Throughout the world people become ill (sometimes fatally) as result of contracting infection or disease from the community in which they live, work and/or travel. The number of cases can range in terms of the penetration within a population and geographic spread, as follows:
|Sporadic||Occasional, isolated incidences only|
|Endemic||Where the infection or disease is prevalent within a set population, or area, and the level of incidences are to be expected and predictable|
|Outbreak||Where there is a sudden, unexpected, localised breaking out or occurrence of infection or disease|
|Epidemic||An outbreak that affects many individuals within a population or region at the same time and exceeds expected rates|
|Pandemic||An epidemic that spreads worldwide|
Therefore, a ‘pandemic’ is the highest category to denote the spread of infection or disease. It identifies that the infection or disease had reached a global scale and is affecting many individuals.