Hot Spring Associated Infectious Diseases in the Great Basin and Southwest

Like all bodies of freshwater, natural hot springs can harbor pathogenic microorganisms that carry the threat of infectious disease. The unique chemistry, increased temperature, and popularity for bathing may alter the risk profile of hot springs compared to other natural bodies of water. Despite this risk, the role of hot springs as a reservoir for infectious diseases remains understudied, particularly within the context of regional public health. Nevada and the Great Basin/Southwest have increasingly promoted hot springs for the purposes of tourism, and they share a strong link to the cultural heritage of the region. The unknown risk profile and the promotion of hot spring bathing could have unintended consequences for public health outcomes in the region and prompted this pilot study. This mixed-methods review investigated hot spring bathing hygiene within the Great Basin region and Southwest by examining hot spring site development, known pathogens, and disease outbreak response. Data for indicator bacteria for known hot spring bathing sites were gathered from public records, peer-reviewed articles, and local and federal water quality surveys which were evaluated against site development. Statistical analysis showed that most indicator bacteria declined as hot spring site development increased. Data for specific pathogens demonstrated general conformity to broader trends in hot springs associated infectious diseases, with a handful of regional outliers, such as Vibrio cholerae and red spider mites. Examination of outbreak responses showed that the most common response was posting warnings and/or guidance at the site itself or online. Remediation techniques, when applied, often consisted of draining or flushing the site to rid it of pathogen colonization. A major impediment to furthering hot spring hygiene seems to be that overlapping authorities and interests of various agencies can create gaps of responsibility and result in unchecked incidents. Final recommendations include increased signage at sites and development of other novel low-cost hygienic infrastructure along with increasing the mandate of environmental agencies to monitor and remediate hot springs in addition to other bodies of water.