Genomic characterization of Listeria monocytogenes recovered from dairy facilities in British Columbia, Canada from 2007 to 2017.

Listeria monocytogenes is a foodborne pathogen of concern in dairy processing facilities, with the potential to cause human illness and trigger regulatory actions if found in the product. Monitoring for Listeria spp. through environmental sampling is recommended to prevent establishment of these microorganisms in dairy processing environments, thereby reducing the risk of product contamination. To inform on L. monocytogenes diversity and transmission, we analyzed genome sequences of L. monocytogenes strains (n = 88) obtained through the British Columbia Dairy Inspection Program. Strains were recovered from five different dairy processing facilities over a 10 year period (2007-2017). Analysis of whole genome sequences (WGS) grouped the isolates into nine sequence types and 11 cgMLST types (CT). The majority of isolates (93%) belonged to lineage II. Within each CT, single nucleotide polymorphism (SNP) differences ranged from 0 to 237 between isolates. A highly similar (0-16 SNPs) cluster of over 60 isolates, collected over 9 years within one facility (#71), was identified suggesting a possible persistent population. Analyses of genome content revealed a low frequency of genes associated with stress tolerance, with the exception of widely disseminated cadmium resistance genes cadA1 and cadA2. The distribution of virulence genes and mutations within internalin genes varied across the isolates and facilities. Further studies are needed to elucidate their phenotypic effect on pathogenicity and stress response. These findings demonstrate the diversity of L. monocytogenes isolates across dairy facilities in the same region. Findings also showed the utility of using WGS to discern potential persistence events within a single facility over time.

The health risks of marine biotoxins associated with high seafood consumption: Looking beyond the single dose, single outcome paradigm with a view towards addressing the needs of coastal Indigenous populations in British Columbia.

People who consume high quantities of seafood are at a heightened risk for marine biotoxin exposure. Coastal Indigenous peoples may experience higher levels of risk than the general population due to their reliance on traditional marine foods. Most evidence on the health risks associated with biotoxins focus on a single exposure at one point in time. There is limited research on other types of exposures that may occur among those who regularly consume large quantities of seafood. The objective of this review is to assess what is known about the unique biotoxin exposure risks associated with the consumption patterns of many coastal Indigenous populations. These risks include [1]: repeated exposure to low doses of a single or multiple biotoxins [2]; repeated exposures to high doses of a single or multiple biotoxins; and [3] exposure to multiple biotoxins at a single point in time. We performed a literature search and collected 23 recent review articles on the human health effects of different biotoxins. Using a narrative framework synthesis approach, we collated what is known about the health effects of the exposure risks associated with the putative consumption patterns of coastal Indigenous populations. We found that the health effects of repeated low- or high-dose exposures and the chronic health effects of marine biotoxins are rarely studied or documented. There are gaps in our understanding of how risks differ by seafood species and preparation, cooking, and consumption practices. Together, these gaps contribute to a relatively poor understanding of how biotoxins impact the health of those who regularly consume large quantities of seafood. In the context of this uncertainty, we explore how known and potential risks associated with biotoxins can be mitigated, with special attention to coastal Indigenous populations routinely consuming seafood. Overall, we conclude that there is a need to move beyond the single-dose single-outcome model of exposure to better serve Indigenous communities and others who consume high quantities of seafood.

A review of biogenic amines in fermented foods: Occurrence and health effects.

Biogenic amines (BAs) are low-molecular decarboxylation products of amino acids formed during microbial fermentation. Several fermented foods may contain BAs such as histamine, tyramine, and/or phenylethylamine, at levels above documented toxic doses. Dietary exposure to foods containing high levels of BAs is associated with many adverse health effects, such as migraines, elevated blood pressure, and tachycardia. BA-mediated toxicity may occur at levels a hundred times below regulatory and suggested toxic doses, depending on an individual's sensitivity and factors such as alcohol consumption and certain medications. Although BAs occur in a wide variety of fermented foods, food safety and public health professionals are not well informed about the potential health risks and control strategies in these foods. In this review, we highlight the health risks and symptoms linked to BA exposures, the BA levels found in different fermented foods, regulatory and suggested toxic doses, and risk mitigation strategies to inform food industry and public health professionals' practice.

Changing Trends in Paralytic Shellfish Poisonings Reflect Increasing Sea Surface Temperatures and Practices of Indigenous and Recreational Harvesters in British Columbia, Canada.

Paralytic shellfish poisoning (PSP) occurs when shellfish contaminated with saxitoxin or equivalent paralytic shellfish toxins (PSTs) are ingested. In British Columbia, Canada, documented poisonings are increasing in frequency based on 62 investigations identified from 1941-2020. Two PSP investigations were reported between 1941 and 1960 compared to 31 since 2001 (p < 0.0001) coincident with rising global temperatures (r2 = 0.76, p < 0.006). The majority of PSP investigations (71%) and cases (69%) were linked to self-harvested shellfish. Far more investigations involved harvests by indigenous communities (24%) than by commercial and recreational groups. Single-case-exposure investigations increased by more than 3.5 times in the decade 2011-2020 compared to previous periods. Clams (47%); mussels (26%); oysters (14%); scallops (6%); and, in more recent years, crabs (4%) were linked to illnesses. To guide understanding of self-harvesting consumption risks, we recommend collecting data to determine when PST-producing algae are present in high concentrations, improving the quality of data in online shellfish harvest maps to include dates of last testing; biotoxin testing results; and a description of bivalve species tested. Over reliance on toxin results in biomonitored species may not address actual consumption risks for unmonitored species harvested from the same area. We further recommend introducing phytoplankton monitoring in remote indigenous communities where self-harvesting is common and toxin testing is unavailable, as well as continuing participatory education about biotoxin risks in seafoods.

Ethanol Concentration of Kombucha Teas in British Columbia, Canada.

ABSTRACT: Kombucha is a sweetened tea beverage fermented by bacterial and yeast cultures. Sweeteners, such as glucose, sucrose, fructose, and others are converted by yeasts into ethanol and then by Acetobacter and other bacterial species into a weak acetic acid solution that is diluted, flavored, and packaged into glass or aluminum cans for consumer consumption. Naturally, fermented kombucha contains 0 to 3% alcohol by volume (ABV). However, kombucha containing ethanol is concerning for pregnant women and young children for whom low levels of ethanol consumption (<3% ABV) create adverse medical outcomes. In the province of British Columbia (BC), Canadian beverages containing >1% ABV are regulated as liquor. This study assessed ethanol concentrations in kombucha collected from processors and purchased at retail venues in BC. Ethanol values were compared with the place of manufacture (country or province) and place of purchase (grocery stores, restaurants, farmers' markets, recreational centers, and processors). Ethanol (n = 684) levels were measured by using a headspace gas chromatography-mass spectrometry method with a detection limit of 0.0002% ABV for ethanol. Overall, teas contained mean and median ethanol of 0.77 and 0.62% ABV, respectively, ranging from nondetectable up to 3.62% ABV. Four kombucha teas (0.6%) made by BC processors tested over 3% ABV, and 31.5% of samples contained ethanol that exceeded the BC regulatory limits for nonalcoholic beverages of 1% ABV. Kombucha manufactured in BC had significantly higher mean ethanol values (1.16% ABV) in comparison to all other places of manufacture. Similarly, mean ethanol tea values obtained from BC processors (1.2% ABV) and restaurants (1.01% ABV) were significantly higher than those obtained at other retail venues. This study demonstrates the potential for alcohol harm to at-risk populations consuming kombucha teas sold in BC.

A Survey of Raw Frozen Breaded Chicken Products for Salmonella in British Columbia, Canada, and Phylogenetically Associated Illnesses.

ABSTRACT: The incidence of Salmonella enterica infection resulting from consumption of chicken products has historically been elevated in British Columbia compared with the rest of Canada. Raw frozen breaded chicken products are often implicated as the source of infection as there is a potential for consumers to not cook these products adequately. This occurs because the production process for these foods involves par-frying, a step which lends a cooked appearance to the product surface without reaching the internal temperatures required to fully inactivate potential pathogens. A survey of frozen chicken products from 10 retail stores of various sizes was conducted in order to determine the type and source of frozen chicken products that are available for purchase in British Columbia. Information on 391 individual products was collected and 50 were sampled for microbiological testing. Raw frozen breaded chicken products represented 59% of the frozen chicken products available to consumers at retail; 34% of these raw products were made by a single processor. The same processor was also found to have the highest proportion (33%) of samples testing positive for Salmonella. Whole genome sequencing of isolates obtained during this study revealed that majority of these isolates were phylogenetically related to clinical isolates of Salmonella. A substantial reduction of risk and increased consumer protection may be achieved by implementing a kill step (e.g., cook process that has been validated to achieve a 7-log reduction) during production of these products.

Outbreaks of Norovirus and Acute Gastroenteritis Associated with British Columbia Oysters, 2016-2017.

Two outbreaks of norovirus and acute gastroenteritis took place in Canada between November 2016 and April 2017. Both outbreaks were linked to oysters from British Columbia (BC) coastal waters. This paper describes the multi-agency investigations to identify the source and control the outbreak. Public health officials conducted interviews to determine case exposures. Traceback was conducted by collecting oyster tags from restaurants and analyzing them to determine the most common farms. Oyster samples were collected from case homes, restaurants, and harvest sites and tested for the presence of norovirus. Potential environmental pollution sources were investigated to identify the source of the outbreak. Four hundred and 49 cases were identified as part of the two outbreak waves. The oysters were traced to various geographically dispersed farms in BC coastal waters. Twelve farms were closed as a result of the investigations. No environmental pollution sources could be identified as the cause of the outbreak. Similarities in the timeframe, genotype, and geographic distribution of identified oyster farms indicate that they may have been one continuous event. Genotype data indicate that human sewage contamination was the likely cause of the outbreak, although no pollution source was identified.

Outbreak of Vibrio parahaemolyticus Associated with Consumption of Raw Oysters in Canada, 2015.

There has been a steady increase in illness incidence of Vibrio parahaemolyticus (Vp). The majority of illnesses are associated with consumption of raw oysters. In the summer of 2015, Canada experienced the largest outbreak associated with the consumption of raw oysters harvested from British Columbia (BC) coastal waters. Case investigation of laboratory-confirmed cases was conducted to collect information on exposures and to assist traceback. Investigations at processors and oyster sampling were conducted. Eighty-two laboratory-confirmed cases of Vp infection were reported between January 1 and October 26, 2015. The majority of the cases were reported in BC, associated with consumption of raw BC oysters in restaurants. Sea surface temperatures were above the historical levels in 2015. This outbreak identified the need to improve surveillance and response to increases in human cases of Vp. This is of particular importance due to the potential for increasing water temperatures and the likelihood of additional outbreaks of Vibrio.

Near-Real-Time Surveillance of Illnesses Related to Shellfish Consumption in British Columbia: Analysis of Poison Center Data.

BACKGROUND: Data from poison centers have the potential to be valuable for public health surveillance of long-term trends, short-term aberrations from those trends, and poisonings occurring in near-real-time. This information can enable long-term prevention via programs and policies and short-term control via immediate public health response. Over the past decade, there has been an increasing use of poison control data for surveillance in the United States, Europe, and New Zealand, but this resource still remains widely underused. OBJECTIVE: The British Columbia (BC) Drug and Poison Information Centre (DPIC) is one of five such services in Canada, and it is the only one nested within a public health agency. This study aimed to demonstrate how DPIC data are used for routine public health surveillance in near-real-time using the case study of its alerting system for illness related to consumption of shellfish (ASIRCS). METHODS: Every hour, a connection is opened between the WBM software Visual Dotlab Enterprise, which holds the DPIC database, and the R statistical computing environment. This platform is used to extract, clean, and merge all necessary raw data tables into a single data file. ASIRCS automatically and retrospectively scans a 24-hour window within the data file for new cases related to illnesses from shellfish consumption. Detected cases are queried using a list of attributes: the caller location, exposure type, reasons for the exposure, and a list of keywords searched in the clinical notes. The alert generates a report that is tailored to the needs of food safety specialists, who then assess and respond to detected cases. RESULTS: The ASIRCS system alerted on 79 cases between January 2015 and December 2016, and retrospective analysis found 11 cases that were missed. All cases were reviewed by food safety specialists, and 58% (46/79) were referred to designated regional health authority contacts for follow-up. Of the 42% (33/79) cases that were not referred to health authorities, some were missing follow-up information, some were triggered by allergies to shellfish, and some were triggered by shellfish-related keywords appearing in the case notes for nonshellfish-related cases. Improvements were made between 2015 and 2016 to reduce the number of cases with missing follow-up information. CONCLUSIONS: The surveillance capacity is evident within poison control data as shown from the novel use of DPIC data for identifying illnesses related to shellfish consumption in BC. The further development of surveillance programs could improve and enhance response to public health emergencies related to acute illnesses, chronic diseases, and environmental exposures.

Spatiotemporal patterns of paralytic shellfish toxins and their relationships with environmental variables in British Columbia, Canada from 2002 to 2012.

BACKGROUND: Harmful algal blooms produce paralytic shellfish toxins that accumulate in the tissues of filter feeding shellfish. Ingestion of these toxic shellfish can cause a serious and potentially fatal condition known as paralytic shellfish poisoning (PSP). The coast of British Columbia is routinely monitored for shellfish toxicity, and this study uses data from the monitoring program to identify spatiotemporal patterns in shellfish toxicity events and their relationships with environmental variables. METHODS: The dinoflagellate genus Alexandrium produces the most potent paralytic shellfish toxin, saxitoxin (STX). Data on all STX measurements were obtained from 49 different shellfish monitoring sites along the coast of British Columbia for 2002-2012, and monthly toxicity events were identified. We performed hierarchical cluster analysis to group sites that had events in similar areas with similar timing. Machine learning techniques were used to model the complex relationships between toxicity events and environmental variables in each group. RESULTS: The Strait of Georgia and the west coast of Vancouver Island had unique toxicity regimes. Out of the seven environmental variables used, toxicity in each cluster could be described by multivariable models including monthly sea surface temperature, air temperature, sea surface salinity, freshwater discharge, upwelling, and photosynthetically active radiation. The sea surface salinity and freshwater discharge variables produced the strongest univariate models for both geographic areas. CONCLUSIONS: Applying these methods in coastal regions could allow for the prediction of shellfish toxicity events by environmental conditions. This has the potential to optimize biotoxin monitoring, improve public health surveillance, and engage the shellfish industry in helping to reduce the risk of PSP.

Efficacy of common disinfectant/cleaning agents in inactivating murine norovirus and feline calicivirus as surrogate viruses for human norovirus.

BACKGROUND: The efficacies of disinfection by sodium hypochlorite, accelerated hydrogen peroxide (AHP), and quaternary ammonium compound (QUAT) commonly used in health care facilities were determined using the surrogate viruses murine norovirus (MNV-1) and feline calicivirus (FCV). METHODS: A virus suspension of known concentration (with or without a soil load) was deposited onto stainless steel discs under wet or dry load conditions and exposed to defined concentrations of the disinfectant/cleaning agent for 1-, 5-, or 10-minute contact time using the quantitative carrier test (QCT-2) method. Virus inactivation was determined by plaque assay. RESULTS: At an exposure time of 1 minute, sodium hypochlorite at 2,700 ppm was able to inactivate MNV-1 and FCV with a >5 log10 reduction. After 10 minutes, MNV-1 was inactivated by AHP at 35,000 ppm, whereas FCV was inactivated at 3,500 ppm. MNV-1 was not inactivated by QUAT at 2,800 ppm. A QUAT-alcohol formulation containing 2,000 ppm QUAT and 70% ethanol was effective in inactivating MNV-1 after 5 minutes, but resulted in only a <3 log10 reduction of FCV after 10 minutes. CONCLUSIONS: AHP and QUAT products were less effective than sodium hypochlorite for the inactivation of MNV-1 and FCV.

Listeriosis outbreaks in British Columbia, Canada, caused by soft ripened cheese contaminated from environmental sources.

Soft ripened cheese (SRC) caused over 130 foodborne illnesses in British Columbia (BC), Canada, during two separate listeriosis outbreaks. Multiple agencies investigated the events that lead to cheese contamination with Listeria monocytogenes (L.m.), an environmentally ubiquitous foodborne pathogen. In both outbreaks pasteurized milk and the pasteurization process were ruled out as sources of contamination. In outbreak A, environmental transmission of L.m. likely occurred from farm animals to personnel to culture solutions used during cheese production. In outbreak B, birds were identified as likely contaminating the dairy plant's water supply and cheese during the curd-washing step. Issues noted during outbreak A included the risks of operating a dairy plant in a farm environment, potential for transfer of L.m. from the farm environment to the plant via shared toilet facilities, failure to clean and sanitize culture spray bottles, and cross-contamination during cheese aging. L.m. contamination in outbreak B was traced to wild swallows defecating in the plant's open cistern water reservoir and a multibarrier failure in the water disinfection system. These outbreaks led to enhanced inspection and surveillance of cheese plants, test and release programs for all SRC manufactured in BC, improvements in plant design and prevention programs, and reduced listeriosis incidence.

Formation of a volunteer harmful algal bloom network in British Columbia, Canada, following an outbreak of diarrhetic shellfish poisoning.

Evidence for shellfish toxin illness in British Columbia (BC) on the west coast of Canada can be traced back to 1793. For over two hundred years, domestically acquired bivalve shellfish toxin illnesses in BC were solely ascribed to paralytic shellfish poisonings caused by algal blooms of Alexandrium. This changed in 2011, when BC experienced its first outbreak of diarrhetic shellfish poisoning (DSP). As a result of this outbreak, Canada's first DSP symposium was held in November, 2012, in North Vancouver, BC. Three of the objectives of the symposium were to provide a forum to educate key stakeholders on this emerging issue, to identify research and surveillance priorities and to create a DSP network. The purpose of this paper is to review what is known about shellfish poisoning in BC and to describe a novel volunteer network that arose following the symposium. The newly formed network was designed for industry shellfish growers to identify harmful algae bloom events, so that they may take actions to mitigate the effects of harmful blooms on shellfish morbidity. The network will also inform public health and regulatory stakeholders of potentially emerging issues in shellfish growing areas.

Outbreak of Diarrhetic Shellfish Poisoning associated with mussels, British Columbia, Canada.

In 2011, a Diarrhetic Shellfish Poisoning (DSP) outbreak occurred in British Columbia (BC), Canada that was associated with cooked mussel consumption. This is the first reported DSP outbreak in BC. Investigation of ill individuals, traceback of product and laboratory testing for toxins were used in this investigation. Sixty-two illnesses were reported. Public health and food safety investigation identified a common food source and harvest area. Public health and regulatory agencies took actions to recall product and notify the public. Shellfish monitoring program changes were implemented after the outbreak. Improved response and understanding of toxin production will improve management of future DSP outbreaks.

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

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.

Occurrence and distribution of listeria species in facilities producing ready-to-eat foods in British Columbia, Canada.

In British Columbia (BC), Canada, food processing facilities licensed under provincial authority are not required to sample for Listeria monocytogenes in food products or processing environments. In 2009, we conducted a survey of dairy, fish, and meat facilities under BC authority to estimate the prevalence of Listeria spp. and L. monocytogenes in ready-to-eat (RTE) foods and production environments. From August to October, 250 RTE food samples and 258 swabs from the food processing environments of 43 facilities were collected. Standard culture methods were applied to both food samples and swabs. Of swabs collected from all 258 environmental surfaces, 15% were positive for Listeria spp. Significantly (P, 0.001) more fish facilities than dairy and meat facilities had food contact surfaces contaminated with Listeria spp. L. monocytogenes was found in RTE foods from fish facilities alone (5 of 12); in all five of the fish facilities with contaminated product, one or more environmental swabs were also positive for L. monocytogenes. The results suggest that while control of L. monocytogenes in BC-inspected dairy and meat facilities is effective in limiting food contamination, there is a need for provincial inspectors to initiate improved monitoring and management of contamination by L. monocytogenes in RTE fish processing facilities.

Identification of Bacillus cereus group species associated with food poisoning outbreaks in British Columbia, Canada.

Food poisoning laboratories identify Bacillus cereus using routine methods that may not differentiate all Bacillus cereus group species. We recharacterized Bacillus food-poisoning strains from 39 outbreaks and identified B. cereus in 23 outbreaks, B. thuringiensis in 4, B. mycoides in 1, and mixed strains of Bacillus in 11 outbreaks.

Amplification by long RT-PCR of near full-length norovirus genomes.

A long RT-PCR method was developed to amplify the norovirus genome. Starting from RNA extracted directly from clinical samples and using broadly reactive primers, it can generate near full-length amplicons that allow for easy determination of the near complete genomic sequence. Two norovirus isolates from Toronto, Canada, in 2002 and 2005 were sequenced. This approach will facilitate molecular epidemiology studies of noroviruses.

An outbreak of norovirus caused by consumption of oysters from geographically dispersed harvest sites, British Columbia, Canada, 2004.

OBJECTIVES: In January 2004, an increase in gastrointestinal illness following oyster consumption was reported in British Columbia. An investigation was initiated to explore the association between norovirus infection and consumption of British Columbia oysters and to identify the source of oyster contamination. METHODS: The outbreak investigation included active surveillance for human cases, two cohort studies, trace-back of oysters, and laboratory testing of oysters and human stools. RESULTS: Enhanced surveillance identified 26 confirmed and 53 clinical cases over 3 months. Oyster consumption was associated with illness in one cohort and suggestive in the other. Oysters were traced to 14 geographically dispersed harvest sites, 18 suppliers, and 45 points of purchase. Norovirus BCCDC03-028 (genotype I.2) was detected in 50% of human specimens. Experimental methods detected norovirus in 12 oyster samples. Sequencing identified mixed clonal patterns in the oysters with one direct sequence match between an oyster sample and the associated human specimen. CONCLUSIONS: The consumption of raw oysters led to norovirus infection. The source of oyster contamination remained unidentified. The geographical dispersion of implicated harvest sites was unusual. APPLICATIONS: This outbreak is unlike most shellfish outbreaks that can be traced back to a common source and challenges conventional thinking that all oyster-related norovirus outbreaks of are a result of point source contamination.