The prevalence and distribution of Alaria alata, a potential zoonotic parasite, in foxes in Ireland

Predicting the risk of Alaria alata infestation in wild boar on the basis of environmental factors

Alaria alata is an emerging parasite that poses a potential risk for those consuming game, pork, snails and frogs. One paratenic host of A. alata that is known to play an important role in its spread through its feeding habitats is the wild boar. However, no statistical analysis of the influence of aquatic environments and carnivores on the occurrence of A. alata in wild boars has yet been performed. The present study combines a small-scale analysis based on hunting districts in the Mazowieckie province with a large-scale analysis based on data for all provinces in Poland. We applied various modeling approaches, including logistic regression and a generalized linear model in order to determine the presence, intensity and prevalence of A. alata. We used the Alaria mesocercariae migration technique (AMT) to estimate the risk of A. alata among wild boar in a given hunting district or province. The small-scale analysis found that mesopredators (red fox (Vulpes vulpes)) and racoon dog (Nyctereutes procyinoides) were likely to influence A. alata infestation of wild boar; however, the effect was weak, probably as a result of the large home range size of these animals. The large-scale analysis found that wetlands influence the prevalence of A. alata in wild boar, with the estimated risk increasing in the north of the country; this finding is consistent with other studies. Our findings indicate that the occurrence of A. alata in wild boar requires analysis on many levels, and environmental factors play a key role in risk assessment.

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Alaria alata presence in wild boar was locally dependent on the red fox density.

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Intensity of Alaria alata could be predicted locally by raccoon dog density.

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Wetlands were significantly explaining the occurrence of Alaria alata in voivodeships.

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Risk of Alaria alata prevalence in wild boar in Poland increase to the north.

Alaria alata in Terms of Risks to Consumers' Health

Alaria alata flukes are cosmopolitan parasites. In Europe, the definitive hosts are red foxes (Vulpes vulpes), wolves (Canis lupus), and raccoon dogs (Nyctereutes procyonoides), as well as animals that belong to the Felidae family. Intermediate hosts, such as snails and frogs, are the sources of infection for definitive hosts. The developmental stages of A. alata mesocercariae may occur in paratenic hosts, including many species of mammals, birds, and reptiles, as well as in wild boars (Sus scrofa), which are important from the zoonotic point of view. Because there are no regulations concerning the detection of A. alata in meat, this fluke is usually detected during official obligatory Trichinella spp. inspections. However, a method dedicated to A. alata detection was developed. The growing popularity of game and organic meat has led to an increased risk of food-associated parasitic infections, including alariosis, which is caused by the mesocercarial stage of A. alata. The aim of this article is to highlight the problem of A. alata as an emerging parasite, especially in the terms of the increasing market for game and organic meats that have been processed with traditional methods, often without proper heat treatment.

Predators in northern Germany are reservoirs for parasites of One Health concern

Urbanisation and invasion of wildlife into urban areas as well as human leisure activities create diverse wildlife-domestic animal-human interfaces, increasing the risk of (zoonotic) parasite spillover from sylvatic to domestic and synanthropic cycles. This study investigated the endo- and ectoparasite fauna, emphasising on parasites of One Health Concern, of the most common predators in northern Germany between November 2013 and January 2016. Eighty red foxes (Vulpes vulpes), 18 stone martens (Martes foina) and nine raccoon dogs (Nyctereutes procyonoides) were available for the study. Overall, 79 (73.8%) of the examined predators (n=107) harboured at least one endoparasite. The most frequently detected endoparasites in red foxes were Toxocara canis (43.8% positive individuals), Capillaria spp. (36.3%), Alaria alata (25.0%), Echinococcus multilocularis (26.3%) and Uncinaria stenocephala (25.0%). Furthermore, Toxascaris leonina, Trichuris vulpis, Taenia ssp., Mesocestoides spp. and coccidian oocysts were observed. The endoparasite species richness in raccoon dogs was comparable to red foxes, while in stone martens, only Capillaria spp. were found. Muscle digestion for detection of Trichinella spp. and antigen testing for Giardia spp. did not show positive results. Ectoparasite analyses revealed infestations with ticks species of the genus Ixodes as well as Dermacentor reticulatus. Scabies mites were not present in digested skin samples, while Demodex spp. mites were observed by faecal flotation in one red fox. Furthermore, fleas (Archaeopsylla erinacei and Chaetopsylla globiceps) were observed in the fur of red foxes, while lice were not present in any predator species. However, infestation frequency with ectoparasites was with 19.2% generally low in available predator skins (n=99). Overall, the present study showed that predators in northern Germany serve as reservoirs for parasites of One Health concern, with four of the five most frequent endoparasites being zoonotic, highlighting the need of parasite surveillance in wildlife predators in order to implement measures avoiding spillovers to domestic animals and humans.

The wild boar (Sus scrofa, Linnaeus, 1758) as an important reservoir host for Alaria alata in the Baltic region and potential risk of infection in humans

Alaria alata trematode is widely distributed throughout Europe and has a complex life cycle in which wild boar serve as a reservoir host. The primary aims of the present study are to establish the occurrence of A. alata mesocercariae in naturally infected wild boar in Latvia and to assess the risk for humans to acquire A. alata infection via consumption of wild boar meat. By summarizing long-term data using the Trichinella inspection method from 2014 to 2019, the overall A. alata prevalence was 8.3%, of which significantly higher A. alata prevalence was observed during the summer seasons. Additionally, 43.9% (n = 485) of wild boar were found to be infected with A. alata using Alaria mesocercariae migration technique. The present study indicates that the probability for humans to acquire A. alata mesocercariae is possible, yet improbable and varies from 0.2% to 2.2%. Most likely, it depends on both frequency of A. alata presence in wild boar population and of a method of preparing wild boar meat for consumption that will allow for the parasite inactivation.

Occurrence of Alaria alata in wild boars (Sus scrofa) in Poland and detection of genetic variability between isolates

Alaria alata is a trematode included among several emerging zoonotic parasites. The mesocercarial larval stage of A. alata named Distomum musculorum suis (DMS) may potentially be infective for humans. In the past, DMS was often observed in wild boar meat during the official Trichinella inspection by artificial digestion before a more specific and effective detection method, the A. alata mesocercariae migration technique (AMT), was introduced. In the present study, the AMT method was used to screen 3589 tissue samples collected from wild boars hunted in Poland during the 2015–2019 period. The survey mainly focused on the southern part of Poland with the majority of samples coming from Małopolskie, Świętokrzyskie, and Dolnoślaskie provinces; samples from ten additional provinces were also included. The total prevalence was 4.2% with mean abundance of 4.7 DMS. Occurrence was dependent upon environmental conditions (i.e., wetland habitats and water reservoirs) rather than on sex of the host or season in which they were hunted. The recovered trematodes were identified as Alaria spp. according to their morphological features. Molecular analysis of 18S rDNA and COI genes confirmed the species identification to be A. alata and documented genetic variability among the isolates.

Distribution of Parasitic Helminths in the Small Intestine of the Red Fox (Vulpes vulpes)

The aim of the study was to analyze the distribution of the main groups of parasitic helminths within the small intestine of the red fox on the example of animals coming from eastern Poland. Two hundred and sixteen red foxes shot in eastern Poland were used in the investigation. Before examination, each small intestine was divided into three equal parts: anterior (A), middle (M), and posterior (P). Each part was examined separately with the sedimentation and counting technique. Six different types of intestinal parasites were detected: Alaria alata (78.7%), Mesocestoides spp. (78.2%), hookworms (72.7%), Taenia spp. (53.2%), Toxocara/Toxascaris (43.1%), and Echinococcus multilocularis (18.5%). Alaria alata was most often found in A and in the only-A variant. Taenia spp. and Toxocara/Toxascaris occurred often in A and were the second (after A. alata) parasites in terms of frequency occurring in the only-A variant. Mesocestoides spp. was most commonly located in M. Parasites with predilection sites located mainly in M and P were E. multilocularis and hookworms. In all parasite species, the variant covering the entire intestine (A + M + P) was found in samples with a higher intensity compared to variants limited to one or two fragments. Our investigation, as one of the few of its type, conducted a comprehensive analysis of the distribution of intestinal helminths in the small intestine of the red fox. It showed significant differences in the distribution of parasitic helminths in the small intestine of the red fox. Determining typical predilection sites for parasites in the intestine can be helpful in creating effective diagnostic methods.

The occurrence of Alaria alata mesocercariae in wild boars (Sus scrofa) in north-eastern Poland

Various species of mammals, including humans and wild boars, can serve as paratenic hosts of Alaria alata mesocercariae – Distomum musculorum suis (DMS). Cases of DMS can be reliably detected by the recent introduction of the A. alata mesocercariae migration technique (AMT). The aim of this study is to present current data on the occurrence of DMS in wild boars in north-eastern Poland, and to compare the findings with those obtained in other European countries. A. alata was identified in 98 of 221 (44.3%) tissue samples of wild boar taken from five provinces in north-eastern Poland during the hunting seasons 2015–2016 and 2016–2017 based on AMT analysis. Positive results were found in all studied regions, but the percentage of infected individuals ranged from 26.3% in the Pomorskie province to 65.5% in the Warmińsko-Mazurskie province. The mean number of larvae exceeded seven larvae per 30 g sample for three provinces: Pomorskie, Mazowieckie and Lubelskie. In turn, lower values were found in the Warmińsko-Mazurskie province (3.3 larvae per 30 g), and the lowest in the Kujawsko-Pomorskie province (1.8 larvae per 30 g). The occurrence and intensity of A. alata infestation in wild boars was found to depend on the environment in which they live. Neither the sex or the age of the wild boar appeared to influence the occurrence nor the intensity of infestation.

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High percentage (44.3) of Alaria alata in samples of wild boars in Poland.

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High prevalence of A. alata infestation in wild boars compared to other reports.

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Sex does not affect the risk or intensity of infestation by A. alata in wild boars.

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Age does not affect the risk or intensity of A. alata infestation in wild boars.

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A. alata poses a potential risk for wild boar consumers in Poland.

First confirmed case of Alaria alata mesocercaria in Eurasian lynx (Lynx lynx) hunted in Latvia

Trematode Alaria spp. have a complex life cycle that includes canids, mustelids, and felids as definitive hosts. However, several mammal species, besides acting as definitive hosts, may also act as paratenic hosts. Alaria spp. life cycles are well studied. Still, there is a lack of knowledge on one host significance as both-the paratenic and definitive host, especially in the case of Eurasian lynx (Lynx lynx). Previous studies have described Eurasian lynx as a definitive host for A. alata although the prevalence has always been low. The aim of the present study was to analyze the occurrence of A. alata in Eurasian lynx in Latvia. The viscera (n = 231) and muscle samples (n = 234) from Eurasian lynx were collected during the hunting seasons from 2004/2005 to 2017/2018. The prevalence of the adult A. alata in Eurasian lynx was 1.7%. However, mesocercariae infection in Eurasian lynx was detected for the first time. These findings suggest that the Eurasian lynx may serve both as paratenic and definitive host for A. alata.

Prevalence of intestinal helminths of red foxes (Vulpes vulpes) in central Europe (Poland): a significant zoonotic threat

BACKGROUND

The red fox (Vulpes vulpes) is widely distributed in the world; in central Europe, it is the most numerous wild species of the family Canidae. It can play the role of a definitive host for many intestinal parasites, including zoonotic helminths. Poland, with its geographical location (central Europe), is an interesting area for parasitological investigations of this species. The aim of this study was to evaluate and compare the prevalence of intestinal helminths in red foxes in different regions of Poland.

METHODS

Intestines of 473 red foxes from four different regions were examined using the sedimentation and counting technique (SCT). In addition, 344 samples of faeces were examined using flotation.

RESULTS

Overall, intestinal helminths were found in 98.9% of red foxes. The average prevalence of detected parasites was as follows: Mesocestoides spp. (84.1%); hookworms (67.9%); Alaria alata (61.5%); Toxocara/Toxascaris (49.5%); Taenia spp. (42.5%); Echinococcus multilocularis (25.6%); and Trichuris vulpis (2.3%). The prevalence of the majority of parasite species was similar in each region. Significant differences between regions were observed in the case of E. multilocularis: a low prevalence in the south-western and northern regions (0% and 0.9%, respectively) and a high prevalence in the south-east and northeast (39.3% and 42.7%, respectively). In the case of A. alata, important differences were found between northern (96.5% and 93.7% in northern and northeast regions, respectively) and southern regions (15.2% and 24.7% for south-western and south-east regions, respectively). The percentage of positive samples obtained with coproscopic examination (except for Trichuris) was significantly lower than that obtained with SCT. Analysis of the prevalence estimated in individual regions with the use of both methods (flotation and SCT) showed a high correlation for all parasite species (except for Mesocestoides spp.). The flotation method also allowed us to detect the eggs of the lung nematode Eucoleus aerophilus (syn. Capillaria aerophila) (76.2% of positive foxes).

CONCLUSIONS

This study showed a very high percentage of red foxes infected with intestinal helminths in different parts of Poland. Depending on the location, some differences were observed regarding the prevalence of dangerous zoonotic parasites, which should be considered in the assessment of infection risk for humans.

Endoparasites of Wild Mammals Sheltered in Wildlife Hospitals and Rehabilitation Centres in Greece

Wildlife parasitic diseases represent an important field of investigation as they may have a significant impact on wild animals’ health and fitness, and may also have zoonotic implications. This study aimed to investigate the occurrence of endoparasites in wild mammals admitted to wildlife hospitals and rehabilitation centres in Greece. Sixty-five animals belonging to 17 species and originated from various areas of continental and insular Greece were included in the survey. The most numerous animal species examined were hedgehogs (n = 19), red foxes (n = 16), and European roe deer (n = 6). Faecal samples were collected individually and examined by floatation and sedimentation method. Parasites were found in 46 (70.7%) of the animals. Most parasites found in canids, felids, and ruminants are of great relevance to the domestic animals’ health and some of them are also of zoonotic importance. To the best of the author’s knowledge, this is the first report of endoparasites in hedgehogs, roe deers, fallow deers, badgers, and bats, and the first report of the pulmonary nematode Troglostrongylus brevior in a wild cat in Greece. The significance of the parasites found in each animal species in regard to their health and their relevance to domestic animals and human health is discussed.

Multiparasitism in a wild cat (Leopardus colocolo) (Carnivora: Felidae) in southern Brazil

Abstract Parasitic diseases reflect the health and balance of ecosystems, affecting not only individuals but also entire populations or communities. The aim of this study was to report on the diversity of parasitic helminths detected in the feces of a wild feline in southern Brazil. Parasites were obtained from fecal samples, and four techniques were used for parasitological examination: direct examination, centrifugal flotation with zinc sulfate (Faust technique), simple sedimentation (Hoffman technique) and Baermann-Moraes. The parasites were identified through micrometry and morphology, as follows: Ancylostoma sp., Toxocara sp., Trichuridae, Aelurostrongylus abstrusus, Alaria sp., and Spirometra sp. We recorded the genus Ancylostoma parasitizing L. colocolo for the first time.

The Increase of Exotic Zoonotic Helminth Infections: The Impact of Urbanization, Climate Change and Globalization

Zoonotic parasitic diseases are increasingly impacting human populations due to the effects of globalization, urbanization and climate change. Here we review the recent literature on the most important helminth zoonoses, including reports of incidence and prevalence. We discuss those helminth diseases which are increasing in endemic areas and consider their geographical spread into new regions within the framework of globalization, urbanization and climate change to determine the effect these variables are having on disease incidence, transmission and the associated challenges presented for public health initiatives, including control and elimination.

Prevalence and intensity of Alaria alata (Goeze, 1792) in water frogs and brown frogs in natural conditions

In the last 15 years, the mesocercariae of Alaria alata have frequently been reported in the wild boar during routine Trichinella inspections made compulsory for the trade of venison meat in Europe. If these studies have focused primarily on mesocercariae isolated from meat, few works have been done so far to understand the circulation of the parasite in natural conditions especially in the intermediate hosts. This study focuses on the second intermediate hosts of this parasite assessing the suitability of two amphibian groups-brown frogs and water frogs sensu lato-for mesocercarial infection on an area where A. alata has already been identified in water snails and wild boars. During this study, both groups showed to be suitable for mesocercarial infection, with high prevalence and parasite burdens. Prevalence was higher in the brown frog group (56.9 versus 11.54 % for water frogs) which would indicate that it is a preferential group for infection on the study area, though reasons for this remain to be investigated. No significant difference among prevalences was observed between tadpoles and frogs. This study, the first focusing on A. alata in these amphibians in Europe, provides further information on circulation of this parasite in natura.

Effect of temperature on the survival of Alaria alata mesocercariae

Recent findings of Alaria alata mesocercariae in wild boars and other animals in Europe reinforced the concern about the public health risk posed by this parasite especially if the game meat is insufficiently heated during preparation. Cooking and freezing are effective methods for the inactivation of parasites in meat whereas refrigeration is considered as an essential part of the Good Hygiene Practice. Additionally, microwave dielectric heating may represent an equally effective tool for parasite inactivation. Therefore, isolated vital mesocercariae were examined with respect to their resilience against heating, refrigeration, freezing, and microwave heating. A. alata mesocercariae stored in Ringer's solution do not survive heating temperatures that exceed 60.0 °C. Similarly, exposure to microwave heating ensured an inactivation of all parasite developmental stages after 90 s of treatment. In contrast, the parasites' tolerance towards cold is far higher as the mesocercariae survived refrigeration temperatures (4.0 ± 2 °C) in Ringer's solution for up to 13 days. An effective inactivation by cold is therefore only guaranteed if the infested game meat is frozen to a core temperature of -13.7 °C for a minimum of 2 h at least. Game meat should be handled with the same or even higher caution than meat of husbandry animals since wild animals may be infected with parasites or other zoonotic agents that are not common in livestock. It is therefore of crucial importance that appropriate temperature time protocols are used for the reliable inactivation of these zoonotic agents.

Effects of in vitro conditions on the survival of Alaria alata mesocercariae

The aim of this study was to determine the effect of different concentrations of table salt (NaCl) and ethanol (v/v) solutions on the viability of Alaria alata mesocercariae. Furthermore, the survival of A. alata mesocercariae during simulated human gastric digestion was evaluated. For this purpose, A. alata mesocercariae migration technique (AMT) was used for the isolation of the parasite from high-positive A. alata mesocercariae meat from wild boar, raccoon, raccoon dog, and badger meat. In total, we have studied the behavior of 582 larvae under different conditions (NaCl, ethanol, and artificial gastric juice) in three independent in vitro experiments. The larvae survived at a NaCl concentration of up to 2.0% until day 21 with a median survival time of 11 days. At 3.0% NaCl concentration, the larvae lost their vitality after less than 24 h. In addition, it was found that ethanol concentrations from 8.0 to 70.0% were effective at reducing survival of A. alata mesocercariae within a short period of time (<1 min). Finally, our studies have revealed that it required 120 min to reliably inactivate all A. alata mesocercariae within HCl-pepsin digestion solution with a pH of 1.5-2.0 at 37°C. Consequently, the results showed that 3.0% is the minimum concentration of NaCl in meat products recommended for human consumption because at lower NaCl concentration the parasite survived for a substantial period of time. Finally, the common concentrations of ethanol used for the disinfection of surfaces in household and/or laboratory, are sufficient for the inactivation of A. alata mesocercariae.

Tenacity of Alaria alata mesocercariae in homemade German meat products

A renewed interest in the pathogenic potential of Alaria alata mesocercariae emerged over the last 10years as a result of increased findings of this parasite in feral pigs during official examination for Trichinella spp. Cases of food associated human alariosis in North America suggest that a risk associated with the consumption of traditional raw cured products from infected wild boar meat cannot be neglected because the commonly applied preservation techniques may not necessarily kill the mesocercariae. In addition, changes in consumer behavior and new preparation methods for game meat (e.g. pink roasting and grilling) may increase the risk for food-associated parasitic infections. Thus, there is a strong need for the evaluation of the tenacity of A. alata mesocercariae against different physical and chemical influences as pertaining to common preservation and preparation techniques. Against this backdrop the aim of our work was a sound analysis of the survivability of A. alata mesocercariae during curing, fermentation, cold smoking and drying in raw cured meat products. Eighty three samples of traditional German meat products were prepared from naturally infected game meat and partly spiked with additional vital mesocercariae to achieve an adequate dose of infection. The resultant products were examined chronologically for dead and viable A. alata mesocercariae with the Alaria mesocercariae migration technique. After 24h of production, vital A. alata mesocercariae were still found in raw type sausages but no vital parasites were detected in the final products. Based on these results a possible risk for the consumer for an infection with A. alata mesocercariae through the consumption of contaminated raw cured products can be largely ruled out if the respective food technological procedures are carried out properly. However, a risk for the consumer cannot be excluded in cases of very early consumption of these products.

First detection of Alaria alata mesocercariae in wild boars (Sus scrofa Linnaeus, 1758) from Bulgaria

The trematode Alaria alata, an intestinal parasite of different carnivore species is widely distributed throughout Europe. The mesocercarial stages of Alaria spp. may infect almost all vertebrate species, including humans, and, in particular, omnivorous scavengers such as wild boars serve as paratenic hosts for the parasite. The introduction of the A. alata mesocercariae migration technique (AMT) opened the way to a reliable detection of Alaria spp. mesocercariae in different body tissues of their paratenic hosts. For the first time, it was possible to detect vital A. alata mesocercariae from two Bulgarian wild boars by means of this new method. In addition, polymerase chain reaction (PCR) examination of the respective parasitic DNA allowed the unequivocal species identification of the parasites as A. alata. Isolation and molecular biological identification of the parasite's developmental stages make significant contributions to completion of data on both the distribution of Alaria spp. in stocks of European game and the relationship between different Eurasian Alaria spp. isolates.