title: Respiratory tract infections during the annual Hajj: potential risks and mitigation strategies.
abstract: OBJECTIVE
  Mass gatherings such as religious pilgrimages, sporting events and music concerts are becoming larger and more frequent. The scale and frequency of large-scale international events pose substantial risks to the spread of infectious diseases. The available literature on respiratory tract infections at the Hajj pilgrimage - annually attended by 3 million pilgrims from all over the globe - are reviewed.
  
  
  RESULTS
  The most common respiratory tract infection viruses are influenza and rhinovirus. Despite the occurrence of the Hajj during the 2009 H1N1 pandemic the available literature did not show an increased rate of infection. In hospitalized patients, pneumonia is a significant cause of admission accounting for 20-50% of such admissions.
  
  
  CONCLUSIONS
  The use of masks may reduce exposure to droplet nuclei, the main mode of transmission of most respiratory tract infections. The practice of social distancing, hand hygiene, and contact avoidance was associated with reduced risk of respiratory illness. In addition, utilizing the recommended vaccines would decrease the risk of acquiring respiratory tract pathogens.
authors: Saudi Aramco Medical Services Organization, Dhahran, Kingdom of Saudi Arabia.
authors: Jaffar A
authors: JA
authors: Al-Tawfiq
authors: Alimuddin
authors: A
authors: Zumla
authors: Ziad A
authors: ZA
authors: Memish
mesh_terms: D006801:Humans; D007251:Influenza, Human / Q000453:epidemiology / Q000517:prevention & control / Q000821:virology; D007514:Islam; D062486:Public Health Surveillance; D012141:Respiratory Tract Infections / Q000453:epidemiology / Q000517:prevention & control / Q000821:virology; D014195:Travel