Inclusion criteria

· Original papers

· English or Spanish language

· Published between January 2000 and May 2014

· Sick population were workers

· Outbreaks started in a working environment

Exclusion criteria

· Occupational outbreaks arising in the context of major pandemics (e.g., severe acute respiratory syndrome, avian influenza) in order to avoid that an excess of publications in this health alerts could modify the profile of outbreaks in working environments.

· Public health or environmental outbreaks (mediated by vectors, water, foods, etc.) as they are far from the subject of the study due to their epidemiological characteristics.

· Outbreaks of person/person transmission, since their occupational origin may be uncertain.

· Outbreaks of zoonosis by contact with live animals not arising from professional activities: wild or domestic animals, etc.