Real-time PCR as a surveillance tool for the detection of Trichinella infection in muscle samples from wildlife

Diversity of Trichinella species in carnivores from Bosnia and Herzegovina

BACKGROUND

In Bosnia and Herzegovina, domestic and wild carnivores represent a significant driver for the transmission and ecology of zoonotic pathogens, especially those of parasitic aetiology. Nevertheless, there is no systematic research of Trichinella species in animals that have been conducted in Bosnia and Herzegovina, even though trichinellosis is considered the most important parasitic zoonosis. The available results of the few studies carried out in Bosnia and Herzegovina are mainly related to the confirmation of parasitic larvae in the musculature of domestic pigs and wild boars or data related to trichinellosis in humans. The objective of our study was to present the findings of a comprehensive investigation into the species composition of Trichinella among 11 carnivorous species within the territory of Bosnia and Herzegovina, as follows: red fox (Vulpes vulpes), grey wolf (Canis lupus), brown bear (Ursus arctos), wildcat (Felis silvestris), pine marten (Martes martes), European badger (Meles meles), weasel (Mustela nivalis), European polecat (Mustela putorius), Eurasian lynx (Lynx lynx), but also dog (Canis lupus familiaris) and cat (Felis catus).

RESULTS

In the period 2013-2023, carnivore musculature samples (n = 629), each consisting of 10 g of muscle tissue, were taken post-mortem and individually examined using the artificial digestion method. In the positive samples (n = 128), molecular genotyping and identification of parasitic larvae of Trichinella spp. were performed using a PCR-based technique up to the species/genotype level. Positive samples were used for basic PCR detection of the genus Trichinella (rrnS rt-PCR technique) and genotyping (rrnl-EVS rt-PCR technique). The Trichinella infection was documented for the first time in Bosnia and Herzegovina among red foxes, grey wolves, brown bears, dogs, badgers and Eurasian lynx, with a frequency rate of 20.3%. Additionally, the presence of T. britovi infection was newly confirmed in Bosnia and Herzegovina, marking the initial documented cases. Furthermore, both T. britovi and T. pseudospiralis infections were observed in the wildcat population, whereas T. britovi and T. spiralis infections were detected in pine martens. Consistent with previous research, our findings align particularly regarding carnivores, with data from other countries such as Germany, Finland, Romania, Poland and Spain, where T. britovi exhibits a wider distribution (62.5-100%) compared to T. spiralis (0.0-37.5%). T. britovi is more common among sylvatic carnivores (89.0%), while T. spiralis prevails in wild boars (62.0%), domestic swine (82.0%) and rodents (75.0%).

CONCLUSION

The results of our study represent the first molecular identification of species of the genus Trichinella in Bosnia and Herzegovina. Additionally, our findings underscore the necessity for targeted epidemiological studies to thoroughly assess trichinellosis prevalence across diverse animal populations. Considering the relatively high frequency of trichinellosis infection in investigated animal species and its public health implications, there is an evident need for establishing an effective trichinellosis surveillance system in Bosnia and Herzegovina.

Wildlife parasitology: sample collection and processing, diagnostic constraints, and methodological challenges in terrestrial carnivores

Wild terrestrial carnivores play a crucial role as reservoir, maintenance, and spillover hosts for a wide parasite variety. They may harbor, shed, and transmit zoonotic parasites and parasites of veterinary importance for domestic hosts. Although wild carnivores are globally distributed and comprise many different species, some living in close proximity to human settlements, only a few studies have investigated parasites of wild terrestrial carnivores using non-specific techniques. Access to samples of wild carnivores may be challenging as some species are protected, and others are secretive, possibly explaining the data paucity. Considering the importance of wild carnivores' health and ecological role, combined with the lack of specific diagnostic methodologies, this review aims to offer an overview of the diagnostic methods for parasite investigation in wild terrestrial carnivores, providing the precise techniques for collection and analysis of fecal, blood, and tissue samples, the environmental impact on said samples, and the limitations researchers currently face in analyzing samples of wild terrestrial carnivores. In addition, this paper offers some crucial information on how different environmental factors affect parasite detection postmortem and how insects can be used to estimate the time of death with a specific highlight on insect larvae. The paper contains a literature review of available procedures and emphasizes the need for diagnostic method standardization in wild terrestrial carnivores.

A new multiplexed magnetic capture-Droplet digital PCR tool for monitoring wildlife population health and pathogen surveillance

Anthropogenic stressors are exacerbating the emergence and spread of pathogens worldwide. In regions like the Arctic, where ecosystems are particularly susceptible, marked changes are predicted in regional diversity, intensity, and patterns of infectious diseases. To understand such rapidly changing host-pathogen dynamics and mitigate the impacts of novel pathogens, we need sensitive disease surveillance tools. We developed and validated a novel multiplexed, magnetic capture, and ddPCR tool for the surveillance of multiple pathogens in polar bears, a sentinel species that is considered susceptible to climate change and other stressors with a pan-Arctic distribution. Through sequence-specific magnetic capture, we concentrated five target template sequences from three zoonotic bacteria (Erysipelothrix rhusiopathiae, Francisella tularensis, and Mycobacterium tuberculosis complex) and two parasitic (Toxoplasma gondii and Trichinella spp.) pathogens from large quantities (<100 g) of host tissue. We then designed and validated two multiplexed probe-based ddPCR assays for the amplification and detection of the low-concentration target DNA. Validations used 48 polar bear tissues (muscle and liver). We detected 14, 1, 3, 4, and 22 tissue positives for E. rhusiopathiae, F. tularensis, M. tuberculosis complex, T. gondii, and Trichinella spp., respectively. These multiplexed assays offer a rapid, specific tool for quantifying and monitoring the changing geographical and host distributions of pathogens relevant to human and animal health.

Real-time PCR versus traditional and Nano-based ELISA in early detection of murine trichinellosis

Trichinellosis is a serious foodborne zoonosis. It poses a serious risk to public health worldwide. Early serological diagnosis of trichinellosis is influenced by an immunological 'silent' phase following infection. This highlights the necessity for developing sensitive diagnostic approaches to be employed when antibodies cannot be detected. In this work, the validity of traditional ELISA, Nano-ELISA and real time polymerase chain reaction (PCR) were evaluated in early diagnosis of Trichinella spiralis. Swiss albino mice were orally infected with 100 and 300 muscle larvae/mouse. Mice were sacrificed 4, 6, 8, 10, 15, and 28 days post-infection (dpi). Blood samples were tested for circulating antigen by traditional ELISA and Nano-ELISA using anti-rabbit polyclonal IgG conjugated with AgNPs and for Rep gene by SYBR green real-time PCR. Rep gene detection by SYBR green real-time PCR could detect T. spiralis with 100% sensitivity in the mild infection group at 8 dpi, while in the severe infection group it reached 100% sensitivity at 4 dpi. Nano-ELISA could detect T. spiralis circulating antigen from 4 dpi in both mild and severe infection and reached 100% sensitivity at 8 dpi and 6 dpi in mild and severe infection, respectively. However, traditional ELISA could detect T. spiralis circulating antigen from 6 dpi and reached maximum sensitivity at 15 dpi in the mild infection group, while in the severe infection group detection began at 4 dpi and reached 100% sensitivity at 8 dpi. Nano-ELISA and real time PCR, using Rep gene, are useful tools for the detection of early T. spiralis infection even in its mild infection state.

Establishment of a method for detecting Trichinella spiralis in ovine muscle tissues using real-time fluorescence quantitative PCR

Trichinellosis is caused by Trichinella spiralis, a meat-borne zoonotic disease transmitted to humans through the consumption of infected undercooked or raw meat. Surveillance using safe and precise diagnostic tools to diagnose T. spiralis in sheep is needed to assess the incidence and probability of transmission from sheep to humans. In this study, we developed a real-time PCR assay to detect T. spiralis DNA in ovine muscle samples that can be used as an alternative surveillance tool to ensure food safety using newly designed primers. The assay is specific for the Scfld4 gene of Trichinella (T1) and enables the detection of larvae in ovine muscle tissue samples with high sensitivity and specificity. Trichuris ovis, Oesophagostomum dentatum, Haemonchus contortus, and Bunostomum trigonocephalum showed no nonspecific amplification. The assay could detect Trichinella DNA concentrations as low as 0.0026 ng/μL, equivalent to 0.0064 larvae, indicating a high sensitivity for T. spiralis detection. We used this real-time PCR to detect 73 ovine muscle samples from an ovine abattoir, and five samples tested positive via real-time PCR but negative via microscopy. This assay may provide a more specific and sensitive method for rapidly detecting Trichinella larvae in ovine muscle tissues.

Zoonotic helminths - why the challenge remains

Helminth zoonoses remain a global problem to public health and the economy of many countries. Polymerase chain reaction-based techniques and sequencing have resolved many taxonomic issues and are now essential to understanding the epidemiology of helminth zoonotic infections and the ecology of the causative agents. This is clearly demonstrated from research on Echinococcus (echinococcosis) and Trichinella (trichinosis). Unfortunately, a variety of anthropogenic factors are worsening the problems caused by helminth zoonoses. These include cultural factors, urbanization and climate change. Wildlife plays an increasingly important role in the maintenance of many helminth zoonoses making surveillance and control increasingly difficult. The emergence or re-emergence of helminth zoonoses such as Ancylostoma ceylanicum, Toxocara, Dracunculus and Thelazia exacerbate an already discouraging scenario compounding the control of a group of long neglected diseases.

Investigation of the Food-Transmitted Parasites Trichinella spp. and Alaria spp. in Wild Boars in Greece by Classical and Molecular Methods and Development of a Novel Real-Time PCR for Alaria spp. Detection

Simple Summary

There are many parasites that may be transmitted to humans via food, and meat is a major source of such infections. Trichinella spp. is one of the most important meat-transmitted parasites, while Alaria spp. may be considered an emerging pathogen, albeit to date rarely reported in humans. Raw and undercooked wild boar meat has been proven as a major source of human infection by both parasites. In the present study, an investigation of the presence of these parasites in wild boar meat was conducted for the first time in Greece. Classical parasitological methods and molecular techniques were implemented for the examination of samples collected from 128 hunted wild boars, and none of them were found positive for Trichinella spp. or Alaria spp. For the detection of Alaria spp., a novel molecular method was developed, offering a powerful complementary diagnostic tool that may be useful for the epizootiological surveillance of the parasite. The epizootiology/epidemiology, clinical implications, and importance of monitoring of these parasitic infections are briefly discussed.

Abstract

Foodborne parasitic diseases represent a major threat to public health. Trichinellosis, caused by the nematode parasite Trichinella spp., is one of the most important foodborne diseases, while alariosis, caused by the trematode parasite Alaria spp., is less common in humans, and rare cases have been reported only in the USA and Canada. Both parasites can infect humans via the consumption of raw or undercooked wild boar meat. In order to investigate the prevalence of these parasites in wild boar meat in Greece, samples from the diaphragm pillars and the region of the mandibular angle from 128 wild boars, hunted in Greece, were collected. The samples were examined by classical parasitological (compression, artificial digestion, and Alaria spp. migration) and by molecular (real-time PCR) methods. For Trichinella spp. an existent real-time PCR detecting all species likely to be present in Greece was applied, while for Alaria spp. a real-time PCR was developed, employing an LNA TaqMan probe targeting the large subunit ribosomal RNA gene. All examined wild boar samples from Greece resulted negative for Trichinella and Alaria species, indicating a low prevalence of infection in the examined population. The novel real-time PCR for Alaria spp. has 81.5% amplification efficiency and is able to detect 0.12 larvae per 50 g of tissue and could be utilized as a complementary to AMT diagnostic tool in surveillance.

A review of testing and assurance methods for Trichinella surveillance programs

While global cases of trichinellosis have fallen since pork regulation began, the disease remains a danger to pork and animal game consumers as well as a liability to producers. Managing food safety risk and supporting agricultural trade requires cost-effective and sensitive diagnostic methods. Several means exist to inspect pork for parasitic infections. Here, we review literature concerning the sensitivity, specificity, and cost of these methods. We found that artificial digestion coupled with optical microscopy to be the best method for verification of Trichinella larva free pork due to its cost efficiency, high specificity, and reliability. Serological techniques such as ELISA are useful for epidemiological surveillance of swine. While current PCR techniques are quick and useful for diagnosing species-specific infections, they are not cost efficient for large-scale testing. However, as PCR techniques, including Lateral Flow- Recombinase Polymerase Amplification (LF-RPA), improve and continue to reduce cost, such methods may ultimately succeed artificial digestion.

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We compared cost, sensitivity, and specificity of available and foreseeable tools.

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The magnetic stir bar method remains the gold standard for Trichinella surveillance.

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Serological methods miss early infections but offer promise for use in surveillance.

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Isothermal methods offer future promise given their speed, accuracy, and ease of use.

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Genetic methods are uneconomical but advances have promise to reduce cost.

Early Detection of Trichinella spiralis DNA in Rat Feces Based on Tracing Phosphate Ions Generated During Loop-Mediated Isothermal Amplification

Early diagnosis of trichinellosis is still difficult because of the lack of specific symptoms and limited window for serological detection. Here we established an assay based on tracing phosphate ions generated during loop-mediated isothermal amplification (LAMP) to detect Trichinella spiralis DNA in rat feces during its early stage of infection. By targeting a 1.6-kb repetitive element of Tri. spiralis, the assay was able to detect Tri. spiralis DNA in the feces of all infected rats as early as 1 day postinfection (dpi). The positive detection lasted to 7 dpi in the rats infected with 250 muscle larvae, and 21 dpi in the rats infected with 5,000 larvae. The assay was highly sensitive, and could detect 1.7 femtograms (fg) of Tri. spiralis DNA with high specificity, and with no cross reactivity with the DNA from Anisakis pegreffii, Gnathostoma spinigerum, Angiostrongylus cantonensis, Enterobius vermicularis, Schistosoma japonicum, and Trypanosoma evansi. Our present study provided a reliable technique for the early diagnosis of trichinellosis with the advantages of simplicity and speed, as well as high sensitivity and specificity.

Comparison of the modified agglutination test and real-time PCR for detection of Toxoplasma gondii exposure in feral cats from Phillip Island, Australia, and risk factors associated with infection

Toxoplasma gondii is considered a disease risk for many native Australian species. Feral cats are the key definitive host of T. gondii in Australia and therefore, investigating the epidemiology of T. gondii in cat populations is essential to understanding the risk posed to wildlife. Test sensitivity and specificity are poorly defined for diagnostic tests targeting T. gondii in cats and there is a need for validated techniques. This study focused on the feral cat population on Phillip Island, Victoria, Australia. We compared a novel real-time PCR (qPCR) protocol to the modified agglutination test (MAT) and used a Bayesian latent class modelling approach to assess the diagnostic parameters of each assay and estimate the true prevalence of T. gondii in feral cats. In addition, we performed multivariable logistic regression to determine risk factors associated with T. gondii infection in cats. Overall T. gondii prevalence by qPCR and MAT was 79.5% (95% confidence interval 72.6-85.0) and 91.8% (84.6-95.8), respectively. Bayesian modelling estimated the sensitivity and specificity of the MAT as 96.2% (95% credible interval 91.8-98.8) and 82.1% (64.9-93.6), and qPCR as 90.1% (83.6-95.5) and 96.0% (82.1-99.8), respectively. True prevalence of T. gondii infection in feral cats on Phillip Island was estimated as 90.3% (83.2-95.1). Multivariable logistic regression analysis indicated that T. gondii infection was positively associated with weight and this effect was modified by season. Cats trapped in winter had a high probability of infection, regardless of weight. The present study suggests qPCR applied to tissue is a highly sensitive, specific and logistically feasible tool for T. gondii testing in feral cat populations. Additionally, T. gondii infection is highly prevalent in feral cats on Phillip Island, which may have significant impacts on endemic and introduced marsupial populations.

Sensitive and rapid detection of Ortleppascaris sinensis (Nematoda: Ascaridoidea) by loop-mediated isothermal amplification

Ortleppascaris sinensis is the dominant nematode species infecting the gastrointestinal tract of the captive Chinese alligator, a critically endangered species. Gastrointestinal nematode infection may cause a loss of appetite, growth, a development disorder, and even mortality in alligators, especially young ones. This research first establishment a loop-mediated isothermal amplification (LAMP) assay in rapidly identifying O. sinensis, upon the basis of the complete internal transcribed spacers (ITS) gene. Eight sets of primers were designed for recognition of the unique conserved ITS gene sequences, and one set was selected to be the most suitable primer for rapid detection. The specific as well as the sensitive features of the most appropriate primer in LAMP reactions for O. sinensis, and feces specimens of Chinese alligators suffering from O. sinensis were determined. Turbidity monitoring and Te Visual Reagent methods were used for determining negative and positive consequences. According to this study, amplification and visualization of the target DNA could be realized through two detection approaches during 50 min at 65 °C isothermal temperature. The sensitivity of LAMP was a detecting limitation of 3.46 pg/µl DNA. No cross-reactions were found between O. sinensis and any other of the nine heterologous nematode parasites, which shows the outstanding specific features of the primers. The LAMP assay could also perform a detection of target DNA of O. sinensis in the feces samples of Chinese alligators. This LAMP assay is useful for directly detecting O. sinensis in the Chinese alligator breeding centers, particularly due to its rapidity, simplicity and low cost.

Synthetic gene as target to assess the sensitivity of PCR to detect Trichinella spp. larvae in meat from a non-endemic region

Trichinellosis is a zoonotic disease exotic in Brazil but commonly found worldwide including South American countries like Argentina. International trading of swine meat needs an official Trichinella-free diagnosis commonly carried out by pepsin-HCl digestion of diaphragm tissue fragments followed by microscopic examination for the presence or absence of Trichinella larvae. The easiness of this diagnostic method allows it to be performed at slaughtering plants but, in contrast, it lacks sensitivity and does not allow species differentiation, which is fundamental for determining geographical and species distribution of different genotypes. In our study, we aimed to evaluate a highly sensitive diagnostic method based on the polymerase chain reaction (PCR) that would allow us to detect and classify different species of Trichinella. Thus, we designed a synthetic gene and selected five sets of primers targeting specific regions of the Trichinella genome. The synthetic gene was cloned into a plasmid and then used to optimize PCR conditions. Using our PCR, we were able to detect 0.001 pg of the synthetic gene, which corresponded to 0.01 larvae. Then, we collected 175 samples of Suidae (domestic and wild boars) diaphragm fragments that were pooled into groups, digested with pepsin-HCl, and had the DNA extracted for analysis by PCR. The clinical samples evaluated were negative by PCR. Our results indicate that the PCR-based method might be a useful diagnostic method complementary to the pepsin-HCl digestion method currently in use, mostly in non-endemic areas.

Human Trichinellosis in Italy: an epidemiological review since 1989

Objectives

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

Study design

We performed a systematic research in Pubmed (MEDLINE).

Methods

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

Results

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

Conclusions

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

Rapid and Visual Detection of Trichinella Spp. Using a Lateral Flow Strip-Based Recombinase Polymerase Amplification (LF-RPA) Assay

Trichinella spp., are amongst the most widespread parasitic nematodes, primarily live in the muscles of a wide range of vertebrate animals and humans. Human infection occurs by ingestion of raw or undercooked meat containing Trichinella larvae. Accurate diagnosis of Trichinella spp. infection in domestic animals is crucial for the effective prevention and control of human trichinellosis. In the present study, a simple, rapid and accurate diagnostic assay was developed combining recombinase polymerase amplification and a lateral flow strip (LF-RPA) to detect Trichinella spp. infection. The LF-RPA assay targets Trichinella spp. mitochondrial small-subunit ribosomal RNA (rrnS) gene and can detect as low as 100 fg DNA of Trichinella strains, which was approximately 10 times more sensitive than a conventional PCR assay. The LF-RPA assay can be performed within 10–25 min, at a wide range of temperatures (25–45°C) and showed no cross-reactivity with DNA of other parasites and related host species of Trichinella. The performance of the LF-RPA assay in the presence of high concentration of PCR inhibitor was better than that of a conventional PCR assay. Results obtained by LF-RPA assay for the detection of experimentally infected mice were comparable to the results obtained by using a conventional PCR, achieving 100% specificity and high sensitivity. These results present the developed LF-RPA assay as a new simple, specific, sensitive, rapid and convenient method for the detection of Trichinella infection in domestic animals.

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.

Early detection of Trichinella spiralis in muscle of infected mice by real-time fluorescence resonance energy transfer PCR

Real-time fluorescence resonance energy transfer (FRET) PCR and melting curve analysis using newly developed fluorophore-labeled hybridization probes were applied for the detection of Trichinella spiralis DNA in muscle of mice following oral inoculation with 300 T. spiralis larvae. The developed assay could detect and differentiate T. spiralis, Trichinella papuae, and Trichinella pseudospiralis DNAs by the different melting temperatures (Tm). The assay had a detection limit of 5 × 10(2) positive control plasmid copies, which was equivalent to 1 ng of T. spiralis DNA spiked into 250 mg of muscle sample. No fluorescence signal was detected when the technique was applied to the DNA of 27 parasites other than Trichinella spp. The assay could detect T. spiralis DNA in muscle at 7, 14, and 21 days postinoculation. The range, mean ± standard deviation, and median of the Tm values of all positive muscle tissue samples were 60.4-60.8, 60.6 ± 0.2, and 60.5, respectively. This assay provides an effective tool for the specific, sensitive, and high-throughput detection of T. spiralis DNA in muscle during the early stage of infection. In addition, the technique can be useful for epidemiologic surveillance in naturally infected wildlife.

Bovine cysticercosis--development of a real-time PCR to enhance classification of suspect cysts identified at meat inspection

Laboratory confirmation methods are important in bovine cysticerosis diagnosis as other pathologies can result in morphologically similar lesions resulting in false identifications. We developed a probe-based real-time PCR assay to identify Taenia saginata in suspect cysts encountered at meat inspection and compared its use with the traditional method of identification, histology, as well as a published nested PCR. The assay simultaneously detects T. saginata DNA and a bovine internal control using the cytochrome c oxidase subunit 1 gene of each species and shows specificity against parasites causing lesions morphologically similar to those of T. saginata. The assay was sufficiently sensitive to detect 1 fg (Ct 35.09 ± 0.95) of target DNA using serially-diluted plasmid DNA in reactions spiked with bovine DNA as well as in all viable and caseated positive control cysts. A loss in PCR sensitivity was observed with increasing cyst degeneration as seen in other molecular methods. In comparison to histology, the assay offered greater sensitivity and accuracy with 10/19 (53%) T. saginata positives detected by real-time PCR and none by histology. When the results were compared with the reference PCR, the assay was less sensitive but offered advantages of faster turnaround times and reduced contamination risk. Estimates of the assay's repeatability and reproducibility showed the assay is highly reliable with reliability coefficients greater than 0.94.

Rapid detection of Trichinella spiralis larvae in muscles by loop-mediated isothermal amplification

Trichinella spiralis is a tissue-dwelling nematode parasite. A loop-mediated isothermal amplification (LAMP) assay was developed and validated for the sensitive and rapid detection of T. spiralis larvae in muscle samples. Sixteen sets of primers were designed to recognise distinct sequences of a conserved gene, a 1.6kb repetitive element of the Trichinella genome. One set of primers was selected as the most appropriate for rapid detection. The specificity and sensitivity of the primers in LAMP reactions for T. spiralis larvae and muscle samples of mice infected with T. spiralis were determined. Another 10 heterologous parasites were selected for specificity assays. The results showed that target DNA was amplified and visualised by monitoring turbidity and adding calcein detection methods within 70min at an isothermal temperature of 63°C. The sensitivity of LAMP with the detection limit of 362fg/μl was >10 times higher than that for PCR. The designed primers had a good specificity. No cross-reactivity was found with the DNA of any other parasites. The assay was able to detect T. spiralis in all mouse muscle samples infected with 10 T. spiralis larvae on day 20 p.i. We believe this is the first report regarding the application of the LAMP assay for detection of T. spiralis larvae in muscle samples from experimentally infected mice. This method demonstrates a potentially valuable means for the direct detection of T. spiralis larvae in meat inspection.