Emerging investigators series: the source and fate of pandemic viruses in the urban water cycle

Several recent high profile outbreaks such as SARS, MERS, Ebola and avian influenzas draw attention to the continued risk of a deadly viral pandemic. In general, these enveloped viruses are not considered a major threat for the wastewater and water industries due to their assumed low concentrations in municipal wastewater and high susceptibilities to degradation in aqueous environments. A number of clinical reports, however, suggest that certain enveloped viruses are excreted in human feces during infection. Furthermore, survivability studies show that many enveloped viruses are capable of retaining infectivity for days to months in aqueous environments. Here, we examine the potential presence and fate of enveloped viruses in the urban water cycle, with emphasis on coronaviruses (e.g., SARS and MERS) and avian influenza viruses. We identify a number of pressing research questions that must be answered before the water and wastewater industries can confidently assure the public, through the dissemination of evidence-based guidance, that irrigation waters, recreation waters, and drinking water sources are safe during a viral outbreak or pandemic event.