Occurrence of Human Norovirus GII and Human Enterovirus in Ontario Source Waters

Hi all…we’re now well aware that impacted watersheds used for drinking water can have high occurrence frequencies of protozoan pathogen (oo)cysts such as those of Giardia and Cryptosporidium. This includes the Grand River in southern Ontario where frequencies can approach 100%. Virus occurrence is less clear though. A just completed thesis reports that Norovirus was detected in 41% of Grand River samples while Enterovirus was found in 18% of samples. Interestingly, Norovirus and Enterovirus were detected in 33% and 29% of groundwater samples. The sampled well was a ‘groundwater under the direct influence of surface water’ (GUDI) source located in the Region of Waterloo. No correlations between virus detection and environmental parameters were found. For those of you who plan to respond to Health Canada’s request for public comment on the updated Enteric Viruses in Drinking Water guideline this might provide additional insight.

Bill

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Occurrence of Human Norovirus GII and Human Enterovirus in Ontario Source Waters
MSc thesis: C.D. LoFranco
University of Guelph 2017
https://atrium.lib.uoguelph.ca/xmlui/bitstream/handle/10214/11950/LoFranco_Cassandra_201710_Msc.pdf?sequence=3&isAllowed=y

ABSTRACT

“Norovirus and Enterovirus are common human viral pathogens found in water sources. Despite causing gastroenteritis outbreaks, most jurisdictions, including Ontario, do not monitor for enteric viruses in waters. The objective of this thesis was to monitor the presence of human Norovirus and Enterovirus in Ontario source waters intended for drinking.

Two untreated source water types (river and ground water) were sampled routinely and following precipitation and snow melt events between January 2015 and April 2016. Physical, chemical, microbiological, and meteorological data were collected, coinciding with sampling events. A modified USEPA Method 1615 was applied to detect and quantify viruses and logistic regression was used to examine relationships between virus presence and environmental parameters.

Norovirus was detected in 41% of river water and 33% of groundwater samples. Enterovirus was detected in 18% of river water and 29% of groundwater samples. No correlations between virus detection and environmental parameters were found.”