[Epidemic of gastroenteritis of viral origin associated with eating imported raspberries]

Involvement of Egyptian Foods in Foodborne Viral Illnesses: The Burden on Public Health and Related Environmental Risk Factors: An Overview

Foodborne viral diseases are a major public health threat and pose a huge burden on the economies of both developed and developing countries. Enteric viruses are the causative agents of most foodborne illnesses and outbreaks. Egypt is classified by WHO among the regions with intermediate to high endemicity for various enteric viruses. This is manifested by the high prevalence rates of different enteric virus infections among Egyptian population such as Hepatitis A and E viruses, human rotaviruses, human noroviruses, human astroviruses, and human adenovirus. Recently, a number of foodborne gastroenteritis and acute hepatitis outbreaks have occurred in the US, Canada, Australia, and the European Union countries. Some of these outbreaks were attributed to the consumption of minimally processed foods imported from Egypt indicating the possibility that Egyptian foods may also be partially responsible for high prevalence of enteric virus infections among Egyptian population. In the absence of official foodborne-pathogen surveillance systems, evaluating the virological safety of Egyptian foods is a difficult task. In this review, we aim to provide a preliminary evaluation of the virological safety of Egyptian foods. A comprehensive review of prevalence studies on enteric virus infections shows hyperendemicity of several enteric viruses in Egypt and provides strong evidence of implication of Egyptian foods in these infections. We also address possible environmental risk factors that may lead to the contamination of Egyptian foods with enteric viruses. In addition, we describe potential obstacles to any plan that might be considered for improving the virological safety of Egyptian foods.

Microbial Contamination of Fresh Produce: What, Where, and How?

Promotion of healthier lifestyles has led to an increase in consumption of fresh produce. Such foodstuffs may expose consumers to increased risk of foodborne disease, as often they are not subjected to processing steps to ensure effective removal or inactivation of pathogenic microorganisms before consumption. Consequently, reports of ready-to-eat fruit and vegetable related disease outbreak occurrences have increased substantially in recent years, and information regarding these events is often not readily available. Identifying the nature and source of microbial contamination of these foodstuffs is critical for developing appropriate mitigation measures to be implemented by food producers. This review aimed to identify the foodstuffs most susceptible to microbial contamination and the microorganisms responsible for disease outbreaks from information available in peer-reviewed scientific publications. A total of 571 outbreaks were identified from 1980 to 2016, accounting for 72,855 infections and 173 deaths. Contaminated leafy green vegetables were responsible for 51.7% of reported outbreaks. Contaminated soft fruits caused 27.8% of infections. Pathogenic strains of Escherichia coli and Salmonella, norovirus, and hepatitis A accounted for the majority of cases. Large outbreaks resulted in particular biases such as the observation that contaminated sprouted plants caused 31.8% of deaths. Where known, contamination mainly occurred via contaminated seeds, water, and contaminated food handlers. There is a critical need for standardized datasets regarding all aspects of disease outbreaks, including how foodstuffs are contaminated with pathogenic microorganisms. Providing food business operators with this knowledge will allow them to implement better strategies to improve safety and quality of fresh produce.

Viral outbreaks linked to fresh produce consumption: a systematic review

AIMS

Α systematic review to investigate fresh produce-borne viral outbreaks, to record the outbreak distribution worldwide and to analyse the implication of different types of fresh produce and viral types as well.

METHODS AND RESULTS

Four databases (PubMed/Medline, Scopus, Eurosurveillance Journal and Spingerlink electronic journal) and a global electronic reporting system (ProMED-mail) were searched up to 2016. One hundred and fifty-two viral outbreaks linked to fresh produce consumption were identified. The majority of the reported outbreaks was reported in Europe, followed by North America, Asia, Australia, Africa and South America. A great number of the outbreaks was recorded in Denmark and Finland. The most common viral pathogens were norovirus (48·7%) and hepatitis A virus (46·1%). The most frequent type of fresh produce involved was frozen raspberries (23·7%). Differences in the reporting of outbreaks were recorded between the scientific literature and ProMED.

CONCLUSIONS

The number of reported illnesses linked to fresh produce has increased in several countries. Consumption of contaminated fresh produce represents a risk to public health in both developed and developing countries, but the impact will be disproportionate and likely to compound existing health disparities. For this reason, all countries should systematically collate and report such data through a disease surveillance system, in order to adopt risk management practices for reducing the likelihood of contamination.

UV-C inactivation of foodborne bacterial and viral pathogens and surrogates on fresh and frozen berries

Outbreaks of foodborne illness associated with berries often involve contamination with hepatitis A virus (HAV) and norovirus but also bacteria such as Escherichia coli O157:H7 and parasites such as Cyclospora caytanensis. We evaluated the applicability of UV-C to the inactivation of pathogens on strawberries, raspberries and blueberries. Our three-step approach consisted of assessing the chemical safety of UV-C-irradiated berries, evaluating the sensory quality after UV-C treatment and finally studying the inactivation of the target microorganisms. Treatments lasting up to 9 min (4000 mJ cm^-2) did not produce detectable levels of furan (<5 μg/kg), a known photolysis product of fructose with genotoxic activity and thus were assessed to be toxicologically safe. No effect on taste or appearance was observed, unless treatment was excessively long. 20 s of treatment (an average fluence of ~ 212 mJ cm^-2) reduced active HAV titer by >1 log₁₀ unit in 95% of cases except on frozen raspberries, while 120 s were required to inactivate murine norovirus to this extent on fresh blueberries. The mean inactivation of HAV and MNV was greater on blueberries (2-3 log₁₀) than on strawberries and raspberries (<2 log₁₀). MNV was more sensitive on fresh than on frozen berries, unlike HAV. Inactivation of Salmonella, E. coli O157:H7 and Listeria monocytogenes was poor on all three berries, no treatment reducing viable counts by >1 log₁₀ unit. In most matrices, prolonging the treatment did not improve the result to any significant degree. The effect was near its plateau after 20 s of treatment. These results provide insight into the effectiveness of UV-C irradiation for inactivating bacterial and viral pathogens and surrogates on fresh and frozen berries having different surface types, under different physical conditions and at different levels of contamination. Overall they show that UV-C as single processing step is unsuitable to inactivate significant numbers of foodborne pathogens on berries.

Norovirus Infection in Older Adults: Epidemiology, Risk Factors, and Opportunities for Prevention and Control

Norovirus is the leading cause of acute gastroenteritis. In older adults, it is responsible for an estimated 3.7 million illnesses; 320,000 outpatient visits; 69,000 emergency department visits; 39,000 hospitalizations; and 960 deaths annually in the United States. Older adults are particularly at risk for severe outcomes, including prolonged symptoms and death. Long-term care facilities and hospitals are the most common settings for norovirus outbreaks in developed countries. Diagnostic platforms are expanding. Several norovirus vaccines in clinical trials have the potential to reap benefits. This review summarizes current knowledge on norovirus infection in older adults.

Rapid detection of norovirus from fresh lettuce using immunomagnetic separation and a quantum dots assay

Current molecular methods that include PCR have been used to detect norovirus in many food samples. However, the protocols require removing PCR inhibitors and incorporate time-consuming concentration steps to separate virus from analyte for rapid and sensitive detection of norovirus. We developed an immunomagnetic separation (IMS) and a quantum dots (QDs) assay to detect norovirus eluted from fresh lettuce with Tris buffer containing 1% beef extract (pH 9.5). IMS facilitated viral precipitation with a 10-min incubation, whereas virus concentration using polyethylene glycol (PEG) requires more than 3 h and an additional high-speed centrifugation step to precipitate virus before reverse transcription PCR (RT-PCR) analysis. The fluorescence intensity of QDs was detected qualitatively on norovirus dilutions of 10(-1) to 10(-3) in a stool suspension (100 RT-PCR units/ml). The results suggest that a fluorescence assay based on IMS and QDs is valid for detecting norovirus qualitatively according to fluorescent signal intensity within the same virus detection limit produced by IMS-RT-PCR and PEG-RT-PCR.

Effect of pH on anti-rotavirus activity by comestible juices and proanthocyanidins in a cell-free assay system

Cranberry (Vaccinium macrocarpon) and grape (Vitis labrusca) juices, and these species' secondary plant metabolites [i.e., proanthocyanidins (PACs)] possess antiviral activity. An understanding of the mechanism(s) responsible for these juices and their polyphenolic constituents' direct effect on enteric virus integrity, however, remains poorly defined. Using the rotavirus (RTV) as a model enteric virus system, the direct effect of manufacturer-supplied and commercially purchased juices [Ocean Spray Pure Cranberry 100 % Unsweetened Juice (CJ), Welch's 100 % Grape Juice (GJ), 100 % Concord (PG) and 100 % Niagara juices (NG)] and these species' cranberry (C-PACs) and grape PACs (G-PACs) was investigated. Loss of viral capsid integrity in cell-free suspension by juices and their PACs, and as a factor of pH, was identified by an antigen (RTV) capture enzyme-linked immunosorbent assay. At native and an artificially increased suspension at or near pH 7, loss of viral infectivity occurred after 5 min, in the order CJ > NG = GJ > PG, and PG > GJ = NG = CJ, respectively. Antiviral activity of CJ was inversely related to pH. Grape, but not cranberry PACs, displayed a comparatively greater anti-RTV activity at a suspension pH of 6.7. Anti-RTV activity of C-PACs was regained upon reduction of RTV-cranberry PAC suspensions to pH 4. An alteration or modification of Type A PAC (of V. macrocarpon) structural integrity at or near physiologic pH is suggested to have impacted on this molecule's antivirus activity. Type B PACs (of V. labrusca) were refractive to alternations of pH. Significantly, findings from pure system RTV-PAC testing paralleled and in turn, supported those RTV-juice antiviral studies. Electron microscopy showed an enshroudment by PACs of RTV particles, suggesting a blockage of viral antigenic binding determinants. The implications of our work are significant, especially in the interpretation of PAC (and PAC-containing food)-RTV interactions in the differing [pH] conditions of the gastrointestinal tract.

Detection of noroviruses in ready-to-eat foods by using carbohydrate-coated magnetic beads

This study used histo-blood group antigen-conjugated beads to detect norovirus (NoV) in contaminated strawberries, green onions, lettuce, and deli ham. In addition, multiple strains of NoV from genogroups I and II were recovered. This provides an effective protocol for food testing in the investigation of suspected NoV outbreaks.

Inactivation of enteric viruses in minimally processed berries and herbs

Several hepatitis A virus (HAV) and human norovirus (HuNoV) outbreaks due to consumption of contaminated berries and vegetables have recently been reported. Model experiments were performed to determine the effectiveness of freeze-drying, freeze-drying combined with heating, and steam blanching for inactivation of enteric viruses that might be present on the surface of berries and herbs. Inactivation of HAV and inactivation of feline calicivirus, a surrogate for HuNoV, were assessed by viral culturing and quantitative reverse transcription PCR (RT-PCR), whereas HuNoV survival was determined only by quantitative RT-PCR. While freeze-drying barely reduced (<1.3 log(10) units) the amount of HAV RNA detected in frozen produce, a greater decline in HAV infectivity was observed. The resistance of HuNoV genogroup I (GI) to freeze-drying was significantly higher than that of HuNoV GII on berries. Addition of a terminal dry heat treatment at 120 degrees C after freeze-drying enhanced virus inactivation by at least 2 log(10) units, except for HuNoV GII. The results suggest that steam blanching at 95 degrees C for 2.5 min effectively inactivated infectious enteric viruses if they were present in herbs. Our results provide data for adjusting food processing technologies if viral contamination of raw materials is suspected.

Survival and transfer of murine norovirus 1, a surrogate for human noroviruses, during the production process of deep-frozen onions and spinach

The reduction of murine norovirus 1 (MNV-1) on onions and spinach by washing was investigated as was the risk of contamination during the washing procedure. To decontaminate wash water, the industrial sanitizer peracetic acid (PAA) was added to the water, and the survival of MNV-1 was determined. In contrast to onions, spinach undergoes a heat treatment before freezing. Therefore, the resistance of MNV-1 to blanching of spinach was examined. MNV-1 genomic copies were detected with a real-time reverse transcription PCR assay in PAA-treated water and blanched spinach, and PFUs (representing infectious MNV-1 units) were determined with a plaque assay. A < or = 1-log reduction in MNV-1 PFUs was achieved by washing onion bulbs and spinach leaves. More than 3 log PFU of MNV-1 was transmitted to onion bulbs and spinach leaves when these vegetables were washed in water containing approximately 5 log PFU/ml. No decline of MNV-1 occurred in used industrial spinach wash water after 6 days at room temperature. A concentration of 20 ppm of PAA in demineralized water (pH 4.13) and in potable water (pH 7.70) resulted in reductions of 2.88 +/- 0.25 and 2.41 +/- 0.18 log PFU, respectively, after 5 min of exposure, but no decrease in number of genomic copies was observed. No reduction of MNV-1 PFUs was observed on frozen onions or spinach during storage for 6 months. Blanching spinach (80 degrees C for 1 min) resulted in at least 2.44-log reductions of infectious MNV-1, but many genomic copies were still present.

Detection and quantification by real-time RT-PCR of hepatitis A virus from inoculated tap waters, salad vegetables, and soft fruits: characterization of the method performances

Water, salad vegetables and fruits exposed to fecal contamination may cause outbreaks of hepatitis A. A protocol of viral concentration by filtration on electronegative membrane filter and a protocol based on a viral elution in Tris-glycine buffer, pH 9.5 with concentration by polyethylene glycol precipitation were associated with real-time, reverse transcriptase-PCR to detect hepatitis A virus (HAV) artificially inoculated in 2 l of tap water, or on 25 g of fruits or salad vegetables. These methods were characterized by an intra-laboratory study using the international standard ISO 16140 on five types of tap water, six types of fruit and five types of salad vegetable. Linear regression models describing the quantitative reactions were good fits to data, and the variances of results were constant in the whole range of viral concentrations tested, which was from about 1.7 to 5.7 log plaque-forming units (PFU) per 2 l of tap water, from about 2.0 to 4.5 log PFU/25 g of fruits, and from 1.5 to 3.5 log PFU/25 g of salad vegetables. Fractions of inoculated viruses recovered were estimated to be about 20% for tap water, about 16% for salad vegetables, and about 7% for fruits. The probability of detecting positive samples was 50% (the critical level of detection) when 2 l samples of tap water were inoculated with 0.7 log PFU of HAV, 25 g samples of iceberg lettuce were inoculated with 1.0 log PFU of HAV, and 25 g samples of fresh and frozen raspberries were inoculated with 1.0 and 1.5 log PFU of HAV, respectively.

Procedure for rapid concentration and detection of enteric viruses from berries and vegetables

Several hepatitis A virus (HAV) and norovirus (NV) outbreaks due to consumption of berries and vegetables have been reported during recent years. To facilitate the detection of enteric viruses that may be present on different fresh and frozen products, we developed a rapid and sensitive detection method for HAV, NV, and rotavirus (RV). Initial experiments focused on optimizing the composition of the elution buffer, improving the viral concentration method, and evaluating the performance of various extraction kits. Viruses were extracted from the food surface by a direct elution method in a glycine-Tris (pH 9.5) buffer containing 1% beef extract and concentrated by ultrafiltration. Occasionally, PCR inhibitors were present in the processed berry samples, which gave relatively poor detection limits. However, this problem was overcome by adding a pectinase treatment in the protocol, which markedly improved the sensitivity of the method. After optimization, this concentration method was applied in combination with real-time reverse transcription-PCR (RT-PCR) using specific primers in various types of berries and vegetables. The average detection limits were 1 50% tissue culture infective dose (TCID(50)), 54 RT-PCR units, and 0.02 TCID(50) per 15 g of food for HAV, NV, and RV, respectively. Based on our results, it is concluded that this procedure is suitable to detect and quantify enteric viruses within 6 h and can be applied for surveillance of enteric viruses in fresh and frozen products.

Intra-laboratory validation of a concentration method adapted for the enumeration of infectious F-specific RNA coliphage, enterovirus, and hepatitis A virus from inoculated leaves of salad vegetables

Salad vegetables exposed to fecal contamination may cause outbreaks of hepatitis or gastro-enteritis if they are eaten raw. A procedure, based on elution with phosphate-buffered saline and concentration by filtration through membrane filters, was developed for the recovery of enteric viruses from salad leaves. The method was evaluated using lettuce leaves inoculated with hepatitis A virus (HAV), poliovirus, and MS2 bacteriophage. In addition, this method was validated by an intra-laboratory study using leaves of various salad vegetables inoculated with MS2 phage. The French standard NF V 03-110 was used to establish the general principle and the technical protocol of the validation procedure. Linear regression models describing the quantitative reactions were good fits to data in the whole range of viral concentrations tested, which was from about 1 to 4 log plaque-forming units (PFU) per 25 g of lettuce. The fractions of inoculated viruses recovered were estimated to be about 64% for HAV, 18% for poliovirus, and 29% for MS2. No significant effect of the food matrix was found using various types of salad vegetable (butter lettuce, iceberg lettuce, romaine lettuce, witloof chicory, curly endive, corn salad, rocket and watercress). Moreover, the variance of the results was constant for all levels of virus contamination within the experimental range. Intermediate reproducibility experiments were also performed to allow calculation of the uncertainty factor, which was found to be 0.58 log PFU/25 g. When used in association with phage enumeration, this validated procedure is rapid enough to be used for screening salad vegetables for evaluation of the efficacy of processes for control of pathogenic microorganisms on such foods.

Norovirus and foodborne disease, United States, 1991-2000

Analysis of foodborne outbreaks shows how advances in viral diagnostics are clarifying the causes of foodborne outbreaks and determining the high impact of norovirus infections.

Efforts to prevent foodborne illness target bacterial pathogens, yet noroviruses (NoV) are suspected to be the most common cause of gastroenteritis. New molecular assays allow for better estimation of the role of NoV in foodborne illness. We analyzed 8,271 foodborne outbreaks reported to the Centers for Disease Control and Prevention from 1991 to 2000 and additional data from 6 states. The proportion of NoV-confirmed outbreaks increased from 1% in 1991 to 12% in 2000. However, from 1998 to 2000, 76% of NoV outbreaks were reported by only 11 states. In 2000, an estimated 50% of foodborne outbreaks in 6 states were attributable to NoV. NoV outbreaks were larger than bacterial outbreaks (median persons affected: 25 versus 15), and 10% of affected persons sought medical care; 1% were hospitalized. More widespread use of molecular assays will permit better estimates of the role of NoV illness and help direct efforts to control foodborne illness.

Detection of noroviruses in raspberries associated with a gastroenteritis outbreak

Following an acute foodborne gastroenteritis outbreak in southern Sweden, stool specimens from five of nine ill patients were found positive for norovirus using reverse transcriptase polymerase chain reaction. Epidemiological data pointed to raspberry cakes as the source of the outbreak. Using a combination of generic and patient-specific primers and novel food analysis methodology (with extraction efficiency control and inhibitor removal), norovirus strains from two different genogroups were directly identified in the contaminated raspberries.

Irrigation water as source of foodborne pathogens on fruit and vegetables

Awareness is growing that fresh or minimally processed fruit and vegetables can be sources of disease-causing bacteria, viruses, protozoa, and helminths. Irrigation with poor-quality water is one way that fruit and vegetables can become contaminated with foodborne pathogens. Groundwater, surface water, and human wastewater are commonly used for irrigation. The risk of disease transmission from pathogenic microorganisms present in irrigation water is influenced by the level of contamination; the persistence of pathogens in water, in soil, and on crops; and the route of exposure. Groundwater is generally of good microbial quality, unless it is contaminated with surface runoff; human wastewater is usually of very poor microbial quality and requires extensive treatment before it can be used safely to irrigate crops; surface water is of variable microbial quality. Bacteria and protozoa tend to show the poorest survival outside a human host, whereas viruses and helminths can remain infective for months to years. Guidelines governing irrigation water quality and strategies to reduce the risk of disease transmission by foodborne pathogens in irrigation are discussed.

Simultaneous detection of enteric viruses by multiplex real-time RT-PCR

A multiplex real-time RT-PCR protocol for the simultaneous detection of noroviruses ("Norwalk-like viruses") of genogroups I and II, human astroviruses and enteroviruses is described. The protocol was developed and evaluated using the LightCycler and corresponding SYBR Green reagents. New primers were designed within conserved genome regions to optimize the detection range of virus subtypes of each genus. To enable the development of a multiplex PCR assay within one tube (capillary), similar mastermix- and cycling-conditions were respected for each individual primer system. Subsequent melting curve analysis allowed the determination of possible dual-contaminations of entero- and noro- or astroviruses by the formation of dual peaks. Special care was taken to minimize the loss of sensitivity, since the detection of small viral contaminations is a crucial parameter especially for food analysis. The multiplex assay was compared successfully to the single SYBR Green assay, and revealed to be at least 10 times more sensitive than the one obtained with an endpoint PCR thermocycler protocol published previously.

Calicivirus infections in children

PURPOSE OF REVIEW

Caliciviruses are a major cause of human illness, and are listed as category B pathogens according to the National Institute of Allergy and Infectious Diseases classification of pathogens important for biodefense. Caliciviruses are commonly encountered in contaminated food and water, and a large variety has been implicated as sources of infection during outbreak investigations.

RECENT FINDINGS

New names for two of the four genera of the Caliciviridae were approved in 2002. They are Norovirus, for what were previously called Norwalk-like viruses or small, round-structured viruses, and Sapovirus, for what were previously called Sapporo-like viruses. Caliciviruses are highly diverse genetically and antigenically. This diversity complicates the design of diagnostic assays, yet can be used to discriminate contaminating and infecting strains during outbreak investigations. Of particular interest is the recent finding of naturally occurring recombinant Norovirus strains, all of which have been virulent and are widely dispersed and apparently ecologically indistinguishable from other calicivirus strains. This finding is considered in light of the evidence for recombination between caliciviruses and picornaviruses, and recombination as a more general phenomenon for virus evolution.

SUMMARY

Continued investigations of calicivirus outbreaks are now focusing on the implicated sources of infection. While many foods and environmental waters have long been implicated as outbreak sources, the methods for detecting caliciviruses are being developed and refined. Recognition is now turning to unexpected sources of contamination, such as presumably clean foods and waters, including bottled water and minimally handled foods. Parallels between Norovirus and Salmonella ecology and epidemiology are noted, as a guide to understanding evolving new information about caliciviruses.

Norwalk-like virus sequences in mineral waters: one-year monitoring of three brands

In a recent study, RNA with nucleotide sequeces specific for "Norwalk-like viruses" (NLV) was detected in 11 different brands of European mineral waters. To clarify this finding, a 1-year monitoring study was conducted. Samples of three European brands of mineral water without gas were monitored weekly by reverse transcriptase PCR using generic and genogroup-specific oligonucleotides. Additional analyses were performed to investigate a possible correlation between NLV sequence contamination and mineral water lot numbers, the long-term stability (persistence) of NLV sequences in mineral water, and the level of contamination. NLV sequences were detected in 53 of 159 samples analyzed (33%) and belonged entirely to genogroup II. Although all NLV strains identified were closely related, three mineral water brand-specific clusters could be identified for both primer systems by sequencing. Analyses of second samples from lots previously shown to be positive for NLV sequences gave corresponding results in 45 of 53 cases (85%) (within a six-pack). NLV persistence was tested by analyzing 10 positive samples after 6 and 12 months of storage in darkness at room temperature. After 6 months, all samples remained positive; after 12 months, 9 of 10 samples were still positive for NLV sequences. No NLV sequences could be detected by analysis of 0.1-liter aliquots of 53 samples shown to be positive by testing of 1-liter volumes. Based on this fact and a test sensitivity of approximately 10 viral units, levels of contamination in positive mineral water samples were estimated to be in the range of 10 to 100 genomic equivalents per liter.

Human caliciviruses in Europe

Caliciviruses are single-stranded RNA viruses, which are divided into four genera based on their morphology and genomic structure. Viruses from two genera, the Norwalk like viruses and Sapporo like viruses, are a common cause of acute, nonbacterial gastroenteritis in humans. Although the first human calicivirus discovered nearly 30 years ago, much of the epidemiological and biological character of these viruses is only now beginning to unfold. Investigation has been difficult due to a number of factors, the viruses cannot be amplified by in vitro cell culture or animal models and electron microscopy (EM) is often not sensitive enough to detect the viruses in stool samples. Recent advances in molecular diagnostic techniques and the advent of a baculovirus expression system have highlighted the clinical and public health importance of calicivirus in all age groups, their ability to cause infection via a number of transmission routes as well as their considerable genetic diversity. These characteristics, in conjunction with the inability of humans to develop long-term immunity make HuCV an important public health issue in Europe and worldwide.

Antibacterial activity of raspberry cordial in vitro

Raspberry juice cordial has a long anecdotal use in Australia for the prophylaxis and treatment of gastroenteritis in livestock, cage birds and humans. The antimicrobial properties of raspberry juice cordial, raspberry juice, raspberry leaf extract and a commercial brand of raspberry leaf tea were investigated against five human pathogenic bacteria and two fungi. Raspberry cordial and juice were found to significantly reduce the growth of several species of bacteria, including Salmonella, Shigella and E. coli, but demonstrated no antifungal activity. No antimicrobial activity was detected in the leaf extract or tea.

Foodborne outbreaks in Canada linked to produce

Examples of foodborne outbreaks traced to fresh fruits and vegetables can be found worldwide. The quantity of produce eaten per capita has been increasing steadily over the past two decades, creating a heightened potential for produce-related foodborne disease. A number of outbreaks identified during this time period were reviewed, with particular emphasis placed on incidents that have occurred in Canada. The collective information highlights the diversity of infectious agents and produce items involved, with a view to the prevention of fresh produce-related foodborne disease in the future.

Norwalk-like virus sequences detected by reverse transcription-polymerase chain reaction in mineral waters imported into or bottled in Switzerland

Norwalk-like viruses (NLVs) is a genus belonging to the Caliciviridae. NLVs are transmitted by the fecal-oral and the aerosol route and are the most common cause of outbreaks of nonbacterial gastroenteritis. NLVs are responsible for an estimated 67% of all illnesses caused by known foodborne pathogens and for 96% of nonbacterial gastroenteritis in the United States. Many outbreaks could be associated with the consumption of primarily or secondarily contaminated foods. To our knowledge, no epidemic arising from contaminated mineral water has been reported. We investigated the presence of NLV sequences in 63 mineral waters of 29 different brands that were imported into or bottled in Switzerland. NLV sequences were detected in 21 mineral waters by reverse transcription-seminested polymerase chain reaction. Specimens of two NLV genogroups (gg), gg I and gg II, were randomly present in the contaminated samples. The presence of NLV sequences could not be correlated either with bottle characteristics or with chemical properties like mineralization, pH, or the presence of carbonic acid. Nucleotide sequence analysis of 12 NLV-positive samples revealed several point mutations. All isolated NLV gg I strains have a similarity of 70 to 87% with the common Desert Shield virus (UO4469), and all isolated NLV gg II strains have a similarity of 89 to 93% with the Camberwell virus (U46500). Possible reasons for the presence of NLV sequences in mineral waters are discussed.