Trichinosis is a parasitic infection with worldwide distribution, which is caused by consuming pork or other meats containing cystic larvae of the parasitic nematode Trichinella Spiralis. This study aimed to investigate the status of infection Trichinella Spiralis in domestic and wild animals. To study the spread of trichinelles in animals, a retrospective analysis was conducted based on the study of research journals and conducted their research methods of compressor trichinelloscopy (microscopic) and digestion of samples in artificial gastric juice (biochemical). A total of 17 positive samples were detected for trichinellosis during the observation period, of which 58.8% belonged to a badger (Meles Meles), and 35.3% to the brown bear (Ursusarctos), and only 5.9% of wild boar (Susscrofa). The mean long-term extent of infection belonged to badgers (18.2%), bears (7.9%), and wild boars (0.05%). The study found that between 2015 and 2020, seventeen Trichinella cases were recorded among wildlife in the Tyumen region and the Khanty-Mansi Autonomous Region. The number of annual Trichinella detection cases was declining, indicating the effectiveness of veterinary services. This study determined that the primary source of infection was bears, badgers, and wild boars. Among the 17 positive samples, 58.8% belonged to the badger, 35.3% to the bear, and only 5.9% to the wild boar.

Minks and brown rats are reservoir hosts for many endoparasites including those of the genus Trichinella, a group of parasite nematodes with a worldwide distribution. However, little is known about the prevalence of Trichinella sp. infection in the American mink (Neovison vison) and rats (Rattus norvegicus) in China. Therefore, we aimed to examine the prevalence of Trichinella sp. infection in farmed minks in Weihai city, Shandong province, China and infer the possible route for Trichinella transmission to farmed American minks. In total, 289 muscle samples from minks and 102 carcasses of rats were collected from Weihai City. The appearance of Trichinella sp. was examined using the pooled artificial HCl-pepsin digestion method. The results showed that muscle larvae were detected in 20 of 289 minks (6.92%) and 2 of 102 synanthropic rats (1.96%). The larval density of Trichinella sp. in mink samples ranged from 0.025 to 0.815 larvae per gram (lpg), while the average larval burden in rats was 0.17 lpg. The isolates derived from minks and rats were identified at the species level using multiplex polymerase chain reaction (PCR), which revealed that the size of the two PCR products matched that of T. spiralis at 173 bp. Furthermore, sequence analysis showed 100% identity of the 5S rDNA inter-gene spacer regions of the two isolates to that of T. spiralis. This study presents a novel report of T. spiralis-mediated infection in minks and synanthropic rats in China. We highlight the vulnerability of farmed minks to Trichinella infection through exposure to synanthropic rats, which may raise a public health concern of potential zoonotic risks for domestic animals.

Trichinellosis in humans is most often caused by the parasite Trichinella spiralis. The clinical course of the disease is diverse and the symptoms can vary from mild to severe. Symptoms usually disappear within a few months, but encysted larvae in the muscles can cause myalgia and weakness that last for years. However, the existence of chronic trichinellosis as a disease is still debatable. This study presents the results obtained at the National Reference Laboratory for Trichinellosis - INEP, Serbia. The study was conducted to assess the immunoserological, biochemical and symptomatic disease parameters of twelve patients who acquired trichinellosis 13 and 18 years ago, respectively. They were involved in two T. spiralis outbreaks in Serbia, at the village of Kumane and the city of Belgrade (nine and three patients, respectively). Results indicated the presence of specific anti-Trichinella antibodies in 83% of the total number of patients. However, while the humoral immune response to Trichinella lasted for more than a decade reaching almost two decades after the acute infection phase (7/9 and 3/3 respectively, in two outbreaks), persistence of chronic muscular pain, as the most prolonged symptom of trichinellosis, could be found in the majority of patients from the Kumane outbreak (7/9). As a consequence, these patients suffered from limitations in daily living activities for the same period of time. The results presented in this paper are our contribution to the view that trichinellosis as a chronic disease with symptoms exists and may be related to the severity of the disease in the acute phase.

Two prominent physicians, Grancher and Brouardel, were sent by the French Health authorities to study the severe ongoing outbreak of trichinellosis in Emersleben, Germany (1883). They produced a highly accurate description of the outbreak and confirmed that they had never observed such cases in France. Grancher performed two necropsies and very precisely described the histological lesions provoked by the larvae entering and transforming muscular fibers. They also had the opportunity to meet Virchow in Berlin and they emphasized his extreme kindness. This French medical mission and cooperation with famous German scientists such as Virchow is probably one of the first examples of international collaboration on trichinellosis. It prefigured the international collaborative efforts made by the International Commission on Trichinellosis which was created in 1958 and is still active.

Trichinellosis is a zoonotic disease, which represents a significant public health concern in some South American countries, such as Argentina and Chile. Its impact is essentially due to absence of adequate control measures on meat from game animals, as well as the presence of illegal slaughterhouses and the trade of meat products without being tested for this parasite. In Argentina, trichinellosis is an endemic disease. At present, Trichinella spiralis, Trichinella patagoniensis, Trichinella pseudospiralis, and Trichinella britovi have been detected in animals from Argentina. Until now, T. patagoniensis had only been found in mountain cougars (Puma concolor) in Argentina but there is limited information available. The present study intends to determine susceptibility, serological response and distribution of muscle larvae in wild boars infected with T. patagoniensis, T. spiralis and T. pseudospiralis. For each of the Trichinella species five wild boars were inoculated with 20,000 muscle larvae. Except for two specimens which died during the experiment, the animals were euthanized 19 weeks post infection (pi). Blood samples were collected throughout the study in order to determine the antibody kinetics. Also, nine muscle samples from each specimen were taken and analysed for determination of larval distribution. Additionally, four muscle samples were used to obtain muscle juices. Wild boars infected with T. patagoniensis showed little to no larvae in the muscle samples analysed while animals infected with T. spiralis and T. pseudospiralis had a significantly high larval load in all the samples analysed. Optical density (OD) values remained above the cut-off value throughout the experiment. This is the first study to characterize the biological aspects of T. patagoniensis in wild boars.

Rodents play an important role as reservoir hosts of zoonotic diseases. As a component of our long-term programme of monitoring parasitic infections in bank vole populations in three ecologically similar sites in NE Poland, we screened blood samples for signs of a serological response to the presence of Trichinella spp. The overall seroprevalence of Trichinella spp. was 1.52%, but prevalence was largely concentrated in one of our three study sites and confined to the oldest individuals in the study. Seroprevalence of Trichinella spp. did not differ between the sexes. Although a local prevalence of 1.52% may seem low, when this is extrapolated to the national population of bank voles in peak years, perhaps numbering hundreds of millions of animals, the number of infected bank voles on a country wide scale is likely to be huge. Our results suggest that bank voles may be reservoirs of Trichinella spp. However, on the basis of our results we consider their importance as epidemiologically significant hosts for Trichinella spp. to be moderate and their role in this context to require further investigation.

Trichinella spp. are relevant zoonotic pathogens in Estonia. The aim of this nationwide cross-sectional study was to estimate the seroprevalence of Trichinella spp. in domestic pigs (Sus scrofa domestica) and hunted wild boars (Sus scrofa). Serum samples from 374 pigs, originating from 14 farms, and meat juice samples from 470 wild boars were tested for immunoglobulin G antibodies against Trichinella excretory/secretory antigens using a commercial enzyme-linked immunosorbent assay (ELISA). Antibodies against Trichinella were not detected in the domestic pigs, indicating effective parasite control strategies in the farms. By contrast, 42.1% of the wild boars tested positive, indicating substantial infection pressure in the sylvatic cycle. Further analysis of a subset of the wild boar samples, using another ELISA and Western blot, yielded a confirmed seroprevalence estimate of 17.4%. A substantial proportion of wild boars in Estonia had evidence of exposure to Trichinella spp. and may have carried infective larvae. Undercooked Estonian wild boar meat is a potential source of Trichinella spp. infections to humans and other hosts.

In recent years the raccoon dog population in Germany has risen dramatically and a steady westward expansion can still be seen. In addition to the highest Trichinella prevalence in wild boar and the most reported Trichinella cases in domestic swine from backyard farms, the North-Eastern part of Germany also has the highest raccoon dog density in the country. Due to their distinct scavenging behavior, raccoon dogs play a significant role as Trichinella reservoir. Therefore, to increase the knowledge on Trichinella spp. in raccoon dogs, we performed a study on the occurrence of Trichinella in the North-Eastern federal state of Brandenburg. In total 1527 raccoon dogs were examined between 2000 and 2014. An average of 1.9% of the raccoon dogs were Trichinella spp. positive. 90% of the positive animals were infected with Trichinella spiralis and one animal each with Trichinella britovi and Trichinella pseudospiralis. In T. spiralis infected animals, the number of larvae found in the muscle tissue ranged between 0.5 and 235 larvae per gram (lpg), with a median of 14 larvae. A tentative temporal increase in Trichinella occurrence was seen between the time periods 2008 to 2010 and 2011 to 2014. Based on the size of the raccoon dog hunting bags of the past decade, the species spread in westerly and north-westerly direction is evident. An interesting question is how the raccoon dog will influence the Trichinella prevalence in the sylvatic cycle in these regions in the years to come.

Over the last decades the golden jackal (Canis aureus) has significantly expanded its range throughout Southeast and Central Europe, and the Balkan Peninsula is considered to be a core area of the species distribution in this part of the range. Due to its increasing number, ability of long distance movement through a wide range of landscapes and opportunistic feeding habits, the golden jackal may represent an important reservoir and transmitter of a variety of zoonotic agents, including parasites. The Balkans, Serbia included, remain an endemic area for various zoonotic parasites including Trichinella spp. Trichinella has recently been recorded in jackals in Serbia, which prompted us to carry out a large-scale survey of its prevalence, distribution and species identification in this host. In cooperation with local hunters, carcasses of a total of 738 legally hunted golden jackals were collected at 24 localities over an 11-year period (2003-2013). Analysis of tongue base tissue revealed Trichinella larvae in 122, indicating a prevalence of infection of 16.5%. No difference in the prevalence of infection was found between genders [16.2% in males and 16.9% in females (χ(2)=0.05, p=0.821)], or among the study years (G=7.22, p=0.705). Trichinella larvae were found in 13 out of the 24 examined localities. Molecular identification was performed for 90 isolates, and 64 (71.1%) larvae were identified as Trichinella spiralis and 25 (27.9%) as Trichinella britovi. Mixed infection (T. spiralis and T. britovi) was recorded in a single case. Although T. spiralis was more prevalent, T. britovi had a wider distribution, and was the only recorded species in jackal populations from the mountainous region of eastern Serbia. On the other hand, T. spiralis was dominant in jackals in the lowlands of central and northern Serbia, where domestic pigs are mostly reared. These results show that the golden jackal is involved in both the domestic and sylvatic cycle, and that it has emerged as a major host species in the sylvatic cycle of the Trichinella genus. Therefore, continued monitoring of Trichinella infection in golden jackals in Serbia and the whole of the Balkans is recommended in order to control transmission of this parasite to humans and domestic animals.

BACKGROUND: Trichinella spp. are zoonotic parasites transmitted to humans by the consumption of raw or insufficiently cooked meat of different animal species. The most common source of infection for humans is meat from pigs and wild boar (Sus scrofa). The aim of the present work was to evaluate the incidence of Trichinella spp. infections in wild boar hunted in Latvia over a 38 year interval (1976 to 2013).
METHODS: A total 120,609 wild boars were individually tested for Trichinella spp. by trichinoscopy and, in case of negativity, by artificial digestion of 25 g muscles, in the 1976-2005 period, and by artificial digestion of 25-50 g muscles in the 2006-2013 period. Trichinella spp. larvae were identified at the species level by multiplex PCR.
RESULTS: In the study period, the overall prevalence of infected wild boar was 2.5%. Trichinella britovi was the predominant (90%) species. The incidence of Trichinella spp. infection in wild boar exhibited two different trends. From 1976 to 1987, the incidence of infected/hunted wild boar increased from 0.23% to 2.56%, then it decreased to 0.19 in 1994. Thereafter, the incidence fluctuated between 0.05% and 0.37%. A statistically significant (P < 0.05) correlation (r = 0.54; p = 0.0199) was found between the trend of Trichinella spp. incidence in hunted wild boar and the number of snow cover days from 1976 to 1993. From 1997 to 2013, the estimated wild boar population of Latvia increased by 4.9 times and the hunting bag by 9.7 times, with a stable incidence of Trichinella spp. in the population. It follows that the biomass of Trichinella spp. larvae and of T. britovi, in particular, increased.
CONCLUSIONS: The incidence trends of Trichinella spp. in wild boar could be related to the role played by the snow in reducing the thermal shock and muscle putrefaction which increases the survival of the larvae in muscle tissues of carrion in the 1976-1993 period; and, in the 1997-2013 period, to the increased biomass of Trichinella spp. due to the increased carnivore populations, which are the main reservoirs of these parasites.