Mass gatherings and infections in Africa: a systematic review

Mass gatherings (MGs) are defined as events in which a large number of people come together for a specific purpose and over a specific period of time. They present a high risk of transmission of communicable diseases due to a variety of factors, including the proximity of individuals in large crowds, which facilitates the human-to-human spread of pathogens. This study examines the impact of these events on the transmission and spread of infectious diseases. This review analyses studies of large gatherings in Africa, describing the occurrence of infection or pathogen carriage among participants or in the general population in areas where these MGs took place. Data were summarised descriptively due to study variability, and quality was assessed using NIH tools. Studies on religious, sporting, and cultural events were included. Respiratory, gastrointestinal, and blood-borne pathogens and resistance genes were detected by qPCR, serology, sequencing, culture, ELISA, and MALDI-TOF. The results showed the detection of pathogens leading to infectious diseases including influenza, malaria, dengue fever, and cholera during the GMT, as well as an outbreak of N. meningitidis at a funeral event in Liberia. These findings strongly suggest that other African religious MGs may risk the importation, amplification, and transmission of infectious diseases between pilgrims and indigenous populations during and after the event. The results of the various studies reviewed underline the important role of clinical and microbial surveillance in public health management during MGs. The implementation of surveillance programmes as conducted Senegal at the GMT should be considered by other African countries hosting recurring annual religious pilgrimages that cater for millions of pilgrims.