexposure – water, air, food etc.www.drjayeshpatidar.blogspot.in
  127. 127. www.drjayeshpatidar.blogspot.in
  128. 128. 5.DATA ANALYSISPerson distribution - Age/ sex/occupation etc. analysed for risk factor ;attack rate ; CFR for those exposed withrespect to those not exposed to the riskfactor.In Food poisoning, attack rate is taken forspecific food items.Purpose of data analysis is to determineany common event /experience, and todelineate the groups at risk due to thiscommon experience.www.drjayeshpatidar.blogspot.in
  129. 129. 6.FORMULATION OF HYPOTHESISBased on person-place-time distribution orthe Agent, Host, Environment model,formulate a hypothesis explaining theepidemic in terms of – Possible source Causative agent Possible modes of spread Environmental factors which enabledspreadwww.drjayeshpatidar.blogspot.in
  130. 130. 7.TESTING OF HYPOTHESISAll reasonable hypothesis are consideredand evaluated – comparisons of attackrates for each group of exposed withsuspected exposure is analysed ; themost reasonable hypothesis has to beaccepted by the epidemiologist.www.drjayeshpatidar.blogspot.in
  131. 131. 8.ECOLOGICAL FACTORS WHICH MAY HAVECONTRIBUTED 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 OFPOPULATION-AT-RISK Further tests for more specific diagnosis Tests of food / water samples Serological studies for clinicallyinapparent cases Classification of exposure and those atriskwww.drjayeshpatidar.blogspot.in
  133. 133. 10.WRITING THE REPORTBackground – Geographic location Climatic condition Demography Organisation of health services Existence of early warning systems Normal diseases prevalencewww.drjayeshpatidar.blogspot.in
  134. 134. 10.WRITING THE REPORTHistorical data – Epidemics in same / nearby area Same disease / related disease First case discovered in present outbreakMethodology of investigation – Case definition Questionnaire used – epidemiological inv. Survey teams – household/ retrospective/prospective/ lab specimens & procedureswww.drjayeshpatidar.blogspot.in
  135. 135. 10.WRITING THE REPORTAnalysis of data –1. Clinical data - Frequency of signs & symptoms Course of disease Differential diagnosis Death / sequelae rates2. Epidemiological data – Mode of occurrence – time/ place/ persondistributionwww.drjayeshpatidar.blogspot.in
  136. 136. 10.WRITING THE REPORT Modes of transmission – Source of infection Route of excretion/ portal of entry Factors influencing transmission3. Laboratory data – Isolation of agent Serological confirmation Significance of resultwww.drjayeshpatidar.blogspot.in
  137. 137. 10.WRITING THE REPORT4. Interpretation of data – Comprehensive picture of outbreak Hypothesis of cause Formulation & testing of hypothesis –statistical analysiswww.drjayeshpatidar.blogspot.in
  138. 138. 10.WRITING THE REPORTControl measures – Define strategies / methodology ofimplementation – constraints, results Evaluation of these measures – efficacy ofresults, 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 nodeath.www.drjayeshpatidar.blogspot.in
  140. 140.  2) Incubation period – a) Define b) Multiplies till sufficient density, equilibriumlost, disease signs appear c) “Median incubation period” – Time taken by50% to occur after exposure 3) Factors determining incubation period a) Generation time :- Receipt – Massinfectivity b) infective dose c) Portal of entry d) Individual susceptibility Note – It is minimum / maximum / differentwww.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 andsecondary case. 7) Communicable period. 8) Secondary Attack Rate –No. developing disease × 100Susceptiblewww.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 andeliminate 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-serawww.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 developedPRIMARYwww.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 marrowlymphocytes) - IgG, IgM, IgA, IgD & IgE – Circulate, neutraliseand are specific. viii) Cellular Immunity – T-cells, ↑ resistance(mainly TB, Leprosy) ix) Combined - SynergesticSECONDARYwww.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, Milkwww.drjayeshpatidar.blogspot.in
  147. 147.  Attributes – 1) Ready-made 2) Temporary 3) No immune memory 4) Less effective C) Herd Immunitywww.drjayeshpatidar.blogspot.in
  148. 148. IMMUNIZING AGENTS a) Vaccines – i) Live vaccines – more potent, multiplyingorganisms, have all major + minor antigeniccomponents, engage tissues locally (oral polio),persistence. ii) Inactivated or Killed vaccines – By heat orchemicals – 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 CHAINATTENUATEDVACCINESKILLED VACCINESVACCINE DOSE LOW (REPLICATES) HIGHANTIBODYPERSISTENCELONG SHORTBOOSTER NEEDED INFREQUENTLY FREQUENTLYREVACCINATION POSSIBLE NONELATENCY POSSIBLE NONEONCOGENICITY ? NONEwww.drjayeshpatidar.blogspot.in
  150. 150. IMMUNIZING AGENTSBCGTYPHOID ORALPLAGUEORAL POLIOYELLOW FEVERMEASLESRUBELLAMUMPSINFLUENZAEPI. TYPHUS LIVEATTENUATEDVACCINEBACTERIALVIRALRICKETTSIALwww.drjayeshpatidar.blogspot.in
  151. 151. TYPHOIDCHOLERAPERTUSSISC.S.MENINGITISPLAGUESALK (POLIO)RABIESINFLUENZAHEPATITIS BJAPANESE –ENCEPHALITISKFDINACTIVATEDKILLEDVACCINEBACTERIALVIRALTOXOIDSDIPHTHERIATETANUSBACTERIALwww.drjayeshpatidar.blogspot.in
  152. 152. IMMUNOGLOBULINS HUMANIMMUNO -GLOBULINSHUMAN NORMAL IgHUMAN SPECIFIC Ig HEPATITIS A MEASLES RABIES TETANUS MUMPS HEPATITIS B VARICELLA DIPHTHERIANON – HUMAN(ANTISERA) DIPHTHERIA TETANUS GAS GANGRENE BOTULISM RABIES BACTERIAL VIRALwww.drjayeshpatidar.blogspot.in
  153. 153. NATIONAL IMMUNIZATION SCHEDULEVaccine AgeBirth 6 weeks 10 weeks14weeks9-12monthsPrimary vaccinationBCG XOral polio X X X XDPT X X XHepatitis B* X X XMeasles XBooster DosesDPT + Oralpolio16 to 24 monthsDT 5 yearsTetanustoxoid (TT)At 10 years and again at 16 yearsVitamin A 9, 18, 24, 30 and 36 monthsPregnant womenTetanus toxoid (PW): 1st dose2nd doseBoosterAs early as possible during pregnancy (first contact)1 month after 1st doseIf previously vaccinated, within 3 yearswww.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. DISINFECTION1) INTRODUCTION – SEMMELWEIS (18181865) demonstrated hand washing withantiseptics reduced puerperal fevers. LISTER(1897 – 1912) used prophylactic antiseptics forwounds.2) ADVANTAGES –i) Controls sepsisii) ↓ disease transmission / spreadiii) Rx of local infectionsiv) Cost ↓ - effectivev) Cleanlinessvi) Easywww.drjayeshpatidar.blogspot.in
  156. 156. 3) DEFINITIONSa) Disinfectant – Substance which destroyspathogenic microbes but not necessarily sporesb) Antiseptic – Destroys or inhibits growth ofmicrobesc) Deodorantd) Sterilizatione) Disinfection4) TYPES –a) Concurrentb) Terminalc) Prophylacticwww.drjayeshpatidar.blogspot.in
  157. 157. 5) AGENTSi. Naturalii. Sunlightiii. Airb) Physicali) Burningii) Hot airiii) Boilingiv) Autoclavingv) Radiationc) Chemical – Done for articles which cannot beboiled or autoclaved. Used for faeces & urine/contaminated water.www.drjayeshpatidar.blogspot.in
  158. 158. Chemical agents – Wide range available withadvantages / disadvantagesPhenol and related compoundsa) Phenol ( Carbolic acid) – Best known. Also referencestandard i.e. R W co-efficient. Used as 10%, 5% formopping floorsb) Cresol – Excellent, 3 to 10 times more powerful yetnot toxic. 5 – 10% for faeces / urine. For 5% - add50ml to one litre of water. It is all purposedisinfectant.c) Saponified cresol emulsions – Lysol, Cyllin – used as2% solution for faeces (powerful disinfectant)d) Chlorhexidine (Hibitane) - Very good skinantiseptic. 0.5% alcohol solution as hand lotion. 1%cream for burnse) Dettol – 5% for instruments, plastics and wounds.Minimum 15 min contactwww.drjayeshpatidar.blogspot.in
  159. 159. 2) Quarternary Ammonia compoundsa) Cetrimide (cetavlon) – 1 – 2% strengthb) Savlon (cetavlon + hibitane) 1:6 spirit3) Halogensa) Bleaching powder – Disinfect water, urine,faeces and as deodorant.b) Sod. Hypochlorite – Stronger (feeding bottles)c) Halazone tablets – 4mg tablet/litre for ½ to1hrd) Iodine – 1 – 2% in alcohol4) Alcohol – 70% spirit5) Formaldehyde – rooms, blankets, beds, books6) Miscellaneous – Lime (quick) 10-20% (2hrsperiod)www.drjayeshpatidar.blogspot.in
  160. 160. DISINFECTION PROCEDURES1)Faeces & Urinea) Collect in impervious vessel + equal quantity ofbleaching powder (5%), crude phenol(10%), Cresol5%, Formalin 10% (contact 2 hrs)b) Boiling waterc) Bedpans – Steam, 2.5% cresol2) Sputum – Burning, boiling or 5% cresol3) Room – Clean; air, sunlight, bleaching powder,2.5% Cresol, 1% Formaldehyde (4hrs)Formaldehyde – 1:2 ratio with water.CONCLUSIONTHANXDISINFECTION TESTSwww.drjayeshpatidar.blogspot.in
  161. 161. NUTITIONAL SURVEILANCE1) INTRODUCTION - It is same as diseasesurveillance. “Keeping watch over nutrition inorder to make decisions to improve populationnutrition”2) OBJECTIVESa) Aid long term planning in health anddevelopmentb) Provide programme management andevaluationc) Timely warning and intervention to preventshort-term food consumption crisis.www.drjayeshpatidar.blogspot.in
  162. 162. 3) Difference in Surveillance Vs Growth monitoringa) Growth Monitoring – Oriented to individualchildb) Nutritional surveillance – Sample children fromcommunity and compare overall nutritionconditionwww.drjayeshpatidar.blogspot.in
  163. 163. FACTOR GROWTHMONITORINGNUTRITIONALASSESSMENTSTRATEGY Preservation ofnormal growthDetection ofundernutritioinAPPROACH Educational –motivationalDiagnostic –interventionalENROLMENT All infants RepresentativesampleAGE Start before 6 monthsand continue monthlyRepresentative agesat longer levelsNUMBER Small groups,preferably between 10& 20Any size group, 50 to100 most efficientWEIGHER/RECORDERMothers guided byworkerTrained workerWEIGHT CARD Simple, emphasisgrowthPrecise, nutritionalstatusCOMPARISON OF GROWTH MONITORING ANDNUTRITIONAL SURVEILLANCEwww.drjayeshpatidar.blogspot.in
  164. 164. FACTOR GROWTHMONITORINGNUTRITIONALASSESSMENTNUTRITIONALEMPHASISMaintaining goodnutritionDetect malnutritionRESPONSE Early homeintervention based onlocal knowledgeNutritionalrehabilitation oftenwith supplementsRESPONSE TIME Brief, resumption ofnormal growthLong, regain of goodnutrition incommunityINTERVENTIONS Primary health care;oral rehydrationtherapy; vaccines;Vit A; deworming;contraceptives;chloroquine; othertreatmentFood supplements ofcommunity – wideresponse, such as foodsubsidyREFERRAL Health system forcheckup and possiblebrief food supplementsMalnutritionrehabilitation, often inspecial centrewww.drjayeshpatidar.blogspot.in
  165. 165. NUTRITIONAL INDICATORSMATERNALNUTRITIONINFANT &PRESCHOOLCHILDRENSCHOOLCHILDNUTRITIONBirth weightHeight for age andweight for height at7yrs or school admissionclinical signsProportion being breastfed andproportion on weaning foods, by agein months, mortality rates in childrenaged 1,2,3&4yrs with emphasis on2yr oldsIf age known – height for age, weightfor ageIf age unknown – weight for height,arm circumference, clinical signs andsyndromeswww.drjayeshpatidar.blogspot.in
  166. 166. SOCIAL ASPECTS OF NUTRITION1) INTRODUCTION – Malnutrition a global andserious social problem of international concern2) PROBLEM OF MALNUTRITION –Pathological state due to relative or absolutedeficiency or excess of one or more essentialnutrientsa) Under nutritionb) Over nutritionc) Imbalanced) Specific deficiencywww.drjayeshpatidar.blogspot.in
  167. 167. FAO :- 15% are malnourished, majority in SE Asia(300 million), mainly children < 5 and pregnantwomen.Malnutrition has direct and indirect effects oncommunity (Diseases & retarded mental /physical growth)Therefore ↑ morbidity & mortality, ↓ vitality &productivityHealth hazards of over nutrition are equally badand harmful e.g. IHD, Diabetes, High BP etc.www.drjayeshpatidar.blogspot.in
  168. 168. ECOLOGY OF MALNUTRITION1) INTRODUCTION – Man-made disease. “Beginsin womb and ends in grave” BD Jelliffe(1966)WHO monograph No. 29 is a masterpiece onthis subject. Various ecological factorsresponsible are :-a) Conditioning influencesb) Cultural influencesc) Socio-economic factorsd) Food productione) Health and other serviceswww.drjayeshpatidar.blogspot.in
  169. 169. a) CONDITIONING INFLUENCES – Infectiousdiseases (children) – Diarrhoea, Intestinalparasites, Measles, Whooping cough, Malaria &TB (vicious cycle ). Further complicated by badenvironmental sanitation/ healthb) CULTURAL INFLUENCES –i. Choose poor dietsii. Food habits, customs, beliefs, traditions andattitudes – Family plays important role, effectspassed on for generations. Staple diet fads,hot/cold-light/heavy foods, forbidden foodsiii. Religioniv. Cooking practicesv. Child rearing – breast feeding, top feed, productsvi. Miscellaneous – Men first, alcoholism etcwww.drjayeshpatidar.blogspot.in
  170. 170. c) SOCIO-ECONOMIC FACTORS – Povertyignorance, illiteracy, lack of knowledge,overpopulation “very nature and culture andstructure of society”d) FOOD PRODUCTION – Uneven, ↓ technologies,↓ facilities for 4M’s, weather, ?distribution.e) HEALTH & OTHER SERVICESi. Surveillanceii. Nutritional rehabilitationiii. Nutrition supplementationiv. Health educationwww.drjayeshpatidar.blogspot.in
  171. 171. PREVENTIVE AND SOCIAL MEASURES1) INTRODUCTIOIN – Outcome of many factors,therefore action at different levels i.e. family,community, national & international. Coordinatedaction by many :- nutrition food, health, education,transport, agriculture, marketing, planning, deliveretc2) FAMILY LEVEL -a) Nutrition educationb) Housewife as managerc) × taboos and fadsd) Breast feede) Baby foodsf) Vulnerable groups careg) Kitchen garden / poultryh) Locally available/ acceptable foodi) FP, ANC, child health and immunization servicesj) Role of HWSwww.drjayeshpatidar.blogspot.in
  172. 172. 3) COMMUNITY LEVELa) Surveyb) Risk approachc) Feeding and nutritional programmesd) ↑ productione) ICDSf) RH Missiong) ↑ sanitationh) ↓ infectious diseasei) ↑ SE Conditions4) NATIONAL LEVELa) Rural developmentb) ↑ agricultural productionc) Stabilize populationd) Nutrition intervention programmese) Health programmesf) Seek help FAO/WHO/ UNICEFwww.drjayeshpatidar.blogspot.in
  173. 173. 5) INTERNATIONAL LEVELa) World Food Programmeb) International agencies :- WHO/ FAO/ ILO/World Bank/ UNICEF/ UNDP/ CARE6) FOOD SURVEILLANCE :- Food, Milk, Meat,Fish, Eggs hygiene, PFA Act 1954CONCLUSION?CORRUPTION ? MALPRACTICES ?↓ CHARACTERCan we forget them ? Cure?THANXwww.drjayeshpatidar.blogspot.in

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