From wildlife to humans: The global distribution of Trichinella species and genotypes in wildlife and wildlife-associated human trichinellosis

Zoonotic nematodes of the genus Trichinella are foodborne parasites that have a global distribution in wild carnivores and omnivores, with spillover and spillback into domestic livestock and people, with concomitant trade and health consequences. Historically, most human cases were linked to domestic pigs infected with Trichinella spiralis, but under current high biosecurity swine production in many countries, wildlife have become a more important source of human trichinellosis. The aim of this review is to update the global distribution of Trichinella species and genotypes reported in wildlife, as well as reported human outbreaks from the consumption of wildlife. Using several online databases and by "snowballing" references, hundreds of reports of Trichinella spp. in wildlife published between January 1991 and December 2023 provide an important update to the host and geographic range for each of the recognized 13 species/genotypes, grouped by continent. Surveillance effort was highest in Europe and North America, while Africa, Asia, Central and South America have had limited surveillance, in some instances with human cases serving as sentinels of transmission in a region. Dozens of human outbreaks are described, with wild boars (Sus scrofa) being the most frequently implicated wildlife species in human outbreaks globally. Bears are an important source of infection in North America, for wildlife tourism, and importation of bear meat has also been implicated in multicountry outbreaks. The largest study limitation was the dearth of molecular identification of larvae in both wildlife surveillance studies and human outbreaks, particulary in under-studied regions. We highlight the need for enhanced molecular epidemiological approaches to outbreaks of this important foodborne parasite, and emphasize the need for a One Health approach to manage Trichinella spp. which transmit among terrestrial and marine wildlife (including migratory birds), pigs, horses, and people, often across large geographic scales and borders.

First Identification and Molecular Characterization of Trichinella britovi (Nematoda: Trichinellidae) from the Pine Marten (Martes martes Linnaeus, 1758) in Romania

Trichinella spp. are etiological zoonotic agents spread throughout the world and affect mammals, birds, and reptiles; they evolve via two cycles: domestic and sylvatic. Martes martes is a carnivorous nocturnal mammal from the family Mustelidae. In Romania, this host is widespread in all forests of the country. Martes martes has an extremely voracious appetite, feeding on fruit and also on a variety of small animals, including rodents such as mice and rats. The aim of this study was the identification and molecular characterization of Trichinella larvae isolated from the muscle tissue of Martes martes collected in different counties of Romania. The muscle samples were examined via artificial digestion, and the larvae were identified at the species level via multiplex PCR. The presence of larvae belonging to Trichinella britovi, a species frequently identified in wild carnivores in temperate zones, was observed. Although T. britovi has been already reported in several host species in Romania, this is the first time this species has been observed in a Martes martes specimen. This finding contributes to our knowledge about the host species involved in the maintenance of the Trichinella sylvatic cycle in Romania, and it confirms that this parasite is consistently present in the wild fauna of this country.

Trichinella proficiency testing in Southeastern European countries

In some Southeastern European (SEE) countries, like Serbia, Romania, and Bulgaria, trichinellosis is one of the most important foodborne zoonotic diseases. In those countries, EU regulation and local authorities require the staff of laboratories performing official controls on meat to be properly trained and to check their competence by participating regularly in proficiency testing (PT). PTs are organized by National Reference Laboratories for Trichinella of each country and involve all official laboratories testing meat. In Romania and Bulgaria, the organization of PT for the detection of Trichinella larvae in meat by Magnetic Stirrer Method (MSM) started in 2012. In Croatia and Serbia PT was first organized in 2015 and 2017, respectively. This study presents data on the performance obtained by official laboratories of SEE countries that organize PT at national level and compares the performance obtained by laboratories belonging to different countries. Results suggest that the constant participation in PT leads to an increase in the performance of participating laboratories by positively affecting the staff accuracy in sample testing by MSM. Since the percentage of recovered larvae was in some cases suboptimal (<80%) and occasionally very poor (<40%), there is room for improvement. The regular participation in PT by laboratories involved in official controls on meat intended for human consumption is fundamental to guarantee consumer safety.

Food safety incidents in the red meat industry: A review of foodborne disease outbreaks linked to the consumption of red meat and its products, 1991 to 2021

Red meat is a significant source of human nutrition, and the red meat industry contributes to the economy of nations. Nonetheless, there is a widespread global concern about public health issues posed by severe food safety incidents within the red meat industry. Most of these incidents are associated with foodborne disease outbreaks that impact individual consumers, food businesses and society. This study adopts a systematic search and review approach to identify three decades of published investigation reports of global foodborne disease outbreaks linked with the consumption of red meat and products made from them. The review aims to evaluate the critical features of these outbreak incidents to get insight into their contributing factors and root causes. In particular, this review discusses the transmission setting (origin of pathogenic agents), the food vehicles mostly incriminated, the causative pathogens (bacteria, viruses, and parasites) causing the most illnesses, and the most commonly reported contributing factors to the outbreaks. This information can help researchers and food business operators (FBOs) inform future risk assessment studies and support risk management activities in developing risk-mitigating strategies for the industry. Findings from this study suggest that implementing food safety management strategies which include adequate control measures at all stages of the food chain, from farm to fork, is imperative in preventing outbreak incidents. Of equal importance is the need for enhanced and sustained public education about the risk of foodborne illnesses associated with meat and its products whilst discouraging the consumption of raw meat products, especially by high-risk groups.

Trichinella infection in Serbia from 2011 to 2020: a success story in the field of One Health

In Serbia, modern pork production systems with implemented control measures, including the detection of Trichinella larvae in meat (ISO18743), have eliminated farmed pork from pigs slaughtered at abattoirs as a source of trichinellosis. Epidemiological data from 2011 to 2020 indicate that the number of human cases and the number of infected domestic pigs has decreased significantly. Over the years, pork was the most frequent source of human infection. Cases generally occurred in small family outbreaks, and the infection was linked to consumption of raw or undercooked pork from backyard pigs. In most of the outbreaks, T. spiralis was the aetiological agent of infection, but in 2016, a large outbreak was caused by consumption of uninspected wild boar meat containing T. britovi larvae. To achieve safe pork, it is important that consumers of pork from animals raised in backyard smallholdings and of wild game meat are properly educated about the risks associated with consumption of untested meat. Laboratories conducting Trichinella testing should have a functional quality assurance system to ensure competency of analysts and that accurate and repeatable results are achieved. Regular participation in proficiency testing is needed.

Exploiting the potential of 2D DIGE and 2DE immunoblotting for comparative analysis of crude extract of Trichinella britovi and Trichinella spiralis muscle larvae proteomes

The Trichinella genus poses an interesting puzzle for researchers, having diverged very early in the evolution of the nematodes. The Trichinella spiralis proteome is a cosmopolitan and well-studied model of Trichinella; however, Trichinella britovi also circulates in the sylvatic environment and both species infect humans, resulting in the development of trichinellosis. Few experiments have examined the proteins belonging to the T. britovi proteome. The aim of the present study was to compare the protein expression profiles of crude extracts of T. spiralis and T. britovi muscle larvae using a highly-sensitive two-dimensional differential in-gel electrophoresis (2D DIGE) technique coupled with 2DE immunoblotting. Selected immunoreactive protein spots were then identified by liquid chromatography coupled with mass spectrometry analysis (LC-MS/MS), and their function in Trichinella and the host-parasite interaction was determined by gene ontology analysis. Spots common to both T. spiralis and T. britovi, spots with different expressions between the two and spots specific to each species were labelled with different cyanine dyes. In total, 196 protein spots were found in both proteomes; of these 165 were common, 23 expressed exclusively in T. spiralis and 8 in T. britovi. A comparative analysis of volume ratio values with Melanie software showed that among the common spots, nine demonstrated higher expression in T. spiralis, and 17 in T. britovi. LC-MS/MS analysis of 11 selected spots identified 41 proteins with potential antigenic characteristics: 26 were specific for T. spiralis, six for T. britovi, and eight were found in both proteomes. Gene Ontology analysis showed that the identified T. spiralis proteins possess hydrolytic endopeptidase, endonuclease and transferase activities. Similarly, most of the T. britovi proteins possess catalytic activities, such as lyase, hydrolase, isomerase and peptidase activity. The applied 2D DIGE technique visualized Trichinella spp. protein spots with different molecular weights or isoelectric point values, as well as those with different expression levels. The identified immunoreactive proteins participate in multiple processes associated with host muscle cell invasion and larval adaptation to the host environment. Their reactivity with the host immune system makes them possible candidates for the development of a novel trichinellosis diagnostic test or vaccine against helminthiasis caused by T. spiralis or T. britovi.

Production of Traditional Meat Products in Small and Micro Establishments in Serbia: Current Status and Future Perspectives

The production of traditional meat products has a considerable potential in the Republic of Serbia, particularly in small and micro (household) establishments. Among a large number of traditional meat products, dry fermented sausages and dried meat products are the most important and commonly appreciated by consumers. There is, however, a need for a better standardization of the production in this meat sector, and also implementation of necessary food hygiene rules and HACCP principles according to hygiene regulations. There are provisions in the Food Safety Law, stating the principles of flexibility, which would allow for traditional meat producers and their associations to apply for derogations in food hygiene regulations. This would enable traditional small and micro food business operators to better use their resources, relax administrative burden and use traditional production methods in the most appropriate manner, always respecting hygiene and safety principals. This review paper analyses the current status of traditional meat production in small and micro establishments in Serbia, emphasizing a need for further improvements in food safety management and standardization.