Emerging Trichinella britovi infections in free ranging pigs of Greece

Wildlife and parasitic infections: A One Health perspective in Greece

While research on the parasitic fauna of wildlife in Greece is currently limited, conducted studies have provided valuable insights into the prevalence of parasitic infections in wild carnivores, omnivores, and herbivores. This review consolidates the existing data on the endoparasites detected in wild animals in Greece, specifically focusing on those that pose established or potential zoonotic risks. Over the last 60 years, various parasite species such as Leishmania infantum, Cryptosporidium spp., Toxoplasma gondii, Sarcocystis spp., Toxocara canis, Ancylostoma caninum, Capillaria spp., Baylisascaris spp., Trichinella spp., Thelazia callipaeda, Dirofilaria immitis, Echinococcus granulosus, Mesocestoides sp., Taenia spp., Alaria alata, and Dicrocoelium dendriticum have been identified in wildlife in Greece. These findings have become increasingly relevant due to the growing interaction between humans and wild animals, which now extends to urban environments, as well as the increased contact between wild and domestic animals. This is further complicated by the geographical expansion of vector-borne diseases due to global warming and the increased movements of humans and animals. Surveillance and monitoring of parasitic infections in Greek wildlife is warranted, and it should be based on interdisciplinary investigations considering the interconnectedness of human, wild, and domestic animals, as well as environmental health, in line with the One Health approach.

Animal Health and Productivity of Organic Greek Pig Farms: The Current Situation and Prospects for Sustainability

A review of organic pig production in Greece was carried out. The aim was to present updated information on the production, development and health status of organic pig farming in Greece and potential prospects for sustainability and future development. The indigenous Greek Black Pig is the main breed reared in Greek organic pig farms. All the reasons why Greek Black Pig breeding is ideal for organic farming are mentioned. Furthermore, respiratory and parasitic infections are the most common health problems, while high piglet mortality rates are the main welfare issue in Greek organic pig farming. Concerns about how farmers and authorities should utilize the demands of modern consumers are discussed.

Could the re-emerging practice of wild boar hunting linked to the recent economic crisis lead to new outbreaks of trichinellosis in Lebanon?

Background: Documented trichinellosis outbreaks in Lebanon date back to the late 19th century. The first published outbreaks were attributed to the consumption of wild boar meat, while those that followed incriminated pork. The practice of hunting wild boar is currently re-emerging in Lebanon given the recent economic crisis that has limited the purchase of livestock meat. Results: In Lebanon, at least 15 outbreaks of trichinellosis have been reported since 1870. We report an outbreak in January 2019, where five of the fifteen people present at a barbecue party were diagnosed with trichinellosis after wild boar meat consumption. Two subspecies of wild boar, Sus scrofa libycus and Sus scrofa scrofa, are commonly targeted by hunters. Hunters and consumers are sometimes unaware of the ineffectiveness of freezing meat and cooking over a wood fire to avoid trichinellosis. Unexpectedly, the National Center for Zoonosis Control receives every year 4 samples of wild boar meat, all free of Trichinella sp. larvae. Conclusion: Trichinellosis, a zoonosis typically unrecognized or undeclared, still represents a risk linked to the consumption of meat from wild animals, especially wild boar. Consumers, hunters, veterinarians, and butchers need to be further educated. Government regulation of wild boar hunting should be implemented to prevent further outbreaks.

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.

First record of Trichinella in Leopardus guigna (Carnivora, Felidae) and Galictis cuja (Carnivora, Mustelidae): new hosts in Chile

Background

Trichinellosis is a zoonotic disease with a worldwide distribution. It is caused by several species of nematodes in the genus Trichinella. Trichinella spp. are transmitted through predation or carrion consumption and occur in domestic and sylvatic cycles. In humans trichinellosis occurs due to the consumption of raw or undercooked, infected meat and is mainly associated with the household slaughter of pigs or the consumption of game animals without veterinary inspection, a cultural practice that is difficult to resolve. Therefore, knowledge of this parasite's reservoir is relevant for better implementing public health strategies. The aim of this study was to assess the presence of Trichinella sp. in several carnivore and omnivore vertebrates in central-southern Chile.

Methods

We collected muscle tissue from a total of 53 animals from 15 species and were digested to detect Trichinella larvae which were further identified to species level using molecular techniques.

Results

We detected Trichinella larvae in Leopardus guigna (Felidae) and Galictis cuja (Mustelidae). We identified the larvae collected from L. guigna as Trichinella spiralis, but we were unable to molecularly characterize the larvae from G. cuja. This is the first record of Trichinella in a native mustelid of South America and the first record of T. spiralis in L. guigna. This study identified two novel hosts; however, further work is needed to identify the role that these and other hosts play in the cycle of Trichinella in Chile.

Neospora caninum and/or Toxoplasma gondii Seroprevalence: Vaccination against PCV2 and Muscle Enzyme Activity in Seropositive and Seronegative Pigs

Neospora caninum and Toxoplasma gondii affect both humans and animals worldwide. To investigate their seroprevalence and differences in seropositivity between pigs vaccinated and unvaccinated against porcine circovirus 2 (PCV2), as well as differences in muscle enzyme activity between seropositive and seronegative pigs, blood samples were collected from 380 sows. Antibodies against T. gondii and N. caninum were detected by an indirect immunofluorescence antibody (IFA) assay, while the activities of creatine kinase (CK) and aspartate aminotransferase (AST) were biochemically assessed. Out of the 364 sows finally included in the study, 4.4%, 3.5%, and 0.5% were seropositive to T. gondii, N. caninum, or both. A significantly higher percentage of seropositivity against T. gondii and/or N. caninum in PCV2 unvaccinated pigs compared with vaccinated pigs was observed. Increased serum activities of CK and AST were detected in 71.43% and 100% of only against T. gondii (T+) and 63.64% and 90.91% of only against N. caninum (N+) seropositive sows, respectively, and were significantly higher compared to seronegative animals. T. gondii and N. caninum seropositivity, especially in presumed immunocompromised pigs, and the evidence of muscle damage highlight their importance as a zoonotic pathogen and animal model of human infection, respectively.

Trichinella britovi as a risk factor for alternative pig production systems in Greece and Europe

Trichinellosis is an important zoonosis and the most common source of human infection is meat from pigs and wild boars. The European Union (EU) supports alternative pig production systems (organic and free-ranging) as sustainable farming systems. However, these systems that allow outdoor access for farm animals, may create new or reintroduce old risks to public health. During the last years, alternative pig production systems (free-ranging or organic pig) are growing in popularity in Greece due to the increasing interest of consumers for organic products. The majority of the trichinellosis outbreaks in the EU were associated with pork and meat products including wild boars. In Greece, from 2009 to 2012, 37 Trichinella spp. positive free-ranging pigs were reported in free-ranging pig farms of Northern-Eastern Greece (31 were identified as T. britovi). The recent re-emerging present of the Trichinella spp. infections in free-ranging pigs and wild boars are a high risk for the consumers and should alarm the Public Health Authorities in Greece and the EU. During the last years, the organic or free-ranging pig production systems are growing in popularity in the EU. However, these systems increase the risk of Trichinella spp. infections, since pigs are possible to be infected by feeding on carcasses or the offal of hunted or dead wild animals. For this reason, it is important for Public Health Authorities to be focused on the training of hunters and farmers in order to avoid the transmission among free-ranging pigs and prevent the cases of human infection.

Human trichinellosis caused by Trichinella britovi in Greece, and literature review

Trichinellosis is a cosmopolitan zoonotic parasitic disease caused by the nematodes of the genus Trichinella, through the consumption of raw or semi-raw infected meat from swine, horses and wild animals. This disease has been sporadically reported in Greece since 1946. The aim of the present study was to describe a trichinellosis case in a patient hospitalized in northern Greece, in 2017. A 47-year-old male was admitted to hospital with intense generalized myalgia, periorbital swelling, fever, exhaustion and anorexia. Biochemical and haematological profile showed eosinophilia and elevated creatine phosphokinase (CPK). Anti-Trichinella spp. IgG and IgM antibodies were detected by serology and Trichinella spp. larvae were found in two muscle biopsies by compressorium and histological examination. A larva collected from the muscle biopsy was identified as Trichinella britovi by polymerase chain reaction (PCR). Albendazole (400 mg twice per day × 10 days) was administered and the clinical condition of the patient promptly improved. This is the first identification of T. britovi in a patient in Greece.

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.

Trichinella britovi from domestic to wild animals of Sardinia, Italy

The zoonotic nematode Trichinella britovi has been documented in animals and/or humans of the Mediterranean islands of Corsica and Sardinia since 2004. From 2005 to 2007 in the Sardinia island, several surveys had shown that T. britovi was circulating among backyard and free-ranging pigs reared in the Orgosolo municipality but all attempts had failed to detect this parasite in wild susceptible animals. The aim of the present work was to investigate the circulation of T. britovi in pigs and wildlife of the Orgosolo municipality, and of surrounding municipalities and provinces in the 2010-2014 slaughtering/hunting seasons. The results show that the T. britovi circulation was still restricted to the Orgosolo municipality with a prevalence of 2.6% in free-ranging pigs and 0.2% in backyard pigs but, for the first time, this parasite was detected also in 0.4% of wild boar, and 27.6% of red foxes. No infection was detected in backyard pigs, wild boar, and red foxes of the other municipalities and provinces. Since 1978, African swine fever is endemic in Sardinia and foci of this virus are still active in the investigated areas favoring cannibalism and, consequently, the T. britovi transmission, due to the high mortality rate caused by this virus. This is the first documented report on the transmission of T. britovi between the domestic and the sylvatic cycle. The health authority of the island must provide a service to dispose animal carcasses and offal, stamping out illegal free-ranging pigs, and train hunters and pig owners to manage waste and by-products according to the EU regulations.

The red fox (Vulpes vulpes) plays a minor role in the epidemiology of the domestic cycle of Trichinella in Romania

Nematode worms of the genus Trichinella are zoonotic parasites with a worldwide distribution. The majority of the biomass of these nematodes circulates among wildlife, but when humans fail in the proper management of domestic animals and wildlife, Trichinella infections are transmitted from the sylvatic to the domestic environment. Such failures occur in Romania, where a high prevalence of Trichinella spiralis has been detected in domestic pigs. The aim of the present study was to provide data about the prevalence of Trichinella spp. infections in red foxes (Vulpes vulpes) that are hunted in Romanian counties, in which the prevalences of Trichinella spp. infection in backyard and free-ranging pigs range from 0.17 to 2.5%, to determine the role played by this carnivore species in the transmission of the parasite to domestic cycle. A total of 121 animals from 45 hunting grounds of three counties were screened to detect Trichinella spp. larvae by the digestion method. Infections were detected in 26 (21.5%) foxes from 18 (40%) hunting grounds of the three counties (13/67 in Arad, 1/3 in Hunedoara, and 12/51 in Timiş). The mean larval density was 10.5 larvae per gram. Of the 25 successfully tested samples, the Trichinella larvae from 24 isolates were identified as T. britovi (96%), and the larvae from one isolate were identified as T. spiralis (4%). No mixed infections were recorded. The present results revealed that the red fox should be considered an important T. britovi reservoir in the sylvatic cycle; in contrast, the detection of only a single T. spiralis-positive isolate suggests that red foxes play a minor role in the epidemiology of the domestic cycle in the investigated area of western Romania.

Exposure of extensively farmed wild boars (Sus scrofa scrofa) to selected pig pathogens in Greece

BACKGROUND

Increased density and distribution of wild boar populations are likely to promote interactions and transmission of certain pathogens, not only among wild boar but also from wild boar to livestock or humans and vice versa.

OBJECTIVE

The purpose of this study was to determine seroprevalence against seven selected pathogens in wild boar living in four different areas in Greece.

ANIMALS AND METHODS

In total, 359 serum samples were collected from extensively farmed wild boar (Sus scrofa scrofa) originating from four distinct geographical areas throughout Greece from April 2012 to August 2013. Samples were tested for antibodies to Actinobacillus pleuropneumoniae, African swine fever virus (ASFV), Aujeszky's disease virus (ADV), classical swine fever virus (CSFV), Erysipelothrix rhusiopathiae, Mycoplasma hyopneumoniae and porcine reproductive and respiratory syndrome virus (PRRSV). Prevalence was compared among the four regions using Fisher's exact test.

RESULTS

Low overall seropositivities of 2.4% and 5.6% were detected for E. rhusiopathiae and PRRSV, respectively, higher ones for ADV (32.0%) and the highest (72.5% and 90.5%) for M. hyopneumoniae and A. pleuropneumoniae, respectively. All sera tested were found negative for antibodies directed against CSFV and ASFV.

CONCLUSIONS

This is the first report of exposure of wild boars to selected pig pathogens in Greece. These results are indicative of the circulation of these pathogens in Greece with the exception of CSFV and ASFV and suggestive of the potential role of wild boars on their maintenance and transmission to their domestic counterparts and vice versa.

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.