Outbreak

Virus outbreaks occur when a virus bypasses infection control measures and a relatively high number of infections are observed where no cases or sporadic cases occurred in the past. The study of pathogenic viral outbreaks is a branch of epidemiology and usually refers to virus outbreaks that make people, animals, or plants sick. As with bacterial outbreaks, viral outbreaks are classified as sporadic (occasional occurrence), endemic (regular cases often occurring in a region), epidemic (an unusually high number of cases in a region), or pandemic (a global epidemic).

See also

• epidemiology
• bacterium
• virus