Survival of Trichinella spiralis in cured meat products

Trichinella Infection in Culled Wild Boar (Sus scrofa) from El Palmar National Park, Argentina, and Exposure Risk in Humans and Dogs Consuming Wild Boar Meat

Trichinellosis is a foodborne disease caused by ingestion of raw or undercooked meat containing Trichinella spp. larvae. Consumption of wild boar (Sus scrofa) meat represents an important source of human trichinellosis worldwide. In El Palmar National Park (EPNP), Argentina, invasive alien wild boars are controlled and meat from culled animals is released for public consumption following on-site artificial digestion (AD) testing. Meat trimmings and offal from the control program are often used as food for dogs (Canis familiaris). We evaluated infection and exposure to Trichinella spp. in wild boars from EPNP, as well as exposure to Trichinella spp. and associated risk factors in dogs and human consumers of wild boar meat. Trichinella spp. larvae were detected in muscle samples from 5/49 wild boars by AD (10.2%; 95% confidence interval [CI], 3.8%-23%), with a mean burden of 0.24 larvae per gram (lpg; range, 0.06-0.95 lpg). Anti-Trichinella antibodies were not detected in wild boar serum samples (n=42). In dogs, 12/34 were seropositive to Trichinella spp. (35.29%; 95%, CI, 20.3%-53.5%). Immunoglobulin (Ig) G antibodies were not detected in human serum samples (n=63). Our results reveal the presence, albeit at low prevalence, of Trichinella spp. in wild boars and exposure in dogs fed game offal. These findings suggest that the low prevalence and parasitic load in wild boars, together with the best practices applied by EPNP culling program personnel, contribute to keeping the risk of infection in people low. The dog results highlight that the parasite is circulating in the area, and therefore the risk of infection is not negligible. We recommend the implementation of an animal surveillance strategy in order to monitor the evolution of this zoonosis in the study area.

Trichinella spiralis-Secreted Products Promote Collagen Capsule Formation through TGF-β1/Smad3 Pathway

Trichinella spiralis (T. spiralis) muscle larvae colonize in the host's skeletal muscle cells, which are surrounded by collagen capsules. The mechanism underlying muscle stage larva-induced collagen capsule formation remains unknown. To clarify the mechanism, a T. spiralis muscular-infected mouse model was established by a single lateral tail vein injection with 20,000 T. spiralis newborn larvae (NBL). The infected mice were treated with or without SB525334 (TGF-β1 receptor type I inhibitor). Diaphragms were obtained post-infection, and the expression levels of the TGF-β1/Smad3 pathway-related genes and collagen genes (type IV and VI) were observed during the process of collagen capsule formation. The changes in myoblasts under stimulation of the excretory-secretory (ES) products of NBL with or without SB525334 were further investigated. Results showed that the expression levels of type IV collagen gene, type VI collagen gene, Tgfb1, and Smad3 were significantly increased in infected mice muscle cells. The expression levels of all the above genes were enhanced by the products of NBL in myoblast cells. These changes were reversed by co-treatment with SB525334 in vivo and in vitro. In conclusion, the TGF-β1/Smad3 pathway can be activated by T. spiralis infection in muscle cells. The activated TGF-β1/Smad3 pathway can stimulate the secretion of collagens by myocytes and plays a promoting role in the process of collagen capsule formation. The research has the limitation that the protein identification of the products of NBL has yet to be performed. Therefore, the specific components in the T. spiralis ES products that induce collagen synthesis should be further investigated.

Prediction of Pseudomonas spp. Population in Food Products and Culture Media Using Machine Learning-Based Regression Methods

Machine learning approaches are alternative modelling techniques to traditional modelling equations used in predictive food microbiology and utilise algorithms to analyse large datasets that contain information about microbial growth or survival in various food matrices. These approaches leverage the power of algorithms to extract insights from the data and make predictions regarding the behaviour of microorganisms in different food environments. The objective of this study was to apply various machine learning-based regression methods, including support vector regression (SVR), Gaussian process regression (GPR), decision tree regression (DTR), and random forest regression (RFR), to estimate bacterial populations. In order to achieve this, a total of 5618 data points for Pseudomonas spp. present in food products (beef, pork, and poultry) and culture media were gathered from the ComBase database. The machine learning algorithms were applied to predict the growth or survival behaviour of Pseudomonas spp. in food products and culture media by considering predictor variables such as temperature, salt concentration, water activity, and acidity. The suitability of the algorithms was assessed using statistical measures such as coefficient of determination (R²), root mean square error (RMSE), bias factor (Bf), and accuracy (A_f). Each of the regression algorithms showed appropriate estimation capabilities with R² ranging from 0.886 to 0.913, RMSE from 0.724 to 0.899, B_f from 1.012 to 1.020, and A_f from 1.086 to 1.101 for each food product and culture medium. Since the predictive capability of RFR was the best among the algorithms, externally collected data from the literature were used for RFR. The external validation process showed statistical indices of B_f ranging from 0.951 to 1.040 and A_f ranging from 1.091 to 1.130, indicating that RFR can be used for predicting the survival and growth of microorganisms in food products. Therefore, machine learning approaches can be considered as an alternative to conventional modelling methods in predictive microbiology. However, it is important to highlight that the prediction power of the machine learning regression method directly depends on the dataset size, and it requires a large dataset to be employed for modelling. Therefore, the modelling work of this study can only be used for the prediction of Pseudomonas spp. in specific food products (beef, pork, and poultry) and culture medium with certain conditions where a large dataset is available.

The Prevalence of Trichinella spiralis in Domestic Pigs in China: A Systematic Review and Meta-Analysis

The meta-analysis was performed to assess the prevalence of T. spiralis in domestic pigs in China. The potential studies from seven databases (Pubmed, Web of science, Scopus, Google Scholar, CNKI, Wanfang, CBM) were searched. I², Cochran's Q statistic and the funnel plot and Egger's test were used to assess heterogeneity and publication bias, respectively. In this study, a total of 179 articles were captured in the initially screened. Of these, we finally obtained 39 significant articles (including 43 studies involving in 551,097 pigs) for the final analysis. We calculated using a random-effects model, and we found the overall infection rate was 0.04 (95% CI 0.03-0.06). The highest prevalence region was Guangxi. The funnel plot and Egger's test showed no publication bias in our meta-analysis. In addition, this high heterogeneity index was suggestive of potential variations which could be due to regions, quality scores, detection methods, publication years, or samplings. These results indicated that T. spiralis were still prevalent in some areas in China. This highlights the need for an increased focus on implementing affordable, appropriate control programs to reduce economic losses and T. spiralis infection in domestic pigs in China.

What lies behind the curtain: Cryptic diversity in helminth parasites of human and veterinary importance

Parasite cryptic species are morphologically indistinguishable but genetically distinct organisms, leading to taxa with unclear species boundaries. Speciation mechanisms such as cospeciation, host colonization, taxon pulse, and oscillation may lead to the emergence of cryptic species, influencing host-parasite interactions, parasite ecology, distribution, and biodiversity. The study of cryptic species diversity in helminth parasites of human and veterinary importance has gained relevance, since their distribution may affect clinical and epidemiological features such as pathogenicity, virulence, drug resistance and susceptibility, mortality, and morbidity, ultimately affecting patient management, course, and outcome of treatment. At the same time, the need for recognition of cryptic species diversity has implied a transition from morphological to molecular diagnostic methods, which are becoming more available and accessible in parasitology. Here, we discuss the general approaches for cryptic species delineation and summarize some examples found in nematodes, trematodes and cestodes of medical and veterinary importance, along with the clinical implications of their taxonomic status. Lastly, we highlight the need for the correct interpretation of molecular information, and the correct use of definitions when reporting or describing new cryptic species in parasitology, since molecular and morphological data should be integrated whenever possible.

Raw meat based diet (RMBD) for household pets as potential door opener to parasitic load of domestic and urban environment. Revival of understated zoonotic hazards? A review

RMBD (acronym of Raw Meat Based Diet) and BARF diets (acronym for Biologically Appropriate Raw Food or Bones and Raw Food) account dietary regimens based on raw ingredients (including raw meat), popular in pet feeding. Animal tissues and organs as well as other uncooked ingredients are more and more popularly used by pet owners to feed household pets. However, the increased risk of exposure to microbiological and parasitic agents poses the question as to whether such diets may be recommendable to be handled and offered to domestic cats and dogs co-living in domestic and urban environment. Above all, the threat of human and animal infections by parasites from raw meat fed to pets is not sufficiently explored and tracked, meanwhile deserving particular surveillance, instead. At this regard, raw meat feeding to pets may represent a route of exposure to the increased risk of environmental load. In fact, some parasites typically found in rural environment can be given the chance to complete their life-cycle, for the closeness between definitive and intermediate hosts. This is of particular concern, as potentially infected pets serving as definitive hosts can become a continuous source of environmental diffusion of parasites, both at domestic and urban level. The handling of raw meat requires adequate knowledge and awareness of the hygienic principles to prevent the onset of disorders related to both manipulation by pet owners and uncooked food consumption by the pet. This review aimed to shed a comprehensive overview of the hygienic aspects related to raw pet feeding, as to handling of raw meat in domestic environment, with special emphasis on parasitic agents and related zoonotic hazards.

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

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