Epidemiology Flashcards
Epidemiology
The study of the occurrence and distribution and determinants of health related evets, states and processes in specified population
- Includes the study of the detriments influences such processes
- includes the application of these things
What does epidemiology allow us to study?
- The frequency of a disease or a condition
- The distribution of a disease or condition
- Causal factors
What are the questions you need to answer in epidemiology?
- How individuals/populations are affected → clinical signs
- What causes →pathogen, causal factors, etc
- When they are affected → time or life stage
- Who is affected → characteristic of those affected (age, sex, breed, etc)
- Where they are affected → location (where is it concentrated)
Also state prevalence/incidence and mode of transportation
The epidemiological triad of disease
Host
Agent
Environment
sometimes vector
Provide three examples of
Host Factors
Epidemiology
- Age
- Sec
- “Use”
- Genetics
- Immunity (includes vaccination status)
- Medical history
- Ect
Provide three examples of:
Agent Factors
Epidimiology
Biological (bacteria, viruses, yeast, ect)
Chemical (toxins, poison, feed, ect)
Mechanical (physical injury, ect)
Nutritional
Provide three examples of:
Environmental factors
Epidemiology
Geographic location
Climate
Water supply
DOES NOT INCLUDE VACCINATION STATUS
Modes of disease Transmission
Epidemiology
Direct - contact must be made between individuals
- Ex. Sexual interaction (contagious equine metris)
Indirect - Transmission via a common source (ex. Water source)
- Can be a vector or a fomite
Vector - Transmission via a living source
- Diseases is carried by a vector but doesn’t cause disease
- They aren’t sick themselves
NOT THE SAME AS CROSS CONTAMINATION
Ex. Mosquitoes, ticks, fleas
Ex. West Nile, EEE, the plague,
Fomite - Transmission via a non-living source
- Contaminated needles, boots, ect
Are we a vector or a formite?
Is it in you (vector), or is it on you (fomite)
Endemic
Continual source of a pathogen in a limited region
* It’s in the environment
* You can’t really get rid of it
Epidemic
Atypical increased occurrence of an illness in a limited region
- Flu season
Pandemic
Increased occurrence of illness that crosses national borders
Outbreak
Epidemic limited to a localized, rapid increase in the incidence of a disease
* Small amount
* Sudden, rapid
What are the types of outbreaks?
Single point of research - Single point of exposure
* One source of exposure to the pathogen at a single point of time
Multiple exposure - Multiple sources of exposure or different groups are susceptible at different times
* Could be endemic
Continuous exposure - A population (or herd) is exposed to a continuous source of disease
* Sickness all the time
* Could be endemic, epidemic, or pandemic
Measures of Occurence
Epidemiology
Incidence - The number of NEW CASES that occur in a population at risk during a specified period of time
Can account for risk and rate
Prevalence - The number of EXISTING cases in a population at a specific time
Could be a single time point or a long term measure (typically the longer term)
In what cases should you measure incidence and what cases should you measure prevalence?
Prevalence
Useful for assessing health statue of a population
* Planning
* Chronic diseases (not useful for acute conditions)
Incidence
Investigation of causation, prevention, and treatments
* Planning
* Can measure repeated events
* (strangles cases, avian influenza, ect)
Surveillance
Epidemiology
“Systematic and continuous collection, analysis, and interpretation of data, closely integrated with the timely and coherent dissemination of the results and assessment to those who have the right to know so that action can be taken.”
Passive vs Active Surveillance
Epidemiology
Passive surveillance
* Data from reported cases
* Reported by primary care physicians, hospitals, or other healthcare providers
* Inexpensive
* Completeness and underreporting are issues
Active Surveillance
* Case finding
* Can involve interviewing, reviewing medical records, visiting field sites
* Expensive
* More accurate reporting
Screening
Epidemiology
“The presumptive identification of unrecognized disease or defect by the application of tests, examinations, or other procedures which can be applied directly”
* FIV testing
* Screening for welfare violation
* Screening for anatomical variations
Which factors do you need to create a case definition
Epidemiology
- How individuals/populations are affected → clinical signs
- What causes →pathogen, causal factors, etc
- When they are affected → time or life stage
- Who is affected → characteristic of those affected such as age, sex,
etc - Where they are affected → location
Mode of transportation
Incidence/Prevalence
Single Point of Exposure
Epidemiology
Single point of exposure - Single point of exposure
* One source of exposure to the pathogen at a single point of time
Multiple Exposure
Epidemiology
Multiple exposure - Multiple sources of exposure or different groups are susceptible at different times
* Could be endemic
Continuous Exposure
Epidemiology
Continuous exposure - A population (or herd) is exposed to a continuous source of disease
* Sickness all the time
* Could be endemic, epidemic, or pandemic
