The annual Hajj pilgrimage - minimizing the risk of ill health in pilgrims from Europe and opportunity for driving the best prevention and health promotion guidelines

•Every year, the Kingdom of Saudi Arabia (KSA) hosts the Hajj pilgrimage, which is the largest mass gathering in the world held on a recurrent annual basis.•Infectious disease outbreaks at the annual Hajj pilgrimage are uncommon and have been controlled to a great extent.•Crush injuries and stampedes, which can pose major risks at mass gatherings, are infrequent during the Hajj relative to its size and logistical complexity.•The KSA runs a well-coordinated, inter-sectoral approach for the planning, communication, public health, and safety issues regarding the Hajj. Planning for Hajj starts soon after the end of the current Hajj and the KSA Ministry of Hajj and Ministry of Health liaise with governments of all countries from which pilgrims come to the KSA.•The KSA also provides regular updated Hajj travel advice and liaises closely with international public health organizations and Hajj travel agencies.•Recent alerts were raised for the prevailing global threats from Middle East respiratory syndrome coronavirus (MERS-CoV), Ebola, influenza and other respiratory tract viruses, multidrug-resistant TB, and multi-antibiotic-resistant bacteria.•The value of the Hajj experience to planners of mass gatherings in sharing best practices is evident, but lessons can go beyond mass gatherings to inform other areas of public health that require inter-sectoral engagement, such as One Health and the control of antimicrobial resistance. Mass gatherings at religious events can pose major public health challenges, particularly the transmission of infectious diseases. Every year the Kingdom of Saudi Arabia (KSA) hosts the Hajj pilgrimage, the largest gathering held on an annual basis where over 2 million people come to KSA from over 180 countries. Living together in crowded conditions exposes the pilgrims and the local population to a range infectious diseases. Respiratory and gastrointestinal tract bacterial and viral infections can spread rapidly and affect attendees of mass gatherings. Lethal infectious disease outbreaks were common during Hajj in the 19th and 20th centuries although they have now been controlled to a great extent by the huge investments made by the KSA into public health prevention and surveillance programs. The KSA provides regular updated Hajj travel advice and health regulations through international public health agencies such as the WHO, Public Health England, the Centers for Disease Control and Prevention, and Hajj travel agencies. During the Hajj,