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# Epidemiology basics

What epidemiology studies, the natural history of disease, the epidemiologic triad and the levels of prevention.

9 pages

- [**Descriptive epidemiology: person, place and time** Descriptive epidemiology sorts cases by who, where and when to reveal patterns and suggest…](https://durgical.com/en/epidemiology/descriptive-epidemiology-person-place-and-time/)
- [**Epidemiologic triad and chain of infection** An infection needs an agent, a susceptible host and an environment that brings them together…](https://durgical.com/en/epidemiology/epidemiologic-triad-and-chain-of-infection/)
- [**High-risk and population prevention strategies** Treating only the highest-risk people helps a few a lot; shifting the whole population a little…](https://durgical.com/en/epidemiology/high-risk-and-population-prevention-strategies/)
- [**History of epidemiology** A few historical studies invented the methods used today: counting, mapping, comparing groups…](https://durgical.com/en/epidemiology/history-of-epidemiology/)
- [**Levels of prevention** Prevention acts before risk appears, before disease, before symptoms, after harm, and also…](https://durgical.com/en/epidemiology/levels-of-prevention/)
- [**Natural history of disease** The course a disease follows with no intervention: from a healthy, exposed person to symptoms…](https://durgical.com/en/epidemiology/natural-history-of-disease/)
- [**Risk and exposure assessment** Risk assessment estimates how much harm a substance or agent can cause, given how many people…](https://durgical.com/en/epidemiology/risk-and-exposure-assessment/)
- [**Spectrum of infection: inapparent, clinical and carriers** Most infections go unseen: clinical cases are the tip of the iceberg, and carriers spread…](https://durgical.com/en/epidemiology/spectrum-of-infection-inapparent-clinical-and-carriers/)
- [**What epidemiology is** Epidemiology studies how much disease a population has, who gets it, where and when it appears…](https://durgical.com/en/epidemiology/what-epidemiology-is/)

## A to Z

- [A](https://durgical.com/en/epidemiology/a-z/a/)
- [B](https://durgical.com/en/epidemiology/a-z/b/)
- [C](https://durgical.com/en/epidemiology/a-z/c/)
- [D](https://durgical.com/en/epidemiology/a-z/d/)
- [E](https://durgical.com/en/epidemiology/a-z/e/)
- [F](https://durgical.com/en/epidemiology/a-z/f/)
- [G](https://durgical.com/en/epidemiology/a-z/g/)
- [H](https://durgical.com/en/epidemiology/a-z/h/)
- [I](https://durgical.com/en/epidemiology/a-z/i/)
- [K](https://durgical.com/en/epidemiology/a-z/k/)
- [L](https://durgical.com/en/epidemiology/a-z/l/)
- [M](https://durgical.com/en/epidemiology/a-z/m/)
- [N](https://durgical.com/en/epidemiology/a-z/n/)
- [O](https://durgical.com/en/epidemiology/a-z/o/)
- [P](https://durgical.com/en/epidemiology/a-z/p/)
- [Q](https://durgical.com/en/epidemiology/a-z/q/)
- [R](https://durgical.com/en/epidemiology/a-z/r/)
- [S](https://durgical.com/en/epidemiology/a-z/s/)
- [T](https://durgical.com/en/epidemiology/a-z/t/)
- [U](https://durgical.com/en/epidemiology/a-z/u/)
- [V](https://durgical.com/en/epidemiology/a-z/v/)
- [W](https://durgical.com/en/epidemiology/a-z/w/)
- [Y](https://durgical.com/en/epidemiology/a-z/y/)

[← Epidemiology, biostatistics and public health](https://durgical.com/en/epidemiology/)

Educational content on epidemiological and statistical methods; the examples use made-up numbers to teach the calculation. Not a clinical or legal guide: current Colombian rules are in the official sources.

Representative model, for educational purposes only.

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Source: https://durgical.com/en/epidemiology/areas/basics/
License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/epidemiology/areas/basics/