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EPIDEMIOLOGY

EPIDEMIOLOGY

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EPIDEMIOLOGY

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  1. EPIDEMIOLOGY

  2. MORBIDITY VS MORTALITY • SUVEILLANCE OF DISEASE OCCURRENCE • REPORTING SYSTEM FROM INDIVIDUAL DOCTORS TO COUNTY, STATE AND FEDERAL PUBLIC HEALTH OFFICIALS • CENTERS FOR DISEASE CONTROL AND PREVENTION • IN ATLANTA GEORGIA

  3. STATISTICS AND EPIDEMIOLOGY • PROBABILITY OF EXPOSURE • PROBABILITY OF TRANSMISSION

  4. HISTORY OF EPIDEMIOLOGY JOHN SNOW AND CHOLERA

  5. TYPES OF STUDIES • DESCRIPTIVE EPIDEMIOLOGY • ANALYTICAL EPIDEMIOLOGYEXPERIMENTAL STUDIES

  6. DESCRIPTIVE EPIDEMIOLOGICAL STUDIES • DESCRIBES PATTERNS OF DISEASE IN POPULATIONS USING AGE, GENDER, GEOGRAPHIC AREA AND TIME OF OCCURENCE

  7. ESCHERICHIA COLI • E. COLI O157:H7 • JANUARY 1993 -WASHINGTON STATE • SEVERE BLOODY DIARRHEA • FOUND IN HAMBURGER MEAT

  8. ANALYTICAL EPIDEMIOLOGICAL STUDIES • USE SCIENTIFIC METHOD • ESTABLISHES CAUSE AND EFFECT RELATIONSHIPS • COHORT STUDY • CASE CONTROL STUDY

  9. COHORT STUDY • MOST DEFINITIVE • STUDY GROUPS WITH AND WITHOUT RISK FACTORS • LEGIONAIRE’S DISEASE

  10. CASE CONTROL STUDY • INDIVIDUALS WITH DISEASE ARE COMPARED WITH THOSE WITHOUT • HANTAVIRUS

  11. EXPERIMENTAL STUDIES • ANIMAL STUDIES • HUMAN STUDIES

  12. TERMS OF EPIDEMIOLOGY • INCIDENCE • NUMBER OF NEW CASES SEEN IN A SPECIFIC TIME PERIOD • PREVELANCE • TOTAL NUMBER OF CASES AT ANY ONE TIME

  13. MORBIDITY RATE • EXPRESSED AS CASES PER 10,000 PER YEAR

  14. MORTALITY RATE • NUMBER OF INDIVIDUALS WHO DIE AS OF A SPECIFIC DISEASE • PUBLISHED IN MORBIDITY AND MORTALITY WEEKLY REPORTS

  15. PATTERNS OF DISEASE OCCURENCE ENDEMIC, EPIDEMIC, PANDEMIC AND SPORADIC DISEASES

  16. ENDEMIC DISEASE • CONSTANTLY PRESENT • PARTICULAR GEOGRAPHIC AREA • INVOLVES RELATIVELY FEW INDIVIDUALS • NOT MAJOR HEALTH PROBLEM • TUBERCULOSIS AND MUMPS IN US • GONORRHEA AND CHANCROID IN WORLD

  17. EPIDEMIC DISEASE • UNUSUAL OCCURENCE OF DISEASE • INVOLVES LARGE SEGMENT OF POPULATION • FOR LIMITED TIME • ENDEMIC DISEASES CAN BECOME EPIDEMIC • INFLUENZA, MEASLES AND CHICKEN POX

  18. PANDEMIC DISEASE • SERIES OF EPIDEMICS • AFFECT SEVERAL COUNTRIES • MAJOR PORTIONS OF THE WORLD • INFLUENZA PANDEMIC OF 1918-1919 • HIV AND AIDS • GENITAL HERPES AND GENITAL WARTS

  19. SPORADIC DISEASES • UNCOMMON • OCCUR IRREGULARLY • AFFECT FEW PEOPLE • DIPHTHERIA AND WHOOPING COUGH • CAN OCCASIONALLY BECOME EPIDEMIC

  20. TYPES OF EPIDEMICS • COMMON SOURCE • PERSON TO PERSON • http://uhavax.hartford.edu/bugl/histepi.htm • http://en.allexperts.com/e/e/ep/epidemic.htm

  21. COMMON SOURCE EPIDEMICS • SINGLE EXPOSURE SOURCE • RAPID ONSET OF DISEASE CASES • RAPID DECLINE OF DISEASE CASES

  22. PERSON TO PERSON EPIDEMIC • PROPOGATED • SLOW PROLONGED RISE OF CASES • SLOW PROLONGED DECLINE IN CASES

  23. INFLUENZA EPIDEMICS • PRIME EXAMPLE OF PERSON TO PERSON EPIDEMICS • WORLD HEALTH ORGANIZATION TRIES TO LIMIT BY VACCINES • SOMETIMES WORKS SOMETIMES NOT

  24. DISEASE TRANSMISSION

  25. RESERVOIRS • SUPPORTS SURVIVAL, MULTIPLICATION, AND TRANSMISSION • LIVING RESERVOIRS • NONLIVING RESERVOIRS

  26. TERMS • VECTORS • VEHICLES • FOMITES

  27. HUMAN RESERVOIRS • MOST HUMAN PATHOGENS CANNOT LIVE OUTSIDE HOST LONG • MANY RESTICTED ALMOST ENTIRELY TO HUMANS

  28. POTENTIALSOURCES • BODY FLUIDS • FECES • URINE • SEMEN AND DISCHARGES FROM GENITOURINARY TRACT • SALIVA FROM MOUTH • MUCUS FROM RESPIRATORY TRACT • BLOOD • DISCHARGES FROM SORES AND WOUNDS

  29. CARRIERS • HOST WHO HARBORS PATHOGENS THAT ARE TRANSMISSIBLE TO OTHERS • HEALTHY CARRIERS • INCUBATORY CARRIERS • CONVALESCENT CARRIERS • INTERMITTENT CARRIERS

  30. RABIES YELLOW FEVER PLAGUE ROCKY MOUNTAIN SPOTTED FEVER TYPHUS FEVER LYME DISEASE LEISHMANIASIS AFRICAN SLEEPING SICKNESS CHAGA’S DISEASE VIRAL ENCEPHALITIS MALARIA ZOONOSES & VECTOR TRANSMITTED DISEASES

  31. FOMITES VEHICLES NONLIVING RESERVOIRS

  32. PORTALS OF ENTRY • SKIN • MUCOUS MEMBRANES • RESPIRATORY • GASTROINTESTINAL TRACT • URINARY TRACT • PARAENTERAL ROUTE • WOUNDS, ANIMAL BITES, INJURIES • PATHOGENS ARE GENERALLY RESTRICTED TO SPECIFIC PORTALS

  33. INFECTIOUS DOSE • NUMBER OF PATHOGENS NEEDED TO CAUSE DISEASE • VARIES FROM ONE TO HUNDREDS OF THOUSANDS • HIV REQUIRES LARGE DOSES • ENCAPSULATED STREPTOCOCCUS PNEUMONIAE JUST A FEW • PATHOGEN MUST OVERCOME HOST DEFENSES

  34. FACTORS THAT AFFECT INFECTIOUS DOSE • HOST DEFENSES • ABILITY OF MICROBE TO OVERCOME DEFENSES • MALNUTRITION • IMMUNITY OF HOST

  35. PORTALS OF EXIT • DISCHARGED WITH BODY FLUIDS AND WASTES • SNEEZING, COUGHING , TALKING • VAGINA AND SEMEN SECRETIONS

  36. TRANSMISSION • AIRBORNE TRANSMISSION • VEHICLE TRANSMISSION FOOD WATER • DIRECT SEXUAL CONTACT • VECTOR TRANSMISSION ZOONOSES • DIRECT SKIN CONTACT • NOSOCOMIAL TRANSMISSION • TRANSMISSION BY BODY FLUIDS

  37. AIRBORNE TRANSMISSION • COMMON CORYZA • INFLUENZA • LEGIONNAIRE’S DISEASE • TUBERCULOSIS • HISTOPLASMOSIS • COCCIDIOMYCOSIS

  38. VEHICLE TRANSMISSION- • FOOD POISONING OR INTOXICATION • INFECTIONS

  39. FOOD POISONING OR INTOXICATAION • STAPHYLOCOCCAL FOOD POISONING • BOTULISM

  40. VIRAL GASTROENTERITIS BACTERIAL GASTROENTERITIS BACTERIAL ENTEROCOLITIS E. COLI O157:H7 TYPHOID FEVER SHIGELLOSIS HEPATITIS GIARDIASIS CYRPTOSPORIDISOSIS TOXOPLASMOSIS YERSINIOSIS GASTROENTERITIS AND ENTEROCOLITIS

  41. SEXUALLY TRANSMITTED DISEASES • AIDS • GENITAL HERPES • GENITAL WARTS • GONORRHEA • SYPHILIS • NONGONOCOCCAL URETHRITIS

  42. DIRECT TRANSMISSION BY SKIN CONTACT • WARTS • LEPROSY • TINEA

  43. INDIRECT CONTACT • FOMITES ARE CONTAMINATED WITH PATHOGENS

  44. VECTORS • ARTHROPODS ARE MOST COMMON VECTOR • MECHANICAL TRANSMISSION • BIOLOGICAL TRANSMISSION

  45. MECHANICAL TRANSMISSION • SIMPLE PASSIVE TRANSPORT • PATHOGENS ARE CARRIED ON INSECTS (USUALLY) FEET OR BODY PARTS • FLIES ON FOOD

  46. BIOLOGICAL TRANSMISSION • MORE COMPLEX • PATHOGENS REPRODUCE BOTH IN VECTOR AND HOST

  47. ALTERNATE HOST • HOST WHERE ASEXUAL REPRODUCTION OCCURS

  48. DETERMINANT HOST • HOST WHERE SEXUAL REPRODUCTION OCCURS

  49. NOSOCOMIAL INFECTIONS • SERUM HEPATITIS • PUERPERAL FEVER\INFECTIONS AFTER SURGERY

  50. SERUM HEPATITIS • EBOLA