Session 3: Epidemiology Flashcards
What can epidemiology be used for?
By looking at frequency and pattern of health events it prevents the occurrence or spread of diseases, and suggests changes (medical, environment, legislative, etc.)
What does frequency refer to in epidemiology?
Frequency refers to the number of health events and the relationship of that number to the size of the population. The resulting rate allows epidemiologists to compare disease occurrence across different populations.
What does pattern refer to in epidemiology?
The occurrence of health-related events by time (annual, seasonal, weekly), place (geographic variation, urban/rural, location), and person (risk of illness, injury, disability, age, sex, and behaviours and environmental exposures).
What is an exposure?
A risk factor for the outcome being investigated: e.g. drinking water from a particular source, contact with a person with an infectious disease, living in an area with disease vectors, behaviours (diet, exercise, etc.). An exposure is basically just the cause (and likeliness) of the outcome.
What is an outcome?
The disease, or event, or health -related state, that we are interested in: e.g. Influenza (infectious disease), Food poisoning (infectious disease), Heart attack (lifestyle related disease), Accidents, Weight gain or loss
What is the chain of infection?
Transmission of an infectious disease can occur when the infectious agent leaves its reservoir or host through a portal of exit, is conveyed by a mode of transmission, and enters through an appropriate portal of entry to infect a susceptible host. (overall: movement of an infection/the infectious bacteria from host to host).
What are reservoirs (chain of infection)?
The source of infection, they can be other humans (measles, smallpox), animals (bats - Ebola, dogs - rabies), or environmental (soil – histoplasmosis, water - cholera).
What is transmission (chain of infection)?
Transmission can be direct (physical contact, droplet spread) or indirect (airborne, food, objects, vectors such as mosquitos).
What are portals of exit (chain of infection)?
The path by which a pathogen leaves its host, such as the human respiratory tract for influenza.
What are portals of entry (chain of infection)?
The way a pathogen enters a susceptible host (respiratory tract, cuts in the skin, reproductive tract).
What is a susceptible host (chain of infection)?
Susceptibility of a host depends on factors such as genetics, health status, specific immunity, and nonspecific factors that affect an individual’s ability to resist infection or to limit pathogenicity (malnutrition, other illnesses etc).
Describe “measures of risk”.
There are numerous measures of risk for a disease or health condition or state used as analytical tools by epidemiologists. These can include: Ratios, Proportions, and Rates. Two of the most frequent measures that are used are incidence and prevalence. Incidence is the number of new cases in a population in a certain time. Prevalence is the total number of individuals with the condition at a point in time (both new and continuing cases). Individuals can leave the prevalence group by either recovering or dying from the disease.
What is a longitudinal study?
A study that occurs over a long period of time (a series of years, e.g. 10 years, 70 years).
