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Incidence is usually more useful than prevalence in understanding the disease etiology: for example, if the incidence rate of a disease in a population increases, then there is a risk factor that promotes the incidence. For example, consider a disease that takes a long time to cure and was widespread in 2002 but dissipated in 2003.
In science, prevalence describes a proportion (typically expressed as a percentage). For example, the prevalence of obesity among American adults in 2001 was estimated by the U. S. Centers for Disease Control (CDC) at approximately 20.9%. [5] Prevalence is a term that means being widespread and it is distinct from incidence.
The term epidemiology is now widely applied to cover the description and causation of not only epidemic, infectious disease, but of disease in general, including related conditions. Some examples of topics examined through epidemiology include as high blood pressure, mental illness and obesity. Therefore, this epidemiology is based upon how the ...
Epidemiological (and other observational) studies typically highlight associations between exposures and outcomes, rather than causation. While some consider this a limitation of observational research, epidemiological models of causation (e.g. Bradford Hill criteria) [7] contend that an entire body of evidence is needed before determining if an association is truly causal. [8]
Malaria has had multiple documented temporary epidemics in otherwise non-affected or low-prevalence areas, but the vast majority of its deaths are due to its constant prevalence in affected areas. [2] Tuberculosis (TB) became epidemic in Europe in the 18th and 19th century, showing a seasonal pattern, and is still taking place globally.
Lessler and others suggest that a hyperendemic region or synonymously a "burden hotspot" (defined as an area of elevated disease incidence or prevalence) should be distinguished from an "emergence hotspot" (defined as an area with a high frequency of emergence or reemergence of diseases or drug-resistant strains) and a "transmission hotspot ...
For instance, to accurately determine the prevalence of pathogen infection in a specific species of fish, it is preferable to examine a sample of 200 fish rather than 100 fish. Several fundamental facts of mathematical statistics describe this phenomenon, including the law of large numbers and the central limit theorem.
In epidemiology, case fatality rate (CFR) – or sometimes more accurately case-fatality risk – is the proportion of people who have been diagnosed with a certain disease and end up dying of it. Unlike a disease's mortality rate, the CFR does not take into account the time period between disease onset and death. A CFR is generally expressed ...