Hi all…with spring just around the corner, for some of us anyway, an interesting paper entitled “Persistence of fecal contamination and pathogenic Escherichia coli O157:H7 in snow and snowmelt” has recently been published. There has been a substantial amount of research conducted in the area of watershed protection as a key element in the production of safe drinking water. While it is certainly acknowledged that rain and/or melting snow can transport pathogens, very little work has been conducted to shed light on how long pathogens can remain viable after being deposited in snow. The authors found that “fecal contamination, and associated pathogens, can persist for months and may accumulate in snow. Further, fecal contaminants in snowmelt runoff may persist for weeks to months in recreational water settings.” These are important observations as they pertain to watershed protection management initiatives.
[Snow was collected from outside the Canada Center for Inland Waters (Burlington, ON). Twelve microcosms were then inoculated with 1 mL of the mixed E. coli culture (see below) while the other twelve were inoculated with 1 mL of sewage influent, collected from the Ashbridge’s Bay Wastewater Treatment Plant (Toronto, ON).]
Bill
Persistence of fecal contamination and pathogenic Escherichia coli O157:H7 in snow and snowmelt
Zachery R. Staley, Dennis D. He, Thomas A. Edge
Journal of Great Lakes Research
Volume 43, Issue 2, April 2017, Pages 248–254
http://ac.els-cdn.com/S0380133017300187/1-s2.0-S0380133017300187-main.pdf?_tid=37207d46-eedb-11e6-8452-00000aab0f01&acdnat=1486653777_5918ce48c61d95f38e0687bd6b44f078
Abstract
“Runoff from snowmelt can be a significant nonpoint source of fecal contamination into waters used for winter recreation, and in spring months leading up to the bathing season. However, little research has been conducted to understand bacterial persistence and potential accumulation in snow, or the fate of fecal contamination in snowmelt in advance of every bathing season in temperate climates. In this study, microcosms containing snow held at either − 10, 0 or 4 °C were inoculated with either a lab culture containing environmental strains of Escherichia coli and a strain of pathogenic E. coliO157:H7, or raw sewage influent. Enumeration of E. coli via culturable and qPCR-methods was performed as well as qPCR enumeration of microbial source tracking (MST) markers for general and human-specific Bacteroidales in sewage-inoculated microcosms. Results showed that culturable E. coliand E. coli O157:H7 concentrations decreased throughout the experiment at all temperatures, while E. coli concentrations and MST markers enumerated via qPCR tended to remain at stable concentrations throughout the duration of the experiment at temperatures of − 10 or 0 °C. Concentrations of all targets, by both culturable and qPCR-enumeration decreased faster at 4 °C, except for general Bacteroidales. These results suggest that fecal contamination, and associated pathogens, can persist for months and may accumulate in snow. Further, fecal contaminants in snowmelt runoff may persist for weeks to months in recreational water settings, with potential implications for winter sports as well as the start of the spring bathing season at some beaches in temperate climates.”
