Outbreak is a term used in epidemiology to describe an occurrence of disease greater
than would otherwise be expected at a particular time and place. It may affect a small
and localized group or impact upon thousands of people. Two linked cases of a rare
infectious disease may be sufficient to constitute an outbreak.
Yet, the term is sometimes distinguished from an epidemic as more localized, or the
term less likely to evoke public panic.
Note: The definitions of outbreak, epidemic, and pandemic, given in this Glossary, are