[Pilgimage and other mass gatherings: epidemiology and prevention].

Hajj is the typical example of a mass gathering. Pilgrims should receive appropriate counselling. Following the late 20th century epidemics, meningococcal ACWY vaccination is obligatory for Saudi Arabia. Respiratory illnesses are frequent and influenza vaccination recommended. Elderly and ill travellers should be aware of the physical constrains during the pilgrimage and the risk of trauma. No epidemic was detected during big sports events, but surveillance is warranted and recommendations need to take local factors into account. Epidemics of influenza and norovirus infections are frequently reported during cruises. Elderly or ill people should be immunized against flu and all tourists should receive adequate counselling on measures of hygiene.