Term
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Definition
| An aggregation of cases over a particular period closely grouped in time and space, regardless of whether the number is more than the expected number |
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Term
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Definition
| More cases of a particular disease than expected in a given area or among a specialized group of people over a particular period of time. |
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Term
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Definition
| Large numbers of people over a wide geographical area are affected |
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Term
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Definition
| An epidemic occurring over several countries or continents and affecting a large proportion of the population. |
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Term
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Definition
| The systematic and ongoing collection, analysis, interpretation, and dissemination of health data. The purpose of public health surveillance is to gain knowledge of the patterns of disease, injury, and other health problems in a community so that we can work towards their prevention and control. |
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Term
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Definition
| A serious, potentially life-threatening infectious disease that is usually transmitted to humans by the bites of rodent fleas. It was one of the scourges of our early history. There are three major forms of the disease: bubonic, septicemic, and pneumonic. |
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Term
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Definition
| An animal that transmits disease. For example a mosquito is a vector for malaria. |
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Term
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Definition
| A physical object that serves to transmit an infectious agent from person to person. |
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Term
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Definition
| The probability that an individual will be affected by, or die from, an illness or injury within a stated time or age span. Risk of illness is generally considered to be the same as the Incidence (see below) and the terms are used interchangeably. Age-span is not usually a consideration in this usage. Risk of death from a particular illness is expressed as the Case Fatality Rate (Number deaths due to a disease/Number with the disease) or the Cause-specific Mortality Rate (Number deaths due to a disease/Number in population). Age span is a more common consideration in this last usage. |
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Term
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Definition
| An infectious disease that is transmissible from animals to humans. |
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Term
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Definition
| Time in between when a person somes into contact with a pathogen and when they first show symptoms or signs of disease. |
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Term
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Definition
| Present at a continuous level throughout a population/geographic area; constant presence of an agent/health condition within a given geographic area/population; refers to the usual prevalence of an agent/condition. |
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Term
| The INCIDENCE of an illness |
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Definition
| The INCIDENCE of an illness is the number of new instances of disease in a population over a given time period. It is expressed as "X cases/Y population/ Z time" |
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Term
| The PREVALENCE of an illness is |
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Definition
| The PREVALENCE of an illness is number of affected persons in the population at any given point in time. It is expressed as "X cases/Y population". Note the only difference is that INCIDENCE (I) includes time while PREVALENCE (P) does not |
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Term
| Hill's Criteria for Causation |
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Definition
| Nine criteria must be met to establish a cause-and-effect relationship. This is commonly known as Hill's Criteria for Causation: |
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Term
| Hill's Criteria for Causation |
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Definition
Strength of Association - relationship is clear and risk estimate is high
Consistency - observation of association must be repeatable in different populations at different times
Specificity - a single cause produces a specific effect
Alternative Explanations - consideration of multiple hypotheses before making conclusions about whether an association is causal or not
Temporality - cause/exposure must precede the effect/outcome
Dose-Response Relationship - an increasing amount of exposure increases the risk
Biological Plausibility - the association agrees with currently accepted understanding of biological and pathological processes
Experimental Evidence - the condition can be altered, either prevented or accelerated, by an appropriate experimental process
Coherence - the association should be compatible with existing theory and knowledge, including knowledge of past cases and epidemiological studies |
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Term
| Chain of Transmission Triad |
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Definition
An external agent
A vector or fomite that transmits the disease
A susceptible host for the disease
This is used to define the major points of a disease case. |
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Term
| Epidemiological Study Designs |
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Definition
Ecological - comparisons of geographical locations
Cross Sectional - a survey,health questionnaire, "snapshot in time"
Case-Control - compare people with and without disease to find common exposures
Cohort - compare people with and without exposures to see what happens to each
Randomized Controlled Trial - human experiment
Quasi Experiments - research similarities with traditional experimental design or RCT, but lack element of random assignment to treatment/control |
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