TRICHINELLA MURRELLI POZIO AND LA ROSA, 2000 IN A GRAY FOX (UROCYON CINEREOARGENTEUS) FROM PENNSYLVANIA: A NEW HOST RECORD FOR THIS ZOONOTIC NEMATODE.

Trichinella murrelli Pozio and La Rosa, 2000, is the primary sylvatic trichinellid encountered in temperate North America. During a survey for Sarcocystis in wild canids, a single worm matching the morphology of encapsulated Trichinella was observed in a muscle tissue squash from a gray fox male originating from Pennsylvania. The worm was photographed and then separated from the host tissue by artificial digestion, and genomic DNA was extracted from the worm. This DNA was subjected to species-specific multiplex PCR and short-read genomic sequencing. The banding pattern of the multiplex PCR indicated that the worm was T. murrelli, and the sequence of the mitochondrial Cytochrome c oxidase 1 gene and the ribosomal 18S ribosomal RNA, Internal Transcribed Spacer 1, 5.8S ribosomal RNA, Internal Transcribed Spacer 2, and 28S ribosomal RNA confirmed the diagnosis. This is the first report of T. murrelli in gray foxes that includes assays for assigning parasite species. This report confirms suspected data from surveys conducted over 30 yr ago and establishes a new host record for T. murrelli.

Trichinella murrelli identified in red foxes (Vulpes vulpes) in Pennsylvania, USA.

Trichinella infections have been eliminated from pork where pigs are raised in biosecure facilities, but wildlife infections persist. Trichinella murrelli is the primary zoonotic species in wild carnivores in the United States, having been identified in several species of omnivores and carnivores. Here, we document its occurrence in seven of 21 (33.3%) red foxes (Vulpes vulpes) from six counties in Pennsylvania. Encysted Trichinella larvae were detected in muscle squashes (<5 g samples) of all seven foxes, and in histological sections of the tongue and limb muscle of three. Larvae from muscle squashes were pooled and tested in a multiplex PCR capable of differentiating all Trichinella species native to the USA; all samples contained only T. murrelli. This is the first identification of T. murrelli in red foxes from Pennsylvania, and the first such survey performed in the last three decades. Results indicate that Trichinella remains endemic in Pennsylvania wildlife and a threat to the health of those who consume wild game.

Invasive wild boar (Sus scrofa) as a functional reservoir for the dynamics of Trichinella in the Patagonia region.

Trichinellosis is a zoonotic disease that has been studied mainly in domestic pigs (Sus scrofa domesticus). The cycle involves infection in domestic and wild fauna, which fulfill complex ecological roles, where Trichinella spiralis is reported in wild boar (Sus scrofa). The objective of this study was to determine the prevalence of trichinellosis in wild boar and evaluate the distance of positive animals to the nearest urbanization areas in Argentina Patagonia. Necropsies were carried out on wild boar hunted in the Nahuel Huapi and Lanín National Parks and surrounding areas. Skeletal muscle samples were collected from 1,694 wild boar and artificial digestion was performed on all samples. Trichinella spp. were found in 96 (5.8%) wild boar (0.2 to 424 Larvae/g). Parasitism in wild boar depends on the distribution of the population in natural and urban areas. Infected wild boar were found near peri-urban areas, demonstrating the importance of routine epidemiological surveillance and sanitary measures in and around cities. More research is needed to identify the Trichinella species that infect wild animals. We recommend the application of active and passive epidemiological surveillance in South America on exotic and native fauna that are hunted and consumed by humans.

TRICHINELLA AND AT LEAST THREE SPECIES OF SARCOCYSTIS PARASITIZE THE MUSCLES OF BOBCATS (LYNX RUFUS) FROM MISSISSIPPI.

Muscles of 25 bobcats (Lynx rufus) from remote areas of Mississippi in 2017 were tested for parasites. Testing for Sarcocystis infections included microscopic examination of fresh unstained muscle squashes, pepsin digestion of hearts and tongues, and histological sections of paraffin-embedded tissues. Sarcocystis spp. infections were detected in the muscles of 21 (84%) by a combination of methods. Sarcocysts were detected in the unstained tongue squashes of 2 bobcats. Sarcocystis sp. bradyzoites were detected in the pepsin digests of 3 of 19 hearts, and 12 of 19 tongues. In paraffin-embedded histological sections, sarcocysts were detected in 7 of 25 hearts, 17 of 25 tongues, and 5 of 23 limb muscles. Based on the character of the cyst wall, at least 3 morphologic types of sarcocysts were detected: those with small spikes on the cyst wall, corresponding to Sarcocystis felis, those with long villar protrusions, corresponding to Sarcocystis neurona, and those lacking visible cyst wall protrusions, representing an unidentified type of sarcocyst. Myositis associated with sarcocysts was seen in the tongues of 3, and in the limb muscles of 1 bobcat. Multilocus genotyping of the DNA extracted from paraffin-embedded sections from 2 bobcats, employing 18S, 28S, COI, ITS-1, and 5.8S and rpoB genes, diagnosed Sarcocystis caninum, S. felis, Sarcocystis lutrae, and S. neurona. An encapsulated species of Trichinella was identified in the tongue of 1; it represents the first documented occurrences in bobcats from Mississippi. Taken together, these observations suggest intensive exposure of these wild carnivores to Trichinella tissue cysts, implies predation or scavenging on these tissues promotes parasite transmission, and raises caution concerning zoonotic risk when such meat is rendered for human consumption.

Molecular based confirmation of puma meat sausages implicated in trichinellosis outbreaks in Argentina.

Trichinellosis is a zoonotic disease caused by Trichinella, with the main source of infection being the consumption of pork and pork-derived products. However, it can also be acquired from eating the meat from wild animals targeted for sport hunting. The objectives of this study were: 1) to develop and implement a molecular method for the identification of Sus scrofa (pig and wild boar) and Puma concolor (Puma) meat in sausages eaten raw, which were linked to trichinellosis outbreaks occurring in Córdoba, Buenos Aires and La Pampa provinces, Argentina, in 2010, 2021, and 2022, respectively; and 2) to identify the Trichinella species present in the food. Specific primers were designed for PCR amplification and nucleotide sequencing of a region of the mitochondrial cytochrome b gene from both host species. Samples from the mentioned outbreaks were analysed, and the molecular identification of Trichinella spp. larvae was also performed. Results of the species identification system revealed that sausages from Córdoba and Buenos Aires had a mixed composition of pork and puma meat, while those from La Pampa contained puma meat only. Trichinella spiralis was implicated in all three outbreaks. The species identification system developed and implemented in this study revealed two host species of Trichinella related to human cases, and alerts about the risk of zoonotic transmission to humans through infected puma meat.

Trichinella pseudospiralis in a red kite (Milvus milvus) from Italy.

Trichinella pseudospiralis is a non-encapsulated species infecting both mammals and birds. In Italy, this species has been reported so far only in central regions (two nocturnal birds of prey, one red fox, and one wild boar) and in northeast regions (four wild boars). In November 2020, Trichinella sp. larvae were isolated by enzymatic digestion from muscle tissues of a red kite (Milvus milvus) specimen belonging to a population residing in the Basilicata region (Southern Italy). The parasite was identified as T. pseudospiralis by multiplex PCR, and the sequencing of the expansion segment V (ESV) region of the nuclear large subunit ribosomal DNA showed, in the microsatellite region, the polymorphism characteristic of the Palearctic population. This represents the first record of T. pseudospiralis in a red kite and the first report of this parasite in Southern Italy. The isolation of the parasite in a resident bird confirms that T. pseudospiralis is present, even if at low prevalence, in the Italian avifauna.

High prevalence, intensity, and genetic diversity of Trichinella spp. in wolverine (Gulo gulo) from Yukon, Canada.

BACKGROUND: Species of Trichinella are globally important foodborne parasites infecting a number of domestic and wild vertebrates, including humans. Free-ranging carnivores can act as sentinel species for detection of Trichinella spp. Knowledge of the epidemiology of these parasites may help prevent Trichinella spp. infections in northern Canadian animals and people. Previous research on Trichinella spp. in wildlife from Yukon did not identify risk factors associated with infection, or the diversity and identity of species of Trichinella in regional circulation, based on geographically extensive sampling with large sample sizes. METHODS: In a cross-sectional study, we determined the prevalence, infection intensity, risk factors, and species or genotypes of Trichinella in wolverine (Gulo gulo) in two regions of Yukon, Canada, from 2013-2017. A double separatory funnel digestion method followed by mutiplex PCR and PCR-RFLP were used to recover and identify species of Trichinella, respectively. RESULTS: We found larvae of Trichinella in the tongues of 78% (95% CI 73-82) of 338 wolverine sampled. The odds of adult (≥ 2 years) and yearling (1 year) wolverine being Trichinella spp.-positive were four and two times higher, respectively, compared to juveniles (<1 year). The odds of Trichinella spp. presence were three times higher in wolverine from southeast than northwest Yukon. The mean intensity of infection was 22.6 ± 39 (SD, range 0.1-295) larvae per gram. Trichinella T6 was the predominant genotype (76%), followed by T. nativa (8%); mixed infections with Trichinella T6 and T. nativa (12%) were observed. In addition, T. spiralis was detected in one wolverine. Out of 22 isolates initially identified as T. nativa in multiplex PCR, 14 were analyzed by PCR-RFLP to distinguish them from T. chanchalensis, a recently discovered cryptic species, which cannot be distinguished from the T. nativa on multiplex PCR. Ten isolates were identified either as T. chanchalensis alone (n = 7), or mixed infection with T. chanchalensis and T. nativa (n = 2) or T. chanchalensis and Trichinella T6 (n = 1)]. CONCLUSIONS: Wolverine hosted high prevalence, high larval intensity, and multiple species of Trichinella, likely due to their scavenging habits, apex position in the food chain, and wide home range. Wolverine (especially adult males) should be considered as a sentinel species for surveys for Trichinella spp. across their distributional range.

Trichinella species and genotypes.

Trichinella spiralis has historically been deemed "the pig parasite" owing to its initial classification within a monospecific genus. However, in recent years, the genus has expanded to include 10 distinct species and at least 3 different genotypes whose taxonomic status remains unstipulated. In contrast to T. spiralis, however, most of these sylvatic species and genotypes do not infect pigs well. Inasmuch as morphological characters cannot be used to define species within this genus, earlier classifications were based upon host and geographical ranges, biological characters, and the presence or absence of a collagen capsule that surrounds the muscle stage larvae. Later, isoenzymes, DNA gel fragmentation patterns and DNA probes were used to help in identification and classification. Today, amidst the "-omics" revolution, new molecular and biochemical-based methodologies have improved detection, differentiation and characterization at all levels including worm populations. These efforts have discernably expanded immunological, epidemiological, and genetic studies resulting in better hypotheses on the evolution of the genus, and on global events, transmission cycles, host associations, and biogeographical histories that contributed to its cosmopolitan distribution. Reviews of this sort are best begun with a background on the genus; however, efforts will divert to the most recent knowledge available on the taxonomy, phylogeny, epidemiology and biochemistry that define this genus in the 21st century.

A two-step morphology-PCR strategy for the identification of nematode larvae recovered from muscles after artificial digestion at meat inspection.

To ensure that meat from livestock and game is safe for human consumption, European legislation lays down rules for mandatory testing. Helminth larvae are a category of zoonotic foodborne pathogens that can contaminate meat. Among helminths, the only zoonotic nematode regulated in Europe regarding meat inspection is Trichinella spp.. It is precisely during Trichinella testing that other potentially zoonotic larvae can be found. Due to current lack of tools, their identification is often very complicated. Nematode larvae other than Trichinella, recovered from artificial digestions of pig and wild boar muscles from France and Germany, were subjected to a newly developed two-step identification scheme, which includes both morphological examination and molecular assays. The first step is a general orientation towards a broad taxonomic group; the second step consists of targeted identification based on the results of first step. Different parasites were identified, some of which were not zoonotic such as Metastrongylus spp. and Angiostrongylus vasorum, but others are known to be zoonotic such as Toxocara cati, Ascaris suum, and Uncinaria stenocephala. The strategy is efficient for the identification of nematode larvae recovered from muscles but could also be applied for larvae from other sources.

Species identification of Trichinella originated from various host and different geographical location by MALDI-TOF.

The foodborne zoonotic nematode Trichinella spp. can cause human trichinellosis when raw or undercooked contaminated meat is ingested. To date, twelve Trichinella species/genotypes have been described. According to EU regulation any Trichinella larvae detected during mandatory routine examinations need to be identified at a species level by a competent laboratory. Currently, Trichinella species identification is performed using molecular biology tools such as multiplex PCR, PCR-sequencing or PCR-RFLP. These techniques require high level of skills for good interpretation of the results. Due to its rapidness and ease of use a matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) protocol was previously developed for the identification of Trichinella species. Using this method, spectra from different Trichinella species and strains were acquired allowing to generate new Main Spectra (MSP). Finally a new MSP database from Trichinella spp. Samples of different countries (France, Germany and Poland), including field samples, was generated. Comparing the different main spectra, Trichinella worms were identified at the species level and differences in the genetic diversities within the different species are discussed. In conclusion, using the previously described method on field samples is a reliable, rapid, easy-to-use and cheap tool for Trichinella species identification. The new Trichinella database could be incremented with new samples. It constitutes a tool, which could be used as an alternative method to replace the actual molecular methods for Trichinella species identification.

Hiding in plain sight: discovery and phylogeography of a cryptic species of Trichinella (Nematoda: Trichinellidae) in wolverine (Gulo gulo).

Understanding parasite diversity and distribution is essential in managing the potential impact of parasitic diseases in animals and people. Imperfect diagnostic methods, however, may conceal cryptic species. Here, we report the discovery and phylogeography of a previously unrecognized species of Trichinella in wolverine (Gulo gulo) from northwestern Canada that was indistinguishable from T. nativa using the standard multiplex PCR assay based on the expansion segment 5 (ESV) of ribosomal DNA. The novel genotype, designated as T13, was discovered when sequencing the mitochondrial genome. Phylogenetic analyses of the mitochondrial genome and of 15 concatenated single copy orthologs of nuclear DNA indicated a common ancestor for the encapsulated clade is shared by a subclade containing Trichinella spiralis and Trichinella nelsoni, and a subclade containing T13 and remaining taxa: T12 + (T2 + T6) + [(T5 + T9) + (T3 + T8)]. Of 95 individual hosts from 12 species of mammalian carnivores from northwestern Canada from which larvae were identified as T. nativa on multiplex PCR, only wolverines were infected with T13 (14 of 42 individuals). These infections were single or mixed with T. nativa and/or T6. Visual examination and motility testing confirmed that T13 is encapsulated and likely freeze-tolerant. We developed a new Polymerase Chain Reaction-Restriction Fragment Length Polymorphism which unequivocally distinguishes between T13 and T. nativa. We propose Trichinella chanchalensis n. sp. for T13, based on significant genetic divergence from other species of Trichinella and broad-based sampling of the Trichinella genome. Exploration of Alaskan and Siberian isolates may contribute to further resolution of a phylogeographically complex history for species of Trichinella across Beringia, including Trichinella chanchalensis n. sp. (T13).

Survey of Toxoplasma gondii and Trichinella spp. in hedgehogs living in proximity to urban areas in the Czech Republic.

Hedgehogs (Mammalia: Erinaceidae) are omnivorous nocturnal animals typically living in anthropogenic areas. They may be suitable as sentinels for a wide range of zoonotic infections. Only a few studies have investigated hedgehogs (and then as representative wildlife species) to establish their role in the life cycle of such tissue parasites with zoonotic potential as Toxoplasma gondii or Trichinella spp. Working with frozen hedgehog cadavers, we tested for these parasites using T. gondii DNA-specific magnetic capture isolation plus polymerase chain reaction and Trichinella spp. digestion assay. All of 50 examined hedgehogs were negative for Trichinella spp. larvae in their muscles, but brain tissue from 5 out of 26 Erinaceus europaeus (19.2%) and 4 out of 24 E. roumanicus (16.6%) tested positive for T. gondii DNA. Frequency of T. gondii for both hedgehog species was equal, as was distribution between males and females and across age categories. Although a few studies have suggested the possibility of Trichinella spp. infection in hedgehogs, the zero prevalence in the tested hedgehogs is not surprising in view of the generally low prevalence of Trichinella spp. in Central Europe. Our results show that hedgehogs are susceptible to infection by T. gondii and can be used as indicator wildlife animal species in anthropogenic ecosystems.

Prevalence and molecular identification of Trichinella species isolated from wildlife originating from Limpopo and Mpumalanga provinces of South Africa.

Trichinella species are widely distributed on all continents with the exception of Antarctica, although the full spectrum of Trichinella species found in sub-Saharan African countries, and their hosts, has not been fully documented. This study was conducted to determine the prevalence of Trichinella in wildlife from the Greater Kruger National Park (GKNP) and adjacent areas located in the Limpopo and Mpumalanga provinces of South Africa, and to identify the species and/or genotypes of Trichinella larvae isolated from muscle tissues, using molecular techniques. A review of Trichinella spp. and their wildlife hosts reported during 1964-2011 was also conducted and the results were compared with our current study. Ninety samples representing 15 mammalian, two bird and three reptile species were screened for Trichinella infection during 2012-2016, using artificial digestion. Isolates detected were identified using a multiplex polymerase chain reaction (PCR) amplification of the internal transcriber spacers ITS1 and ITS2, and expansion segment V (ESV) regions of ribosomal DNA, followed by molecular analysis of the sequences. Twenty samples from seven wildlife species were positive for Trichinella spp. larvae, with an overall prevalence of 21.1% (20/90). The prevalence was higher in carnivores (18.9%, 18/90) than in omnivores (2.2%, 2/90). Analysis of sequences showed that eight of the isolates - two from spotted hyaena (Crocuta crocuta) (2/8), three from lion (Panthera leo) (3/13), one from leopard (Panthera pardus) (1/6), one from small spotted genet (Genetta genetta) (1/2) and one Nile monitor lizard (Varanus niloticus) (1/2) - conformed to Trichinella zimbabwensis. One isolate from a hyaena was grouped under the encapsulated species clade comprising T. nelsoni and genotype Trichinella T8 reported to be present in South Africa. This is the first report confirming natural infection by T. zimbabwensis in hyaena, leopard, genet and Nile monitor lizard, adding to the body of knowledge on the epidemiology of Trichinella infections in the Greater Kruger National Park of South Africa. Ten Trichinella-like larval isolates recovered after digestion from four wildlife species in this study (2012-2016) revealed inconclusive results due to DNA degradation resulting from poor storage or too few larvae for analysis, in comparison to 20 unidentified isolates from five wildlife species during the 1964-2011 period.

Occurrence of Trichinella spp. in rats on pig farms.

INTRODUCTION: The highest risk of trichinellosis for human is considered in eating meat products containing live larvae, mostly from wild boars or pigs. Spreading of Trichinella spp. may occur in various ways, one of which is transmission by vectors. The rat is considered to be the most common vector for Trichinella parasite. The population of rats living on pig farms can play an important role in maintaining or spreading the parasite to other animals. OBJECTIVE: The aim of presented survey was to investigate the occurrence of Trichinella spp. in rats on farms with pigs infected with this parasite. MATERIAL AND METHODS: From pig farms selected for study, the muscles of collected rats were investigated by magnetic stirrer digestion method to assess occurrence of Trichinella in the rat population. Isolated Trichinella parasites were identified under stereomicroscope and multiplex PCR were performed for species identification. RESULTS: Rats infected with Trichinella spp. were discovered on three of five investigated pig farms. The mean extent of invasion in rats from the studied farms was 23.33%. The calculated medium intensity of invasion was 4.09 lpg (larvae per gram) (SD 5.41). All larvae of Trichinella discovered from rats were identified as T.spiralis. CONCLUSIONS: The results obtained indicate that in farms with a high prevalence of Trichinella invasion in pigs there are very likely to be found rats infected by this nematode. This suggests possibility to maintain the invasion in herd and spread into neighborhood farms.

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.

Multiplex TaqMan qPCR assay for specific identification of encapsulated Trichinella species prevalent in North America.

BACKGROUND Human trichinellosis is a foodborne parasitic zoonotic disease caused by ingestion of raw or undercooked meat infected with nematode larvae of the genus Trichinella. In the USA, sporadic cases and outbreaks caused by the consumption of wild game meat infected with Trichinella have been reported. The current methods for diagnosis such as serology and microscopy are not specific, may result in false negative results, and cannot differentiate encapsulated Trichinella larvae to species level. The molecular protocols currently available for the differentiation of all encapsulate Trichinella species prevalent in North America have some limitations such as the inability to identify and resolve the presence of several Trichinella species in a single test. OBJECTIVES/METHODS In this study we developed and evaluated a multiplex TaqMan quantitative real-time polymerase chain reaction (qPCR) assay, which can simultaneously detect, identify and differentiate all species of encapsulated Trichinella occurring in North America i.e., T. nativa, T. spiralis, T. murrelli and Trichinella T6, even in cases of multiple infection in a single sample. We investigated two human biopsies and 35 wild animal meat samples considered as having a high likelihood of harboring Trichinella larvae obtained from the United States during 2009-2017. FINDINGS Using the multiplex assay describe here, 22 (59%) samples that tested positive contained Trichinella spp., were identified as: T. nativa (n = 7, including a human biopsy), T. spiralis (n = 9, including a human biopsy), T. murrelli (n = 3), Trichinella T6 (n = 1). Results also included two rare mixed infection cases in bears, a T. nativa/T. spiralis from Alaska and a T. spiralis/Trichinella T6 from California. The species identifications were confirmed using a conventional PCR targeting the rRNA ITS1-ITS2 region, followed by DNA sequencing analysis. The estimated limit of detection (LOD) was approximately seven larvae per gram of meat. MAIN CONCLUSIONS Differentiation of Trichinella spp. is needed to improve efforts on identification of case, optimize food safety control and better understand the geographic distribution of Trichinella species. The Trichinella qPCR multiplex proved to be a robust, easy to perform assay and is presented as an improved technique for identification of all known encapsulated species occurring in North America continent.

Trichinella britovi in Game Meat Linked to Human Trichinellosis Outbreak in Serbia.

After a human trichinellosis outbreak in Zlatibor District, Serbia, in 2016, Trichinella larvae were found in wild boar ( Sus scrofa) meat products. One hundred and fourteen people were infected during the outbreak. The larvae were determined to be Trichinella britovi using the polymerase chain reaction method. Trichinella britovi has previously been identified in Serbia, but this is the first case of the species being confirmed in food samples linked to human trichinellosis. The results of the study confirmed that the T. britovi is able to affect human health. In addition, this study suggests the role of wild boars as reservoirs of T. britovi in Serbia.

Outbreak of Trichinella T9 Infections Associated with Consumption of Bear Meat, Japan.

An outbreak of trichinellosis occurred in Japan in December 2016. All case-patients had eaten undercooked bear meat, from which Trichinella larvae were subsequently isolated. DNA sequencing analysis of the mitochondrial genes cytochrome c-oxidase subunit 1 and internal transcribed spacer 2 confirmed that Trichinella T9 had caused the outbreak.

Multilocus genotype analysis outlines distinct histories for Trichinella britovi in the neighboring Mediterranean islands of Corsica and Sardinia.

BACKGROUND: The zoonotic nematode Trichinella britovi was discovered in two neighboring Mediterranean islands of Corsica and Sardinia, almost simultaneously at the beginning of the 21st century. An epidemiological link between the two parasite populations was generally assumed. In 2015, an outbreak of trichinellosis in Nice, the South of France, was reportedly caused by the consumption of raw pork delicatessen imported from Corsica. The aims of the present study were to investigate, by multilocus genotype (MLG) analyses, the hypothesis of the common origin of the Corsican and Sardinian T. britovi foci and to trace "from fork to farm" the origin of the pork product, which caused a trichinellosis outbreak in mainland France in 2015. METHODS: Sixty-three T. britovi isolates were collected from animals and pork products of Sardinia and Corsica islands and from mainland of Italy, France and Spain. We analyzed genetic variability at four polymorphic microsatellite loci by two independent algorithms, the Bayesian and multivariate analyses, to evaluate the genetic relationships of 1367 single larvae. RESULTS: Trichinella britovi isolates of the two islands showed different genetic structures and the Bayesian analysis revealed a different membership of the two insular populations. Furthermore, two geographically separate genetic groups were identified among Corsican isolates. Lastly, the origin of the pork delicatessen marketed in Nice was linked to a breeder-butcher in Corsica. CONCLUSIONS: The low level of genetic admixture of the insular T. britovi isolates suggests that this pathogen colonized the two islands by separate events. On the other hand in Corsica, although the isolates share the same genetic structure, geographically separate isolates showed different membership. We suggest the MLG analysis as a suitable method in supporting epidemiological investigations to trace "from fork to farm" insular populations of T. britovi.