Legionnaires' disease outbreak investigation toolbox

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Design of a cohort study [1]

Cohort studies

A cohort study is the best technique for analysing an outbreak in a small, well-defined population.

Definition: epidemiological study in which subsets of a defined population can be identified who are, have been, or in the future may be exposed or not exposed or exposed in different degrees, to a factor, or factors hypothesized to influence the occurrence of a given disease or other outcome. The main feature of a cohort study is observation of a large numbers over a long period (commonly years) with comparison of incidence rates in groups that differ in exposure levels.

  1. BONITA R., BEAGLEHOLE R. & KJELLSTROM T. (2006) Basic Epidemiology World Health Organisation http