Module 3 Flashcards
Disease definition
Interruption, cessation or disorder of body functions systems or organs
Etiology
The study of causation or origination. The study of why things occur
Disease classifications -2
- Infectious: you can catch it from another
2. Noninfectious: non contagious
Sensitivity
Proportion of individuals who truly have the dx and are tested positive
TP/ TP + FN
Specificity
Proportion of those who truly do not have the dx and are tested negative.
TN / TN+FP
Positive predictive value
TP/TP+FP
The proportion of true positive tests out of all positive
Negative predictive value
tN/TN+FN
The proportion of true negative tests out of all negatives
Endemic
Ongoing usual level or constant presence of a disease within a given population or geographical area
Two types of estimation and definitions
- Point estimate, the best single number estimate
2. Confidence interval estimate, range of values or confidence is attached
Mean
Average of all numbers which shows central tendency, This is affected by outliers
Relationship between sensitivity specificity positive and negative predictive value
If we increase sensitivity we reduce specificity and vice versa. Increased specificity affects the positive predictive value inversely and increased specificity has the same effect with negative predictive values. This can help an epidemiologist determine the effectiveness of a screening method and the PPV and NPV help detect how feasible it is. If there is a lot of false positive or negative’s the test is not very accurate and specificity or sensitivity needs to be adjusted
Epidemic
Rapid spread of disease within a short period of time that is higher than what is expected in a population
Pandemic
An epidemic that has spread beyond the immediate population over entire countries, affects many people and can be global.
Strategy to control a disease outbreak that impacts multiple countries
Stop transportation in and out of country until the outbreak is controlled.
Establish programs to help test and treat as many at risk ill people as possible.
Shut down large events where people gather in large numbers.
Implement educational campaigns to teach those at risk how to avoid illness.
Three types of transmission of infectious dx
Contact, vehicle, vector
Contact transmission (3 types)
Direct: immediate transfer of an agent from the host or reservoir to a susceptible host (ex kissing or sex) mono, AIDS
indirect: agent is transferred or carried by an intermediate item, organism, means, or process to a susceptible host, resulting in disease (ex dirty cup or tissue) common cold, hepatitis (dirty needle)
droplet: organisms are in droplets produced by sneezing coughing and talking, don’t travel far. Common cold.
Vehicle transmission (two types)
Transmission of disease agents by medium such as water food or air, two types
Waterborne: carried through water. Cholera.
airborne: droplets or dust particles carried the pathogen to host, Travel more than a meter in air. Fungal spores, measles.
Vector transmission (2 types)
Animals that carry pathogens from one house to another- 2 types
Mechanical: pathogen uses a separate host to physically transfer disease (ex on feet or body parts)
, passive transmission.
biological: pathogen undergoes changes as part of its lifecycle well within the host or vector before being transmitted to a new host. Transmitted through bite, vomit, or fecal matter. Example, Lyme disease and malaria
Stages of natural history of disease
- Stage of susceptibility, well (primordial, primary prevention)
- Preclinical, at risk (secondary)
- Clinical, Symptom onset and usual diagnosis (secondary)
- Post clinical phase, chronic (tertiary)
Ratio variable
This variable has a scale with an inherent order and a true zero
example is height and weight
Interval variable
Variable with definitive intervals
Example is temperature measured in degrees Celsius
Ordinal or ranked variable
More than two responses that are ordered
Example is how happy are you with your service? 1. Extremely happy 2. Happy 3. Neutral 4. Unhappy 5. Very unhappy
Nominal or categorical variable
More than two responses that are not ordered
What make of car do you have? 1. Honda 2. Ford etc…
Binomial variable
Also known as dichotomous variable, a nominal variable with only two outcomes
Example is success or fail
