Mass gatherings (MGs) are held throughout the world. The aim of this review was to assess and identify the health threats based on the type of the MG, type of diseases, and injuries. Research platforms such as Web of Science, Medline, and Scopus were searched through June 2017. All epidemiologic studies that investigated the health threats during the MGs, such as communicable diseases, injuries, high-risk behaviors, and environmental health problems, were included in this review. Out of 1264 references, 45 articles were included in the review.
Three main types of MGs include religious, festival, and sporting event; and fairs such as trade, book, and agricultural types were also reported in the selected studies. In the religious MGs, infectious diseases were the most common health threat. Road traffic accidents and environmental health problems were additional health threats. At MG sporting events, injuries were the most common health problems. Infectious diseases and alcohol and drug-related disorders were other reported public health concerns. In the festival MGs, alcohol and drug-related problems were commonly reported. This review showed that health threats vary, based on the type of mass gathering. The health organizers of MGs should consider the type of the MG and the health needs and safety of the participants to help them plan their action and provide the needed health care services.