3 In a recent report, experts from the Saudi Arabian Ministry of Health shared their knowledge about how to prevent the outbreak of global diseases at mass gatherings. The Ministry has decades of experience in managing the health of pilgrims2 in the yearly Hajj to Mecca in Saudi Arabia. With more than two million pilgrims each year, the Hajj is the largest international mass gathering in the world. Many of the pilgrims arrive from low-income countries and have had little health care. Elderly or sick pilgrims want to complete this very important religious pilgrimage before they die, so they travel to Mecca with thousands of others