Hajj-associated infections.
The Hajj is the largest annual mass gathering event in the world, thus favoring the transmission of various infections: 183 different nationalities, high temperatures, coincidence with the start of the flu season in the Northern hemisphere, a long barefoot walk, tent-type accommodation, communal toilet facilities, absence of food control, and sharing of razors. Infections are the first cause of hospital admission, which often occurs in the home country of pilgrims. Literature review on PubMed from 1952 to November 2015 on the epidemiology and prevention of infections contracted during the Hajj, using the keywords "Hajj" and "infections". Respiratory tract infections, ENT infections, influenza, pyogenic pneumonia, whooping cough, and tuberculosis are most frequently observed during the Hajj. Outbreaks of meningococcal meningitis have been reported in pilgrims and their contacts. Waterborne infections such as gastroenteritis and hepatitis A are common, despite the improvement of health conditions. Pyoderma and furuncles are also frequently observed. Recently, dengue fever, Alkhumra hemorrhagic fever, and Rift Valley fever have emerged but no case of MERS-coronavirus, appeared in Saudi Arabia in 2012, have yet been observed during the 2012-2014 Hajj. Prevention is based on compulsory meningococcal vaccination, vaccination against seasonal influenza and pneumococcal infections for pilgrims at high risk of contracting the infection, and on vaccination against hepatitis A. Updating immunization for diphtheria/tetanus/poliomyelitis/pertussis and measles/mumps is also crucial and pilgrims must comply with hygiene precautions.