title: Global public health implications of a mass gathering in Mecca, Saudi Arabia during the midst of an influenza pandemic.
abstract: BACKGROUND
  Every year millions of pilgrims from around the world gather under extremely crowded conditions in Mecca, Saudi Arabia to perform the Hajj. In 2009, the Hajj coincided with influenza season during the midst of an influenza A (H1N1) pandemic. After the Hajj, resource-limited countries with large numbers of traveling pilgrims could be vulnerable, given their limited ability to purchase H1N1 vaccine and capacity to respond to a possible wave of H1N1 introduced via returning pilgrims.
  
  
  METHODS
  We studied the worldwide migration of pilgrims traveling to Mecca to perform the Hajj in 2008 using data from the Saudi Ministry of Health and international air traffic departing Saudi Arabia after the 2008 Hajj using worldwide airline ticket sales data. We used gross national income (GNI) per capita as a surrogate marker of a country's ability to mobilize an effective response to H1N1.
  
  
  RESULTS
  In 2008, 2.5 million pilgrims from 140 countries performed the Hajj. Pilgrims (1.7 million) were of international (non-Saudi) origin, of which 91.0% traveled to Saudi Arabia via commercial flights. International pilgrims (11.3%) originated from low-income countries, with the greatest numbers traveling from Bangladesh (50,419), Afghanistan (32,621), and Yemen (28,018).
  
  
  CONCLUSIONS
  Nearly 200,000 pilgrims that performed the Hajj in 2008 originated from the world's most resource-limited countries, where access to H1N1 vaccine and capacity to detect and respond to H1N1 in returning pilgrims are extremely limited. International efforts may be needed to assist resource-limited countries that are vulnerable to the impact of H1N1 during the 2009 to 2010 influenza season.
authors.affiliation: Centre for Research on Inner City Health, Keenan Research Centre, Li Ka Shing Knowledge Institute of St. Michael's Hospital, Toronto, Ontario, Canada. khank@smh.toronto.on.ca
authors.forename: Kamran
authors.initials: K
authors.lastname: Khan
authors.forename: Ziad A
authors.initials: ZA
authors.lastname: Memish
authors.forename: Aneesh
authors.initials: A
authors.lastname: Chabbra
authors.forename: Jessica
authors.initials: J
authors.lastname: Liauw
authors.forename: Wei
authors.initials: W
authors.lastname: Hu
authors.forename: David A
authors.initials: DA
authors.lastname: Janes
authors.forename: Jennifer
authors.initials: J
authors.lastname: Sears
authors.forename: Julien
authors.initials: J
authors.lastname: Arino
authors.forename: Michael
authors.initials: M
authors.lastname: Macdonald
authors.forename: Felipe
authors.initials: F
authors.lastname: Calderon
authors.forename: Paulo
authors.initials: P
authors.lastname: Raposo
authors.forename: Christine
authors.initials: C
authors.lastname: Heidebrecht
authors.forename: Jun
authors.initials: J
authors.lastname: Wang
authors.forename: Angie
authors.initials: A
authors.lastname: Chan
authors.forename: John
authors.initials: J
authors.lastname: Brownstein
authors.forename: Michael
authors.initials: M
authors.lastname: Gardam
mesh_terms: D004196:Disease Outbreaks; D005260:Female; D006801:Humans; D053118:Influenza A Virus, H1N1 Subtype; D007251:Influenza, Human / Q000453:epidemiology* / Q000517:prevention & control / Q000635:transmission; D007514:Islam; D008297:Male; D012529:Saudi Arabia / Q000453:epidemiology; D014171:Transients and Migrants; D014195:Travel