Many of those events have involved food vehicles that have not previously been implicated in L. monocytogenes transmission. Prior studies have argued that while improved control measures in some regions have decreased the prevalence of L. monocytogenes in food products such as meat and poultry, the rates of illness and particularly of invasive disease have remained steady or, in some cases, have increased over time, challenging previously held assumptions about the pathogen . The reasons for increased reporting of events linked to nontraditional food vehicles noted in this study may be multifactorial. Cairns and Payne have posited that evolving food distribution practices and government regulations may be a contributing factor . Ercsey-Ravaz et al. also noted that the global scale and complexities of modern food systems contribute to the likelihood and magnitude of foodborne illness . The prevalence and widespread consumption of ready-to-eat products may also play a role . In the past, the organism has often been difficult to enumerate due to limitations in laboratory detection, as well as a long incubation period . In addition, L. monocytogenes has the ability to form biofilms, grow despite refrigeration, and can be resistant to disinfectants . Diagnostic advances leading to early detection in recent years may be another factor associated with the changing epidemiology described in this study.

While pulsed-field gel electrophoresis is often employed as an initial screening tool,container size for blueberries the advent of reliable sequencing technology has allowed for more rapid outbreak identification . WGS, as used in South Africa and in other recent outbreaks, has allowed the improved identification of genetically related isolates . This in turn has assisted in establishing the presence of foodborne outbreaks. Within the EU/ EEA, listeriosis is one of the priority diseases for which supranational WGS-enhanced surveillance was initiated in 2018 . We expect that in the future, additional novel food vehicles will be linked to L. monocytogenes transmission. In addition, with increased compliance testing and more stringent regulatory frameworks for food safety at production and retail in many countries, food recalls are expected to increase accordingly – not only due to Listeria, but other foodborne pathogens as well. It is noteworthy that several Listeria reports in the ProMED database related to foods prepared and served in hospitals. This is of concern, as a growing number of hospitalized patients are immunocompromised hosts susceptible to infectious diseases. The types of food products served in healthcare settings should be selected and prepared to minimize the risk of foodborne disease in vulnerable populations. The incorporation of hazard analysis and critical control points principles at every stage of food handling can be implemented to ensure food safety . As cases may result from a breakdown in only one step of the production and distribution process, food processors, manufacturers, wholesalers, and retail outlets play a key role in maintaining the safety of food products and ingredients. This appears to be the first global overview of listeriosis using an informal-source surveillance methodology.

The strengths of this study lie in the use of ProMED data, which provide a snapshot of emerging infectious disease trends that can otherwise be difficult to elucidate. In many countries, listeriosis is not a notifiable disease, which can make routine data collection challenging. Given these limitations, informal-source surveillance provides an adjunct tool to characterize foodborne outbreaks. In addition, ProMED and other informal surveillance programs allow multinational reporting and comparison. This study found that 14% of all Listeria-associated events reported in ProMED involvedmultiple countries, highlighting the importance of cross-border food distribution surveillance and intense collaboration of public health and food safety authorities and laboratories on an international level. While ProMED data may not provide a comprehensive review of all Listeria outbreaks, sporadic cases, or recalls, reporting on a global level over a long period of time allowed some conclusions to be drawn on Listeria epidemiology. This study was limited by the search terminology used in the database, which may have missed posts due to language choice. In addition, despite standardizing all reports by year, there is the possibility that increased reporting over the study time period in general may have contributed to some of the increases noted in Listeria-associated posts. Listeria monocytogenes is an increasingly important pathogen to recognize given its high case-fatality rate compared to other foodborne diseases. Immunocompromised and other vulnerable individuals are among those at risk of serious disease sequelae. The use of advanced diagnostic technologies such as WGS, enforcement of food safety regulations, and raising awareness of the disease among high-risk groups are critical to infection and prevention control measures. Open data sharing using resources such as ProMED is equally important for supporting cross-border and multinational emerging disease surveillance.

Natural product research continues to be a productive source of unusual chemistry, producing novel compounds for biomedical applications and, increasingly, sustainably providing commercially useful compounds. Despite its long history, the technologies used in natural products research are still amenable to improvements and the introduction of novel methods, materials and reagents. This special issue highlights several recent developments and improvements in the technology for natural products research. In recent years, laboratory culture of microbes has expanded the ability of natural products researchers to examine a wider variety of organisms and facilitated the isolation and identification of rare compounds. Gurusinghe et al. compared the use of standard media with a “rhizochip” device which provided enhanced sampling of the rhizosphere microbiota. They were able to recover organisms not found by other, more traditional methods. The laboratory culture of some of these organisms has led to the identification of several new and unusual metabolites. Biological material for natural products research is often collected in remote areas with limited access to sample storage or processing technology. Collection and sample processing methods can thus impact what can be identified or isolated from the material in a laboratory setting. Juárez-Aragón et al. quantified the impact of a variety of drying methods on the phenolic and flavonoid content and free radical scavenging potential of medicinal plants in the Rhus genus. They report that not only did the method used affect the metabolic content, but that the impact of the methods was species-dependent as well. Solvent extraction is another step that greatly influences the outcome of a natural products program and for this reason alternatives to traditional organic solvents have been examined. The use of supercritical CO2 extraction to obtain commercially useful compounds from microalgae was evaluated by Molino et al. and Mehariya et al.. Both groups report the impact of mechanical pre-treatment methods and the optimal pressure, temperature and flow rates for maximal recovery and highest purity of the desired compounds. Extraction methods can also be tailored to target specific compounds. Yohannes et al. used ionic liquids and ultrasonication to specifically extract alkaloids from the Chinese medicinal plant Radix physochlainae. Their protocol was quicker and more efficient than traditional methods. In order for traditional medicines and herbal extracts to be safely introduced to the market, methods for verifying the provenance, composition and quality of the material are needed. Lee et al.present a UPLC-QTOF/MS analysis of processed ginseng products. Principle component analysis of the results was able to differentiate the products. A similar approach was used by Yuan et al. who coupled gas chromatography to QTOF/MS to study blueberry wines and, again,raspberry grow in pots used principle component analysis to distinguish wines derived from different cultivars. Cabanas-Garcia et al. used UPLC-MS/MS to profile the metabolome of a cactus used in folk medicine and suggested to produce compounds with psychotropic properties. They detected 69 compounds and were able to identify 60 of them by comparison with literature retention times, molecular masses and fragmentation patterns. Tsang et al. present an innovative approach to quality control of a traditional Chinese medicine, Dictamni cortex, used for the treatment of inflammatory diseases. Aqueous and ethanolic extracts of the herbal material applied to human peripheral blood mononuclear cells induced changes in the production of inflammatory chemokines and cytokines, which were monitored by flow cytometry.

This high throughput method was able to distinguish material with different origins and quantify its immunomodulatory activity. Biological activity can be modified dramatically by stereochemistry; thus, its determination is a critical component of natural product structure elucidation. Pearce et al. [10] present new, more robust methods for the determination of the stereochemistry of amino alcohols. Application of their methods to multiple collections of a compound with disputed configuration showed that the stereochemistry varied with the collection, suggested to be the result of “promiscuous biosynthesis”. As the papers in this special issue show, many different facets of technology for natural product research continue to be explored. The processes impacting compound identification and discovery are being probed so that they may be better controlled, and the desired outcomes obtained. Methods to enhance quality control of herbal materials and traditional medicines, and to facilitate characterization of novel metabolites are being developed. We hope these reports will spur further developments and enable natural products research to continue to expand chemical space for the benefit of humanity. An adverse food reaction is defined as any abnormal clinical response that occurs following ingestion of a food or food component . It is often unclear if the pathologic mechanisms of AFR represent a specific immune-mediated response to food antigens, or if the mechanism is related to non-immune intolerance to a component in the food . When manifested as dermatological signs, an AFR is termed a cutaneous adverse food reaction . In addition to cutaneous signs, gastrointestinal signs, symmetric lupoid onychodystrophy, conjunctivitis, sneezing, and anaphylaxis have been associated with AFR in dogs; gastrointestinal and respiratory signs, conjunctivitis, and hyperactive behavior have also been reported in cats . Of these clinical signs, diarrhea and frequent defecation were most often diet-responsive in dogs; in the cat, diet-responsive clinical signs included vomiting and diarrhea . Among dogs and cats presented to their veterinarian for pruritus, the median prevalence of CAFR is estimated to be between 15% and 20% . In dogs in Australia, Europe, and North America, the most common food antigens causingCAFR are beef, dairy products, chicken, wheat, and lamb . In cats, the most common food antigens that are incriminated are beef, fish, and chicken . The best diagnostic procedure for identifying CAFR in companion animals is an elimination diet with subsequent provocation trials . To reliably diagnose CAFR in more than 90% of dogs and cats, elimination diet trials should last at least 8 wk and can be either homemade or commercially produced . Although veterinary dermatologists often consider homecooked diets as their first choice, many pet owners prefer the convenience of commercial “novel” or “hydrolyzed” protein diets, and rely on package labels to select diets that do not contain previously fed ingredients . There are concerns that these diets may contain unlisted food sources, and that unidentified ingredients might cause clinical reactions in hypersensitive patients . Unidentified dietary allergens could preclude a resolution of clinical signs in CAFR-affected patients, yielding misleading results for the elimination diet trial. Inadvertent cross-contamination of pet foods appears common, even in those with “limited ingredients” proposed for elimination diets . Rigorous quality control to screen for accidental contamination using real-time or quantitative polymerase chain reaction has been used in both human and animal food manufacturing as a rapid and sensitive point-of-care application to screen for food-borne bacteria, viruses, or allergens, which can be identified at low concentrations . This screening method has also been used in the production of veterinary prescription diets to validate their contents in order to avoid inadvertent allergen exposures for sensitized pets . Of the quality control analysis methods available, DNA-based protocols are considered most reliable for detecting animal species in processed pet food manufacturing . Historically, these diets were fed to racing greyhounds and sled dogs; this feeding practice began to be extended to pets and became increasingly popular in the 1990’s . Despite evidence of nutritional deficiencies or excesses and potential health risks of feeding raw or undercooked animalsource proteins, advocates of RMBD claim anecdotal health benefits, such as improvement in coat and skin, and a reduction in medical conditions such as allergies . The increasing popularity of RMBD has been demonstrated in multiple studies. A 2008 telephone survey revealed approximately 30% of dogs and 15% of cats in the United States and Australia consumed a combination of “unconventional” diets and commercial pet foods .