Risk of Human Illness from Recreational Exposure to Microbial Pathogens in Freshwater Bodies: A Systematic Review

Recreational use of natural freshwater bodies poses a risk to human health, although the risks associated with different types of exposure in freshwater are not clear. A systematic review was carried out to identify the risks of adverse health outcomes among individuals exposed through primary contact recreation compared to minimal contact recreation in different types of freshwater bodies. Among 5858 potentially relevant titles and abstracts, 35 were eligible for final inclusion. We included studies that reported the type of freshwater exposure and health outcomes, were peer-reviewed, and had full-text articles available in English. Across all studies, general gastrointestinal illness was the most commonly reported (77.1%), followed by skin (37.1%) and ear-related infection (34.3%), respiratory illness (31.4%), and eye-related illness (25.7%). Most studies reported adverse health outcomes from primary contact recreation (85.7%) in comparison to secondary contact activities (17.1%) and no-contact recreation (2.9%). More than half of the included studies (54.3%) focussed on lakes. The continued focus on primary contact recreation in lakes is a concern, given the growing global trend in secondary and non-contact recreation associated with urban wetlands. A better understanding of risks associated with recreational contact with freshwater in these settings is needed.