Clinical Assistant Professor

 

Location:
BC Centre for Disease Control
phone: 604-707-2647

Academic background

  • PhD, University of British Columbia. 2010
  • Watershed Management, University of British Columbia. Certificate. 2008
  • BSc, University of Calgary. Cellular, Molecular and Microbiology (CMMB). 2003
  • BSc, University of Calgary. Environmental Science – Biology Focus. 2003

Awards and Recognition

  • Institute of Infection and Immunity (CIHR-III) Doctoral Research Award, Canadian Foundation for Infectious Disease (CFID)/Canadian Institute for Health Research. 2006-2009
  • Senior Trainee Top-Up Award, Michael Smith Foundation for Health Research (MSFHR). 2006-2008
  • University of British Columbia PhD Tuition Award, University of British Columbia. 2005-2009

Publications

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Assessment of Giardia and Cryptosporidium spp. as a Microbial Source Tracking Tool for Surface Water: Application in a Mixed-Use Watershed.

Related Articles

Assessment of Giardia and Cryptosporidium spp. as a Microbial Source Tracking Tool for Surface Water: Application in a Mixed-Use Watershed.

Appl Environ Microbiol. 2014 Apr;80(8):2328-36

Authors: Prystajecky N, Huck PM, Schreier H, Isaac-Renton JL

Abstract
Knowledge of host specificity, combined with genomic sequencing of Giardia and Cryptosporidium spp., has demonstrated a microbial source tracking (MST) utility for these common waterborne microbes. To explore the source attribution potential of these pathogens, water samples were collected in a mixed rural-urban watershed in the Township of Langley, in southwestern British Columbia (BC), Canada, over a 2-year period. Cryptosporidium was detected in 63% of surface water samples at concentrations ranging from no positive detection (NPD) to 20,600 oocysts per 100 liters. Giardia was detected in 86% of surface water samples at concentrations ranging from NPD to 3,800 cysts per 100 liters of water. Sequencing at the 18S rRNA locus revealed that 50% of Cryptosporidium samples and 98% of Giardia samples contained species/genotypes (Cryptosporidium) or assemblages (Giardia) that are capable of infecting humans, based on current knowledge of host specificity and taxonomy. Cryptosporidium genotyping data were more promising for source tracking potential, due to the greater number of host-adapted (i.e., narrow-host-range) species/genotypes compared to Giardia, since 98% of Giardia isolates were zoonotic and the potential host could not be predicted. This report highlights the benefits of parasite genomic sequencing to complement Method 1623 (U.S. Environmental Protection Agency) and shows that Cryptosporidium subtyping for MST purposes is superior to the use of Giardia subtyping, based on better detection limits for Cryptosporidium-positive samples than for Giardia-positive samples and on greater host specificity among Cryptosporidium species. These additional tools could be used for risk assessment in public health and watershed management decisions.

PMID: 24463970 [PubMed - in process]

A comparative analysis of current microbial water quality risk assessment and management practices in British Columbia and Ontario, Canada.

Related Articles

A comparative analysis of current microbial water quality risk assessment and management practices in British Columbia and Ontario, Canada.

Sci Total Environ. 2014 Jan 15;468-469:544-52

Authors: Dunn G, Harris L, Cook C, Prystajecky N

Abstract
Bacteria, protozoa and viruses are ubiquitous in aquatic environments and may pose threats to water quality for both human and ecosystem health. Microbial risk assessment and management in the water sector is a focus of governmental regulation and scientific inquiry; however, stark gaps remain in their application and interpretation. This paper evaluates how water managers practice microbial risk assessment and management in two Canadian provinces (BC and Ontario). We assess three types of entities engaged in water management along the source-to-tap spectrum (watershed agencies, water utilities, and public health authorities). We analyze and compare the approaches used by these agencies to assess and manage microbial risk (including scope, frequency, and tools). We evaluate key similarities and differences, and situate them with respect to international best practices derived from literatures related to microbial risk assessment and management. We find considerable variability in microbial risk assessment frameworks and management tools in that approaches 1) vary between provinces; 2) vary within provinces and between similar types of agencies; 3) have limited focus on microbial risk assessment for ecosystem health and 4) diverge considerably from the literature on best practices. We find that risk assessments that are formalized, routine and applied system-wide (i.e. from source-to-tap) are limited. We identify key limitations of current testing methodologies and looking forward consider the outcomes of this research within the context of new developments in microbial water quality monitoring such as tests derived from genomics and metagenomics based research.

PMID: 24055670 [PubMed - in process]

Identification of fecal contamination sources in water using host-associated markers.

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Identification of fecal contamination sources in water using host-associated markers.

Can J Microbiol. 2013 Mar;59(3):210-20

Authors: Krentz CA, Prystajecky N, Isaac-Renton J

Abstract
In British Columbia, Canada, drinking water is tested for total coliforms and Escherichia coli, but there is currently no routine follow-up testing to investigate fecal contamination sources in samples that test positive for indicator bacteria. Reliable microbial source tracking (MST) tools to rapidly test water samples for multiple fecal contamination markers simultaneously are currently lacking. The objectives of this study were (i) to develop a qualitative MST tool to identify fecal contamination from different host groups, and (ii) to evaluate the MST tool using water samples with evidence of fecal contamination. Singleplex and multiplex polymerase chain reaction (PCR) were used to test (i) water from polluted sites and (ii) raw and drinking water samples for presence of bacterial genetic markers associated with feces from humans, cattle, seagulls, pigs, chickens, and geese. The multiplex MST assay correctly identified suspected contamination sources in contaminated waterways, demonstrating that this test may have utility for heavily contaminated sites. Most raw and drinking water samples analyzed using singleplex PCR contained at least one host-associated marker. Singleplex PCR was capable of detecting host-associated markers in small sample volumes and is therefore a promising tool to further analyze water samples submitted for routine testing and provide information useful for water quality management.

PMID: 23540340 [PubMed - indexed for MEDLINE]

Multiple clusters of norovirus among shellfish consumers linked to symptomatic oyster harvesters.

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Multiple clusters of norovirus among shellfish consumers linked to symptomatic oyster harvesters.

J Food Prot. 2012 Sep;75(9):1715-20

Authors: McIntyre L, Galanis E, Mattison K, Mykytczuk O, Buenaventura E, Wong J, Prystajecky N, Ritson M, Stone J, Moreau D, Youssef A, Outbreak Investigation Team

Abstract
We describe the investigation of a norovirus outbreak associated with raw oyster consumption affecting 36 people in British Columbia, Canada, in 2010. Several genotypes were found in oysters, including an exact sequence match to clinical samples in regions B and C of the norovirus genome (genogroup I genotype 4). Traceback implicated a single remotely located harvest site probably contaminated by ill shellfish workers during harvesting activities. This outbreak resulted in three recalls, one public advisory, and closure of the harvest site.

PMID: 22947481 [PubMed - indexed for MEDLINE]

Identifying host sources, human health risk and indicators of Cryptosporidium and Giardia in a Canadian watershed influenced by urban and rural activities.

Related Articles

Identifying host sources, human health risk and indicators of Cryptosporidium and Giardia in a Canadian watershed influenced by urban and rural activities.

J Water Health. 2012 Jun;10(2):311-23

Authors: Van Dyke MI, Ong CS, Prystajecky NA, Isaac-Renton JL, Huck PM

Abstract
Cryptosporidium and Giardia were characterized in a watershed in southern Ontario, Canada, over a 2½ year period. River samples were collected every two weeks, primarily near a municipal drinking water treatment plant intake. Cryptosporidium and Giardia were frequently detected with an overall occurrence rate of 88 and 97%, respectively. Giardia concentrations were higher than Cryptosporidium, with median values of 80 cysts 100 L(-1) and 12 oocysts 100 L(-1), respectively. Although pathogens rarely show a significant relationship with fecal or water quality indicators, this study determined that Cryptosporidium, but not Giardia, was significantly correlated with Escherichia coli, turbidity and river flow. There was no correlation between the two types of protozoa, and only Giardia showed a seasonal trend with higher concentrations at cold water temperatures. Cryptosporidium genotyping of all samples found that farm animals and wildlife were an important contributor of oocysts in the watershed, and that Cryptosporidium strains/genotypes of medium to high risk for human infection (C. hominis, C. parvum and C. ubiquitum) were detected in 16% of samples. This study was able to identify Cryptosporidium host sources and human health risk, and to identify differences between Cryptosporidium and Giardia occurrence in the watershed.

PMID: 22717756 [PubMed - indexed for MEDLINE]

Use of Lean response to improve pandemic influenza surge in public health laboratories.

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Use of Lean response to improve pandemic influenza surge in public health laboratories.

Emerg Infect Dis. 2012 Jan;18(1):57-62

Authors: Isaac-Renton JL, Chang Y, Prystajecky N, Petric M, Mak A, Abbott B, Paris B, Decker KC, Pittenger L, Guercio S, Stott J, Miller JD

Abstract
A novel influenza A (H1N1) virus detected in April 2009 rapidly spread around the world. North American provincial and state laboratories have well-defined roles and responsibilities, including providing accurate, timely test results for patients and information for regional public health and other decision makers. We used the multidisciplinary response and rapid implementation of process changes based on Lean methods at the provincial public health laboratory in British Columbia, Canada, to improve laboratory surge capacity in the 2009 influenza pandemic. Observed and computer simulating evaluation results from rapid processes changes showed that use of Lean tools successfully expanded surge capacity, which enabled response to the 10-fold increase in testing demands.

PMID: 22257385 [PubMed - indexed for MEDLINE]