Foodborne viral illness--status in Australia

Rotavirus in developing countries: molecular diversity, epidemiological insights, and strategies for effective vaccination

Rotavirus (RV) causes the loss of numerous children's lives worldwide each year, and this burden is particularly heavy in low- and lower-middle-income countries where access to healthcare is limited. RV epidemiology exhibits a diverse range of genotypes, which can vary in prevalence and impact across different regions. The human genotypes that are most commonly recognized are G1P[8], G2P[4], G3P[8], G4P[8], G8P[8], G9P[8], and G12P[8]. The diversity of rotavirus genotypes presents a challenge in understanding its global distribution and developing effective vaccines. Oral, live-attenuated rotavirus vaccines have undergone evaluation in various contexts, encompassing both low-income and high-income populations, demonstrating their safety and effectiveness. Rotavirus vaccines have been introduced and implemented in over 120 countries, offering an opportunity to assess their effectiveness in diverse settings. However, these vaccines were less effective in areas with more rotavirus-related deaths and lower economic status compared to wealthier regions with fewer rotavirus-related deaths. Despite their lower efficacy, rotavirus vaccines significantly decrease the occurrence of diarrheal diseases and related mortality. They also prove to be cost-effective in regions with a high burden of such diseases. Regularly evaluating the impact, influence, and cost-effectiveness of rotavirus vaccines, especially the newly approved ones for worldwide use, is essential for deciding if these vaccines should be introduced in countries. This is especially important in places with limited resources to determine if a switch to a different vaccine is necessary. Future research in rotavirus epidemiology should focus on a comprehensive understanding of genotype diversity and its implications for vaccine effectiveness. It is crucial to monitor shifts in genotype prevalence and their association with disease severity, especially in high-risk populations. Policymakers should invest in robust surveillance systems to monitor rotavirus genotypes. This data can guide vaccine development and public health interventions. International collaboration and data sharing are vital to understand genotype diversity on a global scale and facilitate the development of more effective vaccines.

Rapid Detection of Hepatitis A Virus in Foods Using a Bioluminescent Assay in Real-Time (BART) and Reverse Transcription Loop-Mediated Isothermal Amplification (RT-LAMP) Technology

Foodborne hepatitis A infections have been considered as a major threat for public health worldwide. Increased incidences of hepatitis A virus (HAV) infection has been associated with growing global trade of food products. Rapid and sensitive detection of HAV in foods is very essential for investigating the outbreaks. Real-time RT-PCR has been most widely used for the detection of HAV by far. However, the technology relies on fluorescence determination of the amplicon and requires sophisticated, high-cost instruments and trained personnel, limiting its use in low resource settings. In this study, a robust, affordable, and simple assay, reverse transcription loop-mediated isothermal amplification (RT-LAMP) assay in combination with a bioluminescence-based determination of amplification in real-time (BART), was developed for the detection of HAV in different food matrices, including green onion, strawberry, mussel, and milk. The efficiencies of a one-step RT-LAMP-BART and a two-step RT-LAMP-BART were investigated for the detection of HAV in different food matrices and was compared with that of real-time RT-PCR. The sensitivity of the RT-LAMP-BART assay was significantly affected by Mg²⁺ concentration (P < 0.05), in addition to primer quality. The optimal Mg²⁺ concentration was 2 mM for one-step RT-LAMP-BART and 4 mM for two-step RT-LAMP-BART. Compared with cartridge-purified primers, HPLC-purified primers could greatly improve the sensitivity of the RT-LAMP-BART assay (P < 0.05). For detecting HAV in different food matrices, the performance of two-step RT-LAMP-BART was comparable with that of real-time RT-PCR and was better than that of one-step RT-LAMP-BART. The detection limit of the two-step RT-LAMP-BART for HAV in green onion, strawberry, mussel, and milk was 8.3 × 10⁰ PFU/15 g, 8.3 × 10¹ PFU/50 g, 8.3 × 10⁰ PFU/5 g, and 8.3 × 10⁰ PFU/40 mL, respectively. The developed RT-LAMP-BART was an effective, simple, sensitive, and robust method for foodborne HAV detection.

Rotaviruses: From Pathogenesis to Disease Control-A Critical Review

Since their first recognition in human cases about four decades ago, rotaviruses have remained the leading cause of acute severe dehydrating diarrhea among infants and young children worldwide. The WHO prequalification of oral rotavirus vaccines (ORV) a decade ago and its introduction in many countries have yielded a significant decline in the global burden of the disease, although not without challenges to achieving global effectiveness. Poised by the unending malady of rotavirus diarrhea and the attributable death cases in developing countries, we provide detailed insights into rotavirus biology, exposure pathways, cellular receptors and pathogenesis, host immune response, epidemiology, and vaccination. Additionally, recent developments on the various host, viral and environmental associated factors impacting ORV performance in low-and middle-income countries (LMIC) are reviewed and their significance assessed. In addition, we review the advances in nonvaccine strategies (probiotics, candidate anti-rotaviral drugs, breastfeeding) to disease prevention and management.

Efficient capturing and sensitive detection of hepatitis A virus from solid foods (green onion, strawberry, and mussel) using protamine-coated iron oxide (Fe3O4) magnetic nanoparticles and real-time RT-PCR

Hepatitis A virus (HAV) continues to be a public health concern and has caused large foodborne outbreaks and economic losses worldwide. Rapid detection of HAV in foods can help to confirm the source of outbreaks in a timely manner and prevent more people getting infected. In order to efficiently detect HAV at low levels of contamination in foods, rapid and easy-to-use techniques are required to separate and concentrate viral particles to a small volume. In the current study, HAV particles were eluted from green onion, strawberry, and mussel using glycine buffer (0.05 M glycine, 0.14 M NaCl, 0.2% (v/v) Tween 20, pH 9.0) and suspended viral particles were captured using protamine-coated magnetic nanoparticles (PMNPs). This process caused a selective concentration of the viral particles, which could be followed by quantitative real-time RT-PCR analysis. Results showed that pH, NaCl concentration, and PMNP amount used for the capturing had significant effects on the recovery efficiency of HAV (P < 0.05). The highest recovery rate was obtained at pH 9.0, 0.14 M NaCl, and 50 μL of PMNPs. The optimized PMNP capturing method enabled the rapid capture and concentration of HAV. A sensitive real-time RT-PCR test was developed with detection limits of 8.3 × 10⁰ PFU/15 g, 8.3 × 10¹ PFU/50 g, and 8.3 × 10⁰ PFU/5 g of HAV in green onion, strawberry, and mussel, respectively. In conclusion, the PMNP method is rapid and convenient in capturing HAV from complex solid food samples and can generate concentrated HAV sample solutions suitable for high-sensitivity real time RT-PCR detection of the virus.

Efficacy and mechanisms of murine norovirus inhibition by pulsed-light technology

Pulsed light is a nonthermal processing technology recognized by the FDA for killing microorganisms on food surfaces, with cumulative fluences up to 12 J cm(-2). In this study, we investigated its efficacy for inactivating murine norovirus 1 (MNV-1) as a human norovirus surrogate in phosphate-buffered saline, hard water, mineral water, turbid water, and sewage treatment effluent and on food contact surfaces, including high-density polyethylene, polyvinyl chloride, and stainless steel, free or in an alginate matrix. The pulsed-light device emitted a broadband spectrum (200 to 1,000 nm) at a fluence of 0.67 J cm(-2) per pulse, with 2% UV at 8 cm beneath the lamp. Reductions in viral infectivity exceeded 3 log10 in less than 3 s (5 pulses; 3.45 J cm(-2)) in clear suspensions and on clean surfaces, even in the presence of alginate, and in 6 s (11 pulses; 7.60 J cm(-2)) on fouled surfaces except for stainless steel (2.6 log10). The presence of protein or bentonite interfered with viral inactivation. Analysis of the morphology, the viral proteins, and the RNA integrity of treated MNV-1 allowed us to elucidate the mechanisms involved in the antiviral activity of pulsed light. Pulsed light appeared to disrupt MNV-1 structure and degrade viral protein and RNA. The results suggest that pulsed-light technology could provide an effective alternative means of inactivating noroviruses in wastewaters, in clear beverages, in drinking water, or on food-handling surfaces in the presence or absence of biofilms.

Evaluation of Immunomagnetic Separation Method for the Recovery of Hepatitis A Virus and GI.1 and GII.4 Norovirus Strains Seeded on Oyster and Mussel

Outbreaks of viral diseases are frequently associated with the consumption of minimally processed shellfish. Among the viruses in these outbreaks, hepatitis A virus (HAV) and human norovirus (NoV) have been increasingly reported as the most common food-borne pathogens. These viruses must be concentrated in tested samples in order to be detected. In this study, a method for the detection of NoV and HAV in shellfish using an immuno-magnetic separation (IMS) procedure combined with reverse transcriptase (RT)-PCR was developed. The IMS/RT-PCR method was applied to investigate the recovery rates of HAV, NoV GI.1, and GII.4 from oyster and mussel. Based on IMS/RT-PCR results, recovery rates for HAV from oyster and mussel test samples were 2.4 and 1.1%, respectively. The NoV GI.1 recovery rates from oyster and mussel samples were 4.9-9.2% (mean 6.9%) and 4.3-8.6% (mean 6.2%), respectively, and the NoV GII.4 recovery rates were 8.8 and 8.5%, respectively. These results verified that HAV, NoV GI.1, and GII.4 can be detected in all the test samples using the IMS/RT-PCR method, although the three inoculated viruses were recovered with low efficiency. In conclusion, the IMS/RT-PCR method can be used to efficiently and rapidly detect viruses such as HAV and NoV in shellfish such as oyster and mussel.

Determination of thermal inactivation kinetics of hepatitis A virus in blue mussel (Mytilus edulis) homogenate

Hepatitis A virus (HAV) is a food-borne enteric virus responsible for outbreaks of hepatitis associated with shellfish consumption. The objectives of this study were to determine the thermal inactivation behavior of HAV in blue mussels, to compare the first-order and Weibull models to describe the data, to calculate Arrhenius activation energy for each model, and to evaluate model efficiency by using selected statistical criteria. The times required to reduce the population by 1 log cycle (D-values) calculated from the first-order model (50 to 72°C) ranged from 1.07 to 54.17 min for HAV. Using the Weibull model, the times required to destroy 1 log unit (tD = 1) of HAV at the same temperatures were 1.57 to 37.91 min. At 72°C, the treatment times required to achieve a 6-log reduction were 7.49 min for the first-order model and 8.47 min for the Weibull model. The z-values (changes in temperature required for a 90% change in the log D-values) calculated for HAV were 15.88 ± 3.97°C (R(2), 0.94) with the Weibull model and 12.97 ± 0.59°C (R(2), 0.93) with the first-order model. The calculated activation energies for the first-order model and the Weibull model were 165 and 153 kJ/mol, respectively. The results revealed that the Weibull model was more appropriate for representing the thermal inactivation behavior of HAV in blue mussels. Correct understanding of the thermal inactivation behavior of HAV could allow precise determination of the thermal process conditions to prevent food-borne viral outbreaks associated with the consumption of contaminated mussels.

Shellfish-borne viral outbreaks: a systematic review

Investigations of disease outbreaks linked to shellfish consumption have been reported in the scientific literature; however, only few countries systematically collate and report such data through a disease surveillance system. We conducted a systematic review to investigate shellfish-borne viral outbreaks and to explore their distribution in different countries, and to determine if different types of shellfish and viruses are implicated. Six databases (Medline, Embase, Scopus, PubMed, Eurosurveillance Journal and Spingerlink electronic Journal) and a global electronic reporting system (ProMED) were searched from 1980 to July 2012. About 359 shellfish-borne viral outbreaks, alongside with nine ProMED reports, involving shellfish consumption, were identified. The majority of the reported outbreaks were located in East Asia, followed by Europe, America, Oceania, Australia and Africa. More than half of the outbreaks (63.6 %) were reported from Japan. The most common viral pathogens involved were norovirus (83.7 %) and hepatitis A virus (12.8 %). The most frequent type of consumed shellfish which was involved in outbreaks was oysters (58.4 %). Outbreaks following shellfish consumption were often attributed to water contamination by sewage and/or undercooking. Differences in reporting of outbreaks were seen between the scientific literature and ProMED. Consumption of contaminated shellfish represents a risk to public health in both developed and developing countries, but impact will be disproportionate and likely to compound existing health disparities.

Human norovirus surrogate reduction in milk and juice blends by high pressure homogenization

Novel processing technologies such as high pressure homogenization (HPH) for the inactivation of foodborne viruses in fluids that retain nutritional attributes are in high demand. The objectives of this research were (i) to determine the effects of HPH alone or with an emulsifier (lecithin) on human norovirus surrogates-murine norovirus (MNV-1) and feline calicivirus (FCV-F9)-in skim milk and orange juice, and (ii) to determine HPH effects on FCV-F9 and MNV-1 in orange and pomegranate juice blends. Experiments were conducted in duplicate at 0, 100, 200, 250, and 300 MPa for <2 s and plaque was assayed in duplicate. In milk, FCV-F9 was reduced by ≥4 and ∼1.3 log PFU/ml at 300 and 250 MPa, respectively, and ≥4- and ∼1-log PFU/ml reductions were obtained in orange juice at 300 and 250 MPa, respectively. In orange juice or milk combined with lecithin, FCV-F9 was reduced to nondetectable levels at 300 MPa, and by 1.77 and 0.78 log PFU/ml at 250 MPa. MNV-1 in milk was reduced by ∼1.3 log PFU/ml only at 300 MPa, and by ∼0.8 and ∼0.4 log PFU/ml in orange juice at 300 and 250 MPa, respectively. MNV-1 in milk or orange juice containing lecithin at 300 MPa showed 1.32- and 2.5-log PFU/ml reductions, respectively. In the pomegranate-orange juice blend, FCV-F9 was completely reduced, and MNV-1 was reduced by 1.04 and 1.78 log PFU/ml at 250 and 300 MPa, respectively. These results show that HPH has potential for commercial use to inactivate foodborne virus surrogates in juices.

Survival and inactivation of human norovirus surrogates in blueberry juice by high-pressure homogenization

Human noroviruses (HNoV) have been implicated in gastrointestinal outbreaks associated with fresh produce, juices, and ready-to-eat foods. In order to determine the risk of HNoV transmission by contaminated blueberry juice, survival characteristics of cultivable HNoV surrogates (murine norovirus, MNV-1; feline calicivirus, FCV-F9; and bacteriophage MS2) in blueberry juice (pH = 2.77) after 0, 1, 2, 7, 14, and 21 days at refrigeration temperatures (4°C) were studied. High-pressure homogenization (HPH) was studied as a novel processing method for noroviral surrogate inactivation in blueberry juice. Blueberry juice or phosphate-buffered saline (PBS; pH 7.2 as control) was inoculated with each virus, stored over 21 days at 4°C or subjected to HPH, and plaque assayed. FCV-F9 (∼5 log(10) PFU/mL) was undetectable after 1 day in blueberry juice at 4°C. MNV-1 (∼4 log(10) PFU/ml) showed minimal reduction (1 log(10) PFU/mL) after 14 days, with greater reduction (1.95 log(10) PFU/mL; p < 0.05) after 21 days in blueberry juice at 4°C. Bacteriophage MS2 (∼6 log(10) PFU/mL) showed significant reduction (1.93 log(10) PFU/mL; p < 0.05) after 2 days and was undetectable after 7 days in blueberry juice at 4°C. FCV-F9 remained viable in PBS for up to 21 days (2.28 log(10) PFU/mL reduction), while MNV-1 and MS2 survived after 21 days (1.08 and 0.56 log(10) PFU/mL reduction, respectively). Intriguingly, FCV-F9 and bacteriophage MS2 showed reduction after minimal homogenization pressures in blueberry juice (pH = 2.77), possibly due to the combination of juice pH, juice components, and mechanical effects. MNV-1 in blueberry juice was only slightly reduced at 250 (0.33 log(10) PFU/mL) and 300 MPa (0.71 log(10) PFU/mL). Virus surrogate survival in blueberry juice at 4°C correlates well with the ease of HNoV transmission via juices. HPH for viral inactivation in juices is dependent on virus type, and higher homogenization pressures may be needed for MNV-1 inactivation.

Comparison of reduction in foodborne viral surrogates by high pressure homogenization

With the increasing global spread of human noroviral infections and the emergence of highly virulent noroviral strains, novel inactivation methods are needed to control foodborne outbreaks. High pressure homogenization (HPH) is a novel method that can be applied for foodborne virus reduction in fluids being continuously processed. Our objective in the present study was to compare the titer reduction by HPH between feline calicivirus strain F9 (FCV-F9) and murine norovirus 1 (MNV-1) as surrogates for human noroviruses, and MS2 (single-stranded F-RNA coliphage) and somatic coliphage φX174 (single-stranded DNA) as indicators of fecal contamination. Duplicate experiments with each virus in phosphate-buffered saline were carried out with homogenization pressures of 0, 100, 200, 250, and 300 MPa, with exposure temperatures of 24, 46, 63, 70, and 75°C, respectively, for <2 s. FCV-F9 was found highly susceptible to HPH treatment pressures of 300 MPa, with a reduction of >4.95 log PFU/ml. Lower pressures of 250, 200, and 100 MPa resulted in reductions of 1.61, 0.60, and 0.18 log PFU/ml of FCV-F9, respectively, while MNV-1 was not reduced at these lower pressures. Coliphage φX174 showed no significant reduction at 300 MPa or lower homogenization pressures in comparison with MS2, which did show 3.3-log PFU/ml reduction at 300 MPa. Future studies using juices for industrial application of HPH to determine microbial inactivation with simultaneous retention of sensory and nutritional value of foods are needed.

Effects of technological processes on the tenacity and inactivation of norovirus genogroup II in experimentally contaminated foods

Contaminated food is a significant vehicle for human norovirus transmission. The present study determined the effect of physicochemical treatments on the tenacity of infective human norovirus genogroup II in selected foods. Artificially contaminated produce was subjected to a number of processes used by the food industry for preservation and by the consumer for storage and preparation. Virus recovery was carried out by using ultrafiltration and was monitored by using bacteriophage MS2 as an internal process control. Norovirus was quantified by using monoplex one-step TaqMan real-time reverse transcription (RT)-PCR and an external standard curve based on recombinant RNA standards. An RNase pretreatment step was used to avoid false-positive PCR results caused by accessible RNA, which allowed detection of intact virus particles. Significant reductions in titers were obtained with heat treatments usually applied by consumers for food preparation (baking, cooking, roasting). Generally, processes used for preservation and storage, such as cooling, freezing, acidification (>or=pH 4.5), and moderate heat treatments (pasteurization), appear to be insufficient to inactivate norovirus within a food matrix or on the surface of food. Besides data for persistence in processed food, comparable data for individual matrix-specific protective effects, recovery rates, and inhibitory effects on the PCRs were obtained in this study. The established procedure might be used for other noncultivable enteric RNA viruses that are connected to food-borne diseases. The data obtained in this study may also help optimize the process for inactivation of norovirus in food by adjusting food processing technologies and may promote the development of risk assessment systems in order to improve consumer protection.

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.

Salmonella and Shigella in freshly squeezed orange juice, fresh oranges, and wiping cloths collected from public markets and street booths in Guadalajara, Mexico: incidence and comparison of analytical routes

A survey of the presence of Salmonella and Shigella in freshly squeezed orange juice and related samples was conducted in Guadalajara, Mexico. One hundred samples of freshly squeezed orange juice were collected from 49 street booths and 51 small food service establishments. In addition, 75 fresh orange samples, each consisting of five orange units, and 75 wiping cloths were collected from the same establishments from which juice had been collected. Salmonella was isolated from 14, 20, and 23% of samples of orange juice, orange surfaces, and wiping cloths collected from street vendors, while Shigella was isolated from 6, 17, and 5% of these samples. In general, the frequency of isolation of these pathogens in samples from juice serving establishments at public markets was significantly lower than that found among street vendors (P < 0.05). Salmonella enterica serotypes Agona, Typhimurium, and Anatum were found in orange juice, fresh oranges, and wiping cloth samples, while serotype Mexico was found on fresh oranges and in wiping cloths and serotypes Muenchen and Panama were found only in wiping cloth samples. Regarding Shigella species, Shigella sonnei was found in all three types of sample tested; Shigella dysenteriae was found in juice and orange samples, Shigella boydii in orange and wiping cloth samples, and Shigella flexneri on oranges only. Thirty-one percent and 39% of the juice samples showed aerobic plate counts of > or = 5.0 log CFU/ml and Escherichia coli counts of > 3.0 log CFU/ml, respectively. These high counts may indicate poor sanitation and potential exposure to fecal contamination either in the raw materials or during the orange-crushing and juice-serving process. These data may be useful for a further risk assessment of Salmonella or Shigella in unpasteurized, freshly squeezed juice.

Surrogates for the study of norovirus stability and inactivation in the environment: aA comparison of murine norovirus and feline calicivirus

Human noroviruses (NoVs) are the leading cause of food- and waterborne outbreaks of acute nonbacterial gastroenteritis worldwide. As a result of the lack of a mammalian cell culture model for these viruses, studies on persistence, inactivation, and transmission have been limited to cultivable viruses, including feline calicivirus (FCV). Recently, reports of the successful cell culture of murine norovirus 1 (MNV-1) have provided investigators with an alternative surrogate for human NoVs. In this study, we compared the inactivation profiles of MNV-1 to FCV in an effort to establish the relevance of MNV-1 as a surrogate virus. Specifically, we evaluated (i) stability upon exposure to pH extremes; (ii) stability upon exposure to organic solvents; (iii) thermal inactivation; and (iv) surface persistence under wet and dry conditions. MNV-1 was stable across the entire pH range tested (pH 2 to 10) with less than 1 log reduction in infectivity at pH 2, whereas FCV was inactivated rapidly at pH values < 3 and > 9. FCV was more stable than MNV-1 at 56 degrees C, but both viruses exhibited similar inactivation at 63 and 72 degrees C. Long-term persistence of both viruses suspended in a fecal matrix and inoculated onto stainless steel coupons were similar at 4 degrees C, but at room temperature in solution, MNV-1 was more stable than FCV. The genetic relatedness of MNV-1 to human NoVs combined with its ability to survive under gastric pH levels makes this virus a promising and relevant surrogate for studying environmental survival of human NoVs.

Effect of Temperature on the Survival of F-Specific RNA Coliphage, Feline Calicivirus, and Escherichia coli in Chlorinated Water

We compared the survival of F-specific RNA coliphage MS2, feline calicivirus, and E. coli in normal tap water and in tap water treated to an initial concentration of 50 ppm free chlorine and held at 4 degrees C, 25 degrees C, or 37 degrees C for up to 28 days. Our aim was to determine which of these two organisms (coliphage or E. coli) was better at indicating norovirus survival under the conditions of the experiment. There was a relatively rapid decline of FCV and E. coli in 50 ppm chlorine treated water and both organisms were undetectable within one day irrespective of the temperature. In contrast, FRNA phage survived for 7 to 14 days in 50 ppm chlorine treated water at all temperatures. All organisms survived for 28 days in tap water at 4 degrees C, but FCV was undetectable on day 21 and day 7 at 25 degrees C and 37 degrees C, respectively. Greater survival of FRNA phage compared to E. coli in 50 ppm chlorine treated water suggests that these organisms should be further investigated as indicators of norovirus in depurated shellfish, sanitized produce, and treated wastewater which are all subject to high-level chlorine treatment.

Pathogenesis of Astrovirus Infection

Astroviruses are one of the leading causes of diarrhea worldwide. In spite of its impact on human health, little is known about astrovirus pathogenesis. One reason for this may be the lack of a suitable small animal model for infection. In recent years, there has been increasing information on the mechanism of astrovirus-induced disease in mammals (including humans) and birds. This review summarizes our current state of knowledge on astrovirus pathogenesis.

Emerging waterborne pathogens: can we kill them all?

The rapid emergence of Cryptosporidium parvum and Escherichia coli 0157:H7 have created a threat to the drinking water industry and there is a growing need to develop a strategy for recognizing potential emerging waterborne pathogens. Globalization of trade, changing population demographics and changes in treatment technology have been driving factors in the emergence of these new pathogens. An understanding of disinfectant action and microbial resistance to treatment processes is needed to better identify those pathogens likely to be of greatest concern. Recent research on microbial resistance to treatment and disinfection demonstrates that the microbial surface structure and composition and the nature of the genome are key to determining the potential for waterborne transmission of emerging pathogens.

Major Foodborne Illness Causing Viruses and Current Status of Vaccines Against the Diseases

Even though viruses, unlike bacteria, cannot grow in or on foods, foodborne illnesses are associated with viruses due to contamination of the fresh produce or processed food by virus-containing fecal material. The commonly reported major foodborne illnesses are due to Noroviruses, hepatitis A and E viruses, rotaviruses, and astroviruses. Among all illnesses caused by foodborne pathogens, recent estimates of as high as 67% have been attributed to viruses alone, and an upward trend in the of transmission of viruses by food and water has been recently acknowledged. Due to the highly infectious nature of these viruses and their survival under drastic conditions such as high acidic pH and low temperatures, it has long been recognized that immunization against such pathogens is the ideal solution to provide protection against the illness and disease outbreaks associated with these viruses. With an increased recognition of the clinical significance and impact of acute viral illness associated with food and water in humans of all ages, there has been a recent surge in developing prophylactic vaccines against such viruses. So far, except for hepatitis A virus, there are no vaccines available to prevent illness associated with foodborne viruses. Outbreaks of hepatitis A have been significantly reduced due to widespread immunization of some risk groups. It is clear from the literature that novel strategies currently in development may lead to vaccines against noroviruses and rotaviruses in the near future, offering hope that such vaccines will significantly reduce the burden associated with foodborne illnesses associated with these viruses.

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.

The effect of bovine lactoferrin and lactoferricin B on the ability of feline calicivirus (a norovirus surrogate) and poliovirus to infect cell cultures

AIMS

To characterize the effect of bovine lactoferrin and lactoferricin B against feline calicivirus (FCV), a norovirus surrogate and poliovirus (PV), as models for enteric viruses.

METHODS AND RESULTS

Crandell-Reese feline kidney (CRFK) cells were used for the propagation of FCV and monkey embryo kidney (MEK) cells for PV. The assays included visual assessment of cell lines for cytopathic effects and determination of the percentage cell death using MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium] dye reduction assay. Incubation of bovine lactoferrin with CRFK cells either prior to or together with FCV inoculation substantially reduced FCV infection. In contrast, the interference of lactoferrin with the infection of cells with PV was demonstrated only when lactoferrin was present with cell lines and virus for the entire assay period. Using indirect immunofluorescence, lactoferrin was detected on the surface of both CRFK and MEK cells, suggesting that the interference of viral infection may be attributed to lactoferrin binding to the surfaces of susceptible cells, thereby preventing the attachment of the virus particles. Lactoferricin B, a cationic antimicrobial peptide derived from the N-terminal domain of bovine lactoferrin, reduced FCV but not PV infection.

CONCLUSION

Lactoferrin was shown to interfere with the infection of cells for both FCV and PV. However, lactoferricin B showed no interference of infection with PV and interference with infection for FCV required the presence of lactoferricin B together with the cell line and virus.

SIGNIFICANCE AND IMPACT OF THE STUDY

An in vitro basis is provided for the effects of bovine lactoferrin and lactoferricin B in moderating food-borne infections of enteric viruses.

Viral cytopathic changes in urine cytology of ileal conduit attributed to adenovirus: Report of a case

Urine cytology from ureteral diversions utilizing intestinal segment as reservoir or conduit, constructed during cystectomy performed usually for advanced bladder neoplasia, differs from bladder urine cytology in that the presence of abundant intestinal mucosal cells with degenerative and inflammatory changes interferes with the recognition of other important cellular changes, particularly of recurrent neoplasia in the upper urinary tract, not to mention other less frequent yet note worthy pathologic changes, such as viral type indigenous to the urinary tract. When confronted with diseases involving the intestinal segment, such as viral enteritides, the diagnostic problem becomes more complex and special effort is needed to recognize and characterize them correctly, differentiating them from other pathologies or artifacts seen in such specimens. We report one such case in which viral changes affecting columnar intestinal epithelium were identified and by immunocytochemistry characterized as adenoviral involving primarily cells of the intestinal conduit. We discuss the significance of such infection in comparison to other viral changes indigenous to the urinary tract, which could also occur in such specimens.

The role of the home environment in the transmission of infectious diseases

The purpose of this paper is to examine current health care literature (1980-2000) regarding the microbiology of the home environment, to summarize evidence of transmission within the home, and to assess effectiveness of cleaning practices and products. The home environment, particularly the kitchen and bathroom, serves as a reservoir of large numbers of microorganisms, particularly Enterobacteriacae, and infectious disease transmission has been demonstrated to occur in 6-60% of households in which one member is ill. Current food preparation and cleaning practices provide multiple opportunities for intra-household member spread. Routine cleaning is often sufficient, but in cases of household infection, may not adequately reduce environmental contamination. The effectiveness of disinfectants varies considerably and depends on how they are used as well as their intrinsic efficacy. The behavioral aspects of infection prevention in the home (e.g., foodhandling and cleaning practices) warrant increased public attention and education.