WEEK ONE Epidemiology epi upon demos man people and logos study word I the study of health and disease at the population level looking at 1 overall distribution variation in occurrence of the disease 2 subgroup patterns and trends race ethnicity gender SES 3 determinants presumed and causal agents independent variables a any factor that brings about a change of health condition i biological bacteria ii chemical living next to a plant lead paint pesticides iii social SES diet exercise 4 outcomes possible results dependent variable lead paint determinant lead poisoning outcome II Different than medicine 1 individual medicine a b c signs and symptoms diagnosis treatment 2 population epidemiology overall population trends risk factors effects of screening clinical trials Aims of epidemiology describe health status as a population distribution and rates predict disease occurrence monitor health of community surveillance screening explain disease causes transmission control distribution of disease prevention containment of disease Types of data quantitative measures of disease occurrence or magnitude morbidity mortality incidence prevalence risk rate measures of association or relative risk odds ratio rate ratio risk ratio qualitative use of focus groups interviews or case studies to describe distribution patterns determinants and outcome qualitative can be collected by case studies focus groups quantitative rigorous numerical vs qualitative risch description texts Core Areas of public health epidemiology biostatistics more sophisticated quantitative analysis health education behavior people who go out and target certain groups policy planning ban certain things warning labels restrictions environmental occupational health Changing Patterns of Disease demographic transition aging of the population population is living longer epidemiologic transition shift from infectious to chronic disease causes altered diagnostic criteria sanitation age structure every country is at a different stage of transition Trends disappearing disorders emerging disorders HIV Lyme disease residual disorders cause prevention known health effects of tobacco persisting disorders effective prevention cure unknown some forms of cancer and mental disorders History of Epidemiology I Hippocrates 1 Known as father of medicine and 1st epidemiologist 2 3 4 observational methods first to describe disease from a rational basis rather than supernatural Identified both environmental and behavioral determinants of health a swampy areas malaria yellow fever 5 termed epidemic endemic a epidemic sharp increase of number of cases b endemic continuous but low incident rate 6 4 humors a yellow bile black bile blood phlegm II Middle Ages Black Death 1346 1352 1 Bubonic plague 1 3 of European population killed 2 caused by a bacterial infection of Yersinia pestis transmitted via flea bites from rodents a animals humans 3 60 case fatality 60 of people who get it die from it III Renaissance 1200 1699 John Graunt 1 Columbus of Statistics first to compile population level vital statistics statistics of life death in a life table a gender ratios in births and deaths infant mortality seasonal mortality 2 Bills of Mortality a weekly count of deaths in London b patterns of fertility and morbidity c seasonal patterns of illness d 4 different plague spikes e most common cause of death Development of Epidemiology I Overview 1 2 systematic methods for describing and summarizing disease 3 quantitative assessment of disease recognition of a biologic basis of disease II Late 1600s early 1700 s 1 scientific experiments a James Lind and scurvy i the idea of using comparison groups emerges b Edward jenner and smallpox cowpox inoculation prevents smallpox vaccination i ii procedures replaces variolation by 1840 III 19th Century William Farr 1 Rise of public health and prevention medicine a proposed that disease is multifactorial 2 Farr drew many inferences about the English population rate of illegitimate births over time a average age of population b c association between elevation and cholera deaths d association between population density and mortality e association between improvements in sanitation and mortality rates International Classification of Disease how doctors describe illness 3 4 Web of causation more than one factor can contribute to an illness John Snow 1 anesthesiologist 2 investigated London cholera outbreak a pandemic 500 deaths in a 10 day period 3 Disagreed that cholera is caused by bad airs called miasmata 4 conducts the first modern outbreak investigation a used systematic methods to investigate cause of the cholera outbreak b door door interviews shoe leather epi assess number of deaths from cholera and company that supplies the water c conducted natural experiment charted frequency and distribution of cholera outbreak laid groundwork for descriptive and analytic epidemiology d e People didn t believe him Vibrio cholerae finally identified in 1880s IV Bacterial Revolution late 1800 s early 1900s 1 scientific understanding of etiology of infectious diseases and basis for public health efforts focus on infectious diseases 2 3 Louis Pasteur a french chemist pasteurization 4 Robert Koch 4 postulates a criteria to establish a causal relationship between a causative microbe and a disease i organism must be found in all organisms suffering from the disease but should not be found in healthy organisms ii organism must be isolated from a diseased organism and grown in pure iii iv culture the cultured organism should cause disease when introduced into a healthy organism the organism must be reisolated from the inoculated diseased experimental host and identified as being identical to the original specific causative agent V Early 20th Century 1 pandemic influenza 2 Alexander Fleming a killed 50 100 million people globally 1 3 of the world developed clinical illness a discovered penicillin in 1928 used as an antibiotic VI Contemporary Era 1941 present 1 World War II a b influence of demographic sociologists and statisticians rise in study of chronic diseases first national cancer survey i ii advent of study designs and analytic methods used today randomized clinical trials odds ratio relative risk 2 Post World War II landmark reports and studies refinements in methods a b understanding and preventing chronic diseases VII Landmark Studies 1 Framingham Study 1948 present a cohort study to evaluate risk factors for coronary heart disease b