Trichinella spiralis a new alien parasite in Italy and the increased risk of infection for domestic and wild swine

Eleven Years of Health Monitoring in Wild Boars (Sus scrofa) in the Emilia-Romagna Region (Italy)

In recent years, the growth of wild ungulates has increased the focus on their health monitoring. In particular, the health status of wild boars is relevant for the economic impact on the pig industry. The Emilia-Romagna region activated a wildlife monitoring plan to better evaluate the health status of the wild boar population. Between 2011 and 2021, samples of found dead and hunted wild boar have been examined for trichinellosis, tuberculosis, brucellosis, african swine fever, classical swine fever, Aujeszky's disease, swine vesicular disease, and swine influenza A. Trichinella britovi was identified in 0.001% of the examined wild boars; neither M. bovis nor M. tuberculosis were found in M. tuberculosis complex positive samples; 2.3% were positive for Brucella suis; 29.4% of the sera were positive for Aujeszky's disease virus; and 0.9% of the samples were positive for swine influenza A virus. With an uncertain population estimate, the number of animals tested, the number of positives, and the sampling method do not allow us to make many inferences but suggest the need to implement and strengthen the existing surveillance activity, as it seems to be the only viable alternative for safeguarding animal and human health.

Occurrence and fate of antibiotics in swine waste treatment: An industrial case

This study mapped the fate of antibiotics in a swine farm with integrated waste treatment including anoxic stabilization, fixed-film anaerobic digestion, anoxic-oxic (A/O), and composting. Results show the prevalent and consistent occurrence of 12 antibiotics in swine waste. Mass balance of these antibiotics was calculated to track their flow and evaluate their removal by different treatment units. The integrated treatment train could effectively reduce antibiotic loading to the environment by 90% (measured as combined mass of all antibiotic residues). Within the treatment train, anoxic stabilization as the initial treatment step, accounted for the highest contribution (43%) to overall antibiotic elimination. Results also show that aerobic was more effective than anaerobic regarding antibiotic degradation. Composting accounted for an additional of 31% removal of antibiotics while anaerobic digestion contributed to 15%. After treatment, antibiotic residues in the treated effluent and composted materials were 2 and 8% of the initial antibiotic loading in raw swine waste, respectively. Ecological risk assessment showed negligible or low risk quotient associated with most individual antibiotics released into the aquatic environment or soil from swine farming. Nevertheless, antibiotic residues in treated water and composted materials together showed significant ecological risk to water and soil organisms. Thus, further work to improve treatment performance or develop new technologies is necessary to reduce the impact of antibiotics from swine farming.

Trichinella spiralis and T. britovi in North-Eastern Romania: A Six-Year Retrospective Multicentric Survey

Simple Summary

The genus Trichinella includes roundworm parasites with a wide geographical spread that can cause illness in humans and animals. In this context, an epidemiological study of Trichinella infection was carried out in the northeastern part of Romania to investigate for the first time its prevalence in pigs, horses, wild boars and bears, the geographical distribution of Trichinella species and the natural reservoir of the parasites. Between 2010 and 2015, a total of 166,270 animals were examined by specific methods in order to calculate the prevalence of Trichinella infection, the involved species, and their geographical distribution. The overall prevalence of Trichinella infection in animals was 0.188%. But the specific prevalence varied as follows: in pigs 0.096%, horses 0.021%, wild boar 1.46% and bears 36.76%. The geographical distribution showed that T. spiralis was dominant, occupying the entire northeastern part of Romania, being identified in pigs, horses, wild boars and bears. T britovi occupied five mountain counties, being identified only in wild boars and bears. These results validate the presence of T. spiralis and T. britovi in domestic and game animals in northeast Romania and warn about the risk of human infection in the region.

Abstract

The genus Trichinella includes species with a wide geographical spread that cause pathology in humans and animals. In this context, an epidemiological study of Trichinella infection was carried out in the northeastern part of Romania to investigate for the first time the prevalence of this infection in pigs, horses, wild boars and bears, the geographical distribution of Trichinella species and the natural reservoir of Trichinella infection. Between 2010 and 2015, a total of 166,270 animals were examined by the method of artificial digestion, in order to calculate the annual and general prevalence of Trichinella infection, according to the host and the Trichinella species involved, the Pearson correlation coefficient (r), trendline and geographical distribution of species of the genus Trichinella. Taxonomic framing was performed by the multiplex PCR method. The overall prevalence of Trichinella infection in animals was 0.188%. Within the host species, the prevalence varied as follows: in pigs 0.096%, horses 0.021%, wild boar 1.46% and bears 36.76%. The geographical distribution showed that T. spiralis was dominant, occupying the entire northeastern part of Romania, being identified in pigs, horses, wild boars and bears. T britovi occupied five mountain counties, being identified only in wild boars and bears. These results validate the presence of T. spiralis and T. britovi in domestic and game animals in the northeastern part of Romania.

Trichinella surveillance program in wild birds, Emilia-Romagna (northern Italy), 2006–2021. First report of Trichinella pseudospiralis in western marsh harrier (Circus aeruginosus) in Italy

The nematode Trichinella pseudospiralis is a cosmopolitan parasite capable of infecting both birds and mammals including humans. T. pseudospiralis has a limited zoonotic importance in comparison to that of the other Trichinella species. However, it has been recognized as the etiological agent of two outbreaks of trichinellosis due to the consumption of wild boar meat. The role played by birds in the epidemiology of T. pseudospiralis is still unclear and needs to be deepened. The aim of our work was to show the results of an extensive wild bird surveillance carried out in the Emilia-Romagna (E-R) region, northern Italy, over the last 16 years. As part of the regional wildlife surveillance program, 14,933 raptors and carrion-eating birds’ carcasses were necropsied from 2006 to 2021 and tested for the presence of Trichinella spp. larvae with only one positive result, an adult female of western marsh harrier. The larvae load (LPG) was evaluated on breast (100 LPG), wings (3.6 LPG), shoulder (2 LPG), head (4.5 LPG), thighs (8 LPG), lower legs (2 LPG) and tongue (0.77 LPG). The results of the present study confirm that also in northern Italy T. pseudospiralis has a low prevalence comparing to that of other Trichinella species. However, this study demonstrates that T. pseudospiralis can reach a high parasitic load in infested birds. The large distribution range, probably facilitated by its ability to infest birds, suggests the need for a continuous monitoring program.

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Results of a Trichinella monitoring program in wild birds during the period 2006–2021.

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First report of Trichinella pseudospiralis in a western marsh harrier (Circus aeruginosus) in Italy.

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T. pseudospiralis can reach a high parasitic load in infested birds.

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The highest larval burden (100 LPG) was detected in the breast muscles of the affected marsh harrier.

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The ongoing isolation of this parasite suggests a stable presence of T. pseudospiralis in Italy.

Trichinella britovi outbreak in Piedmont, North-West Italy, 2019-2020: Clinical and epidemiological insights in the one health perspective

BACKGROUND

Trichinellosis, a foodborne zoonosis due to nematodes of the genus Trichinella, occurs in the form of outbreaks following meat consumption. North Italy has been rarely involved. We report here the most significant wildlife derived trichinellosis outbreak ever registered in the Piedmont region.

METHOD

We retrospectively included 96 outpatients referred to our institution (December 20th, 2019-January 15th, 2020) 2020 after consuming raw sausages prepared from a single wild boar hunted in the Susa Valley, 59 km away from Torino, in November 2019.

RESULTS

We confirmed 35 cases and found additional 10 probable/suspected cases. Our cohort found that 47% of patients were symptomatic, with a median time from symptoms to presentation at clinic and serology testing of 14 days. Peripheral blood eosinophilia >500/μl and CK alterations were common. Further qualitative and quantitative analysis at the International Trichinella Reference Center c/o ISS, Rome identified T. britovi as the causative agent.

CONCLUSIONS

No autochthonous human case has ever been detected in Torino province, and a single wild boar has tested positive for Trichinella since active surveillance was implemented in 2013. This outbreak should raise attention on the preventive role of veterinary surveillance and the need to optimize sampling procedures and targeted health education.

Animal welfare and zoonosis risk: anti-Trichinella antibodies in breeding pigs farmed under controlled housing conditions

Background

Domesticated pigs are the main source of Trichinella sp. infections for humans, particularly when reared in backyards or free-ranging. In temperate areas of southern Europe, most pigs are farmed under controlled housing conditions, but sows and sometimes fattening pigs have access to outdoors to improve animal welfare. The aim of the present study was to investigate whether outdoor access of breeding pigs farmed under controlled housing conditions can represent a risk for Trichinella sp. transmission when the farm is located in an agricultural area interspersed with wooded areas and badlands, where Trichinella spp. could be present in wildlife.

Methods

Serum samples were collected from 63 breeding sows and one boar before and after their access to an open fenced area for 2 months and from 84 pigs that never had outdoor access. Samples were screened for anti-Trichinella antibodies by ELISA, and positive sera were confirmed using Western blot (Wb) excretory/secretory antigens. To detect Trichinella sp. larvae, muscle tissues from serologically positive and negative pigs were tested by artificial digestion.

Results

Thirteen (20.6%) sows and one boar tested positive with both ELISA and Wb. No larvae were detected in muscle samples of serologically positive and serologically negative pigs. Positive serum samples were then tested by Wb using crude worm extract as antigens. The Wb banding pattern displayed was that characteristic of encapsulated species (Trichinella spiralis or Trichinella britovi).

Conclusions

The detection of anti-Trichinella antibodies without larvae in the pig muscles, supported by epidemiological data, suggests that pigs may have been exposed to T. britovi. This study stresses the importance of instigating monitoring systems at farm level to prevent Trichinella sp. transmission and to investigate, through a landscape parasitological study, the suitability of a site before the planting of a high containment level pig farm in which the sows can have outside access to improve their welfare during pregnancy.

Graphical abstract

First report of Trichinella pseudospiralis in a wolf (Canis lupus italicus)

Within the genus Trichinella, Trichinella pseudospiralis is the only recognized non-encapsulated species known to infect mammals and birds. In October 2020, larvae recovered from muscle tissues of a wolf (Canis lupus italicus) originating from Molise Region, Central Italy, were molecularly confirmed as those of Trichinella britovi and T. pseudospiralis. This is the first detection of T. pseudospiralis from a wolf. In Italy, this zoonotic nematode was detected in a red fox (Vulpes vulpes), three birds (Strix aluco, Athene noctua, Milvus milvus) and five wild boars (Sus scrofa), and was also identified as the etiological agent of a human outbreak of trichinellosis in 2015. Since T. pseudospiralis is rarely reported from carnivore mammals in comparison to the encapsulated species frequently detected in these hosts, this finding opens the question of the role of carnivores as reservoirs for this parasite.

Second outbreak of Trichinella pseudospiralis in Europe: clinical patterns, epidemiological investigation and identification of the etiological agent based on the western blot patterns of the patients' serum

Trichinellosis is a zoonotic disease due to the ingestion of raw or undercooked meat from animals infected with the larvae of nematodes belonging to the genus Trichinella. In January-February 2015, an outbreak of trichinellosis occurred in Genoa, Northern Italy. The epidemiological link was traced back to a dinner served at an agritourism farm on 31 December 2014, where a majority of the 52 guests had consumed the 'beef' steak tartare. The source of infection was not traced; however, it was noted that the amount of beef purchased officially for providing at the dinner did not correspond with that served, suggesting that meat of a different origin had been added to the beef to prepare the steak tartare. Clinical and laboratory data of 30 individuals out of the 52 (57.7%), of which four were hospitalized, were consistent with that of the case definition of trichinellosis. Western blot patterns of the sera from patients with confirmed trichinellosis were similar to the diagnostic pattern identified for the reference sera of Trichinella pseudospiralis but different from those of the control sera tested for patients infected with Trichinella spiralis and Trichinella britovi. Identification of T. pseudospiralis as the aetiological agent responsible for the outbreak of trichinellosis using an indirect tool represents an advancement in the epidemiological investigation of this zoonotic disease.

Flooding on Beef and Swine Farms: A Scoping Review of Effects in the Midwestern United States

BACKGROUND

Increasing uncertainty and variability in weather due to climate change puts enormous stress on the sustainability of agricultural communities in several parts of the continental United States. Rural agriculture-based communities, such as those in North Carolina, Nebraska, and Illinois are particularly vulnerable to the impacts of flooding. These extreme weather events affect many animal facilities, and flooding can cause long-term impacts on animal health and productivity.

OBJECTIVES

This scoping review investigated the potential short- and long-term ramifications of flooding on beef cattle and swine farms with theoretical locations in the Midwestern U.S. The goal of this review is to create a concept map to identify research gaps related to efforts to support those animals and peoples ravaged by floods. This was accomplished by performing a scoping review using search terms "beef OR swine AND flood" to assess direct effects and then "beef OR swine AND direct effect" to evaluate secondary and tertiary effects.

RESULTS

Our findings were based on a total of 89 peer-reviewed publications, with 50 publications relating to beef cattle, 24 relating to swine, and 15 containing information applicable to both. On beef farms, the effects of flooding can be broad and long-lasting. The short-term risks of flooding are reasonably well-understood, including the comingling of unfamiliar cattle, nutritional restriction, and disease transmission. However, long-term impacts, including potential effects on reproduction, nutrition, and carcass quality, have been less studied. In particular, further research is needed on mold species that contaminate hay post-flood, the effect of moldy hay ingestion on cattle, and the effects of heavy metal consumption on cattle and consumers. Little research is available regarding the effects of flooding on swine farms, likely due to the highly intensive nature of swine operations. In general, swine farms suffer from acute infectious diseases and biosecurity risks after flooding events.

CONCLUSIONS

The potential ramifications of flooding on livestock farms differ among farm operations. Beef farms should prepare for long-term impacts on nutrition and reproduction, while swine farms should prepare for short-term impacts on biosecurity.

Genotyping and Phylogenetic Position of Trichinella spiralis Isolates from Different Geographical Locations in China

In China, the nematode Trichinella spiralis is the main aetiological agent of human trichinellosis. We performed multi-locus microsatellite typing of T. spiralis isolates to improve the current knowledge of the evolution and population diversity. First, seven polymorphic microsatellite loci were used to infer the genetic diversity of T. spiralis collected in 10 endemic regions. Then, a Bayesian model-based STRUCTURE analysis, a clustering based on the neighbor-joining method, and a principal coordinate analysis (PCA) were performed to identify the genetic structure. Finally, the phylogenetic position of Chinese isolates was explored based on six mitochondrial and nuclear genetic markers (cox1, cytb, 5S ISR, ESV, ITS1, and 18S rDNA) using the maximum likelihood and Bayesian methods. In addition, the divergence time was estimated with multiple genes using an uncorrelated log-normal relaxed molecular-clock model. A total of 16 alleles were detected in 2,310 individuals (1,650 muscle larvae and 660 adult worms) using seven loci. The STRUCTURE analysis indicated that the T. spiralis isolates could be organized and derived from the admixture of two ancestral clusters, which was also substantiated through the clustering analysis based on the allelic data. PCA separated most samples from Tiandong, Guangxi (GX-td), and Linzhi, Tibet (Tibet-lz), from the remaining isolates. However, both maximum likelihood and Bayesian inference supported the close relationship between Xiangfan, Hubei (HB-xf), and GX-td. The molecular dating analysis suggested that the Chinese isolates started to diverge during the Late Pleistocene (0.69 Mya). Generally, T. spiralis was observed to harbor low genetic variation, and further investigation with deeper sampling is needed to elucidate the population structure.

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.

Retrospective analysis of hospital discharge records for cases of trichinellosis does not allow evaluation of disease burden in Italy

Human trichinellosis is a disease caused by nematode worms of the genus Trichinella. In Italy, as well as in most other European countries, notification of Trichinella infections in humans is mandatory; however, no information is available on the number of cases occurring annually. The aim of the present study was to retrospectively evaluate the burden of trichinellosis in Italy from 2005 to 2016. Hospital discharge records (HDRs) showing the code for trichinellosis (124) were registered and screened. Results were then compared with yearly reports issued by the Italian National Reference Laboratory for Trichinella (NRLT), with reports from the European Centre for Disease Prevention and Control (ECDC), and with literature data. A total of 102 HDRs revealed that the 124 code was erroneously reported in 72 (70.6%) records. Out of the 30 (29.4%) records with a correct diagnosis of trichinellosis, nine cases were reported by HDRs only, 21 cases were documented by both HDRs and the NRLT, whereas the NRLT documented 100 additional cases. In the studied period, the average yearly incidence was 0.01 cases per 100,000 inhabitants. This study highlights the limitations of using HDRs to obtain a clear picture of the prevalence and incidence of trichinellosis in Italy. These findings demonstrate the need to intensify the surveillance system for trichinellosis through the development of an Italian registry. This would allow the identification of patients with severe infections and pauci-symptomatic patients, and would avoid the need for clinical analyses and unnecessary treatments, reducing the resulting economic burden on the Italian National Health Service.

Development of EST-derived microsatellite markers to investigate the population structure of sparganum - the causative agent of zoonotic sparganosis

The plerocercoid (sparganum) of Spirometra erinaceieuropaei is the main aetiological agent of human sparganosis. To improve the current knowledge on S. erinaceieuropaei evolution, we performed multi-locus microsatellite typing of sparganum isolates from China for the first time. All available expressed sequence tag (EST) sequences for the Spirometra were downloaded from the GenBank. The identification and localization of microsatellites in ESTs was accomplished by MISA. Based on the selected microsatellites, the genetic structure of 64 sparganum isolates collected from 11 geographical locations in southwest China were investigated through principal component analysis, STRUCTURE analysis and neighbour-joining clustering. A total of 522 non-redundant ESTs containing 915 simple sequence repeats were identified from 12 481 ESTs screened. Five primer pairs were finally selected. Using these loci, a total of 12 alleles were detected in 64 sparganum isolates. Little variability was observed within each of geographical population, especially among isolates derived from Kunming of Yunnan (YN-KM) province. Both STRUCTURE analysis and the clustering analysis supported that two genotypes existed among the sparganum isolates from southwest China. In conclusion, five microsatellite markers were successfully developed, and sparganum population was observed to harbour low genetic variation, further investigation with deeper sampling was needed to elucidate the population structure.

The Golden jackal (Canis aureus) as an indicator animal for Trichinella britovi in Iran

Nematodes of the genus Trichinella are zoonotic parasites causing trichinellosis. In Iran, these parasites occur in several animal species and rare cases have been recorded in humans. To monitor the epidemiological pattern of these parasites in the Khorasan-e-Razavi province, Northeastern Iran, muscle tissues were collected from the tongues of roadkill animals between 2016 and 2017: 295 stray dogs, one red fox (Vulpes vulpes), 12 golden jackals (Canis aureus), and one wild boar (Sus scrofa). Trichinella spp. larvae were retrieved using the artificial digestion method and identified to the species level by multiplex PCR. Larvae identified as Trichinella britovi were detected in five stray dogs (1.7%) and one golden jackal (8.3%). The results confirm the circulation of T. britovi in animals of the Khorasan-e-Razavi province, as previously documented. A review of the literature on Trichinella spp. in animals in Iran showed that these parasites were previously detected in 20.02% and 0.04% of carnivore and omnivore mammals, respectively, and that golden jackals can be screened as indicator animals for these zoonotic nematodes. Convenient sampling of Trichinella susceptible roadkill animals may provide a suitable method of monitoring the circulation of these parasites within any given region.