Surveillance and outbreaks

Public health surveillance, the epidemic curve, attack rate and outbreak investigation.

7 pages

Measure

• Attack rateThe attack rate is the share of exposed people who fall ill in an outbreak; comparing rates by…
• Basic reproduction number (R0) and herd immunityR0 tells how many people one case infects in a population with no immunity; from it comes the…

Concept

• Case definitionA case definition is the fixed rule that decides who counts as a case in an investigation or in…
• Endemic, epidemic, outbreak and pandemicAn epidemic is defined not by how many cases there are, but by how many more than expected…
• Epidemic curveThe epidemic curve is a histogram of cases by date of symptom onset; its shape tells how the…
• Outbreak investigationInvestigating an outbreak means confirming it, counting and describing cases, finding the…
• Public health surveillanceSurveillance collects, analyses and shares health data continuously to spot problems and act in…

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← Epidemiology, biostatistics and public health

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.