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Introduction of Epidemiology

Introduction of Epidemiology. SUNPETCH ANGKITITRAKUL, Ph.D. สรรเพชญ อังกิติตระกูล. One World One Health. One World: Earth One Health: Humans, Animals, Environment Emerging Infectious Disease (EID) Avian Influenza (H5N1), SARS (Severe Acute Respiratory Syndrome) Nipah virus

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Introduction of Epidemiology

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  1. Introduction of Epidemiology SUNPETCH ANGKITITRAKUL, Ph.D. สรรเพชญ อังกิติตระกูล

  2. One World One Health • One World: Earth • One Health: Humans, Animals, Environment • Emerging Infectious Disease (EID) • Avian Influenza (H5N1), • SARS (Severe Acute Respiratory Syndrome) • Nipah virus • Influenza A (H1N1)

  3. Emerging Infectious Diseases • infectious diseases with an increasing in patient report over the past 20 years • infectious diseases with an increasing possibility in the near future • AIDS, Avian Influenza, and drug resistant tuberculosis • Antimicrobial resistant organisms

  4. Re-emerging Infectious Diseases • infectious diseases that used to create outbreak in the past and subsided for a number of years but are occurred again • tuberculosis, hemorrhage fever and malaria

  5. Emerging and re-emerging Infectious Diseases

  6. Global of emerging and re-emerging infectious diseases

  7. Factors of EID • Humans (Africa, Asia and Latin America) • Wildlife (Forest encroachment) • Climate change • Pathogens • Spread of pathogen (air or insect) • Virus (mutation)

  8. Epidemiology • Epi = on, upon • Demos = people • Logos = knowledge

  9. Historical of epidemiology • Hippocrates (400 BC) • John Graunt (1662) • John Snow (1854) • Out break of cholera occurred in a small area of central London (Golden Square)

  10. What is Epidemiology? • The study of the distribution and determinants of health-related states or events in specified populations and the application of this study to the control of health problems (CDC)

  11. What is Epidemiology? • focused on the health and disease status of a population • the study of how disease is distributed in populations and the factors that influence or determine this distribution

  12. Epidemiology is a scientific discipline that involves the study of the frequency and distribution of health and disease in order to find risk factors in populations for prevention and control

  13. Discipline: the general approach is to creating order and structure from incomplete knowledge Study: combines learning about epidemiology theory with on the job field application Frequency: means that we count characteristics in a population of people or animals Distribution: describes the patterns of disease in a population, in a particular place during a period of time

  14. Health: refers to measures of optimum productivity due to lack of disease (meat, eggs or milk) Disease: refers generally to an imbalance in the health status of individuals or populations that result in decreased productivity, illness or death Population: refers to the group of individual animals or people that are considered or affected

  15. Risk factors: risk is the probability that a factor the population is exposed to be associated with the occurrence of disease Prevent: means not providing the opportunity for a disease to occur Control: method to reduce the extent of disease in a population or area

  16. Objective of Epidemiology • To identity the etiology (cause) of disease and the relevant risk factors • To determine the extent of disease found in the community • To study the natural history and prognosis of disease

  17. Objective of Epidemiology • To evaluate both existing and newly developed preventive and therapeutic measure and modes of health care delivery • To provide the foundation for developing public policy relating to environmental problems

  18. Use of Epidemiology • Describe the distribution of disease • Describe the natural history of disease • Identify factors that increase/decrease risk • Predict trends • Consider mechanisms of transmissions • Test efficacy & evaluate interventions • Identify health needs

  19. Epidemiology VS Clinical medicine

  20. Field Epidemiology • Field Epidemiology is the front line • There is health emergency or an immediate need to understand the health status of a population • Emerging Infectious Disease (EID): no information, very limited

  21. Field Epidemiology • Attempts to gather and organize data to bring order and meaning to it • Can be applied to disease outbreaks, situation assessments and policy evaluation. • Relies on a systematic approach to gather and organize data in a way that will support a better understanding of a disease situation

  22. Goal ofVeterinary field epidemiology • Prevention and control disease agents • Health of animals, humans and environment • Concepts and methods of epidemiology • Practical and information

  23. Epidemiology approach • Try and understand what factors may be increasing or reducing the risk of disease • Promoting and protecting the health of animal and human populations

  24. Endemic(โรคประจำถิ่น) • the constant occurrence of a disease that commonly presents in a particular place with stability in the level of infection • Sporadic: An irregular occurrence of a disease that commonly presents in a particular place

  25. Endemicpattern Sporadic pattern

  26. Epidemic(โรคระบาด) • the occurrence of a disease that the level of infection exceeds that normal expectancy in a specific region, spreads rapidly and usually lasts for a limited period of time • Pandemic: widespread epidemic that affects a large part of population in many countries • Epizootic: epidemic that involves animal host population

  27. Epidemicpattern

  28. Epidemic patterns

  29. Disease outbreak • survey of disease data • count of cases • describe • person / animal • place • time

  30. Relax

  31. Epidemiology triad: explain why diseases occur in a population

  32. Host Agent Environment Host Agent Host Agent Environment Environment

  33. Host Agent Environment Host Agent Environment

  34. Agents • Biological • Viruses Bacteria Parasites or prions • Chemical • Toxins • Man-made (Dioxins and melamine) • Inorganic/organic: zearalenone • Physical • Foreign bodies • Trauma • Radiation

  35. Agent Factors • Dose • Environmental hardiness • Virulence (microbial) • Infectivity (microbial) • Toxicity (poisons)

  36. Host • Natural host: • agent has adapted itself and co-exists in balance in the host • Atypical host: • agent is not normally encountered

  37. Host • Demography • Age, Sex, Species, Breed • Production type / level, Density • Biology • Genetics, behavior • Management • Intensive (housing) / extensive (free roaming) • Nutrition • Hygiene • Husbandry • Vaccination / medication

  38. Host • Marketing • Profitability related to prices (economics) • Distance from market • Herd immunity • Innate (genetic capability) • Acquired through vaccination or deliberate exposure • Proportion of total population that is resistant to a disease agent • Susceptibility • Lack of resistance to the disease agent

  39. Host Factors • Innate resistance (e.g. gastric barrier, mucocilliary transport mechanism) • Previous exposure • Passive immune status (neonates) • Vaccination status and response • Age • Gender

  40. Host Factors • Behavior (e.g. mutual grooming, dominance, pica) • Production status (e.g., lactating vs. non-lactating) • Reproductive status (e.g., pregnant vs. non-pregnant, sterile vs. intact) • Genetics

  41. Environment • Natural environment • Geography • Climate • Season • pH • Ammonia concentration • Water activity • Ultraviolet light • Organic matter

  42. 2) Human aspects • Animal management systems • Marketing systems and economics • Government policies

  43. Environmental Factors • Animal stocking density • Animal movement between groups • Housing (e.g. ventilation, sanitation) • Environmental conditions (e.g. temperature, humidity, wind velocity, precipitation) • Nutrition (protein, energy and macromineral and micromineral adequacy)

  44. Example • Increased animal density may lead to increased microbial load in the environment • a roof may prevent exposure of microbe to killing UV • low ventilation • increase humidity • increases environmental survival of the organism • increases exposure dose and infects more animals. "Bovine mastitis is a disease of man with signs in the cow." "Bad management will overwhelm the best immunology."

  45. Break 15 mins

  46. Risk factors Death recover Normal Disease disabled Natural history of disease

  47. Natural history of disease • Stage of susceptibility • Stage of preclinical disease • Stage of clinical disease • Stage of disability

  48. Iceberg principle of disease

  49. Iceberg (phenomenon) Principle

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