Trichinellosis outbreak caused by meat from a wild boar hunted in an Italian region considered to be at negligible risk for Trichinella

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.

A Large-Scale Outbreak of Trichinellosis from Infected Wild Boar Meat in Croatia and the Role of Real-Time PCR Assays in Confirming the Source of the Disease

BACKGROUND

Trichinellosis in Croatia posed a significant health concern during the 1990s, followed by a notable improvement in the epidemiological situation. However, in 2017, there was a resurgence, with 37 recorded cases in 3 outbreaks and 3 sporadic cases. The source of this epidemic was homemade meat products derived from wild boar meat, leading to 26 infections.

METHODS

At the beginning of the outbreak and during the treatment of the patients, the medical and epidemiological records prepared throughout the investigation and over the course of patient treatment were reviewed. The recovery of the first-stage (L1) larvae from suspect meat products was achieved by artificial digestion. The molecular identification of the isolated larvae was performed by multiplex PCR. The molecular identification of the meat used to prepare the meat products was performed by real-time PCR assays.

RESULTS

The epidemic started in early 2017. In total, 71 exposed persons were documented: 26 with clinical symptoms and 3 hospitalised in two cities in different counties. The L1 burden in three different meat products was from 5.25 to 7.08 larvae per gram (LPG), and T. spiralis was determined as the aetiological agent of the outbreak. The molecular and biological identification confirmed that implicated meat products were made solely from wild boar meat.

CONCLUSIONS

Although trichinellosis is no longer a frequent occurrence in Croatia, several cases are still registered nearly every year. Wild boar meat poses an important risk factor for human health if compulsory testing is not conducted before consumption, especially if the meat products are consumed without proper thermal processing.

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.

Increased neutrophil derived chemokines (CXCL10 and CCL2) in human trichinellosis as possible serological markers of the polarization of the immune response against the parasite

Trichinella britovi is a widely distributed parasitic nematode, transmitted through ingestion of raw or poorly cooked meat containing muscle larvae. This helminth can regulate the host immune system during the early phase of infection. The immune mechanism mainly involves the interaction of Th1 and Th2 responses and related cytokines. Chemokines (C-X-C or C-C) and matrix metalloproteinases (MMPs) have also shown to be implicated in a number of parasitic infections, mainly malaria, neurocysticercosis, angiostronyloidosis, and schistosomiasis, but poor is known about their role in human Trichinella infection. We previously found that serum MMP-9 levels were significantly increased in T. britovi infected patients with relevant symptoms such as diarrhea, myalgia, and facial oedema, which makes these enzymes a potential reliable indicator of inflammation in trichinellosis patients. These changes were also observed in T. spiralis/T. pseudospiralis experimentally infected mice. No data are available about circulating levels of two pro-inflammatory chemokines, CXCL10 and CCL2, in trichinellosis patients with or w/o clinical signs of the infection. In this study, the association of serum level of CXCL10 and CCL2 with clinical outcome of T. britovi infection and their relation to MMP-9 were investigated. Patients (median age 49 ± 0.33 years) acquired infection by consuming raw sausages prepared with wild boar and pork meat. Sera were collected during the acute and the convalescent phases of the infection. A positive significant association (r = 0.61, p = 0.0004) was observed between MMP-9 and CXCL10 levels. The CXCL10 level significantly correlated with the severity of symptoms in patients being particularly higher in patients suffering diarrhea, myalgia, and facial oedema, thus suggesting a positive association of this chemokine with symptomatologic traits, especially myalgia (and increased LDH and CPK levels) (p < 0.005). No correlation was found between levels of CCL2 and the clinical symptoms.

Scheme of Effective Epidemiological Investigations in Trichinella Outbreaks on Pig Farms

Trichinellosis is a parasitic, zoonotic disease caused by larvae of the genus Trichinella. Infection occurs via the consumption of raw or undercooked meat containing this parasite. Symptoms of the disease manifest as intestinal disorders, followed by facial swelling, fever, muscle pain and other symptoms, eventually leading to neurological and cardiac complications and even death. In Europe, trichinellosis is most often associated with the consumption of meat from wild boars, pigs and horses. In recent years, wild boars that are hunted illegally and not tested for Trichinella spp. have been the most common cause of trichinellosis in humans; however, there have also been cases where infected pigs have been the source of infection. When trichinellosis is suspected in humans, epidemiological measures are taken to identify the source. Similarly, an epidemiological investigation should be initiated whenever Trichinella spp. has been detected in pigs. However, commonly used actions do not provide sufficient data to determine the source of infection for pigs and to prevent further transmission. Therefore, in this article, we propose a scheme for effective epidemiological investigations into Trichinella outbreaks on pig farms that can help trace the transmission mechanisms of the parasite and that takes into account currently available testing tools. The proposed pathway can be easily adopted for epidemiological investigations in routine veterinary inspection work.

The genus Trichinella and its presence in wildlife worldwide: A review

The genus Trichinella has a worldwide distribution, infecting people, domestic animals, and wildlife. It includes 13 genotypes, which are geographically delimited; Trichinella is transmitted to people through the ingestion of undercooked meat. Historically, it has been associated with pigs, but most Trichinella species affect wildlife, and cases of trichinellosis due to the consumption of game meat have been emerging. Therefore, it is important to monitor the sources of transmission to domestic animals and humans. The objective of this work was to analyse reports of Trichinella spp. in wild/feral animals around the world to identify the needs of future research in the epidemiology of the sylvatic cycle. A search of studies published until 2021 was conducted using Web of Science and SciELO. In the Palearctic, the most commonly studied hosts were wild boars and red foxes, and hosts with the highest prevalence rates were polar bears and martens. In the Nearctic, red foxes and black bears were the most frequently studied hosts, and the highest prevalence was found for wolverines and brown bears. In the Neotropics, positive reports were only identified in two countries, with wild boars being the most commonly studied species, and armadillos featuring the highest prevalence. In the Afrotropics, Trichinella limits its presence to Sub-Saharan Africa, where lions are the most studied hosts, and spotted hyenas have the highest prevalence. In the Indo-Malaya and Australasia ecozones, information on wildlife is scarce; the Norwegian rat is the most frequently studied host, and the Tasmanian devil has the highest prevalence of infection. In the last decade, research on world wildlife has increased which is associated with more frequent trichinellosis outbreaks caused by the consumption of wild meat. The results suggest the need to increase research in developing countries, particularly where more diverse sources of meat are available for human consumption.

Wildmeat consumption and zoonotic spillover: contextualising disease emergence and policy responses

Zoonotic diseases are estimated to constitute 75% of all emerging infectious diseases, of which more than 70% come from wild species. The potential threat of zoonotic spillover from the consumption of wildmeat has been the subject of policy and media attention, especially in the context of the COVID-19 pandemic; however, little is known about the actual conditions that contribute to the risk of spillover and associated disease transmission. In this Review, we compile existing evidence from available literature on the conditions of spillover associated with wildmeat consumption, including the types of wild animal and disease, modes of transmission, and the conditions in which spillover is thought to have occurred. We suggest that stronger understanding of the context of spillover from wildmeat is needed to enable more targeted and effective policy responses that reduce the risk of future pandemics of zoonotic origin. Such interventions could also lead to the avoidance of unintended adverse consequences for human communities that rely on wild produce, including wildmeat, as sources of dietary protein, fat, and micronutrients.

A Review on Alaria alata, Toxoplasma gondii and Sarcocystis spp. in Mammalian Game Meat Consumed in Europe: Epidemiology, Risk Management and Future Directions

Simple Summary

In many European countries, game meat consumption is related to the traditional hunting culture. Its demand and consumption are increasing, also due to the growing populations of wild ungulates. However, specific public health issues exist and should be taken into account. This review focuses on the causal agents, epidemiology, potential risk for human health and its management along the supply chain, including parasite detection at slaughtering and inactivation in meat, of three parasites (Alaria alata, Toxoplasma gondii and Sarcocystis spp.), which can be transmitted by the main mammalian game meat species in the EU: wild boar (Sus scrofa), red deer (Cervus elaphus), roe deer (Capreolus capreolus), fallow deer (Dama dama), Alpine chamois (Rupicapra rupicapra), moose (Alces alces), hare (Lepus europaeus) and wild rabbit (Oryctolagus cuniculus). By presenting the main issues and knowledge gaps, this study aims to contribute to an improved control supporting the risk analysis process.

Abstract

Game meat is increasingly appreciated and consumed in Europe, also due to the growing population of wild ungulates. In addition to interesting nutritional properties and market opportunities, game meat is characterized by some specific public health issues. This review focuses on the etiology, epidemiology, public health aspects and risk management along the supply chain, including parasite detection at slaughtering and inactivation in meat, of three selected foodborne parasitic hazards (Alaria alata, Toxoplasma gondii and Sarcocystis spp.) in the main mammalian game meat species in the EU: wild boar (Sus scrofa), red deer (Cervus elaphus), roe deer (Capreolus capreolus), fallow deer (Dama dama), Alpine chamois (Rupicapra rupicapra), moose (Alces alces), hare (Lepus europaeus) and wild rabbit (Oryctolagus cuniculus). The presented data point out the main issues, and knowledge gaps as well as the potential for improved control in order to contribute to the risk analysis process. To pursue an effective management of these parasitic zoonoses, awareness raising should involve all figures in the supply chain, including hunters, restaurateurs and consumers. Human behaviour and the lack of knowledge regarding meat borne parasitic zoonoses and the health risks they pose seem to be the most important factors responsible for human infections. However, detection methods, starting from the sampling procedure, should be further developed and standardized in order to improve the collection of accurate and up-to-date epidemiological data.

Serological Detection of Trichinellosis among Suspected Wild Boar Meat Consumers in North and Northeast of Iran

Background

Trichinellosis is a foodborne zoonosis disease worldwide. Humans acquire infection by ingesting raw or uncooked animal flesh containing viable Trichinella larvae. The most common reservoirs of this helminth are pigs and wild boars. In northern Iran, hunting and consuming wild boars meat by some communities, including ethnic Armenians, may expose them to trichinellosis. Here, we investigated anti-Trichinella IgG antibodies in high-risk individuals in northeastern Iran.

Methods

From Mar to Aug 2020, we collected 189 blood samples from individuals with a history of wild boar meat consumption and examined the sera for anti-Trichinella IgG antibodies using a commercial ELISA kit (NovaTec Immunodiagnostica GmbH, Germany). Sera from 30 individuals with no history of eating wild boar meat was used to determine the range of actual negative values and possible cross-reactivity with other similar antigens.

Results

Of the 189 participants, 5 (2.6%) had anti-Trichinella IgG antibodies (OD, 1.176 ±0.154). None of the 30 negative controls became positive (OD, 0.198 ± 0.044). The age, gender, occupation, and education showed no significant association with Trichinella seropositivity rate (P>0.05). All five seropositive cases were among 112 individuals (4.46% seropositivity) that resided in the western part of the study area, stretching from Behshar to Gorgan.

Conclusion

Eating wild boar meat might expose individuals to trichinellosis in the north and northeast of Iran. Further studies with more individuals from different parts of the country and confirmation of the ELISA by additional tests like Western blot will give a more in-depth insight into human trichinellosis epidemiology in Iran.

Trich-tracker - a practical tool to trace Trichinella spiralis transmission based on rapid, cost-effective sampling of genome-wide genetic variation

Molecular epidemiology using traditional sequencing has been notoriously difficult in inbred parasites due to a lack of genetic variation available for discriminating among parasites. Next generation sequencing techniques offer a solution to this problem by increasing the number of loci that can be sequenced. Here, we introduce Trich-tracker, a tool that makes efficient use of diagnostic variation distributed throughout the genome of Trichinella spiralis to more rapidly, and conclusively, resolve connections and distinctions among focal outbreaks of T. spiralis. In particular, we rapidly characterised genetic variation among a sample of parasites from Polish farms and wildlife, sampling genomic variation using double digest restriction site-associated DNA sequencing (ddRADseq). Approximately 400,000 bases of sequence were generated from each sample and shown to be distributed across the genome with single nucleotide polymorphisms occurring at a frequency of approximately one base in 10,000. Both phylogenetic and Bayesian clustering analyses indicated that ddRADseq genotypes formed distinct clusters for specific outbreaks and were quite distinct from wild boar samples. Two of the investigated outbreaks were more similar to each other than to other outbreak samples, suggesting a link between these outbreaks. Hence, the Trich-tracker procedure identified informative genomic variation which afforded unprecedented epidemiological resolution. Trich-tracker is very flexible tool, quickly and inexpensively mining genomes of even highly inbred populations of T. spiralis to support outbreak investigations. The simplicity of the entire procedure, and time and cost effectiveness of Trich-tracker support its practical application in ongoing Trichinella outbreaks. The discriminating power of this tool is tunable and scalable, allowing application in a variety of epidemiological contexts, and is easily adapted to other parasite systems.

Animal welfare and zoonosis risk: anti-Trichinella antibodies in breeding pigs farmed under controlled housing conditions

Background

Domesticated pigs are the main source of Trichinella sp. infections for humans, particularly when reared in backyards or free-ranging. In temperate areas of southern Europe, most pigs are farmed under controlled housing conditions, but sows and sometimes fattening pigs have access to outdoors to improve animal welfare. The aim of the present study was to investigate whether outdoor access of breeding pigs farmed under controlled housing conditions can represent a risk for Trichinella sp. transmission when the farm is located in an agricultural area interspersed with wooded areas and badlands, where Trichinella spp. could be present in wildlife.

Methods

Serum samples were collected from 63 breeding sows and one boar before and after their access to an open fenced area for 2 months and from 84 pigs that never had outdoor access. Samples were screened for anti-Trichinella antibodies by ELISA, and positive sera were confirmed using Western blot (Wb) excretory/secretory antigens. To detect Trichinella sp. larvae, muscle tissues from serologically positive and negative pigs were tested by artificial digestion.

Results

Thirteen (20.6%) sows and one boar tested positive with both ELISA and Wb. No larvae were detected in muscle samples of serologically positive and serologically negative pigs. Positive serum samples were then tested by Wb using crude worm extract as antigens. The Wb banding pattern displayed was that characteristic of encapsulated species (Trichinella spiralis or Trichinella britovi).

Conclusions

The detection of anti-Trichinella antibodies without larvae in the pig muscles, supported by epidemiological data, suggests that pigs may have been exposed to T. britovi. This study stresses the importance of instigating monitoring systems at farm level to prevent Trichinella sp. transmission and to investigate, through a landscape parasitological study, the suitability of a site before the planting of a high containment level pig farm in which the sows can have outside access to improve their welfare during pregnancy.

Graphical abstract

Reprint of: Survival of Trichinella spiralis in cured meat products

Processing of meat is one possible approach to control meat-borne parasites. Processing methods such as freezing, cooking and irradiation are recommended for the control of Trichinella in pork, horse or game meat if specific technical conditions are fulfilled. Curing is a widely used preservation process influencing product characteristics such as shelf life, food safety, and taste. As curing methods are characterized by high parameter variability and predictions about inactivation of parasitic stages in raw meat products are difficult, curing and smoking are not recommended for Trichinella control. The objective of this study was to investigate the survival of T. spiralis in cured raw sausages taking into account water activity (a_w-value), pH value, temperature, and time. For this purpose, four different types of sausage (Knackwurst, vacuum packed Knackwurst, short ripened salami, long ripened salami) were produced using T. spiralis infested batter. After production, the sausages were stored at product specific conditions for up to 35 days. During storage, pH value and a_w-value of the sausages were monitored over time. Further, sausages of each type were digested using the magnetic stirrer method and the viability of the isolated larvae was assessed using a previously published larval motility test as a proxy for viability and infectivity of Trichinella larvae. In this context, we also introduce a three-level rated infectivity score (RIS) with a clear categorization scheme allowing the assessment of the infectivity of larvae. Based on the RIS, larvae isolated from the salamis were regarded as potentially infective until day 2 (short ripened salami) or day 3 (long ripened salami) post ripening, whereas in Knackwurst, potentially infective larvae were still found by day 8 post ripening. In contrast potentially infective larvae were detected in vacuum-packed Knackwurst until day 24 post ripening. Finally, using the RIS approach, data from previously published studies were collected and subjected to a correlation analysis to identify matrix factors linked to short Trichinella inactivation times.

Perception of the Health Threats Related to the Consumption of Wild Animal Meat-Is Eating Game Risky?

Consumer interest in game meat has increased in recent years. Consumers appreciate its nutritional value but still have many concerns. Based on data from a quantitative study conducted in the group of 450 purposively selected Polish respondents declaring to consume the game meat, consumers were segmented concerning the perception of health risks associated with its consumption. Three separate clusters were identified using hierarchical cluster analysis: Indifferent (42%), Fearful (30%), and Selective (28%). The clusters differed significantly in the perception of the role of game in their lives and taking actions to mitigate the health risks associated with its consumption. In addition, their socioeconomic profiles were significantly different. The Indifferent segment-significantly more often than the other segments-believes that game has a positive impact on health, and the way to counteract the health risks is to not eat raw meat. The Selective segment attaches great importance to the choice of consumption place as a warranty of access to safe meat. The Fearful segment is willing to pay more for good quality meat and search for information. The results proved that the game consumers are not a homogenous group. Recognizing the differences can indicate a path for the traders to efficiently meet the consumers' expectations and needs.

First record of Trichinella in Leopardus guigna (Carnivora, Felidae) and Galictis cuja (Carnivora, Mustelidae): new hosts in Chile

Background

Trichinellosis is a zoonotic disease with a worldwide distribution. It is caused by several species of nematodes in the genus Trichinella. Trichinella spp. are transmitted through predation or carrion consumption and occur in domestic and sylvatic cycles. In humans trichinellosis occurs due to the consumption of raw or undercooked, infected meat and is mainly associated with the household slaughter of pigs or the consumption of game animals without veterinary inspection, a cultural practice that is difficult to resolve. Therefore, knowledge of this parasite's reservoir is relevant for better implementing public health strategies. The aim of this study was to assess the presence of Trichinella sp. in several carnivore and omnivore vertebrates in central-southern Chile.

Methods

We collected muscle tissue from a total of 53 animals from 15 species and were digested to detect Trichinella larvae which were further identified to species level using molecular techniques.

Results

We detected Trichinella larvae in Leopardus guigna (Felidae) and Galictis cuja (Mustelidae). We identified the larvae collected from L. guigna as Trichinella spiralis, but we were unable to molecularly characterize the larvae from G. cuja. This is the first record of Trichinella in a native mustelid of South America and the first record of T. spiralis in L. guigna. This study identified two novel hosts; however, further work is needed to identify the role that these and other hosts play in the cycle of Trichinella in Chile.

Temporal and geographic analysis of trichinellosis incidence in Chile with risk assessment

Trichinellosis is a foodborne disease caused by several Trichinella species around the world. In Chile, the domestic cycle was fairly well-studied in previous decades, but has been neglected in recent years. The aims of this study were to analyze, geographically, the incidence of trichinellosis in Chile to assess the relative risk and to analyze the incidence rate fluctuation in the last decades. Using temporal data spanning 1964-2019, as well as geographical data from 2010 to 2019, the time series of cases was analyzed with ARIMA models to explore trends and periodicity. The Dickey-Fuller test was used to study trends, and the Portmanteau test was used to study white noise in the model residuals. The Besag-York-Mollie (BYM) model was used to create Bayesian maps of the level of risk relative to that expected by the overall population. The association of the relative risk with the number of farmed swine was assessed with Spearman's correlation. The number of annual cases varied between 5 and 220 (mean: 65.13); the annual rate of reported cases varied between 0.03 and 1.9 cases per 10⁵ inhabitants (mean: 0.53). The cases of trichinellosis in Chile showed a downward trend that has become more evident since the 1980s. No periodicities were detected via the autocorrelation function. Communes (the smallest geographical administrative subdivision) with high incidence rates and high relative risk were mostly observed in the Araucanía region. The relative risk of the commune was significantly associated with the number of farmed pigs and boar (Sus scrofa Linnaeus, 1758). The results allowed us to state that trichinellosis is not a (re)emerging disease in Chile, but the severe economic poverty rate of the Mapuche Indigenous peoples and the high number of backyard and free-ranging pigs seem to be associated with the high risk of trichinellosis in the Araucanía region.

Trichinella spiralis in a cougar (Puma concolor) hunted by poachers in Chile

Trichinellosis is a zoonosis caused by nematodes of the Trichinella genus, of which 10 species have been described. Species identification when larvae is found is only possible using molecular tools. Meat from pigs and game animals not subjected to veterinary inspection are the main sources of human infections. The hunting of native carnivores is prohibited in Chile due to conservation issues and the fact that those animals favor pest control. The illegal hunting of a cougar (Puma concolor) occurred in September 2020. Herein, the molecular identification of Trichinella larvae, by analyzing nuclear (expansion segment V) and mitochondrial (cytochrome C oxidase subunit I) sequences are described. Both the amplification of the expansion segment V region and the phylogenetic analysis of a segment of a fragment of the cytochrome c-oxidase subunit I sequence confirmed that the larvae belonged to T. spiralis. The case described herein represents the first evidence of illegal hunting of a protected mammal infected with Trichinella in Chile, highlighting the 'One Health' perspective to face this disease in the rural-sylvatic interphase.

Second outbreak of Trichinella pseudospiralis in Europe: clinical patterns, epidemiological investigation and identification of the etiological agent based on the western blot patterns of the patients' serum

Trichinellosis is a zoonotic disease due to the ingestion of raw or undercooked meat from animals infected with the larvae of nematodes belonging to the genus Trichinella. In January-February 2015, an outbreak of trichinellosis occurred in Genoa, Northern Italy. The epidemiological link was traced back to a dinner served at an agritourism farm on 31 December 2014, where a majority of the 52 guests had consumed the 'beef' steak tartare. The source of infection was not traced; however, it was noted that the amount of beef purchased officially for providing at the dinner did not correspond with that served, suggesting that meat of a different origin had been added to the beef to prepare the steak tartare. Clinical and laboratory data of 30 individuals out of the 52 (57.7%), of which four were hospitalized, were consistent with that of the case definition of trichinellosis. Western blot patterns of the sera from patients with confirmed trichinellosis were similar to the diagnostic pattern identified for the reference sera of Trichinella pseudospiralis but different from those of the control sera tested for patients infected with Trichinella spiralis and Trichinella britovi. Identification of T. pseudospiralis as the aetiological agent responsible for the outbreak of trichinellosis using an indirect tool represents an advancement in the epidemiological investigation of this zoonotic disease.

Trichinella britovi infection in wild boar in Portugal

Trichinella spp. infection occurs when a host ingests muscle tissue containing infective larvae (L1 stage). Wild boar meat and its products represent the second largest source of human trichinellosis worldwide. For this reason, and since that in Portugal wild boar is the most hunted large game specie, the laboratory of Technology, Quality and Food Safety (TQFS) from the University of Trás-os-Montes e Alto Douro created a free service to test wild boar meat for Trichinella spp. From December 2015 to February 2020, and 857 samples were analysed. From those, the majority (719/857, 83.9%) were tested after October 2018 when a specific national legislation came into force, demanding that meat from wild boar hunted in a defined risk area should be tested for Trichinella spp. Under TQFS laboratory activity, in January 2020, a positive case was identified, being the first molecular confirmation of Trichinella britovi infection in wild boar in Portugal. Additionally to this activity, in 2019, a questionnaire was submitted to 100 hunters to acquire information about wild boar meat usage and consumption behaviours. From the total respondents, 86% declared they intended to use meat for private consumption. Of those, 93% also stated that have sold part of the meat and/or homemade sausages, the majority (80%) without prior testing for Trichinella spp., as required by EU Regulation. These results alert the hunters to a risk for human infection, which could be extended to outside the hunter's household. Given the actual epidemiological situation, it should be emphasized that testing for Trichinella spp. in wild boar meat should be maintained and reinforced, particularly in the risk area. The results presented in this report strongly support the importance of specific national legislation to mitigate the risk of trichinellosis due to consumption of non-tested wild boar meat.

Foodborne Zoonoses Common in Hunted Wild Boars

The northern European wild boar population has increased during the last decade. Highest wild boar numbers in Finland have been reported in the southeastern part near the Russian border. Wild boars may be infected with several human and animal pathogens. In this study, we investigated the presence of important foodborne pathogens in wild boars hunted in 2016 in Finland using serology, PCR and culturing. Seroprevalence of Salmonella (38%) and Yersinia (56%) infections was high in wild boars. Antibodies to hepatitis E virus, Toxoplasma gondii and Brucella were found in 18%, 9% and 9% of the wild boars, respectively. Trichinella antibodies were detected in 1% of the animals. We recorded no differences in the seroprevalence between males and females. However, Yersinia and T. gondii antibodies were detected significantly more often in adults than in young individuals. Listeria monocytogenes (48%) and stx-positive Escherichia coli (33%) determinants were frequently detected in the visceral organs (spleen and kidneys) by PCR. Yersinia pseudotuberculosis O:1 and L. monocytogenes 2a and 4b were identified by culturing from the PCR-positive samples. Brucella suis biovar 2 was isolated from visceral organs. No African swine fever, classical swine fever or Aujeszky's disease were detected in the wild boars. Our study shows that wild boars are important reservoirs of foodborne pathogens.

Survival of Trichinella spiralis in cured meat products

Processing of meat is one possible approach to control meat-borne parasites. Processing methods such as freezing, cooking and irradiation are recommended for the control of Trichinella in pork, horse or game meat if specific technical conditions are fulfilled. Curing is a widely used preservation process influencing product characteristics such as shelf life, food safety, and taste. As curing methods are characterized by high parameter variability and predictions about inactivation of parasitic stages in raw meat products are difficult, curing and smoking are not recommended for Trichinella control. The objective of this study was to investigate the survival of T. spiralis in cured raw sausages taking into account water activity (aw-value), pH value, temperature, and time. For this purpose, four different types of sausage (Knackwurst, vacuum packed Knackwurst, short ripened salami, long ripened salami) were produced using T. spiralis infested batter. After production, the sausages were stored at product specific conditions for up to 35 days. During storage, pH value and aw-value of the sausages were monitored over time. Further, sausages of each type were digested using the magnetic stirrer method and the viability of the isolated larvae was assessed using a previously published larval motility test as a proxy for viability and infectivity of Trichinella larvae. In this context, we also introduce a three-level rated infectivity score (RIS) with a clear categorization scheme allowing the assessment of the infectivity of larvae. Based on the RIS, larvae isolated from the salamis were regarded as potentially infective until day 2 (short ripened salami) or day 3 (long ripened salami) post ripening, whereas in Knackwurst, potentially infective larvae were still found by day 8 post ripening. In contrast potentially infective larvae were detected in vacuum-packed Knackwurst until day 24 post ripening. Finally, using the RIS approach, data from previously published studies were collected and subjected to a correlation analysis to identify matrix factors linked to short Trichinella inactivation times.

Trichinella britovi as a risk factor for alternative pig production systems in Greece and Europe

Trichinellosis is an important zoonosis and the most common source of human infection is meat from pigs and wild boars. The European Union (EU) supports alternative pig production systems (organic and free-ranging) as sustainable farming systems. However, these systems that allow outdoor access for farm animals, may create new or reintroduce old risks to public health. During the last years, alternative pig production systems (free-ranging or organic pig) are growing in popularity in Greece due to the increasing interest of consumers for organic products. The majority of the trichinellosis outbreaks in the EU were associated with pork and meat products including wild boars. In Greece, from 2009 to 2012, 37 Trichinella spp. positive free-ranging pigs were reported in free-ranging pig farms of Northern-Eastern Greece (31 were identified as T. britovi). The recent re-emerging present of the Trichinella spp. infections in free-ranging pigs and wild boars are a high risk for the consumers and should alarm the Public Health Authorities in Greece and the EU. During the last years, the organic or free-ranging pig production systems are growing in popularity in the EU. However, these systems increase the risk of Trichinella spp. infections, since pigs are possible to be infected by feeding on carcasses or the offal of hunted or dead wild animals. For this reason, it is important for Public Health Authorities to be focused on the training of hunters and farmers in order to avoid the transmission among free-ranging pigs and prevent the cases of human infection.

The Disease Ecology, Epidemiology, Clinical Manifestations, and Management of Trichinellosis Linked to Consumption of Wild Animal Meat

Historically, human trichinellosis was caused by Trichinella spiralis and transmitted to humans by consumption of undercooked domestic pork. Today, most cases of trichinellosis are caused by other Trichinella species and transmitted by consumption of raw or undercooked wild game meats. Given the increasing global prevalence of wild animal meat-linked trichinellosis, the objectives of this review are: 1) to describe the life cycle and global distribution of Trichinella worms; 2) to describe the changing epidemiology of trichinellosis; 3) to describe the clinical phases of trichinellosis; 4) to recommend the latest diagnostic tests; and 5) to recommend treatment and prevention strategies. Internet search engines were queried with keywords as subject headings to meet the objectives of this review. Although trichinellosis surveillance systems and laws regulating commercial pork production have limited T spiralis-caused trichinellosis in Europe and the United States, trichinellosis due to consumption of raw and undercooked wild boar and feral hog meat continues to occur throughout Southeast Asia. Trichinellosis due to consumption of raw or undercooked meats of other infected game, such as bear, deer, moose, and walrus, continues to occur worldwide. Only adherence to hygienic practices when preparing wild game meats and cooking wild game meats to recommended internal temperatures can prevent transmission of trichinellosis to humans. Wilderness medicine clinicians should be prepared to advise hunters and the public on the risks of game meat-linked trichinellosis and on how to diagnose and treat trichinellosis to prevent fatal complications.

The Immunological Properties of Recombinant Multi-Cystatin-Like Domain Protein From Trichinella Britovi Produced in Yeast

Trichinellosis is a globally-distributed zoonotic parasitic disease caused by nematode worms of the genus Trichinella. One of the most common species of Trichinella known to affect human health is T. britovi; however, it is relatively poorly investigated. A thorough knowledge of the proteins expressed by Trichinella is important when developing immunological detection methods and vaccines and studying its interactions with the host. The present study uses the Pichia pastoris expression system to produce a soluble TbCLP antigen which induces strong antibody responses in the host during natural infection. Our results demonstrate the feasibility of TbCLP antigen production in yeasts, which are able to carry out post-translational modifications such as glycosylation and disulfide bond formation; they also indicate that the glycosylated TbCLP antigen had immunogenic effects in the tested mice and induced a mixed Th1/Th2 response, and was associated with a reduced larval burden after challenge with T. britovi. Subsequent in vitro stimulation of mice splenocytes revealed that TbCLP most likely possesses immunomodulatory properties and may play a significant role in the early phase of infection, affecting host immunological responses.

Retrospective analysis of hospital discharge records for cases of trichinellosis does not allow evaluation of disease burden in Italy

Human trichinellosis is a disease caused by nematode worms of the genus Trichinella. In Italy, as well as in most other European countries, notification of Trichinella infections in humans is mandatory; however, no information is available on the number of cases occurring annually. The aim of the present study was to retrospectively evaluate the burden of trichinellosis in Italy from 2005 to 2016. Hospital discharge records (HDRs) showing the code for trichinellosis (124) were registered and screened. Results were then compared with yearly reports issued by the Italian National Reference Laboratory for Trichinella (NRLT), with reports from the European Centre for Disease Prevention and Control (ECDC), and with literature data. A total of 102 HDRs revealed that the 124 code was erroneously reported in 72 (70.6%) records. Out of the 30 (29.4%) records with a correct diagnosis of trichinellosis, nine cases were reported by HDRs only, 21 cases were documented by both HDRs and the NRLT, whereas the NRLT documented 100 additional cases. In the studied period, the average yearly incidence was 0.01 cases per 100,000 inhabitants. This study highlights the limitations of using HDRs to obtain a clear picture of the prevalence and incidence of trichinellosis in Italy. These findings demonstrate the need to intensify the surveillance system for trichinellosis through the development of an Italian registry. This would allow the identification of patients with severe infections and pauci-symptomatic patients, and would avoid the need for clinical analyses and unnecessary treatments, reducing the resulting economic burden on the Italian National Health Service.

Human Trichinellosis in Italy: an epidemiological review since 1989

Objectives

Trichinellosis is a worldwide zooantroponosis caused by a nematode of the genus Trichinella that can pose a risk to human health. Among the species of Trichinella, T. Spiralis is the most common represented. The main source of human infection is the consumption of raw or undercooked meat (especially from pigs, wild boars and horses). Infection with Trichinella was one of the most frequent parasitic diseases in Italy until 1959 when obligatory screening for these parasites in slaughtered swines was introduced. As the last review on this topic was performed in 1989, the aim of our study was to describe the epidemiology of Trichinellosis in Italy from 1989 to 2017.

Study design

We performed a systematic research in Pubmed (MEDLINE).

Methods

We included in our review studies that were published in the peer reviewed literature using the MESH terms “Trichinellosis” and “Italy”. The only restrictions were the language (articles should be in English, Italian, Spanish or French) and the date of publication: from 1989 to March 2017. We excluded all the articles which referred to trichinellosis in the animals or which focused only on molecular biology of trichinella or on diagnostic techniques.

Results

We found 56 studies, but only 8 were considered eligible. During the study period, 764 cases of Trichinellosis occurred in Italy: 13.7% caused by T. Britovi and 84.4% by T. spiralis; in 14 cases the identification of the parasite was not performed. The outbreaks occurred in Umbria, Piedmont, Apulia (500 cases in 1990, by T. spiralis), Basilicata, Tuscany, Abruzzo, Emilia Romagna, Sardinia. In 2001 and in 2008 two outbreaks occurred in Lazio and Veneto respectively, but imported from abroad. The most important sources of infections were: horse meat (82.2%); wild boar meat (11.9%); pig meat (5.9%).

Conclusions

Trichinellosis is still present in Italy, but often forgotten by general practitioners and infectious diseases specialists. It’s pivotal to improve awareness about this parasitic disease in Physicians and veterinarians. A strict surveillance, especially on meat products from endemic countries or from wild animals is necessary to considerably reduce the risk of acquiring the infection.

Toxoplasma gondii and Trichinella infections in wild boars (Sus scrofa) from Northeastern Patagonia, Argentina

Wild boar (Sus scrofa) was introduced in many countries of the world and is recognized as carrier of many infectious diseases. Wild game meat consumption is recognized as a source of transmission of Toxoplasma gondii and Trichinella spp. The aim of the present study was to evaluate the prevalence of antibodies to T. gondii and Trichinella spp. in free-range wild boars in Northeastern Argentine Patagonia. Between 2014 and 2018, 144 blood samples and 423 muscle samples from 423 carcasses were collected. To detect T. gondii IgG, 144 sera were processed by an immunofluorescent antibody test, and to detect anti-Trichinella IgG, 125 sera and 304 muscle juice samples were processed by ELISA. Detection of first stage larvae in muscle was performed by artificial digestion. A total of 423 wild boars muscle samples were negative to Trichinella spp. by artificial digestion. Antibodies to Trichinella spp. were detected in 2.4% (3/125) of serum samples and in 1.64% (5/304) of meat juice samples. Antibodies to T. gondii infection were detected in 12.5% (18/144) of the serum samples. This is the first study to reveal the presence of antibodies to T. gondii in wild boars from Argentina. The present results suggest that consumption of raw or undercooked wild boar meat could represent a potential source risk for toxoplasmosis in humans and that Trichinella spp. is infrequent and/or that it circulates in low burdens among wild boars in Northeastern Patagonia.

Epidemiology of taeniosis, cysticercosis and trichinellosis in Iran: A systematic review

BACKGROUND

The aim of this review was to establish the current epidemiology of taeniosis, cysticercosis and trichinellosis among humans and animals in Iran by carrying out a comprehensive assessment of published articles reporting on these foodborne zoonotic diseases across the country.

METHODS

The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guideline was used in the search for relevant published articles reporting on cysticercosis, taeniosis and trichinellosis in Iran using a number of appropriate key words. The search was conducted through PubMed, Web of Science, Google Scholar, SpringerLink, SCOPUS, WHOLIS, FAO and CDC. Published scientific articles including journals, books and book chapters reporting on cysticercosis, taeniosis and trichinellosis in Iran for the period between 1967 and 2018 were selected.

RESULTS

A total of 37 articles met the search criteria and were incorporated in this review. Of these, 10 (27%) reported on human taeniosis, 15 (40.5%) on cysticercosis (10 on Taenia saginata and five on Taenia spp. cysticercosis) and 12 (32.5%) on trichinellosis. T. saginata was implicated in all human taeniosis cases. All Taenia spp. cysticercosis cases were reported among domesticated pigs and wild animals. A case of neurocysticercosis was reported in a male patient at Shohada Hospital in Tehran. Eleven (91.7%) of the 12 studies reported on trichinellosis among wild animals, while one (8.3%) study detected anti-Trichinella IgG in 8 (2.2%) of the 364 at-risk human beings tested. Nevertheless, most of these studies were carried out in northern Iran.

CONCLUSION

This review found T. saginata to be the most prevalent and of greater economic and public health significance in Iran. However, T. solium and Trichinella spp. were of little significance to human health. More studies should focus on other regions besides northern Iran.

Differentiation of Trichinella species (Trichinella spiralis/Trichinella britovi versus Trichinella pseudospiralis) using western blot

BACKGROUND

Trichinellosis is a meat-borne zoonotic disease caused by parasites of the genus Trichinella. To date, 12 taxa have been described. The identification of Trichinella species is crucial in order to identify the possible source of infection, the geographical origin of the parasite and to assess risk of infection for domestic pigs and humans. Specific identification of the etiological agent is not always feasible using direct methods since the source of infection can be untraceable. The aim of this study was to develop a diagnostic tool to infer the causative Trichinella species using western blot patterns of sera derived from infected animal and human hosts.

METHODS

Sera from mice experimentally infected with Trichinella spiralis, Trichinella britovi, Trichinella pseudospiralis and Trichinella papuae were tested by western blot using homologous and heterologous crude worm extracts (CWE) and a highly sensitive detection system based on chemiluminescence. In addition, sera from pigs experimentally infected with T. spiralis, T. britovi and T. pseudospiralis and from patients with confirmed T. spiralis, T. britovi and T. pseudospiralis infections, were also included.

RESULTS

Sera from mice infected with one Trichinella species reacted with CWE proteins from all four investigated species. Likewise, sera derived from pigs and humans infected with one Trichinella species reacted with CWE proteins from all the three investigated species. Using T. spiralis CWE, sera from T. pseudospiralis-infected hosts yielded a characteristic pattern of reactivity using Wb, which differed to that produced by T. spiralis/T. britovi- or T. papuae-infected host sera.

CONCLUSIONS

The present study suggests that western blot using T. spiralis CWE may be a useful tool to distinguish Trichinella infections caused by T. pseudospiralis from those caused by T. spiralis or T. britovi. This method may support epidemiological investigations, particularly when the source of infection is not traceable.

Wild Boar: A Reservoir of Foodborne Zoonoses

Wild boar populations around the world have increased dramatically over past decades. Climate change, generating milder winters with less snow, may affect their spread into northern regions. Wild boars can serve as reservoirs for a number of bacteria, viruses, and parasites, which are transmissible to humans and domestic animals through direct interaction with wild boars, through contaminated food or indirectly through contaminated environment. Disease transmission between wild boars, domestic animals, and humans is an increasing threat to human and animal health, especially in areas with high wild boar densities. This article reviews important foodborne zoonoses, including bacterial diseases (brucellosis, salmonellosis, tuberculosis, and yersiniosis), parasitic diseases (toxoplasmosis and trichinellosis), and the viral hepatitis E. The focus is on the prevalence of these diseases and the causative microbes in wild boars. The role of wild boars in transmitting these pathogens to humans and livestock is also briefly discussed.

Trichinella britovi muscle larvae and adult worms: stage-specific and common antigens detected by two-dimensional gel electrophoresis-based immunoblotting

Background

Trichinella britovi is the second most common species of Trichinella that may affect human health. As an early diagnosis of trichinellosis is crucial for effective treatment, it is important to identify sensitive, specific and common antigens of adult T. britovi worms and muscle larvae. The present study was undertaken to uncover the stage-specific and common proteins of T. britovi that may be used in specific diagnostics.

Methods

Somatic extracts obtained from two developmental stages, muscle larvae (ML) and adult worms (Ad), were separated using two-dimensional gel electrophoresis (2-DE) coupled with immunoblot analysis. The positively-visualized protein spots specific for each stage were identified through liquid chromatography-tandem mass spectrometry (LC-LC/MS).

Results

A total of 272 spots were detected in the proteome of T. britovi adult worms (Ad) and 261 in the muscle larvae (ML). The somatic extracts from Ad and ML were specifically recognized by T. britovi-infected swine sera at 10 days post infection (dpi) and 60 dpi, with a total of 70 prominent protein spots. According to immunoblotting patterns and LC-MS/MS results, the immunogenic spots recognized by different pig T. britovi-infected sera were divided into three groups for the two developmental stages: adult stage-specific proteins, muscle larvae stage-specific proteins, and proteins common to both stages. Forty-five Ad proteins (29 Ad-specific and 16 common) and thirteen ML proteins (nine ML-specific and four common) cross-reacted with sera at 10 dpi. Many of the proteins identified in Ad (myosin-4, myosin light chain kinase, paramyosin, intermediate filament protein B, actin-depolymerizing factor 1 and calreticulin) are involved in structural and motor activity. Among the most abundant proteins identified in ML were 14-3-3 protein zeta, actin-5C, ATP synthase subunit d, deoxyribonuclease-2-alpha, poly-cysteine and histide-tailed protein, enolase, V-type proton ATPase catalytic and serine protease 30. Heat-shock protein, intermediate filament protein ifa-1 and intermediate filament protein B were identified in both proteomes.

Conclusions

To our knowledge, this study represents the first immunoproteomic identification of the antigenic proteins of adult worms and muscle larvae of T. britovi. Our results provide a valuable basis for the development of diagnostic methods. The identification of common components for the two developmental stages of T. britovi may be useful in the preparation of parasitic antigens in recombinant forms for diagnostic use.

Occurrence of selected zoonotic food-borne parasites and first molecular identification of Alaria alata in wild boars (Sus scrofa) in Italy

Wild boar is a source of human infections with zoonotic pathogens, including food-borne parasites. With the aim of a characterization of the human exposure risk, a survey on wild boars intended for human consumption was planned, selecting three pathogens, Toxoplasma gondii, Alaria alata, and Trichinella spp., as markers of meat infection. Diaphragm muscle samples from 100 wild boars hunted in Piedmont region (Northern Italy) in two hunting seasons (2015-2016) were collected. Concerning T. gondii, a combined approach of antibody detection and molecular techniques with genotyping was performed. For the detection of A. alata and Trichinella spp., the larva migration technique and the magnetic stirrer method were employed, respectively; in addition, molecular confirmation of the morphological identification of the recovered specimen was performed. Anti-T. gondii antibodies were found in meat juice samples (43.3%) and T. gondii DNA (type II) was detected in three animals (7.1%) out of 42 seropositive examined. In none of the sampled wild boars (0%), Trichinella spp. larvae were found, whereas one animal (1%) scored positive to A. alata mesocercariae. The molecular diagnosis proved the morphological identification of the trematode. This is the first finding of A. alata in Italian wild boar population. The present study confirmed the role of wild boars as a source of parasitic zoonotic diseases and thus the risk derived for humans posed by the consumption of game meat. Considering the zoonotic implications, the results underline the importance of monitoring and surveillance of zoonotic parasites in Italian wild boar populations.

The Golden jackal (Canis aureus) as an indicator animal for Trichinella britovi in Iran

Nematodes of the genus Trichinella are zoonotic parasites causing trichinellosis. In Iran, these parasites occur in several animal species and rare cases have been recorded in humans. To monitor the epidemiological pattern of these parasites in the Khorasan-e-Razavi province, Northeastern Iran, muscle tissues were collected from the tongues of roadkill animals between 2016 and 2017: 295 stray dogs, one red fox (Vulpes vulpes), 12 golden jackals (Canis aureus), and one wild boar (Sus scrofa). Trichinella spp. larvae were retrieved using the artificial digestion method and identified to the species level by multiplex PCR. Larvae identified as Trichinella britovi were detected in five stray dogs (1.7%) and one golden jackal (8.3%). The results confirm the circulation of T. britovi in animals of the Khorasan-e-Razavi province, as previously documented. A review of the literature on Trichinella spp. in animals in Iran showed that these parasites were previously detected in 20.02% and 0.04% of carnivore and omnivore mammals, respectively, and that golden jackals can be screened as indicator animals for these zoonotic nematodes. Convenient sampling of Trichinella susceptible roadkill animals may provide a suitable method of monitoring the circulation of these parasites within any given region.

T-cell clones in human trichinellosis: Evidence for a mixed Th1/Th2 response

In humans, studies on the cellular immune response against Trichinella are scarce. Aim of this study was to characterize the cytokine profile of T cells specific for Trichinella britovi in trichinellosis patients. Peripheral blood mononuclear cells (PBMC) were obtained from five patients involved in a trichinellosis outbreak caused by T. britovi, which occurred in 2013 in Tuscany (Italy). All the patients resulted positive for Trichinella-specific IgG, IgE and presented eosinophilia. T cells were investigated for their proliferation to excretory/secretory antigens from Trichinella spiralis muscle larvae (TsES) and for their cytokine profile. A total of 284 CD4+ and 42 CD8+ T-cell clones were obtained from the TsES-specific T-cell lines from PBMC. All T-cell clones proliferated in response to mitogen. Of the 284 CD4+ T-cell clones generated from TsES-specific T-cell lines, 135 (47%) proliferated significantly to TsES; 26% CD8+ T-cell clones showed proliferation to TsES. In the series of the 135 TsES-specific CD4+ clones, 51% expressed a Th2 profile, 30% a Th0 and 19% Th1. In the series of the 11 TsES-specific CD8+ T-cell clones, 18% were Tc2, 45% Tc0 and 36% Tc1. In human trichinellosis, the cellular immune response is, during the chronic phase, mixed Th1/Th2.

Outbreak of trichinellosis related to eating imported wild boar meat, Belgium, 2014

Trichinellosis is a rare parasitic zoonosis caused by Trichinella following ingestion of raw or undercooked meat containing Trichinella larvae. In the past five years, there has been a sharp decrease in human trichinellosis incidence rates in the European Union due to better practices in rearing domestic animals and control measures in slaughterhouses. In November 2014, a large outbreak of trichinellosis occurred in Belgium, related to the consumption of imported wild boar meat. After a swift local public health response, 16 cases were identified and diagnosed with trichinellosis. Of the 16 cases, six were female. The diagnosis was confirmed by serology or the presence of larvae in the patients' muscle biopsies by histology and/or PCR. The ensuing investigation traced the wild boar meat back to Spain. Several batches of imported wild boar meat were recalled but tested negative. The public health investigation allowed us to identify clustered undiagnosed cases. Early warning alerts and a coordinated response remain indispensable at a European level.

Trichinellosis outbreak due to wild boar meat consumption in southern Italy

We report a Trichinella britovi outbreak investigated during February-March 2016 in southern Italy. The source of infection was meat from infected wild boars that were illegally hunted and, hence, not submitted to post-mortem veterinary inspection. Thirty persons reported having eaten raw dried homemade sausages; five cases of trichinellosis were confirmed. Wild game meat consumers need to be educated about the risk for trichinellosis.

Validation studies of the latex agglutination test for the detection of Trichinella larvae in meat products

Human trichinellosis is a foodborne disease caused by ingestion of meat infected with Trichinella muscle larvae. To control Trichinella spp. infection in the European Union, all slaughtered pigs from holdings that are not officially recognized as applying controlled housing conditions and other animals susceptible to Trichinella infection and intended for human consumption should be examined by one of the approved digestion methods described in Regulation (EU) No. 2015/1375. In the past, Trichinella outbreaks due to the consumption of cured wild boar or pork products have been described in several European countries, making the identification of the larvae from these products relevant for Trichinella control. Therefore, this study aimed to validate the newly approved latex agglutination test (Trichin-L) for routine testing of cured meat products. The test was validated based on the OIE Guidelines using pork products spiked with Trichinella larvae. The sensitivity of the method varied greatly depending on the investigated meat product and was usually lower than for the gold standard, the magnetic stirrer method. The detection rate reached 80% for three larvae and 60% for one larva in cured pork sausages. A detection rate of 100% for three larvae and 50% for one larva was found in bacon. For frozen samples (-20°C) the Trichin-L kit is similarly sensitive as for cured samples. Further, to determine the performance of the test under field conditions, pork products from regions with known high Trichinella prevalences confiscated by customs authorities at two German international airports were analyzed. Problems associated with the Trichin-L test were incomplete digestion due to fatty ingredients, spices and very dry meat products, resulting in data which could not be evaluated. Therefore, the test is currently not suitable for the detection of Trichinella larvae in cured meat products and needs further adaptation steps to increase both usability and sensitivity.

Eosinophilia in Infectious Diseases

In determining the etiology of eosinophilia, it is necessary to consider the type of patient, including previous travel and exposure history, comorbidities, and symptoms. In this review, we discuss the approach to the patient with eosinophilia from an infectious diseases perspective based on symptom complexes.

Matrix metalloproteinase (MMP)-9: A realiable marker for inflammation in early human trichinellosis

Matrix Metalloproteinases (MMPs) are involved in many physiological and pathological processes. As regards parasitic infections, the role of these proteins has been particularly studied in malaria, neurocysticercosis and angiostrongyloidosis. Recently, we evaluated serum levels of MMP-9 and -2 (gelatinases) in mice experimentally infected with Trichinella spiralis or Trichinella pseudospiralis, which cause different degrees of myositis and we found their significant increase in the former and, at a lesser extent, in the latter, thus suggesting the possibility that these gelatinases, particularly MMP-9, represent a marker of inflammation. Our aim was to evaluate the levels of MMP-9 and 2 in trichinellosis patients, to assess their possible clinical significance. Serum samples from 31 Trichinella britovi-infected individuals (20 males and 11 females), living in Tuscany, Central Italy, were analysed for MMP-9 and MMP-2 serum levels. Patients acquired infection with Trichinella after consuming raw or undercooked meat of wild boar. Their median age was 49±0.33years (range from 7 to 91). Sera was collected before starting anti-inflammatory treatment, aliquoted and stored at -20°C until use. Sera from healthy subjects was considered as controls. The gelatinolytic activity of MMPs was analysed by gelatin zymography on 8% polyacrylamide-SDS gels containing 0.1% porcine gelatin, under non-reducing conditions. Clear bands corresponding to the digested areas were evaluated with an appropriate software. MMP-9 levels were additionally determined in 15 patients using a commercial ELISA kit for human MMP-9. The zymographic analysis of the gels showed the presence in serum samples of gelatinase bands at approximately 125-kDa, 92-kDa and 72-kDa, corresponding to the MMP-9/Neutrophil gelatinase-associated lipocalin (NGAL) complex and proenzyme forms of MMP-9 and MMP-2, respectively. A significant (p<0.01) increase in gelatinolytic activity in patients compared to the control group was observed for pro-MMP-9 in 25 out of 31. The mean increase in activity was 39.25%±16.67%. No significant differences were observed for pro-MMP-2 activity. The MMP-9 levels detected by ELISA showed significant correlation with zymographic data (r²=0.62, p<0.003) and were higher in more affected patients (suffering diarrhea, facial edemas and myalgia). In conclusion, MMP-9 might be considered as a marker of inflammation in T. britovi patients. On the contrary, MMP-2 did not result significantly different in patients, compared to controls.

Hunting dogs as sentinel animals for monitoring infections with Trichinella spp. in wildlife

Background

Nematode parasites of the genus Trichinella are important foodborne pathogens transmitted by ingestion of striated muscles harbouring infective larvae. Wild carnivorous and omnivorous animals are the most important reservoirs of these parasites. Hunting activities play an important role in Trichinella spp. epidemiology. The aim of the present work was to assess if serological detection of anti-Trichinella IgG in hunting dogs can be a tool to indirectly monitor Trichinella spp. infections in wildlife.

Methods

An ELISA and a Western blot (Wb) were developed and validated. To validate the assays, serum samples were collected from 598 dogs considered to be Trichinella-free, 15 naturally infected dogs, and six experimentally infected foxes. Sera were tested by ELISA with Trichinella spiralis excretory/secretory antigens. The diagnostic sensitivity and specificity of ELISA were 100 % (95 % CI: 83.89–100 %) and 95.65 % (95 % CI: 93.69–97.14 %), respectively. Sera from Trichinella-infected dogs/foxes tested by Wb showed a three-band pattern ranging from 48 to 72 kDa. Since the prevalence of Toxocara canis is very high in dogs, the specificity of the ELISA and Wb was further assessed by testing sera for anti-T. canis IgG using T. canis excretory/secretory antigens. No cross-reactivity was observed. To evaluate the test’s reliability in the field, serum samples were collected from wild boar hunting dogs from Central Italy where Trichinella britovi was circulating among wildlife.

Results

Out of 384 hunting dog sera, 189 (49.2 %) tested positive by ELISA and of these, 56 (29.6 %) tested positive by Wb, showing an overall prevalence of 14.6 % (56/384) in the wild boar hunting dog population of the investigated area. The serological prevalence in hunting dogs was significantly (P < 0.001) associated with the hunting district’s altitude. This is in agreement with previous investigations, which had shown that the prevalence of T. britovi in wildlife was higher in mountainous areas than in lowland areas of Italy.

Conclusion

The results suggest that the circulation of Trichinella spp. among wildlife can be monitored by testing sera from hunting dogs, which could act as sentinel animals of Trichinella spp. circulation in wildlife.

Trichinellosis in Vietnam

Trichinellosis is a zoonotic parasitic disease with a worldwide distribution. The aim of this work was to describe the epidemiological and clinical data of five outbreaks of trichinellosis, which affected ethnic minorities living in remote mountainous areas of northwestern Vietnam from 1970 to 2012. Trichinellosis was diagnosed in 126 patients, of which 11 (8.7%) were hospitalized and 8 (6.3%) died. All infected people had consumed raw pork from backyard and roaming pigs or wild boar at wedding, funeral, or New Year parties. The short incubation period (average of 9.5 days), the severity of the symptoms, which were characterized by diarrhea, abdominal pain, fever, myalgia, edema, weight loss, itch, and lisping, and the high mortality, suggest that patients had ingested a high number of larvae. The larval burden in pigs examined in one of the outbreaks ranged from 70 to 879 larvae/g. These larvae and those collected from a muscle biopsy taken from a patient from the 2012 outbreak were identified as Trichinella spiralis. Data presented in this work show that the northern regions of Vietnam are endemic areas for Trichinella infections in domestic pigs and humans.

A 38-year study on Trichinella spp. in wild boar (Sus scrofa) of Latvia shows a stable incidence with an increased parasite biomass in the last decade

Background

Trichinella spp. are zoonotic parasites transmitted to humans by the consumption of raw or insufficiently cooked meat of different animal species. The most common source of infection for humans is meat from pigs and wild boar (Sus scrofa). The aim of the present work was to evaluate the incidence of Trichinella spp. infections in wild boar hunted in Latvia over a 38 year interval (1976 to 2013).

Methods

A total 120,609 wild boars were individually tested for Trichinella spp. by trichinoscopy and, in case of negativity, by artificial digestion of 25 g muscles, in the 1976–2005 period, and by artificial digestion of 25–50 g muscles in the 2006–2013 period. Trichinella spp. larvae were identified at the species level by multiplex PCR.

Results

In the study period, the overall prevalence of infected wild boar was 2.5%. Trichinella britovi was the predominant (90%) species. The incidence of Trichinella spp. infection in wild boar exhibited two different trends. From 1976 to 1987, the incidence of infected/hunted wild boar increased from 0.23% to 2.56%, then it decreased to 0.19 in 1994. Thereafter, the incidence fluctuated between 0.05% and 0.37%. A statistically significant (P < 0.05) correlation (r = 0.54; p = 0.0199) was found between the trend of Trichinella spp. incidence in hunted wild boar and the number of snow cover days from 1976 to 1993. From 1997 to 2013, the estimated wild boar population of Latvia increased by 4.9 times and the hunting bag by 9.7 times, with a stable incidence of Trichinella spp. in the population. It follows that the biomass of Trichinella spp. larvae and of T. britovi, in particular, increased.

Conclusions

The incidence trends of Trichinella spp. in wild boar could be related to the role played by the snow in reducing the thermal shock and muscle putrefaction which increases the survival of the larvae in muscle tissues of carrion in the 1976–1993 period; and, in the 1997–2013 period, to the increased biomass of Trichinella spp. due to the increased carnivore populations, which are the main reservoirs of these parasites.

Trichinella spp. imported with live animals and meat

Nematodes of the genus Trichinella are widely distributed throughout the world in omnivorous and carnivorous animals (mammals, birds, and reptiles) and in incidental hosts. To prevent the transmission of these zoonotic parasites to humans, meat samples from Trichinella spp. susceptible animals are tested at the slaughterhouse or in game processing plants. The aim of the present review was to collect documented cases on Trichinella infected animals, meat, or meat derived products which reached the international trade or were illegally introduced from one to another country in personal baggage. In the course of the last 60 years in the international literature, there have been 43 reports of importation of Trichinella spp. infected animals or meat, most of which (60%, 26/43) related to live horses or their meat. Meat or meat derived products from pigs, wild boar and bears, account only for 18.6% (8/43), 4.7% (3/43), and 14.3% (6/43), respectively. However, only live horses or their meat intended for human consumption, meat from a single wild boar, and live polar bears caught in the wild for zoos, were imported through the international market; whereas, meat from pigs, wild boars and bears were illegally introduced in a country in personal baggage. Trichinella infected animals or meat which were officially or illegally introduced in a country were the source of 3443 Trichinella infections in humans in a 40-year period (1975-2014). Most of these infections (96.8%) have been linked to horsemeat consumption, whereas meat from pigs, wild boars and bears accounted only for 2.2%, 0.7% and 0.3% of cases, respectively. This review shows the Trichinella spp. risk in the international animal and meat trade has been linked mainly to horses and only one time to wild boar, if they carcasses are not adequately tested, whereas pigs and other wild animals or their derived products infected with Trichinella spp. are unlikely to reach the international market by the official animal and meat trade.