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Chapter 8 Advising Travelers With Specific Needs

Travel to Mass Gatherings

C. Virginia Lee, Gary W. Brunette, Nancy M. Gallagher


Every year, millions of people travel internationally for mass gatherings that range from major sports events to fairs, festivals, concerts, or political rallies. These mass gatherings pose special risks for travelers, because large numbers of people in small areas can facilitate the spread of infectious diseases or increase the risk of injury. These issues should be considered when providing pre-travel consultations.

A mass gathering is usually defined as more than a specified number of people (which may be as few as 1,000 people, although 25,000 people is most commonly used), at a specific location, for a specific purpose, for a defined period of time. The World Health Organization defines a mass gathering as “an event [where] the number of people attending is sufficient to strain the planning and response resources of the community, state, or nation hosting the event.” Although mass gatherings can be spontaneous events, such as a funeral for a head of state, or a form of political expression, such as a rally or march, most are planned events. Some mass gatherings occur regularly at different locations (such as the Olympic Games or the FIFA World Cup), and others recur in the same location (such as the Hajj or Wimbledon).

Mass gatherings can be characterized by purpose, location, participants, and duration. The reason for the gathering will often set a predictable tone for the event. Rock concerts are expected to be loud and boisterous, and segments of the crowd will engage in more risky behaviors. On the other hand, a religious event, such as a papal visit, would have other predictable characteristics. The purpose often influences the characteristics of the participants (age, origin, culture, homogeneity). For example, religious and family-oriented events tend to have participants at the extremes of age, who may have increased susceptibility to certain diseases.

The location will determine the climate and weather and will give some indication of social and political stability in that area. There will be diseases endemic to that area, and there may be specific disease outbreaks occurring that could affect the health of visitors. Geography (particularly altitude) and climate can predispose visitors to problems such as altitude sickness, heat-related illnesses, and dehydration. The actual venue can be fixed (stadium, open space) or mobile (procession, pilgrimage). Some gatherings are indoors or in protected spaces that can shield against the elements, while others are completely exposed. The health infrastructure at the event and in the area will determine the ability to respond to both anticipated and unanticipated incidents. Facilities for food, water, and sanitation can affect the health of attendees. Often these facilities are temporary, recently erected, and may not meet the needs of the population.

The density of the crowd influences the potential risks, such as problems with crowd control, disease transmission, and injury. Large crowds can quickly overwhelm facilities. Crowd characteristics, such as age, mood, and availability of drugs or alcohol, will influence whether violence is a risk. Densely packed crowds are more likely to be violent. Events with large numbers of international participants tend to have increased risk of infectious disease outbreaks. This is in part related to differences in patterns of endemic diseases and levels of vaccinations between host and home countries. The longer an event lasts, the more likely that stresses to facilities, organizers, and participants will occur.

The most common health problems reported at mass gatherings are injuries, respiratory and cardiac issues, heat-related illness, alcohol or drug effects, and gastrointestinal illnesses. These problems can typically be addressed by either on-site clinics or nearby health facilities. However, circumstances leading to mass casualties have occurred at many different types of events.

Although communicable diseases are an understandable concern for organizers of large gatherings, they have historically not been a major cause of adverse health events. For example, infectious diseases contributed to <1% of health care visits during the 1996 Atlanta Olympic Games and the 2000 Sydney Olympic Games. Furthermore, illnesses such as influenza may be difficult to definitively attribute to attendance at an event. On the other hand, meningococcal meningitis transmission during the Hajj not only caused illness but also resulted in changes in requirements for Hajj pilgrims (see Chapter 4, Hajj Pilgrimage, Saudi Arabia).

Mass gatherings held in the context of an outbreak or pandemic pose additional risks for travelers and the population of host countries. International attendees bring to the gathering their cultures, languages, social and health behaviors, and disease susceptibilities, all of which may affect the course of the outbreak. Organizers of these events, in cooperation with local officials and health authorities, should strongly consider these factors when conducting a risk assessment for the event. If a decision is made to continue with the event while the outbreak is ongoing, special precautions might be recommended for attendees.


All travelers to international mass gatherings should be evaluated by a travel health provider, ideally 4–6 weeks before travel, to assess the level of risk faced by the traveler and to take steps to manage the risk. Travelers should take precautions to mitigate risks associated with mass gatherings:

  • Be aware of the most likely health risks associated with the particular event they are attending and what they can do to stay healthy and safe.
  • Be up-to-date with all routine immunizations, including influenza vaccine, when available.
  • Maintain vigilance at gatherings where drug and alcohol use could contribute to dangerous behavior.
  • Avoid gatherings where political or religious fervor may contribute to violence, or where inadequate facilities may contribute to an unhealthy environment.
  • Try to avoid densely congested areas with limited egress.
  • Be aware of emergency precautions and locate exit routes and medical facilities.

Knowledge of the country or region being visited is essential. Country information can be obtained from destination pages on the CDC Travelers’ Health website (, which provides destination-specific information and will often post specific guidance for major events. The Department of State website ( may provide additional information about countries and specific events.


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