epidemiology

epidemiology Epidemiology (epi/dem/o/logy) comes from Epi: meaning “on or upon” Demos: meaning “people” Ology: meaning “the study of” Epidemiology is the study of the distribution and determination of the causes of health-related conditions or events in populations. It is used in healthcare and especially with infectious disease. epidemiology

How epidemiology is used

community health assessment These questions are researched when doing a community assessment: What are the actual and potential health problems in the community? Where do they occur? Who is at risk? Which problems are declining over time? Which ones are increasing or have the potential to increase? How do these patterns relate to the level and distribution of services available? community health assessment

The Epidemiologic Approach Case Definition A set of standard criteria for deciding whether a person has a particular disease or other health- related condition The Epidemiologic Approach

Statistics and Reports When physicians diagnose a case of a reportable disease they send a report of the case to their local health department. Time - when the case occurred Place - where the patient lived Person - the age, race, and sex of the patient Statistics and Reports

Statistics and Reports Health departments convert the case counts into rates, which relate the number of cases to the size of the population where they occurred Statistics and Reports

Types of Epidemiology

Descriptive Epidemiology Organize and summarize data according to time, place, and person Time – disease rates change over time Example: the seasonal increase in influenza with the onset of cold weather Time data is usually shown on a graph Descriptive Epidemiology

Descriptive Epidemiology Place - describe a health event by place to gain insight into the geographical extent of the problem and similarities in location. Residence Birthplace Place of employment School district Hospital unit Descriptive Epidemiology

Descriptive Epidemiology Person: inherent characteristics of people Age Race Sex Acquired Characteristics Immunity Marital status Descriptive Epidemiology

Descriptive Epidemiology Activities Occupation Leisure activities Use of medications/tobacco/drugs Descriptive Epidemiology

Descriptive Epidemiology Conditions in which people live Socioeconomic status Access to medical care Descriptive Epidemiology

Analytic Epidemiology Used to search for causes and effects, or the why and the how. Looks for relationships in the data Analytic Epidemiology

Causation

Cause of disease is a factor (characteristic, behavior, event, etc Cause of disease is a factor (characteristic, behavior, event, etc.) that influences the occurrence of disease. An increase in the factors leads to an increase in disease. Reduction of the factors leads to a reduction in disease Causation

Epidemiologic triangle Traditional model of infectious disease causation.

Epidemiologist use the Chain of infection

Epidemiology: Level of Disease Level of Disease - amount of a particular disease that is usually present in a community Increasing amount of disease Sporadic Endemic Epidemic Pandemic Epidemiology: Level of Disease

Epidemiology: Level of Disease Sporadic - irregular pattern of occurrence, with occasional cases occurring at irregular intervals Endemic - persistent level of occurrence with a low to moderate disease level Epidemic or Outbreak- occurrence of a disease within an area is clearly in excess of the expected level for a given time period Example: Ebola epidemic or outbreak of 2014 Pandemic - an epidemic spreads over several countries or continents, affecting a large number of people Example: Bubonic plague and AIDS Epidemiology: Level of Disease