Alaria alata mesocercariae in raccoons (Procyon lotor) in Germany

Detection of Spirocerca lupi and an unknown Trichinella-like nematode in raccoon (Procyon lotor)

The raccoon Procyon lotor (Carnivora: Procyonidae) is an invasive species of growing importance for the introduction of alien pathogens or as additional hosts for autochthonous pathogens in Europe, including zoonotic parasites. As the population is steadily increasing and outcompeting the red fox (Vulpes vulpes) in Germany, the consumption of raccoon meat raises concerns about pathogens they may transmit. Therefore the presence of Trichinella larvae was here investigated in muscle samples (n = 904) of raccoons from northern Germany. No Trichinella larvae were found, thus confirming the general low occurrence of this parasite in Germany. However, Spirocerca lupi (n = 12) and an unidentified Trichinella-like nematode (n = 1) were accidently detected in the examined samples. The first is not a zoonotic parasite but has a high veterinary relevance as it can cause severe diseases in dogs. It is the first documented autochthonous infection of this nematode in Germany. The larvae of an unidentified Trichinella-like nematode were found in high abundance in all examined muscles of one raccoon, though they could not be identified to species level. Histological investigation revealed intramuscular cystic structures. This is the largest study investigating muscular parasites of raccoons in Europe so far, which suggests that this invasive animal species is infected by S. lupi and by a yet unknown Trichinella -like parasite.

Invasive mammalian wildlife and the risk of zoonotic parasites

Invasive wild mammals are present in all continents, with Europe, North America, and the Asian-Pacific region having the largest number of established species. In particular, Europe has been the continent with the highest number of zoonotic parasites associated with invasive wild mammals. These invasive species may represent a major threat for the conservation of native ecosystems and may enter in the transmission cycle of native parasites, or act as spreaders of exotic parasites. Here, we review the role of invasive wild mammals as spreaders of zoonotic parasites, presenting important examples from Europe, America, and the Asia-Pacific region. Finally, we emphasize the need for more research on these mammals and their parasites, especially in areas where their monitoring is scantily performed.

SARS-CoV-2 and West Nile Virus Prevalence Studies in Raccoons and Raccoon Dogs from Germany

Unlike farm animals, wild animals are not subject to continuous health surveillance. Individual projects designed to screen wildlife populations for specific pathogens are, therefore, also of great importance for human health. In this context, the possible formation of a reservoir for highly pathogenic zoonotic pathogens is a focus of research. Two of these pathogens that have received particular attention during the last years are the novel severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2), due to its fast global spread and high impact to the human health, and, since its introduction into Germany, the flavivirus West Nile virus (WNV). Especially in combination with invasive vertebrate species (e.g., raccoons (Procyon lotor) and raccoon dogs (Nyctereutes procyonoides) in Germany), risk analysis must be done to enable health authorities to assess the potential for the establishment of new wild life reservoirs for pathogens. Therefore, samples were collected from raccoons and raccoon dogs and analyzed for the presence of SARS-CoV-2 and WNV infections in these populations. Molecular biological and serological data obtained imply that no SARS-CoV-2 nor WNV reservoir has been established in these two wild life species yet. Future investigations need to keep an eye on these invasive carnivore populations, especially since the close contact of these animals to humans, mainly in urban areas, would make animal-human transmission a challenge for human health.

A molecular survey of spotted fever group rickettsiae in introduced raccoons (Procyon lotor)

Background

The raccoon Procyon lotor (Linnaeus, 1758) (Carnivora; Procyonidae) is one of the most important and most intensively studied invasive mammal species in Europe. Within the last 30 years the raccoon has spread at an increasing rate, resulting in the establishment of local populations in various regions of Europe. In these newly colonised areas, gaps in knowledge of the raccoon’s biology concern not only most aspects of its ecology in a broad sense, but also its pathogens and parasites. Most micropathogens recorded hitherto in the raccoons that have colonised Europe have documented epizootic and zoonotic potential. Thus, it is considered especially important to investigate the role played by the raccoon in the spread of pathogens through both animal-animal and animal-human pathways.

Methods

Tissue samples of raccoons from Poland and Germany were examined in this study. In total, 384 tissue samples from 220 raccoons (170 spleen samples, 82 liver biopsies, 132 ear biopsies) were examined using molecular methods. The presence of Rickettsia spp. DNA was screened through amplification of a fragment of the gltA gene. Samples that were PCR positive for gltA were tested for other rickettsial genes, ompB and a 17-kDa antigen. For taxonomic purposes, the obtained sequences were compared with corresponding sequences deposited in GenBank using the Basic Local Alignment Search Tool, and phylogenetic analyses were conducted using Bayesian inference implemented in MrBayes software.

Results

Rickettsia DNA was confirmed only in skin biopsies; no isolates from the spleen or liver were positive for Rickettsia DNA. With the exception of one sample from Germany, which was positive for Rickettsia helvetica DNA, all the samples positive for Rickettsia DNA derived from the Polish population of raccoons. DNA of Rickettsia spp. was detected in 25 samples, i.e. 11.4% of the tested raccoons, and R. helvetica was confirmed in 52% of the positive samples. Additionally, single cases of Rickettsia monacensis, Rickettsia raoultii, and Candidatus Rickettsia kotlanii-like were found, and in 32% of all the positive samples similarity was shown to different Rickettsia endosymbionts. Out of the samples that tested positive for gltA, amplicons of ompB and 17 kDa were successfully sequenced from 14 and three samples, respectively.

Conclusions

To the best of our knowledge, this study provides, for the first time, evidence of the occurrence of Rickettsia pathogens and endosymbionts in the European population of raccoons. Further, broader research on different species of wild vertebrates, and ticks, as potential vectors and hosts for tick-borne pathogens, in natural as well as in peri-urban environments, is therefore required.

Graphical abstract

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 mesocercariae prevalence and predilection sites in amphibians in Latvia

Alaria alata is known as a trematode with a complex life cycle. The trematode Alaria alata infects amphibians as second intermediate hosts. In the present study, we examined 390 amphibians-European water frogs Pelophylax esculentus complex (n = 335), common frogs Rana temporaria (n = 19), moor frogs Rana arvalis (n = 3), and common toads Bufo bufo (n = 30) collected from randomly selected wetland habitats in Latvia. Out of all examined specimens, 80 were tadpoles and 310 were adult amphibians. Mesocercariae of A. alata was detected in 108 specimens from all examined amphibian species, except the common toad, reaching the overall prevalence of 27.7%. Tadpoles were found to be more frequently infected with A. alata, when compared with adults, 58.8% and 22.4%, respectively. The results showed that mesocercariae accumulate in visceral membranes, different internal organs, and muscles in the head area. This is a comprehensive study to identify A. alata mesocercariae predilection sites in amphibians.

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.

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.

Fecal survey of parasites in free-roaming cats in northcentral Oklahoma, United States

Cats can be infected by various intestinal parasites, some that are zoonotic. Although surveys of parasite prevalence in owned and shelter cats have been published, none addressed free-roaming, wild-trapped, domestic cat (Felis catus) populations. An opportunity to determine the prevalence of intestinal parasites in wild-trapped, free-roaming cats in northcentral Oklahoma, United States occurred through a trap-neuter-return (TNR) program conducted at Oklahoma State University, Boren Veterinary Medical Hospital, between February 2015 and April 2016. Approximately 1 g to 5 g of feces was collected from 846 free-roaming cats either from cage traps, when available, or rectally using disposable fecal loops and examined by centrifugal fecal flotation tests with 33% zinc sulfate solution. Parasite infections were confirmed by microscopic detection of eggs, cysts, or oocysts and visual detection of proglottids. Approximately 63.9% (541/846) of free-roaming cats were infected by at least one parasite, and 24.9% (211/846) of cats were infected by multiple parasites. The most common intestinal parasite infections detected were: Toxocara cati (44.6%; 377/846), followed by Alaria (13.4%; 113/846), Ancylostoma (11.2%; 95/846), Cystoisospora (9.7%; 82/846), taeniids (7.7%; 65/846), Dipylidium caninum (4.5%; 38/846), Physaloptera (2.2%; 19/846), Eucoleus aerophilus (1.4%; 12/846), Giardia (1.2%; 10/846), and a small (10-12 μm in diameter) Toxoplasma-like oocyst (0.1%; 1/846). A few ectoparasites, Demodex gatoi (0.5%; 4/846) and Cheyletiella (0.1%; 1/846), were also detected by fecal flotation. Our findings indicate that a higher prevalence of parasite infections occurs in free-roaming cats in Oklahoma than in owned cats, and these free-roaming cats contribute to contamination of the environment with several zoonotic parasites. Regional data on the prevalence of parasites in free-roaming cats can aid in the justification for parasite control programs in owned cats since both can share the same environment and supports the current practice of routine broad-spectrum anthelmintic and ectoparasite treatments for owned cats.

Alaria spp. mesocercariae in Eurasian badger (Meles meles) and wild boar (Sus scrofa) from the Białowieża Forest, north-eastern Poland

Alaria spp. mesocercariae are commonly found in wild boar and other omnivorous mammals. In Europe, the number of cases presenting Alaria mesocercariae infections has been on the rise in the last years. From October to December 2016, samples of muscle from tongue, neck, and mandibular regions were collected from 1 Eurasian badger (Meles meles) and 14 wild boars (Sus scrofa) hunted in the Białowieża Forest, north-eastern Poland. Using the Alaria migration technique (AMT), Alaria mesocercariae were isolated and morphologically identified in one badger and one wild boar. To the authors' knowledge, this is the first report of Alaria mesocercariae in paratenic hosts from the Białowieża Forest.

Epidemiological survey of zoonotic helminths in feral cats in Gran Canaria island (Macaronesian archipelago-Spain)

The presence of zoonotic parasites in feral cats have been widely considered all over the world. In Gran Canaria (Macaronesian archipelago, Canary Islands, Spain) the number of feral cats has grown out of control in urban and rural areas. 48 of Felis catus captured in different Gran Canaria areas were studied. Animals were necropsied and several organs were systematically examined in order to collect and identify macroscopic parasites. In addition, coprological tests were done in 28 cats. There were no statistically significant differences in the prevalence rate among sex, age or capture area, showing an overall prevalence of helminths of 77.1%. The most common tapeworms were Dipylidium caninum (64.6%) and Taenia taeniaeformis (31.3%), followed by the nematodes Toxocara cati (20.8%), Ancylostoma tubaeforme (18.8%), Aelurostrongylusabstrusus (10.4%) and Trichuris vulpis (2.08%). We also find several eggs of Alaria alata in the small intestine of one cat (2.08%), being the first description of this trematode in cats in the Canary Islands. Aproximatelly, 40% of the studied cats harboured more than one parasite. High rates of zoonotic species found in these animals suggest the need of controling parasitic infections and preventive measures against them.

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.

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.