World distribution of Trichinella spp. infections in animals and humans

Identification and characterization of conserved miRNAs with its targets mRNA in Trichinella Spiralis

microRNAs (Small regulatory non-coding RNAs) have an important role in gene regulation and evolutionarily conserved molecules. Trichinella spiralis infect majority of species. Therefore, it is of interest to identify conserved miRNAs and their targets using sequences from EST, GSS and full length nucleotides obtained from NCBI against previously reported worm miRNAs. We identify 11 novel miRNAs in T. spiralis by using bioinformatics-homology based search. In addition, we predicted target mRNA genes form complementary base pair in seed region of miRNAs. Further, gene annotation using Uniprot shows that these target genes of miRNAs are involved in various metabolism, enzymatic activity and constituents of membrane components.

Partially protective immunity induced by the 14-3-3 protein from Trichinella spiralis

Trichinellosis, a widespread zoonosis, is considered to be an emerging or re-emerging infectious parasitic disease. The development of vaccines to prevent Trichinella infection in domestic animals and humans is important for disease control. In a previous study, we identified Ts14-3-3 as an immunodominant protein from Trichinella spiralis (T. spiralis) adult worms recognized by early infection sera from pigs and mice. In this study, we further confirmed that Ts14-3-3 mRNA is expressed in both adult worms and in the larval stages of T. spiralis. Immunostaining with anti-Ts14-3-3 mouse sera further confirmed that native Ts14-3-3 is highly expressed on the surface of T. spiralis muscle larvae. The immune recognition by infected sera, its expression in both adult and larval stages and its exposure on the surface of the parasite led us to explore Ts14-3-3 as a vaccine antigen. Recombinant Ts14-3-3 formulated with an ISA50v2 adjuvant produced strong total IgG and balanced IgG1 and IgG2a responses in vaccinated mice and stimulated mouse splenocytes to produce high levels of Th1 (INF-γ, IL-2) and Th2 (IL4, IL5) cytokines. These results indicate that Ts14-3-3 is highly immunogenic and is able to induce balanced Th1/Th2 immune responses. These vaccine-induced immune responses resulted in a reduction in muscle larvae of up to 46.2% in vaccinated mice upon subsequent larval challenge relative to the number of larvae in mice received PBS control. The significant reduction in muscle larvae in vaccinated mice suggests that Ts14-3-3 is a promising vaccine target for potential use in domestic pigs to prevent trichinellosis transmission.

Rapid Identification of the Foodborne Pathogen Trichinella spp. by Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry

Human trichinellosis occurs through consumption of raw or inadequately processed meat or meat products containing larvae of the parasitic nematodes of the genus Trichinella. Currently, nine species and three genotypes are recognized, of which T. spiralis, T. britovi and T. pseudospiralis have the highest public health relevance. To date, the differentiation of the larvae to the species and genotype level is based primarily on molecular methods, which can be relatively time consuming and labor intensive. Due to its rapidness and ease of use a matrix assisted laser desorption / ionization time of flight mass spectrometry (MALDI-TOF MS) reference spectra database using Trichinella strains of all known species and genotypes was created. A formicacid/acetonitrile protein extraction was carried out after pooling 10 larvae of each Trichinella species and genotype. Each sample was spotted 9 times using α-cyano 4-hydoxy cinnamic acid matrix and a MicroFlex LT mass spectrometer was used to acquire 3 spectra (m/z 2000 to 20000 Da) from each spot resulting in 27 spectra/species or genotype. Following the spectra quality assessment, Biotyper software was used to create a main spectra library (MSP) representing nine species and three genotypes of Trichinella. The evaluation of the spectra generated by MALDI-TOF MS revealed a classification which was comparable to the results obtained by molecular methods. Also, each Trichinella species utilized in this study was distinct and distinguishable with a high confidence level. Further, different conservation methods such as freezing and conservation in alcohol and the host species origin of the isolated larvae did not have a significant influence on the generated spectra. Therefore, the described MALDI-TOF MS can successfully be implemented for both genus and species level identification and represents a major step forward in the use of this technique in foodborne parasitology.

Phylogenomic and biogeographic reconstruction of the Trichinella complex

Trichinellosis is a globally important food-borne parasitic disease of humans caused by roundworms of the Trichinella complex. Extensive biological diversity is reflected in substantial ecological and genetic variability within and among Trichinella taxa, and major controversy surrounds the systematics of this complex. Here we report the sequencing and assembly of 16 draft genomes representing all 12 recognized Trichinella species and genotypes, define protein-coding gene sets and assess genetic differences among these taxa. Using thousands of shared single-copy orthologous gene sequences, we fully reconstruct, for the first time, a phylogeny and biogeography for the Trichinella complex, and show that encapsulated and non-encapsulated Trichinella taxa diverged from their most recent common ancestor ∼21 million years ago (mya), with taxon diversifications commencing ∼10-7 mya.

Trichinella spiralis Paramyosin Binds Human Complement C1q and Inhibits Classical Complement Activation

BACKGROUND

Trichinella spiralis expresses paramyosin (Ts-Pmy) as a defense mechanism. Ts-Pmy is a functional protein with binding activity to human complement C8 and C9 and thus plays a role in evading the attack of the host's immune system. In the present study, the binding activity of Ts-Pmy to human complement C1q and its ability to inhibit classical complement activation were investigated.

METHODS AND FINDINGS

The binding of recombinant and natural Ts-Pmy to human C1q were determined by ELISA, Far Western blotting and immunoprecipitation, respectively. Binding of recombinant Ts-Pmy (rTs-Pmy) to C1q inhibited C1q binding to IgM and consequently inhibited C3 deposition. The lysis of antibody-sensitized erythrocytes (EAs) elicited by the classical complement pathway was also inhibited in the presence of rTs-Pmy. In addition to inhibiting classical complement activation, rTs-Pmy also suppressed C1q binding to THP-1-derived macrophages, thereby reducing C1q-induced macrophages migration.

CONCLUSION

Our results suggest that T. spiralis paramyosin plays an important role in immune evasion by interfering with complement activation through binding to C1q in addition to C8 and C9.

Effect of myrrh and thyme on Trichinella spiralis enteral and parenteral phases with inducible nitric oxide expression in mice

Trichinellosis is a serious disease with no satisfactory treatment. We aimed to assess the effect of myrrh (Commiphora molmol) and, for the first time, thyme (Thymus vulgaris L.) against enteral and encysted (parenteral) phases of Trichinella spiralis in mice compared with albendazole, and detect their effect on inducible nitric oxide synthase (iNOS) expression. Oral administration of 500 mg/kg of myrrh and thyme led to adult reduction (90.9%, 79.4%), while 1,000 mg/kg led to larvae reduction (79.6%, 71.3%), respectively. Administration of 50 mg/kg of albendazole resulted in adult and larvae reduction (94.2%, 90.9%). Positive immunostaining of inflammatory cells infiltrating intestinal mucosa and submucosa of all treated groups was detected. Myrrh-treated mice showed the highest iNOS expression followed by albendazole, then thyme. On the other hand, both myrrh and thyme-treated groups showed stronger iNOS expression of inflammatory cells infiltrating and surrounding encapsulated T. spiralis larvae than albendazole treated group. In conclusion, myrrh and thyme extracts are highly effective against both phases of T. spiralis and showed strong iNOS expressions, especially myrrh which could be a promising alternative drug. This experiment provides a basis for further exploration of this plant by isolation and retesting the active principles of both extracts against different stages of T. spiralis.

Innovative molecular diagnosis of Trichinella species based on β-carbonic anhydrase genomic sequence

Trichinellosis is a helminthic infection where different species of Trichinella nematodes are the causative agents. Several molecular assays have been designed to aid diagnostics of trichinellosis. These assays are mostly complex and expensive. The genomes of Trichinella species contain certain parasite‐specific genes, which can be detected by polymerase chain reaction (PCR) methods. We selected β‐carbonic anhydrase (β‐CA) gene as a target, because it is present in many parasites genomes but absent in vertebrates. We developed a novel β‐CA gene‐based method for detection of Trichinella larvae in biological samples. We first identified a β‐CA protein sequence from Trichinella spiralis by bioinformatic tools using β‐CAs from Caenorhabditis elegans and Drosophila melanogaster. Thereafter, 16 sets of designed primers were tested to detect β‐CA genomic sequences from three species of Trichinella, including T. spiralis, Trichinella  pseudospiralis and Trichinella  nativa. Among all 16 sets of designed primers, the primer set No. 2 efficiently amplified β‐CA genomic sequences from T. spiralis, T. pseudospiralis and T. nativa without any false‐positive amplicons from other parasite samples including Toxoplasma gondii, Toxocara cati and Parascaris equorum. This robust and straightforward method could be useful for meat inspection in slaughterhouses, quality control by food authorities and medical laboratories.

Intestinal microbes influence the survival, reproduction and protein profile of Trichinella spiralis in vitro

The interactions between intestinal microbes and parasitic worms play an essential role in the development of the host immune system. However, the effects of gut microbes on Trichinella spiralis are unknown. The aim of this work was to explore microbe-induced alterations in the survival and reproduction of T. spiralis in vitro. To further identify the proteins and genes involved in the response of nematodes to microbes, quantitative proteomic analysis of T. spiralis was conducted by iTRAQ-coupled LCMS/MS technology and quantitative real-time-PCR was used to measure changes in mRNA expression. The results showed Lactobacillus acidophilus, and especially Lactobacillus bulgaricus, significantly enhanced the survival and reproductive rates of nematodes. Salmonella enterica, and especially Escherichia coli O157:H7 (EHEC), had opposite effects. Genetic responses were activated mainly by EHEC. A total of 514 proteins were identified and quantified, and carbohydrate metabolism-related proteins existed in a higher proportion. These findings indicated that some gut bacteria are friendly or harmful to humans and in addition they may have similar beneficial or detrimental effects on parasites. This may be due to the regulation of expression of specific genes and proteins. Our studies provide a basis for developing therapies against parasitic infections from knowledge generated by studying the gut microbes of mammals.

Early serodiagnosis of trichinellosis by ELISA using excretory-secretory antigens of Trichinella spiralis adult worms

BACKGROUND

The excretory-secretory (ES) antigens of Trichinella spiralis muscle larvae (ML) are the most commonly used diagnostic antigens for trichinellosis. Their main disadvantage for the detection of anti-Trichinella IgG is false-negative results during the early stage of infection. Additionally, there is an obvious window between clinical symptoms and positive serology.

METHODS

ELISA with adult worm (AW) ES antigens was used to detect anti-Trichinella IgG in the sera of experimentally infected mice and patients with trichinellosis. The sensitivity and specificity were compared with ELISAs with AW crude antigens and ML ES antigens.

RESULTS

In mice infected with 100 ML, anti-Trichinella IgG were first detected by ELISA with the AW ES antigens, crude antigens and ML ES antigens 8, 12 and 12 days post-infection (dpi), respectively. In mice infected with 500 ML, specific antibodies were first detected by ELISA with the three antigen preparations at 10, 8 and 10 dpi, respectively. The sensitivity of the ELISA with the three antigen preparations for the detection of sera from patients with trichinellosis at 35 dpi was 100%. However, when the patients' sera were collected at 19 dpi, the sensitivities of the ELISAs with the three antigen preparations were 100% (20/20), 100% (20/20) and 75% (15/20), respectively (P < 0.05). The specificities of the ELISAs with the three antigen preparations were 98.11, 95.60 and 89.31%, respectively (P < 0.05).

CONCLUSIONS

The sensitivity and specificity of the T. spiralis AW ES antigens were superior to those of the AW crude antigens and ML ES antigens. Thus, the AW ES antigens might serve as potential antigens for the early and specific serodiagnosis of trichinellosis.

Wild boars meat as a potential source of human trichinellosis in Poland: current data

Trichinellosis is an epidemiological problem with a global distribution. In Poland a substantial increase of the wild boar population has been observed since 2010, together with an increased incidence of trichinellosis after ingestion of raw or undercooked wild boar products containing Trichinella spp. larvae. However, the actual number of human cases remains particularly difficult to determine. The aim of the present study was to determine the current prevalence and spread of these parasites within wild boars. The diaphragm pillars and tongue from 833 wild boars were collected from 2010 to 2014, as well as one wild boar meat sausage known to be a source of infection. The samples were tested for Trichinella spp. using pepsin digestion. Recovered larvae were identified at species level by multiplex polymerase chain reaction (multiplex PCR). The overall prevalence in all examined samples was found to be 2.0% (17/833). Recovered larvae were identified as T. spiralis and T. britovi (9/18 and 5/18, respectively). T. spiralis larvae were isolated from the sausage. Mixed infection was confirmed only once. Three isolates were not identified. The results of our study confirm that the wild boar plays a key role in the maintenance of Trichinella nematodes through the sylvatic cycle.

The first report of Trichinella pseudospiralis presence in domestic swine and T. britovi in wild boar in Bosnia and Herzegovina

The Balkans is endemic for nematodes of the genus Trichinella in both domestic and wild animals. The high prevalence of these zoonotic pathogens in animals linked with the food habits to consume raw meat and meat derived products resulted in a very high prevalence of trichinellosis in humans living in this European region. In spite of numerous epidemiological investigations carried out in this region, very few information is available on the Trichinella species circulating in Bosnia and Herzegovina. Trichinella spp. larvae were isolated from a domestic pig reared in a backyard and from a hunted wild boar whose meat had been the source of trichinellosis in one case. Both Trichinella pseudospiralis and T. spiralis have been identified in the domestic pig, whereas, T. britovi was detected in the wild boar. While, T. spiralis is the Trichinella species most frequently detected in domestic pigs, T. pseudospiralis has been previously documented in domestic pigs only three times in Russia, Slovakia and Croatia. The detection of T. britovi in the wild boar confirms that this nematode is the most frequent species circulating among wildlife of Europe.

A serosurvey for selected pathogens in Greek European wild boar

OBJECTIVES

Serum samples, collected from 94 European wild boar (Sus scrofa) during the hunting seasons 2006 -2010 from different regions of Greece, were examined in order to estimate the role of these wildlife species as reservoir of pathogens important for livestock and/or public health.

MATERIALS AND METHODS

The assays used for this purpose were commercial indirect ELISA for the detection of antibodies against porcine circovirus type 2 (PCV-2), porcine reproductive and respiratory syndrome (virus) (PRRSV), Aujeszky's disease virus (ADV), influenza A (IA) virus, Actinobacillus pleuropneumoniae, Mycoplasma hyopneumoniae, Salmonella species, Trichinella species and indirect immunofluorescence antibody test for the detection of antibodies against Toxoplasma gondii and Neospora caninum.

RESULTS

Antibodies against PCV-2, PRRSV, ADV, IA virus,A. pleuropneumoniae, M. hyopneumoniae, Salmonella species, Trichinella species, T. gondii and N. caninum were detected in 19.1 per cent, 12.8 per cent, 35.1 per cent, 1.1 per cent, 57.4 per cent, 0 per cent, 4.3 per cent, 6.4 per cent, 5.2 per cent and 1.1 per cent of the samples, respectively. Cluster analysis revealed a hot spot of seropositivity near Bulgarian border; seropositivity to ADV was more common among female animals.

CONCLUSIONS

These results indicate exposure of wild boar to most of the above-mentioned pathogens, raising concern about the possibility that these species may pose a significant health risk for livestock and/or humans.

Partially Protective Immunity Induced by a 20 kDa Protein Secreted by Trichinella spiralis Stichocytes

Background

Trichinella spiralis infection induces protective immunity against re-infection in animal models. Identification of the antigens eliciting acquired immunity during infection is important for vaccine development against Trichinella infection and immunodiagnosis.

Methods and Findings

The T. spiralis adult cDNA library was immunoscreened with sera from pigs experimentally infected with 20,000 infective T. spiralis larvae. Total 43 positive clones encoding for 28 proteins were identified; one of the immunodominant proteins was 20 kDa Ts-ES-1 secreted by Trichinella stichocytes and existing in the excretory/secretory (ES) products of T. spiralis adult and muscle larval worms. Ts-ES-1 contains 172 amino acids with a typical signal peptide in the first 20 amino acids. The expression of Ts-ES-1 was detected in both the adult and muscle larval stages at the mRNA and protein expression levels. Mice immunized with recombinant Ts-ES-1 (rTs-ES-1) formulated with ISA50v2 adjuvant exhibited a significant worm reduction in both the adult worm (27%) and muscle larvae burden (42.1%) after a challenge with T. spiralis compared to the adjuvant control group (p<0.01). The rTs-ES-1-induced protection was associated with a high level of specific anti-Ts-ES-1 IgG antibodies and a Th1/Th2 mixed immune response.

Conclusion

The newly identified rTs-ES-1 is an immunodominant protein secreted by Trichinella stichocytes during natural infection and enables to the induction of partial protective immunity in vaccinated mice against Trichinella infection. Therefore, rTs-ES-1 is a potential candidate for vaccine development against trichinellosis.

Mitochondrial genomes of Trichinella species and genotypes – a basis for diagnosis, and systematic and epidemiological explorations

In the present study we sequenced or re-sequenced, assembled and annotated 15 mitochondrial genomes representing the 12 currently recognised taxa of Trichinella using a deep sequencing-coupled approach. We then defined and compared the gene order in individual mitochondrial genomes (14 to 17.7 kb), evaluated genetic differences among species/genotypes and re-assessed the relationships among these taxa using the mitochondrial nucleic acid or amino acid sequence data sets. In addition, a rich source of mitochondrial genetic markers was defined that could be used in future systematic, epidemiological and population genetic studies of Trichinella. The sequencing-bioinformatic approach employed herein should be applicable to a wide range of eukaryotic parasites.

New finding of Trichinella britovi in a European beaver (Castor fiber) in Latvia

We report the first finding of Trichinella britovi in a European beaver. In Latvia, beaver is a common game animal and frequently used in human diet. A high prevalence of Trichinella infections in Latvia is present in the most common hosts-carnivores and omnivores. In total, 182 European beaver muscle samples were tested for Trichinella larvae accordingly to the reference method of European Communities Commission Regulation (EC) No. 2075/2005 (2005). Trichinella britovi larvae were detected in one animal (prevalence 0.5%; intensity 5.92 larvae per gram of muscle). This finding suggests that the consumption of European beaver meat can be a risk to human health. Further studies are needed in order to determine if the present observation represents an isolated individual case or low prevalence of Trichinella infection in beavers.

Oral vaccination of mice with Trichinella spiralis nudix hydrolase DNA vaccine delivered by attenuated Salmonella elicited protective immunity

We have previously reported that Trichinella spiralis Nudix hydrolase (TsNd) bound to intestinal epithelial cells (IECs), and the vaccination of mice with recombinant TsNd protein (rTsNd) produced a partial protective immunity against challenge infection in mice. In this study, the full-length cDNA sequence of TsNd gene was cloned into the eukaryotic expression plasmid pcDNA3.1, and the recombinant TsNd DNA was transformed into attenuated Salmonella typhimurium strain ⊿cyaSL1344. Oral immunization of mice with TsNd/S. typhimurium elicited a significant local mucosal IgA response and a systemic Th1/Th2 immune response. Cytokine profiling also showed a significant increase in the Th1 (IFN-γ, IL-2) and Th2 (IL-4, 10) responses in splenocytes of immunized mice upon stimulation with the rTsNd. The oral immunization of mice with TsNd/S. typhimurium displayed a statistically significant 73.32% reduction in adult worm burden and a 49.5% reduction in muscle larvae after challenge with T. spiralis muscle larvae, compared with PBS control group. Our results demonstrated that TsNd DNA delivered by attenuated live S. typhimurium elicited a local IgA response and a mixed Th1/Th2 immune response, and produced a partial protection against T. spiralis infection in mice.

Prevalence of Endemic Pig-Associated Zoonoses in Southeast Asia: A Review of Findings from the Lao People's Democratic Republic

The increasing intensification of pork production in southeast Asia necessitates an urgent requirement to better understand the dual impact of pig-associated zoonotic disease on both pig production and human health in the region. Sharing porous borders with five countries and representing many regional ethnicities and agricultural practices, the Lao People's Democratic Republic (Lao PDR) appears well placed to gauge the levels of pig-associated zoonoses circulating in the wider region. Despite this, little is known about the true impact of zoonotic pathogens such as leptospirosis, Trichinella, hepatitis E virus (HEV), Japanese encephalitis (JE), and Taenia solium on human health and livestock production in the country. A comprehensive review of the published prevalences of these five pig-associated zoonoses in Lao PDR has demonstrated that although suspicion remains high of their existence in pig reservoirs across the country, epidemiological data are scarce; only 31 epidemiological studies have been undertaken on these diseases in the past 25 years. A greater understanding of the zoonoses prevalence and subsequent risks associated with pork production in the southeast Asian region could help focus public health and food safety interventions at key points along the value chain, benefiting both livestock producers and the broader animal and human health systems in the region.

Trichinella pseudospiralis in the Iberian peninsula

Nematode worms of the genus Trichinella are zoonotic parasites circulating in most continents, including Europe. In Spain, Trichinella spiralis and Trichinella britovi are highly prevalent in wildlife but seldom in domestic pigs. In Portugal, only T. britovi was documented in wild carnivores. In the period 2006-2013 in Spain, 384 (0.0001%) pigs and 1399 (0.20%) wild boars (Sus scrofa) were positive for Trichinella spp. larvae, which were identified as T. spiralis or T. britovi. In 2014, Trichinella pseudospiralis larvae were isolated from a wild boar hunted in the Gerona province, Cataluña region, North-East of Spain, near the border to France. This is the first report of T. pseudospiralis in the Iberian peninsula, which suggests a broad distribution area of this zoonotic nematode in Europe. Since larvae of this Trichinella species do not encapsulate in the host muscles, they can be detected only by artificial digestion of muscle samples. T. pseudospiralis is the only Trichinella species infecting both mammals and birds. Birds can spread this pathogen over great distances including islands triggering new foci of infections in areas previously considered at low risk for this pathogen.

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.

Efficacy of albendazole:β-cyclodextrin citrate in the parenteral stage of Trichinella spiralis infection

Albendazole-β-cyclodextrin citrate (ABZ:C-β-CD) inclusion complex in vivo antiparasitic activity was evaluated in the parenteral phase of Trichinella spiralis infection in mice. An equimolar complex of ABZ:C-β-CD was prepared by spray-drying and tested in CBi-IGE male mice orally infected with L1 infective larvae. Infected animals were treated with 50 or 30mg/kg albendazole, (ABZ) equivalent amounts of the ABZ:C-β-CD complex and non treated (controls). Mice received a daily dose on days 28, 29 and 30 post-infection. A week later, larval burden and percentage of encysted dead larvae were assessed in the host by counting viable and non-viable larvae in the tongue. Complexation of ABZ with C-β-CD increased the drug dissolution efficiency nearly eightfold. At 37 days p-i, the reduction percentage in muscle larval load was 35% in mice treated with 50mg/kg/day ABZ and 68% in those given the complex. Treatment with the lower dose showed a similar decrease in parasite burden. Treated animals showed a high percentage of nonviable larvae, the proportion being significantly higher in mice receiving the complex than in control animals (72-88% vs. 11%, P=0.0032). These data indicate that ABZ:C-β-CD increases bioavailability and effectiveness of ABZ against encapsulated Trichinella larvae, thus allowing the use of small doses.

Induction of protection in murine experimental models againstTrichinella spiralis: an up-to-date review

The parasitic nematodeTrichinella spiralis, an aetiological agent of the disease known as trichinellosis, infects wild and domestic animals through contaminated pig meat, which is the major source forTrichinellatransmission. Prevention of this disease by interrupting parasite transmission includes vaccine development for livestock; however, major challenges to this strategy are the complexity of theT. spiralislife cycle, diversity of stage-specific antigens, immune-evasion strategies and the modulatory effect of host responses. Different approaches have been taken to induce protective immune responses byT. spiralisimmunogens. These include the use of whole extracts or excretory–secretory antigens, as well as recombinant proteins or synthesized epitopes, using murine experimental models for trichinellosis. Here these schemes are reviewed and discussed, and new proposals envisioned to block the zoonotic transmission of this parasite.

Cultural drivers and health-seeking behaviours that impact on the transmission of pig-associated zoonoses in Lao People's Democratic Republic

Pig rearing is an important income source in the Lao People's Democratic Republic (PDR), with many smallholder farmers using traditional free-range pig production systems. Despite the potentially significant health risks posed by pig production regarding pig-associated zoonoses, information on the sociocultural drivers of these zoonoses is significantly lacking. This review summarises the existing sociocultural knowledge on eight pig-associated zoonoses suspected to be endemic in Southeast Asia: brucellosis, Q fever (Coxiella burnetii), trichinellosis, hepatitis E virus, leptospirosis, Japanese encephalitis, Streptococcus suis and Taenia solium taeniasis-cysticercosis. It summarises current knowledge on these diseases grouped according to their clinical manifestations in humans to highlight the propensity for underreporting. A literature search was conducted across multiple databases for publications from 1990 to the present day related to the eight pig-associated zoonoses and the risk and impact connected with them, with Lao PDR as a case study. Many of these pig-associated zoonoses have similar presentations and are often diagnosed as clinical syndromes. Misdiagnosis and underreporting are, therefore, substantial and emphasise the need for more robust diagnostics and appropriate surveillance systems. While some reports exist in other countries in the region, information is significantly lacking in Lao PDR with existing information coming mainly from the capital, Vientiane. The disease burden imposed by these zoonoses is not only characterised by morbidity and mortality, but directly impacts on livelihoods through income reduction and production losses, and indirectly through treatment costs and lost work opportunities. Other factors crucial to understanding and controlling these diseases are the influence of ethnicity and culture on food-consumption practices, pig rearing and slaughter practices, hygiene and sanitation, health-seeking behaviours and, therefore, risk factors for disease transmission. Published information on the knowledge, attitudes and beliefs of people regarding pig zoonoses and their risk factors is also extremely limited in Lao PDR and the broader Southeast Asian region. The need for more transdisciplinary research, using a One Health approach, in order to understand the underlining social determinants of health and their impacts on health-seeking behaviours, disease transmission and, ultimately, disease reporting, cannot be more emphasized.

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.

Immunoproteomic profile of Trichinella spiralis adult worm proteins recognized by early infection sera

Background

Trichinellosis, a widespread zoonosis, is regarded as an emerging or reemerging disease. Effective treatment and prognosis of trichinellosis depends on early diagnosis of the infection. The objective of this study was to identify sensitive and specific antigens for early diagnosis or effective vaccine antigens for preventing infection.

Methods

The somatic proteins of T. spiralis adult worms were separated by two-dimensional gel electrophoresis (2-DE). The separated proteins were probed with early infection sera from swine or mice infected with T. spiralis for 7 days. The primary immunoreactive spots were characterized by MALDI-TOF/TOF-MS analysis in combination with bioinformatics. The identified proteins were annotated using WEGO based on their functions. The immunodominant protein was chosen for expression as recombinant protein in E. coli and the purified recombinant protein was used to confirm its antigenicity by Western blot with the same infection sera.

Results

Approximately 300 spots were separated by 2-DE, with molecular weights ranging from 10 to 130 kDa, and pI values ranging from pH 4 to 10. The sera from swine and mice infected with T. spiralis for 7 days recognized 64 proteins. MALDI-TOF/TOF-MS analysis identified 55 proteins, some with different isoforms. Finally, 40 individual immunoreactive proteins were obtained with a wide range of biological functions. Several proteins, such as heat shock protein 70, 14-3-3 protein, and cysteine protease could be used as immunodiagnostic or vaccine antigens. Among these identified proteins, the highly immunodominant Ts14-3-3 was chosen for expression in E. coli and purified recombinant Ts14-3-3 was able to be strongly recognized by the same T. spiralis infected sera used for identifying these antigens, therefore the most promising antigen for early immunodiagnosis of Trichinella infection.

Conclusions

A total of 64 proteins from the adult worm were recognized by early infection sera from swine and mice infected with T. spiralis for 7 days. Several proteins, are of particular interest as immunodiagnostic or vaccine antigens, especially with Ts14-3-3 as most promising due to its highly immunogenicity during early infection, expressed protein can be recognized by Trichinella early infection sera and the native Ts14-3-3 expression in both adult and larval stages.

Molecular identification of Trichinella spiralis nudix hydrolase and its induced protective immunity against trichinellosis in BALB/c mice

BACKGROUND

Nudix hydrolases (Nd) is a widespread superfamily, which is found in all classes of organism, hydrolyse a wide range of organic pyrophosphates and has a 'housecleaning' function. The previous study showed that Trichinella spiralis Nd (TsNd) bound to intestinal epithelial cells (IECs), and the vaccination of mice with T7 phage-displayed TsNd polypeptides produced protective immunity. The aim of this study was to clone, express and identify the full-length TsNd and to investigate its immune protection against T. spiralis infection.

METHODS

The full-length cDNA sequence of TsNd gene encoding a 46 kDa protein from T. spiralis intestinal infective larvae (IIL) was cloned and identified. The antigenicity of rTsNd was analyzed by Western blot. Transcription and expression of TsNd at T. spiralis different stages were observed by RT-PCR and IFT. The levels of the specific total IgG, IgG1 and IgG2a antibodies to rTsNd were determined by ELISA. The immune protection of rTsNd against T. spiralis infection was investigated.

RESULTS

Sequence and phylogenetic analysis revealed that TsNd had a nudix motif located at 226-244aa, which had high homology and the closest evolutionary status with T. pseudospiralis. The rTsNd was obtained after expression and purification. Western blot analysis showed that anti-rTsNd serum recognized the native TsNd protein in crude antigens of muscle larvae (ML), IIL, adult worms (AW) and newborn larvae (NBL), and ES antigens of ML. Transcription and expression of TsNd gene was observed in all developmental stages of T. spiralis (ML, IIL, AW and NBL), with high level expression in IIL. An immunolocalization analysis identified TsNd in the cuticle, stichocytes and reproductive organs of the parasite. Following immunization, anti-rTsNd IgG levels were increased, and the levels of IgG1 were more significantly higher than that of IgG2a. After a challenge infection with T. spiralis, mice immunized with the rTsNd displayed a 57.7% reduction in adult worms and a 56.9% reduction in muscle larval burden.

CONCLUSIONS

TsNd induced a partial protective immunity in mice and could be considered as a novel candidate vaccine antigen against trichinellosis.

First report of a mixed infection of Trichinella nelsoni and Trichinella T8 in a leopard (Panthera pardus) from the Greater Kruger National Park, South Africa

At least three Trichinella species, namely Trichinella nelsoni, Trichinella britovi and Trichinella zimbabwensis, and one genotype (Trichinella T8), have been isolated from sylvatic carnivores on the African continent. With the exception of T. britovi, the other species are known to circulate in wildlife of the Kruger National Park (KNP), South Africa, and KNP neighbouring game reserves (collectively known as the greater KNP area). Lions (Panthera leo) and spotted hyenas (Crocuta crocuta) appear to be the most important reservoirs of T. nelsoni and Trichinella T8 in the KNP and surrounding areas. Interspecies predation between lions and hyenas has been implicated as a primary mode of maintaining the life cycles of these two Trichinella species. This is the first report of a mixed natural infection of T. nelsoni and Trichinella T8 in a leopard (Panthera pardus) from South Africa. Trichinella muscle larvae were identified to species level by multiplex polymerase chain reaction (PCR). Probable sources of infection, based on the known dietary preference and prey species' range of leopards, are also discussed. The described occurrence of Trichinella species in a leopard from the greater KNP area raises the question of possible sources of infection for this predator species.

Anti-Trichinella IgG in ethnic minorities living in Trichinella-endemic areas in northwest Vietnam: study of the predictive value of selected clinical signs and symptoms for the diagnosis of trichinellosis

The objective of this study was to assess the presence of anti-Trichinella IgG in the serum of persons from ethnic minorities from northwest Vietnam with clinical signs and symptoms that are compatible with trichinellosis. A total of 645 persons were enrolled, of which 200 people lived in two villages where outbreaks of human trichinellosis had been documented in 2004 and 2008, and 445 people who were hospitalized in the Dien Bien and Son La provincial hospitals without a definitive diagnosis. Presence of anti-Trichinella IgG was demonstrated in serum samples by a standardized Enzyme-linked Immunosorbant Assay (ELISA); positive serum samples were subjected to Western blot (WB) for confirmation. Seven (3.5%; 95% CI: 1.4-7.1) persons from the villages and seven (1.6%; 95% CI: 0.6-3.2) hospitalized patients, tested positive by both ELISA and WB. Fever (N=13), eosinophilia (N=12), myalgia (N=9), facial edema (N=9) and leukocytosis (N=8) were the most common clinical signs and symptoms in the serologically positive persons. The concomitant occurrence of facial edema and myalgia among the enrolled persons from the villages, accounted for 75% of the positive predictive value (PPV) and 99.5% of the negative predictive value (NPV), suggesting that they could be used for suspecting trichinellosis when serology is not available. The high prevalence (1.6-3.5%) of anti-Trichinella IgG in persons from Vietnamese provinces where Trichinella spiralis is circulating in pigs strongly supports the need to develop control programs to eliminate the infection from pigs and for consumers' education and protection.

Protective immunity against enteral stages of Trichinella spiralis elicited in mice by live attenuated Salmonella vaccine that secretes a 30-mer parasite epitope fused to the molecular adjuvant C3d-P28

The development of a veterinary vaccine against T. spiralis infection is an alternative strategy to control trichinellosis. In an effort to develop an efficient vaccine, BALB/c mice were immunized with attenuated Salmonella enterica serovar Typhimurium SL3261 that expresses a 30-mer peptide (Ag30) derived from the gp43 of T. spiralis muscle larvae fused to three copies of the molecular adjuvant P28 (Ag30-P283) and it was either displayed on the surface or secreted by recombinant Salmonella strains. Salmonella strain secreting Ag30-P283, reduced the adult worm burden 92.8% following challenge with T. spiralis muscle larvae compared to 42% achieved by recombinant Salmonella displaying Ag30-P283 on the surface. The protection induced by secreted Ag30-P283 was associated with a mixed Th1/Th2 with predominance of Th2 phenotype, which was characterized by the production of IgG1, intestinal IgA antibodies and IL-5 secretion. This finding could provide an efficient platform technology for the design of novel vaccination strategies.

Protective effect of a prime-boost strategy with the Ts87 vaccine against Trichinella spiralis infection in mice

Trichinellosis is a widespread zoonosis primarily caused by Trichinella spiralis. Mucosal immunity is crucial for preventing Trichinella spiralis infection. In our previous study, a DNA vaccine with the Trichinella antigen Ts87 delivered by an attenuated Salmonella typhimurium elicited partial protection against Trichinella spiralis infection in mice. In the current study, to elicit a more robust immune response and develop a potent vaccination strategy against trichinellosis, a heterologous prime-boost vaccination regimen for Ts87 was used in mice and the protective efficacy was evaluated compared to the homologous DNA prime-boost or protein prime-boost immunization alone. The results revealed that the DNA-prime/protein-boost vaccination with Ts87 induced higher levels of both humoral and cellular immune responses. The challenge results showed that mice with the DNA-prime/protein-boost vaccination displayed higher muscle larval reduction than those immunized with DNA prime-boost or protein prime-boost. The results demonstrated that mice vaccinated with Ts87 in a DNA-prime/protein-boost strategy effectively elicited a local IgA response and mixed Th1/Th2 immune response that might be responsible for improved protection against Trichinella spiralis infection.

The wolf (Canis lupus) as an indicator species for the sylvatic Trichinella cycle in the Central Balkans

Wildlife is the most important reservoir of Trichinella spp. worldwide. Although the Balkans are a recognized European endemic region for Trichinella infections, data on wildlife are scarce. To monitor the circulation of these zoonotic parasites in the Central Balkan region, the wolf (Canis lupus) was selected because of its abundance (>2,000 individuals) and because it is at the top of the food chain. A total of 116 carcasses of wolves were collected in Serbia and in the neighboring areas of Macedonia and Bosnia and Herzegovina (B&H) between 2006 and 2013. Trichinella spp. larvae were found in 54 (46.5%) wolves. The great majority (90.5%) originated from Serbia, where 52 of the 105 examined animals were Trichinella positive (49.5%; 95% confidence interval  =39.9-59.1). One positive animal each was found in B&H and Macedonia. All larvae were identified as Trichinella britovi. The high prevalence of Trichinella infection in wolves suggests that this carnivore can be a good indicator species for the risk assessment of the sylvatic Trichinella cycle in the Central Balkans.

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

The wild boar is an important source of trichinellosis for people in European countries as a large number of hunted animals escape veterinary control. In November 2012, uncooked sausages made with meat from wild boar were consumed by 38 persons in a village of the Lucca province (Tuscany region, Italy). Of them, 34 were serologically positive, 32 developed clinical signs and symptoms of trichinellosis, and two were asymptomatic. Trichinella britovi larvae were detected in vacuum-packed sausages made with the same batch of sausages consumed raw which had been prepared with meat from wild boar hunted in the Lucca province. As no case of trichinellosis had been reported in this region during the last 20 years, the regional public health authority considered the risk for this zoonosis to be negligible and put in place a surveillance programme on Trichinella spp. in indicator animals (mainly foxes and including wild boar for private consumption), by testing only a percentage of heads. The experience from this outbreak shows that the definition of a region with a negligible risk for Trichinella infection is not applicable to wild boar and stresses the need to test all Trichinella-susceptible wild animals intended for human consumption and to implement risk communication to consumers and hunters.

Patterns and risks of trichinella infection in humans and pigs in northern Laos

Several outbreaks of trichinellosis associated with the consumption of raw pork have occurred in Laos since 2004. This cross-sectional study was conducted in four provinces of northern Laos to investigate the seroepidemiology of trichinellosis in the human population and determine the prevalence and species of Trichinella infection in the domestic pig population. Serum samples and questionnaire data were obtained from 1419 individuals. Serum samples were tested for Trichinella antibodies by ELISA using larval excretory–secretory (ES) antigens and a subset of 68 positive samples were tested by western blot. The seroprevalence of Trichinella antibodies was 19.1% (95% confidence interval (CI) = 17.1–21.1%). The risk of having antibodies detected by ELISA using ES antigens increased with age, being of Lao-Tai ethnicity, living in Oudomxay province and being male. Tongue and diaphragm muscle samples were collected from 728 pigs and tested for Trichinella larvae by the artificial digestion method. Trichinella larvae were isolated from 15 pigs (2.1%) of which 13 were identified as T. spiralis by molecular typing; the species of the two remaining isolates could not be determined due to DNA degradation. Trichinella spp. are endemic in the domestic environment of northern Laos and targeted preventative health measures should be initiated to reduce the risk of further outbreaks occurring.

Trichinellosis is one of the most widely distributed parasitic zoonoses worldwide and is caused by infection with nematodes of the genus Trichinella. Infection occurs after consuming larvae in the muscle of infected animals. Several outbreaks of trichinellosis have occurred in Laos since 2004, resulting in a substantial public health problem. The principal risk factor for trichinellosis is consumption of uncooked or partially cooked meat from domestic pigs and game. We visited communities in four ethnically diverse provinces of northern Laos to determine the seroprevalence of trichinellosis in the human population and explore the population and individual level risk factors of exposure. In addition, we also examined muscle samples collected from pigs post-slaughter to determine the prevalence of Trichinella infection and identify the species of Trichinella circulating in the domestic pig population. Our findings indicate that Trichinella spp. are endemic in the domestic environment of northern Laos and consumption of uncooked pork is common for all ethnic groups. Targeted preventative health measures, taking a one health approach by bringing together medical, veterinary and health sociology professionals, should be initiated to prevent the transmission of Trichinella and other foodborne pathogens in Laos.

Heat shock protein 70 from Trichinella spiralis induces protective immunity in BALB/c mice by activating dendritic cells

Trichinella spiralis heat shock protein 70 (Ts-Hsp70) is a protective antigen that induces partial protective immunity against T. spiralis infection in mice. To determine whether dendritic cells are involved in the mechanism responsible for the protection induced by Ts-Hsp70, mouse bone marrow-derived dendritic cells (DCs) were incubated with recombinant Ts-Hsp70 (rTs-Hsp70), and the DC-secreted cytokines and expressed surface markers were measured. The results demonstrated that rTs-Hsp70 activated DC maturation that was characterized by the secretion of IL-1β, IL-12p70, TNF-α, and IL-6 and the increased surface expression of CD11c, MHC II, CD40, CD80, and CD86. The rTs-Hsp70-activated DCs enabled the stimulation, proliferation and secretion of Th1/2 cytokines (i.e., INF-γ, IL-2, IL-4 and IL-6) in CD4(+) T cells from T. spiralis-infected mice. The mice that received rTs-Hsp70-activated DCs exhibited a 38.4% reduction in muscle larvae upon larval challenge with T. spiralis compared to the group that received PBS-incubated DCs. This partial protection was correlated with Th1 and Th2 mixed anti-Ts-Hsp70-specific immune responses that included high titers of total IgG, IgG1 and IgG2a and increased levels of Th1/2 cytokines (i.e., IFN-γ, IL-2, IL-4, IL-6). These results indicate that the rTs-Hsp70-induced protective immunity was mediated by the activation of the DCs and that rTs-Hsp70-loaded DCs could be an alternative vaccine approach against trichinellosis.

Extraintestinal nematodes of the red foxVulpes vulpesin north-west Italy

Extraintestinal nematodes of the red fox (Vulpes vulpes) are a wide group of parasites that infect wild and domestic carnivores and occasionally humans. Nematodes in the cardiopulmonary system, stomach, urinary apparatus and muscle tissue of 165 red foxes (Vulpes vulpes) from north-west Italy (Liguria and Piedmont) were investigated between 2009 and 2012. Of the cardiopulmonary nematodes, a high prevalence ofAngiostrongylus vasorumandEucoleus aerophilus(syn.Capillaria aerophila) was found, 78.2% and 41.8% respectively;Crenosoma vulpis(15.8%) andFilaroidesspp. (4.8%) were also found.Spirocerca lupi(23.5%),Aonchotheca putorii(syn.Capillaria putorii) (8.6%) andPhysalopteraspp. (2.5%) were detected in the stomach andPearsonema plica(syn.Capillaria plica) (56.8%) in the bladder.Eucoleus boehmi(syn.Capillaria boehmi)was also detected in the nasal cavities of one of the two foxes examined. A coprological examination revealed eggs ofE. aerophilus,A. putorii,S. lupi,Physalopteraspp. and eggs of intestinal parasites. Filarial worms were absent in all the 165 animals examined, nor was there evidence ofTrichinellaspp. in any of the foxes. The foxes were found to host a high prevalence of many species of extraintestinal nematodes. The prevalence ofA. vasorumin foxes found in the present study is among the highest in Europe. In addition, to the best of our knowledge,E. boehmiandFilaroidesspp. have never been reported before in this host in Italy.

Mapping of the complement C9 binding domain on Trichinella spiralis paramyosin

Background

Trichinellosis is an important foodborne zoonosis that is distributed worldwide. Trichinella spiralis may evade host complement-mediated attack by expressing complement inhibitory proteins, such as paramyosin (Pmy). Previous studies have shown that Trichinella spiralis paramyosin (Ts-Pmy) is able to bind to the human complement component C9 to inhibit the complement activation and protect the parasite from complement-mediated attack. Further determination of the complement-binding domain on Ts-pmy will enable us to better understand the Ts-Pmy’s biofunction in the immune evasion and provide feasible approach to develop epitope-based subunit vaccine against trichinellosis.

Methods

The complement C9 binding region on Ts-Pmy was determined by expression of overlapped fragments of Ts-Pmy and their binding activities to C9. The exact binding site was further narrowed-down to a 14-amino acid peptide at C-terminus using synthesized peptides with different size of amino acid sequence. The C9 complement-binding of the 14-amino acid peptide and its interference in the C9 polymerization and the complement-mediated lysis of rabbit erythrocytes was investigated.

Results

The protein interaction between human C9 and native Ts-Pmy was further confirmed by immunoprecipitation with T. spiralis lysates. The fragmental expression and C9 binding assays identified that the binding region of Ts-Pmy to C9 is located within 831–885 of Ts-Pmy C-terminus. The exact binding site on Ts-Pmy to C9 was narrowed down to 14 amino acid residues (⁸⁶⁶Val-⁸⁷⁹Met) by using different sizes of synthesized peptides. In the presence of the synthesized 14-amino acid peptide, human C9 polymerization and the hemolytic activity of the human complement was inhibited.

Conclusions

Our results revealed the precise molecular basis for T. spiralis to produce Ts-Pmy as an immunomodulator to evade the attack of the host complement system as a survival mechanism.

Identification of early diagnostic antigens from major excretory-secretory proteins of Trichinella spiralis muscle larvae using immunoproteomics

Background

The excretory-secretory (ES) proteins of Trichinella spiralis muscle larvae (ML) come mainly from the excretory granules of the stichosome and the cuticles (membrane proteins), are directly exposed to the host’s immune system, and are the main target antigens, which induce the immune responses. Although the ES proteins are the most commonly used diagnostic antigens for trichinellosis, their main disadvantage are the false negative results during the early stage of infection. The aim of this study was to identify early specific diagnostic antigens from the main components of T. spiralis muscle larval ES proteins.

Methods

Two-dimensional electrophoresis (2-DE) combined with Western blot were used to screen the early diagnostic antigens from the main components of T. spiralis muscle larval ES proteins. The protein spots recognized by the sera from BALB/c mice infected with T. spiralis at 18 days post-infection (dpi) were identified by MALDI-TOF/TOF-MS and putatively annotated using GO terms obtained from the InterPro databases.

Results

The ES proteins were analyzed by 2-DE, and more than 33 protein spots were detected with molecular weight varying from 40 to 60 kDa and isoelectric point (pI) from 4 to 7. When probed with the sera from infected mice at 18 dpi, 21 protein spots were recognized and then identified, and they were characterized to correlate with five different proteins of T. spiralis, including two serine proteases, one deoxyribonuclease (DNase) II, and two kinds of trypsin. The five proteins were functionally categorized into molecular function and biological process according to GO hierarchy.

Conclusions

2-DE and Western blot combined with MALDI-TOF/TOF-MS were used to screen the diagnostic antigens from the main components of T. spiralis muscle larval ES proteins. The five proteins of T. spiralis identified (two serine proteases, DNase II and two kinds of trypsin) might be the early specific diagnostic antigens of trichinellosis.

Searching for Trichinella: not all pigs are created equal

Each year, millions of pigs worldwide are tested for Trichinella spp. at slaughterhouses with negative results. Yet, thousands of people acquire trichinellosis by consuming pork. So, where is the problem? Testing for Trichinella spp. is often performed on the 'wrong' animals; while the parasites are mainly circulating in backyard and free-ranging pigs, herds kept under controlled management conditions are the ones tested. Veterinary services should: (i) introduce a risk-based surveillance system for Trichinella by documenting the control of housing conditions and feedstuff sources, and (ii) introduce a capillary network of field laboratories for monitoring the parasites in free-ranging and backyard pigs. Investment of funds into the education of farmers, hunters, and consumers should be a priority for public health services.

The hidden burden of trichinellosis in Vietnam: a postoutbreak epidemiological study

A cross-sectional study was conducted in Muong Lat town (Thanh Hoa province, North Vietnam), following the confirmed diagnosis of trichinellosis in six patients from that town who had eaten hunted wild boar meat during the Vietnamese lunar year celebration. All inhabitants who declared to have eaten undercooked or raw wild boar meat at the celebration and showed at least one clinical symptom compatible with trichinellosis were included in the study and blood sampled. Anti-Trichinella IgG were determined by ELISA and Western Blot. Seropositive persons were given appropriate albendazole treatment and were followed up. A total of 100 inhabitants met the inclusion criteria. Among these, 30 (30%) had antibodies to Trichinella. Serologically confirmed cases had fever (90.0%), myalgia (86.7%), facial oedema (63.3%), diarrhoea (53.3%), and pain of the masseter muscles (43.3%). Eosinophilia was detected in 83.3% of these individuals. Clinical symptoms resolved in all patients during albendazole treatment. The results suggest that only a proportion of the trichinellosis cases had sought health care during the outbreak. There is a need to implement surveillance and better diagnosis for trichinellosis and to set up educational programs to prevent infection in North Vietnam.

Parasite zoonoses and wildlife: One Health, spillover and human activity

This review examines parasite zoonoses and wildlife in the context of the One Health triad that encompasses humans, domestic animals, wildlife and the changing ecosystems in which they live. Human (anthropogenic) activities influence the flow of all parasite infections within the One Health triad and the nature and impact of resulting spillover events are examined. Examples of spillover from wildlife to humans and/or domestic animals, and vice versa, are discussed, as well as emerging issues, particularly the need for parasite surveillance of wildlife populations. Emphasis is given to Trypanosoma cruzi and related species in Australian wildlife, Trichinella, Echinococcus, Giardia, Baylisascaris, Toxoplasma and Leishmania.

Protective immunity against Trichinella spiralis infection induced by a multi-epitope vaccine in a murine model

Trichinellosis is one of the most important food-borne parasitic zoonoses throughout the world. Because infected pigs are the major source of human infections, and China is becoming the largest international producer of pork, the development of a transmission-blocking vaccine to prevent swine from being infected is urgently needed for trichinellosis control in China. Our previous studies have demonstrated that specific Trichinella spiralis paramyosin (Ts-Pmy) and Ts-87 antigen could provide protective immunity against T. spiralis infection in immunized mice. Certain protective epitopes of Ts-Pmy and Ts-87 antigen have been identified. To identify more Ts-Pmy protective epitopes, a new monoclonal antibody, termed 8F12, was produced against the N-terminus of Ts-Pmy. This antibody elicited significant protective immunity in mice against T. spiralis infection by passive transfer and was subsequently used to screen a random phage display peptide library to identify recognized epitopes. Seven distinct positive phage clones were identified and their displayed peptides were sequenced. Synthesized epitope peptides conjugated to keyhole limpet hemocyanin were used to immunize mice, four of which exhibited larval reduction (from 18.7% to 26.3%, respectively) in vaccinated mice in comparison to the KLH control. To increase more effective protection, the epitope 8F7 that was found to induce the highest protection in this study was combined with two other previously identified epitopes (YX1 from Ts-Pmy and M7 from Ts-87) to formulate a multi-epitope vaccine. Mice immunized with this multi-epitope vaccine experienced a 35.0% reduction in muscle larvae burden after being challenged with T. spiralis larvae. This protection is significantly higher than that induced by individual-epitope peptides and is associated with high levels of subclasses IgG and IgG1. These results showed that a multi-epitope vaccine induced better protective immunity than an individual epitope and provided a feasible approach for developing a safer and more effective vaccine against trichinellosis.