Epidemiology and detection as options for control of viral and parasitic foodborne disease

Foodborne Pathogens and Antimicrobial Resistance in Ethiopia: An Urgent Call for Action on "One Health"

Foodborne pathogens are the most common cause of foodborne disease worldwide. They contaminate food at all stages of the food chain, at the agricultural production level (soil and irrigation), from animal sources or at the time of preparation by food handlers. Therefore, food security is a critical issue that affects everyone in the world. Current studies indicate that the problem is more severe in low-income countries like Ethiopia. The majority of studies in Ethiopia have been conducted partially on human, animal or environmental samples with conventional culture-based diagnostic methods. Therefore, this review was conducted to gather information on the main foodborne pathogens and identify gaps in their traceability. Clinically important foodborne pathogens in Ethiopia include (A. lubmbricoids, Toxocara spp., H. nana. E. histolytica/dispar, G. intestinalis, H. diminuta and C. belli), bacteria (Salmonella spp, E. coli O157:H7, B. anthracis, Yersinia, C. perfringens, Klebsiella spp. M. paratuberculosis, and L. monocytogenes), and viruses like (rotaviruses, enteroviruses and astroviruses, hepatitis E virus). In Ethiopia, all isolated foodborne bacterial pathogens showed high rates of antimicrobial resistance (AMR). In particular, the most studied foodborne pathogens, Staphylococcus spp., Salmonella spp., and E. coli from specific sources, showing high levels of resistance to most of the antibiotics prescribed in Ethiopia. The occurrence and persistence of AMR in food is one of the main factors causing the spread of antimicrobial resistance in different compartments, humans, animals and the environment. Therefore, strategies of coordination and struggle from a One Health perspective is an urgent strategy to control antibiotic resistance in order to achieve better outcomes for human and animal health.

Current status of intestinal parasitic infections and associated factors among primary school children in Birbir town, Southern Ethiopia

Background

Intestinal parasites still pose major public health problems in developing countries like Ethiopia. Local epidemiological data is indispensable in order to design and monitor prevention and control strategies. Therefore the present study aimed to assess the prevalence of intestinal parasitic infections and associated factors among students at Birbir town, Southern Ethiopia.

Methods

A school-based cross-sectional study was conducted from March to May 2018. Three hundred fifty-one students, who were selected by stratified followed by systematic random sampling, participated in the study. Socio-demographic information was collected using a structured questionnaire. Anthropometric measurements of height and weight were taken at the time of interview. Stool samples were collected and processed by direct wet mount and formol-ether concentration techniques for microscopic detection of intestinal parasites. Data was analyzed using SPSS version 20.

Results

Among 351 (180 male and 171 female) children participated, 135 (38.5%) and 216 (61.5%) were within the age groups of 5–9 and 10–14 respectively. Ninety five (27.1%; 95%CI: 22.2–31.9) of them were tested positive for intestinal parasites. Helminths and protozoa account 21.1 and 7.1% prevalences respectively. Seventy eight children were infected with a single parasite species while 17 were positive for double or triple infections. A. lumbricoides (31, 8.8%) was the most frequently detected parasite followed by T. trichiura (20, 5.7%) and hookworms (19, 5.4%). Age group of 10–14 years (AOR = 2.51; 95%CI: 1.41–4.45, p = 0.002) and absence of hand washing habit after toilet (AOR = 4.49; 95%CI: 2.00–10.1, p = 0.001) were significantly associated with intestinal parasitic infection.

Conclusions

The prevalence of intestinal parasitic infection among school age children is still unacceptably high. Age group of 10–14 year old and not having habit of hand washing after toilet were significantly associated with intestinal parasitic infection. The ongoing school based deworming should be strengthened and be integrated with school health programs.

Electronic supplementary material

The online version of this article (10.1186/s12879-019-3879-5) contains supplementary material, which is available to authorized users.

Bacterial contamination of vegetables sold in Arba Minch Town, Southern Ethiopia

Objective

Unhygienically handled fruits and vegetables which are usually consumed in raw serve to transmit various infectious diseases. Bacteria are among the common vegetable contaminants. However, the species of contaminants and rate of contamination depends on various environmental and human factors. Hence, a cross-sectional study was conducted to assess the level of bacterial contamination and associated factors among vegetables marketed in Arba Minch town from January to March, 2018. A structured questionnaire was used to collect data regarding factors associated with bacterial contamination of vegetables. Selected vegetables were purchased and processed for examination of bacterial contamination by standard culture technique following standard protocols. All data were analyzed using SPSS version 20.0.

Results

A total of 347 vegetable samples were examined, of which 169 (48.7%) were positive for bacteria contamination. Cabbage (71.9%) was the most frequently contaminated vegetable. E. coli (31.4%) was the most frequent contaminant detected. Type of vegetables (p = 0.000) and market place (p = 0.039) show significant association with bacterial contamination. Bacterial contamination rate in the present study was significantly considerable. Therefore we recommend for the local health office to continuously monitor the contamination status of raw edible vegetables and take respective measures.

Bacterial lipopolysaccharide binding enhances virion stability and promotes environmental fitness of an enteric virus

Enteric viruses, including poliovirus and reovirus, encounter a vast microbial community in the mammalian gastrointestinal tract, which has been shown to promote virus replication and pathogenesis. Investigating the underlying mechanisms, we find that poliovirus binds bacterial surface polysaccharides, which enhances virion stability and cell attachment by increasing binding to the viral receptor. Additionally, we identified a poliovirus mutant, VP1-T99K, with reduced lipopolysaccharide (LPS) binding. Although T99K and WT poliovirus cell attachment, replication, and pathogenesis in mice are equivalent, VP1-T99K poliovirus was unstable in feces following peroral inoculation of mice. Consequently, the ratio of mutant virus in feces is reduced following additional cycles of infection in mice. Thus, the mutant virus incurs a fitness cost when environmental stability is a factor. These data suggest that poliovirus binds bacterial surface polysaccharides, enhancing cell attachment and environmental stability, potentially promoting transmission to a new host.

Enhancement of enteric adenovirus cultivation in a novel Ras-overexpressing cell line

Enteric human adenoviruses (HAdVs; serotypes 40 and 41) have been identified as an emerging cause of drinking water contamination. Due to their fastidious characteristics, HAdVs are difficult to cultivate and therefore not detected easily by standard mammalian cell cultivation methods. Here we found that human embryonic kidney 293 cells, transformed transiently with Ras, enhanced HAdV replication by more than threefold. We also constructed a stable cell line overexpressing the Ras protein, 293-Ras, in which the replication of three HAdV strains of serotypes 40 and 41 was increased markedly. However, only HAdV replication was enhanced; infection of 293 and 293-Ras cells with human rhinivorus-6 showed no significant differences in replication rate. Infected 293-Ras cells exhibited an increased level and phosphorylation of extracellular regulated kinase (ERK). In addition, the Ras-mediated increase in HAdV replication was impaired by the mitogen-activated protein kinase/ERK kinase (MEK1) inhibitor U0126, suggesting direct involvement of the MEK1/ERK pathway in enhanced HAdV replication. Based on these results, we suggest that the 293-Ras cell line be used for the efficient detection and cultivation of HAdV strains in both clinical and environmental specimens.

Transfer of noroviruses between fingers and fomites and food products

Human norovirus (NoV) contaminated hands are important routes for transmission. Quantitative data on transfer during contact with surfaces and food are scarce but necessary for a quantitative risk assessment. Therefore, transfer of MNV1 and human NoVs GI.4 and GII.4 was studied by artificially contaminating human finger pads, followed by pressing on stainless steel and Trespa® surfaces and also on whole tomatoes and cucumber slices. In addition, clean finger pads were pressed on artificially contaminated stainless steel and Trespa® surfaces. The transfers were performed at a pressure of 0.8-1.9 kg/cm(2) for approximately 2s up to 7 sequential transfers either to carriers or to food products. MNV1 infectivity transfer from finger pads to stainless steel ranged from 13 ± 16% on the first to 0.003 ± 0.009% on the sixth transfer on immediate transfer. After 10 min of drying, transfer was reduced to 0.1 ± 0.2% on the first transfer to 0.013 ± 0.023% on the fifth transfer. MNV1 infectivity transfer from stainless steel and Trespa® to finger pads after 40 min of drying was 2.0 ± 2.0% and 4.0 ± 5.0% respectively. MNV1 infectivity was transferred 7 ± 8% to cucumber slices and 0.3 ± 0.5% to tomatoes after 10 min of drying, where the higher transfer to cucumber was probably due to the higher moisture content of the cucumber slices. Similar results were found for NoVs GI.4 and GII.4 transfers measured in PCR units. The results indicate that transfer of the virus is possible even after the virus is dried on the surface of hands or carriers. Furthermore, the role of fingers in transmission of NoVs was quantified and these data can be useful in risk assessment models and to establish target levels for efficacy of transmission intervention methods.

Zoonotic parasites of bobcats around human landscapes

We analyzed Lynx rufus fecal parasites from California and Colorado, hypothesizing that bobcats shed zoonotic parasites around human landscapes. Giardia duodenalis, Cryptosporidium, Ancylostoma, Uncinaria, and Toxocara cati were shed. Toxoplasma gondii serology demonstrated exposure. Giardia and Cryptosporidium shedding increased near large human populations. Genotyped Giardia may indicate indirect transmission with humans.

Thermal stability of structurally different viruses with proven or potential relevance to food safety

Aims:  To collect comparative data on thermal stability of structurally different viruses with proven or potential relevance to food safety.

Methods and Results:  Suspensions with poliovirus Sabin1, adenovirus type5, parechovirus1, human norovirus (NoV) GII.4, murine NoV (MNV1) and human influenza A (H1N1) viruses were heated at 56 and 73°C. Infectivity was tested by culture assay for all but human NoV GII.4 that cannot be cultivated in vitro. Time to first log₁₀ reduction (TFL‐value) was calculated based on best fit using the monophasic, biphasic or Weibull models. The Weibull model provided the best fit at 56°C for all viruses except influenza virus. The TFL at 56°C varied between a high of 27 min (parechovirus) to a low of 10 s (adenovirus) and ranked parechovirus > influenza > MNV1 > poliovirus > adenovirus. The monophasic model best described the behaviour of the viruses at 73°C, in which case the TFL was MNV1(62s) > influenza > adenovirus > parechovirus > poliovirus(14s).

Conclusions:  Viruses do not follow log‐linear thermal inactivation kinetics and the thermostability of parechovirus and influenza virus is similar to that of proven foodborne viruses.

Significance and Impact of the Study:  Resistant fractions of viruses may remain infectious in thermal inactivation processes and inactivation of newly discovered or enveloped viruses in thermal food preparation processes should not be assumed without further testing.

Foodborne illness associated with Cryptosporidium and Giardia from livestock

Waterborne outbreaks caused by Cryptosporidium and Giardia are well documented, while the public health implications for foodborne illness from these parasites have not been adequately considered. Cryptosporidium and Giardia are common in domestic livestock, where young animals can have a high prevalence of infection, shedding large numbers of oocysts and cysts. Molecular epidemiological studies have advanced our knowledge on the distribution of Cryptosporidium and Giardia species and genotypes in specific livestock. This has enabled better source tracking of contaminated foods. Livestock generate large volumes of fecal waste, which can contaminate the environment with (oo)cysts. Evidence suggests that livestock, particularly cattle, play a significant role in food contamination, leading to outbreaks of cryptosporidiosis. However, foodborne giardiasis seems to originate primarily from anthroponotic sources. Foodborne cryptosporidiosis and giardiasis are underreported because of the limited knowledge of the zoonotic potential and public health implications. Methods more sensitive and cheaper are needed to detect the often-low numbers of (oo)cysts in contaminated food and water. As the environmental burden of Cryptosporidium oocysts and Giardia cysts from livestock waste increases with the projected increase in animal agriculture, public health is further compromised. Contamination of food by livestock feces containing Cryptosporidium oocysts and Giardia cysts could occur via routes that span the entire food production continuum. Intervention strategies aimed at preventing food contamination with Cryptosporidium and Giardia will require an integrated approach based on knowledge of the potential points of entry for these parasites into the food chain. This review examines the potential for foodborne illness from Cryptosporidium and Giardia from livestock sources and discusses possible mechanisms for prevention and control.

Enhancement of enteric adenovirus cultivation by viral transactivator proteins

Human enteric adenoviruses (HAdVs; serotypes 40 and 41) are important waterborne and food-borne pathogens. However, HAdVs are fastidious, are difficult to cultivate, and do not produce a clear cytopathic effect during cell culture within a reasonable time. Thus, we examined whether the viral transactivator proteins cytomegalovirus (CMV) IE1 and hepatitis B virus (HBV) X promoted the multiplication of HAdVs. Additionally, we constructed a new 293 cell line expressing CMV IE1 protein for cultivation assays. We analyzed the nucleic acid sequences of the promoter regions of both E1A and hexon genes, which are considered to be the most important regions for HAdV replication. Expression of either HBV X or CMV IE1 protein significantly increased the promoter activities of E1A and hexon genes of HAdVs by as much as 14-fold during cell cultivation. The promotion of HAdV expression was confirmed by increased levels of both adenoviral DNA and mRNA expression. Finally, the newly developed 293 cell line expressing CMV IE1 protein showed an increase in viral DNA ranging from 574% to 619% compared with the conventional 293 cell line. These results suggest that the newly constructed cell line could be useful for efficient cultivation and research of fastidious HAdVs.

Cryptosporidium: detection in water and food

Water and food are major environmental transmission routes for Cryptosporidium, but our ability to identify the spectrum of oocyst contributions in current performance-based methods is limited. Determining risks in water and foodstuffs, and the importance of zoonotic transmission, requires the use of molecular methods, which add value to performance-based morphologic methods. Multi-locus approaches increase the accuracy of identification, as many signatures detected in water originate from species/genotypes that are not infectious to humans. Method optimisation is necessary for detecting small numbers of oocysts in environmental samples consistently, and further work is required to (i) optimise IMS recovery efficiency, (ii) quality assure performance-based methods, (iii) maximise DNA extraction and purification, (iv) adopt standardised and validated loci and primers, (v) determine the species and subspecies range in samples containing mixtures, and standardising storage and transport matrices for validating genetic loci, primer sets and DNA sequences.

Development of a method for detection of Giardia duodenalis cysts on lettuce and for simultaneous analysis of salad products for the presence of Giardia cysts and Cryptosporidium oocysts

We report a method for detecting Giardia duodenalis cysts on lettuce, which we subsequently use to examine salad products for the presence of Giardia cysts and Cryptosporidium oocysts. The method is based on four basic steps: extraction of cysts from the foodstuffs, concentration of the extract and separation of the cysts from food materials, staining of the cysts to allow their visualization, and identification of cysts by microscopy. The concentration and separation steps are performed by centrifugation, followed by immunomagnetic separation using proprietary kits. Cyst staining is also performed using proprietary reagents. The method recovered 46.0% +/- 19.0% (n = 30) of artificially contaminating cysts in 30 g of lettuce. We tested the method on a variety of commercially available natural foods, which we also seeded with a commercially available internal control, immediately prior to concentration of the extract. Recoveries of the Texas Red-stained Giardia cyst and Cryptosporidium oocyst internal controls were 36.5% +/- 14.3% and 36.2% +/- 19.7% (n = 20), respectively. One natural food sample of organic watercress, spinach, and rocket salad contained one Giardia cyst 50 g(-1) of sample as an indigenous surface contaminant.

Towards standard methods for the detection of Cryptosporidium parvum on lettuce and raspberries. Part 1: development and optimization of methods

No standard method is available for detecting protozoan parasites on foods such as soft fruit and salad vegetables. We report on optimizing methods for detecting Cryptosporidium parvum on lettuce and raspberries. These methods are based on four basic stages: extraction of oocysts from the foodstuffs, concentration of the extract and separation of the oocysts from food materials, staining of the oocysts to allow their visualization, and identification of oocysts by microscopy. The concentration and separation steps are performed by centrifugation, followed by immunomagnetic separation using proprietary kits. Oocyst staining is also performed using proprietary reagents. The performance parameters of the extraction steps were extensively optimized, using artificially contaminated samples. The fully developed methods were tested several times to determine their reliability. The method to detect C. parvum on lettuce recovered 59.0+/-12.0% (n=30) of artificially contaminated oocysts. The method to detect C. parvum on raspberries recovered 41.0+/-13.0% (n=30) of artificially contaminated oocysts.

Occurrence of Escherichia coli, noroviruses, and F-specific coliphages in fresh market-ready produce

Forty samples of fresh produce collected from retail food establishments were examined to determine the occurrence of Escherichia coli, F-specific coliphages, and noroviruses. An additional six samples were collected from a restaurant undergoing investigation for a norovirus outbreak. Nineteen (48%) of the retail samples and all outbreak samples were preprocessed (cut, shredded, chopped, or peeled) at or before the point of purchase. Reverse transcription-PCR, with the use of primers JV 12 and JV 13, failed to detect norovirus RNA in any of the samples. All six outbreak samples and 13 (33%) retail samples were positive for F-specific coliphages (odds ratio undefined, P = 0.003). Processed retail samples appeared more likely to contain F-specific coliphages than unprocessed samples (odds ratio 3.8; 95% confidence interval 0.8 to 20.0). Only two (5.0%) retail samples were positive for E. coli; outbreak samples were not tested for E. coli. The results of this preliminary survey suggest that F-specific coliphages could be useful conservative indicators of fecal contamination of produce and its associated virological risks. Large-scale surveys should be conducted to confirm these findings.

Noroviruses: agents in outbreaks of acute gastroenteritis

Noroviruses are the most common cause of acute gastroenteritis in the United States and are believed to be the most common cause of food borne illnesses.1 Noroviruses have avoided attention for years due to the difficulty of detection and inability to be cultured. Norovirus outbreaks have major implications for health care workers as they can occur in nursing homes and hospitals. To further complicate the picture, these viruses can infect persons of all ages which is a feature that distinguishes noroviruses from other agents. Factors that contribute to the significant impact of noroviruses include a large human reservoir, low infection dose, and the ability to be transmitted by various routes. This article provides an overview of noroviruses particularly as it relates to health care workers.

Challenges and approaches to reducing foodborne illness

Microorganisms have successfully adapted to changes in food production, processing, and preservation techniques, resulting in a number of new and emerging foodborne pathogens and the re-emergence of organisms that have been problematic in the past. To protect public health, science must meet the challenges that result from the remarkable adaptability of foodborne pathogens. However, not all of the challenges of preventing foodborne illness reside in the realm of science. Food safety policy must evolve in response to new scientific understanding of hazards in the food supply and an ever-changing food processing industry. The laws, regulations, and organizations comprising the food safety system frequently lag behind current scientific knowledge of the risks posed by foodborne pathogens. Future systemic changes to enhance food safety will require better understanding of risks associated with specific pathogens occurring in the food supply and the costs and benefits of implementing mitigation strategies.

Emerging waterborne infections: contributing factors, agents, and detection tools

Because microorganisms are easily dispersed, display physiological diversity, and tolerate extreme conditions, they are ubiquitous and may contaminate and grow in water. The presence of waterborne enteric pathogens (bacteria, viruses, and protozoa) in domestic water supplies represents a potentially significant human health risk. Even though major outbreaks of waterborne disease are comparatively rare, there is substantial evidence that human enteric pathogens that are frequently present in domestic water supplies are responsible for low-level incidence of waterborne microbial disease. Although these diseases are rarely debilitating to healthy adults for more than a few hours to a few days, enteric pathogens can cause severe illness, even death, for young children, the elderly, or those with compromised immune systems. As the epidemiology of waterborne diseases is changing, there is a growing global public health concern about new and reemerging infectious diseases that are occurring through a complex interaction of social, economic, evolutionary, and ecological factors. New microbial pathogens have emerged, and some have spread worldwide. Alternative testing strategies for waterborne diseases should significantly improve the ability to detect and control the causative pathogenic agents. In this article, we provide an overview of the current state of knowledge of waterborne microbial pathogens, their detection, and the future of new methods in controlling these infectious agents.

Simultaneous detection and identification of hepatitis A virus and rotavirus by multiplex nucleic acid sequence-based amplification (NASBA) and microtiter plate hybridization system

Human rotavirus and hepatitis A virus (HAV) are two of the most common causes of virus-mediated food-borne illness. Epidemiological investigations of outbreaks associated with these viruses have been hindered by the lack of available methods for their detection in foodstuffs. In this study, a multiplex nucleic acid sequence-based amplification (NASBA) system was developed to detect specifically and simultaneously human rotavirus and HAV. Two sets of primers selected from published nucleic acid sequences were used in the NASBA mixture to amplify viral RNA from both viruses. Denaturing gel electrophoresis revealed two distinct RNA products with 268 and 474 nucleotides amplified from rotavirus and HAV, respectively. The specificity of the multiplex NASBA was confirmed by a microtiter plate hybridization and detection system and by Northern blot analysis using specific oligonucleotide probes. The presence of non-homologous nucleic acid and non-target microorganisms did not have any effect on the specificity of the multiplex NASBA. Using the optimized NASBA and microtiter plate hybridization conditions, as little as 400 PFU ml x (-1) of HAV and 40 PFU ml x (-1) of rotavirus were detected. The multiplex NASBA system offers advantages over monoplex virus detection systems in terms of turnaround time and cost-effectiveness.

Prevalence of vaccine-derived polioviruses in the environment

A survey of poliovirus in river and sewage water was conducted from October 1993 to September 1995 in Toyama Prefecture, Japan. In this study, 25 isolates differentiated as type 2 vaccine-derived polioviruses (VDPVs) were characterized using mutant analysis by PCR and restriction-enzyme cleavage (MAPREC) to estimate the ratio of 481-G revertants correlated to neurovirulence in a virus population. Of these isolates, 23 (92%) comprised between 44 and 96% 481-G revertants by MAPREC. The other two isolates had revertant percentages close to the 0.6% of the attenuated reference strain. It was presumed that these 23 isolates would be variant with potential neurovirulence by MAPREC analysis. Of the 23 isolates, three were isolated from river water. Moreover, our results by MAPREC showed that type 2 poliovirus was phenotypically more variable than type 1 (69%) or type 3 (55%), as determined in previous studies. The prevalence of virulent-type VDPVs in river and sewage water suggested that the oral poliovaccine itself had led to wide environmental pollution in nature. To terminate the cycle of virus transmission in nature, the ecology of VDPVs should be studied further. A hygiene programme, inactivated poliovirus vaccine immunization and well-maintained herd immunity may play key roles in reducing the potential risk of infection by virulent VDPVs.

Gastrointestinal infections

Advances in public health have reduced the risk of contracting certain enteric diseases, but many remain, and new pathogens have emerged and/or recently have been discovered. The pathogenic agents are varied and consist of a variety of bacteria and select viruses and parasites. Selected use of microbiologic assays to detect these pathogens is encouraged. When tests are ordered non-judiciously, costs rapidly accrue. The age of the patient, time of year, travel history, and clinical presentation all provide clues to the etiologic agent. Microbiologic assays should be used judiciously to confirm or exclude the likely infectious agents.

Simplified procedure for detection of enteric pathogenic viruses in shellfish by RT-PCR

Epidemiological evidence linking the transmission of enteric viral disease to shellfish has been known for a long time. A variety of methods have been described for the detection of viral contaminants in shellfish using RT-PCR. However, these methods generally include numerous, often fastidious and time consuming steps for virus release from shellfish tissues and viral RNA isolation. A simplified procedure based on the enzymatic liquefaction of shellfish digestive tissues without any mechanical homogenisation step, followed by a simple clarification of the lysate using dichloromethane extraction, was developed. Viral RNA is isolated directly from the shellfish extract by a guanidium thiocyanate-silica extraction method, adapted for the use of a vacuum manifold system. Virus-specific RT-PCR assays were set up for detection of genomic sequences of the predominant viral pathogens, HAV, Astrovirus and Norwalk-like viruses (from genogoups I or II). The specificity of the amplicons is confirmed finally by hybridisation with DIG-labelled specific probes. The overall procedure applied to shellfish samples spiked with HAV particles allowed a detection of 20 pfu of HAV per g of hepatopancreas. In addition, up to 20 samples can be tested within 24 h.

The use of epidemiological data in the control of foodborne viruses

The Codex Committee on Food Hygiene has recommended the adoption of Hazard Analysis and Critical Control Point (HACCP) as the basis for food safety control. To provide an objective basis for the construction of HACCP systems, epidemiological data are required. The data should be accurate, up-to-date, and identify emerging pathogens, such as viruses. The number of laboratory reports of small, round-structured viruses in England and Wales has increased from 400 cases in 1990 to 2387 in 1996. Although a food vehicle is not essential for the spread of viral particles, food my be the primary unidentified vehicle. The Advisory Committee on the Microbiological Safety of Foods recommends the use of the Kaplan Criteria, which can give strong circumstantial evidence that an outbreak is attributable to small, round-structured viruses. The application of these criteria would give a more accurate reflection of the involvement of viruses in the incidence of foodborne disease. This review considers the use of epidemiological data to support HACCP and risk-assessment systems. It discusses the implications of focusing on traditional pathogens, for example Salmonella spp., as opposed to emerging pathogens, for the design of control systems. Recommendations are made for improving the system of data collection.