Surveillance of important bacterial and parasitic infections in Danish wild boars (Sus scrofa)

Parasitological Examination of the Digestive System of Wild Boar from a Practical Point of View-Endoparasitological Sampling under Field Conditions

From 2015 to 2023, we conducted a comprehensive study in the 11,893-hectare hunting area managed by the Marcal-Bitvaközi Hunting Company, characterised by its substantial wild boar population. The research was carried out across various settings, including a free-range wild boar garden during large-scale hunts and free-living areas during individual hunts. We examined 216 wild boars in total, with 173 individuals from free-living areas and 43 from free-range areas. Throughout the sample collection process, we encountered numerous technical challenges that are infrequently detailed in the professional literature, often mentioned only tangentially. This oversight in existing publications neglects the significance of addressing field sampling difficulties, which are crucial for ensuring the precision and accuracy of research. This paper details the equipment requirements, sampling methodologies, and practical solutions to streamline fieldwork. While our primary focus was on endoparasitic infections of the stomach and small intestine, the described methodologies and findings are broadly applicable to research involving all internal organs.

Prevalence, molecular characterisation and phylogenetic analyses of hydatid cysts and cysticercus tenuicollis isolates and first report of E. canadensis (G6/G7) in wild boars in Bingol province, Türkiye

Wild boars can directly or indirectly transmit numerous zoonotic helminths to humans in rural communities as they serve as reservoir hosts. This study was conducted to determine the occurrence and molecular characterisation of cystic metacestode forms of helminth parasites in wild boar and to identify haplotypes. To this end, 23 wild boar carcasses shot by hunters during the 2023 hunting season were necropsied and all internal organs were examined. Cysticercus tenuicollis (n = 07) and hydatid cyst (n = 10) isolates were obtained from the examined boars. Species identification of Cysticercus and hydatid cyst isolates was performed by amplification of partial fragments of the cox1 gene. According to BLAST search, all sequences of C. tenuicollis isolates were identified as Taenia hydatigena. Out of the hydatid cyst isolates, seven were classified as Echinococcus granulosus sensu stricto (G1/G3) and one sample was identified as Echinococcus canadensis (G6/G7). All isolates of E. granulosus s.s. (G1/G3) were re-amplified with the NADH dehydrogenase subunit 5 (nad5) in order to distinguish between G1 and G3 genotypes. Based on the sequence analysis, it was found that five of the E. granulosus s.s. isolates were classified as G1, while two were classified as G3. Based on the results of this study, it can be concluded that the G1 genotype is the most prevalent genetic variant among wild boar populations in Bingol province, Türkiye. In this study, a total of five novel haplotypes were identified. A previously unidentified haplotype was revealed through the haplotype analysis of E. canadensis (G6/G7). All isolates in the haplotype network of T. hydatigena were shown to exhibit distinct and geographically specific haplotypes. According to the findings of the study, wild boars include a substantial amount of genetic variety in E. granulosus s.s. And T. hydatigena.

A Comparison of the Prevalence of Gastrointestinal Parasites in Wild Boar (Sus scrofa L.) Foraging in Urban and Suburban Areas

The aim of this study was to compare the species composition of gastrointestinal parasites in wild boar feeding in the city of Szczecin with those in its suburban area, as well as to determine the prevalence and intensity of this parasite infection. The intestines and stomachs of 57 wild boars were supplied by a municipal hunter from the city of Szczecin. Both analysed groups of animals were infected with the following parasites: Eimeria debliecki, E. suis, E. polita, E. scabra, Isospora suis, Ascaris suum and Oesophagostomum dentatum. Wild boar from the city were characterised as having a significantly higher prevalence of total Eimeria (p = 0.04) and a lower prevalence of noted species of nematodes (p = 0.15) compared to those from the suburban area. Since the wild boars were mainly infected with Eimeria, it should be assumed that they may pose a real health threat to farm pigs and other farm animals for which Eimeria is a pathogenic parasite. The occurrence of coccidiosis leads to serious health problems and economic losses for breeders. Although the prevalence of A. suum was low, it should be taken into account that this nematode is able to both infect and complete their life cycle in humans.

Estimating parasite-condition relationships and potential health effects for fallow deer (Dama dama) and red deer (Cervus elaphus) in Denmark

Parasites can exert a substantial influence on the ecology of wildlife populations by altering host condition. Our objectives were to estimate single and multiparasite-condition relationships for fallow deer (Dama dama) and red deer (Cervus elaphus) in Denmark and to assess potential health effects along the parasite burden gradient. Fallow deer hosted on average two endoparasite taxa per individual (min = 0, max = 5) while red deer carried on average five parasite taxa per individual (min = 2, max = 9). Body condition of both deer species was negatively related to presence of Trichuris ssp. eggs while body condition of red deer was positively related to antibodies of the protozoan Toxoplasma gondii. For the remaining parasite taxa (n = 12), we either found weak or no apparent association between infection and deer body condition or low prevalence levels restricted formal testing. Importantly, we detected a strong negative relationship between body condition and the sum of endoparasite taxa carried by individual hosts, a pattern that was evident in both deer species. We did not detect systemic inflammatory reactions, yet serology revealed reduced total protein and iron concentrations with increased parasite load in both deer species, likely due to maldigestion of forage or malabsorption of nutrients. Despite moderate sample sizes, our study highlights the importance of considering multiparasitism when assessing body condition impacts in deer populations. Moreover, we show how serum chemistry assays are a valuable diagnostic tool to detect subtle and sub-clinical health impacts of parasitism, even at low-level infestation.

Presence of Foodborne Bacteria in Wild Boar and Wild Boar Meat-A Literature Survey for the Period 2012-2022

The wild boar is an abundant game species with high reproduction rates. The management of the wild boar population by hunting contributes to the meat supply and can help to avoid a spillover of transmissible animal diseases to domestic pigs, thus compromising food security. By the same token, wild boar can carry foodborne zoonotic pathogens, impacting food safety. We reviewed literature from 2012-2022 on biological hazards, which are considered in European Union legislation and in international standards on animal health. We identified 15 viral, 10 bacterial, and 5 parasitic agents and selected those nine bacteria that are zoonotic and can be transmitted to humans via food. The prevalence of Campylobacter, Listeria monocytogenes, Salmonella, Shiga toxin-producing E. coli, and Yersinia enterocolitica on muscle surfaces or in muscle tissues of wild boar varied from 0 to ca. 70%. One experimental study reported the transmission and survival of Mycobacterium on wild boar meat. Brucella, Coxiella burnetii, Listeria monocytogenes, and Mycobacteria have been isolated from the liver and spleen. For Brucella, studies stressed the occupational exposure risk, but no indication of meat-borne transmission was evident. Furthermore, the transmission of C. burnetii is most likely via vectors (i.e., ticks). In the absence of more detailed data for the European Union, it is advisable to focus on the efficacy of current game meat inspection and food safety management systems.

Spatio-Temporal Distribution of Brucellosis in European Terrestrial and Marine Wildlife Species and Its Regional Implications

Brucellosis is an important bacterial zoonosis of domestic and wildlife species. This disease has a significant public health concern and is characterized by reproductive failure resulting in economic losses in the livestock industry. Among thirteen known species, B. abortus, B. melitensis, B. suis, and B. canis are human pathogens. Brucellosis has been extensively investigated in humans and domestic animals. However, the situation in wildlife is still not completely reported and studied. Therefore, a systematic literature search and screening were done to clarify the situation of brucellosis in wildlife in Europe. Sixty-five articles from a total of 13,424 reports published between 1991 and 2021 were selected, applying defined inclusion criteria. Wild boars and brown hares were the most often studied terrestrial wildlife species, whereas seals and porpoises were the most often investigated marine wildlife. Poland, Croatia, and Belgium showed the highest seroprevalences of wild boars caused by B. suis biovar 2. In marine wildlife, brucellosis was mainly caused by B. ceti and B. pinnipedialis. Most samples were from carcasses. Thus, sera could not be collected. It is worrisome that B.abortus and B. melitensis were reported from both terrestrial and marine wild animals, posing a zoonotic threat to people exposed to wild animals. Currently, there is no approved vaccine available for wild animals. The main challenges are the development of specific diagnostics and their validation for use in wildlife.

First description of Eucoleus garfiai (Gallego and Mas-Coma, 1975) in wild boar (Sus scrofa) in Italy

Eucoleus garfiai (syn. Capillaria garfiai) is a nematode infecting lingual tissue of domestic and wild swine. Prevalence data for this parasite are scant and often related to accidental findings, occurring only in Japan and a few European countries. In this study, an epidemiological survey was performed in order to identify E. garfiai in wild boar from the Campania region, southern Italy. A total of 153 wild boar carcasses were inspected over the course of two hunting seasons (2019-2020). Histological examinations were performed on tongue samples fixed and stained with haematoxylin and eosin. The scraping of dorsal tongue tissue was carried out to collect adult worms for parasitological examination. Out of 153 wild boars, 40 (26.1%, 95% CI: 19.8-33.6%) tested positive for helminths and/or eggs in tongue tissues. Parasites were identified morphologically and identification was confirmed by molecular analysis of the 18S rRNA gene, showing a 99% nucleotide match with E. garfiai sequences available in literature. No statistically significant differences were found according to age, sex nor hunting province. Our findings agree with previous histopathological data confirming the low pathogenic impact of this nematode. The present study represents the first report of E. garfiai in wild boar from Italy.

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.

Lungworms (Metastrongylus spp.) and intestinal parasitic stages of two separated Swiss wild boar populations north and south of the Alps: Similar parasite spectrum with regional idiosyncrasies

Metastrongylus sp. is a lungworm with worldwide distribution in wild boars and other suids. In Switzerland, two wild boar populations are geographically divided by the Alps. We investigated 84 wild boars, 52 from north and 32 from south of the Alps, different in sex and age (juveniles, subadults, adults), shot between September and December 2018. The lungs were macroscopically examined and dissected for the detection of Metastrongylus specimens. Additionally, faecal samples were obtained from 55 animals and analysed by sedimentation/flotation and the mini-FLOTAC® method. Overall, 12′774 Metastrongylus sp. specimens were isolated: prevalence was 77.4% and mean burden 196.5 (range: 1–2589), with no significant differences between north (80.8%, 218.0) and south (71.9%, 157.4) nor between sexes and age groups. Macroscopically, dense nodular lesions associated with Metastrongylus sp. were present in 19 out of 65 (33.9%) positive lungs. Five Metastrongylus sp. were detected: M. pudendotectus (67.9%), M. salmi (63.1%), M. confusus (56%), M. apri (44%) and M. asymmetricus (17.9%), with a significant difference (p = 0.012) between north (32.7%) and south (62.5%) for M. apri. The lungworm population was female biased. The number of Metastrongylus sp. eggs in faecal samples did not correlate with worm burdens. Furthermore, the following endoparasites were detected: Isospora suis/Eimeria sp. (74.5%), Strongyloides suis (27.3%%), Trichuris suis (20.0%), Hyostrongylus rubidus/Oesophagostomum sp. (18.2%), Globocephalus sp. (9.1%), Capillaria sp. (7.3%), Ascaris suum (3.6%), Giardia sp. (3.6%) and Balantidium coli (1.8%), with significant differences for S. suis (north 36.1% > south 10.5%) and Globocephalus sp. (only south, 26.3%). Although geographically separated, both Swiss wild boar populations share similar parasite spectra, while also showing some regional idiosyncrasies partially explained by ecological and climatic factors. Despite their clinical relevance being unknown, accurate knowledge concerning the distribution of endoparasites in the wildlife reservoir is relevant to better understand risk factors for the domestic pig population.

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12′774 Metastrongylus sp. were isolated from wild boars north and south of the Alps.

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Metastrongylus prevalence was 77.4%, mean burden 196.5, five species were detected.

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No significant differences between wild boar sexes and age groups.

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Overall, similar parasite spectra with regional idiosyncrasies were identified.

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Known parasite occurrence is relevant to evaluate risk factors for domestic pigs.