Validation of a new commercial serine protease artificial digestion assay for the detection of Trichinella larvae in pork

Efficacy of an aerosol-resistant pepsin powder used in artificial digestion for the detection of Trichinella larvae in meat

Trichinellosis is an important worldwide foodborne zoonosis. The gold standard test to detect Trichinella spp. larvae in muscle samples of animals intended for human consumption is the artificial digestion method. Handling and dispensing of conventional pepsin powder present significant safety risks for analysts. The use of pepsin powder that is resistant to aerosolization should alleviate these safety concerns. The aim of this study was to compare the efficacy of an aerosol-resistant pepsin powder to conventional pepsin powder in the artificial digestion method. Proficiency samples of pork diaphragm containing specific numbers of viable Trichinella spiralis larvae were tested in two laboratories. The results revealed that aerosol-resistant pepsin was simple, effective and convenient to use, and showed good solubility and larval recovery that met the requirements of the European Union regulation EU 2015/1375. Overall, the efficacy of the aerosol-resistant pepsin was comparable to the conventional pepsin and safer for analysts.

Evaluation of the PrioCHECK™ Trichinella AAD kit to detect Trichinella spiralis, T. britovi, and T. pseudospiralis larvae in pork using the automated digestion method Trichomatic-35

Trichinellosis is a potentially deadly parasitic zoonosis that is contracted by consuming undercooked infected meat. Reliable detection of infectious Trichinella spp. larvae in meat is therefore pivotal to ensure consumer's safety. The recently authorised PrioCHECK™ Trichinella Alternative Artificial Digestion (AAD) test kit appears promising when used with the standard magnetic stirrer method, but evaluation with other apparatus types is lacking. In this study, the performance of the AAD kit in an adapted Trichomatic-35 (TM35) instrument was evaluated, first, at the Swiss National Reference Laboratory for trichinellosis (NRL); second, in a ring trial involving four Swiss official laboratories. Proficiency pork samples spiked with larvae of Trichinella spiralis, T. britovi, or T. pseudospiralis were tested with the AAD kit and with the reference pepsin-HCl digestion method in TM35 instruments. At the NRL, both methods yielded identical qualitative and similar quantitative results independently of the Trichinella species. In the ring trial, satisfactory results were obtained for 47/50 (94.0%) (AAD) and 62/67 (92.5%) (reference method) of the analysed samples. Technical problems impairing analysis were more frequently observed with the AAD kit (n = 22) than with the reference method (n = 5) and were mainly (16/22) reported by one of the external labs. When no technical issues were recorded, the performance of both methods was comparable, in agreement with the observations at the NRL; however, these results suggest a need for further training with the kit and standardisation of the adapted TM35 instruments.

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.

Helminths of the Wild Boar (Sus scrofa) from Units of Conservation Management and Sustainable Use of Wildlife Installed in the Eastern Economic Region of Mexico

Wild boars (Sus scrofa) were introduced in Mexico for sport hunting and meat trading for human consumption, but the available data regarding their role in pathogen transmission are limited. This research and field work aimed to identify the helminths of the wild boar produced in three units of conservation management and sustainable use of wildlife placed in the eastern economic region of Mexico. Samples of feces and serum were collected from 90 animals that came from three different ranches. Stool examination and antibody determination to Fasciola hepatica, Taenia crassciceps, Ascaris suum, Toxocara canis (ELISA), and Trichinella spiralis (Western blot) were performed. In addition, 30 diaphragm samples from one ranch were obtained for artificial digestion. Eggs of Strongyloides sp. (72.2%), Metastrongylus sp. (57.7%), Oesophagostomum sp. (53.3%), and Trichuris sp. (37.7%) were found in addition to oocysts of Eimeria sp. (75.6%). Antibodies to Fasciola (8.9%), Taenia (4.4%), Ascaris (32.2%), Toxocara (20%), and Trichinella (5.5%) were found. The eggs of Strongyloides and Oesophagostomum were associated to female hosts. One nematode larva was found by artificial digestion. This is the first report to identify helminths from wild boars in Mexico. In addition, this study identifies the potential risk of the wild boar as a transmission channel of parasites that can have an impact on public health.

Test sensitivity of a commercial serine protease digestion kit for the detection of Trichinella spiralis and Trichinella pseudospiralis larvae in pig muscle

The reference method for Trichinella detection at meat inspection is the magnetic stirrer method (MSM) utilising HCl-pepsin for pooled sample digestion. Due to availability and quality issues with pepsin, alternative digestion methods are being offered, such as the Priocheck Trichinella AAD kit (T-AAD), based on serine endopeptidase digestion. In this study the T-AAD kit was compared to the reference method. Minced pork samples were spiked with T. spiralis muscle larvae (ML) with- and without capsule or T. pseudospiralis ML, and analysed with both tests. Test results of individually spiked test samples were analysed by generalised linear modelling. The T-AAD test kit was comparable to the reference method for the qualitative detection of T. spiralis in pigs, but not quantitatively. Overall, 94% of spiked T. spiralis were recovered using MSM against 75.2% when using T-AAD (p < 0.0001). Using the MSM 80.0% of spiked T. pseudospiralis were recovered against 20% with the T-AAD (p < 0.0001). Based on our experience with the T-AAD kit, we strongly recommend validating the method on site prior to introduction into routine diagnostic laboratories, but this will not alleviate the poor test sensitivity of the T-AAD for the detection of T. pseudospiralis.