A<unk>  is an unusually large aggregation of a relatively uncommon medical condition or event within a particular geographical location or period. Recognition of a<unk>  depends on its size being seen as greater than would be expected by the play of chance. Identification of a suspected<unk>  may initially depend on anecdotal evidence. Epidemiologists and biostatisticians need to assess whether the suspected<unk>  corresponds to an actual increase of<unk>  in the area. Typically, when<unk> s are recognized, they are reported to public health departments in the local area. If<unk> s are of sufficient size and importance, they may be re-evaluated as outbreaks. John Snow's pioneering investigation of the 1854 cholera outbreak in Soho, London, is seen as a classic example of the study of such a<unk> .
Disease cluster
Risk factor
Head injury criterion
Dose profile
Sentinel event
Epidemic curve
Cancer cluster
VACTERL association