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Aim: Many fish species can harbour a wide range of pathogenic agents in their tissues. Of many pathogens, the parasitic nematode of genus Contracaecum, which resides in the tissues of fish species, can results in fish-borne infections in humans. This study was planned to assess consumers' awareness of fish-borne zoonoses in the fishing sites of Lake Chamo, Arba Minch, Ethiopia. The study was also aimed at demonstrating the zoonotic nematode, Contracaecum parasites in the Oreochromis niloticus and Lates niloticus fishes collected from Lake Chamo, Arba Minch, Ethiopia., Methods and Results: Assessment of awareness about fish-borne zoonoses was conducted in randomly selected participants (n = 162) using face-to-face interviews via a structured and semi-structured questionnaire. Besides, 70 fishes (O. niloticus = 35 and L. niloticus = 35) were examined for the presence of larva of Contracaecum and other anisakid genera through standard dissection, pepsin-hydrochloric acid digestion and microscopic observation. Consumers have inadequate awareness about fish-borne zoonoses based on the answers they provided to the questions. The majority of respondents (82%) consume raw fish in the area. Of these, a significantly higher proportion were male (p < 0.001), completed their elementary or high school (p = 0.004), Orthodox Christian (p = 0.044), fishermen (p < 0.001) and participants without previous information about fish-borne zoonoses (p < 0.001). Overall, of examined fishes (n = 70), n = 15 (21.4%, 95% CI, 12.8-33.2) were infected with Contracaecum larva. A significant (p = 0.028) higher infection prevalence was noted in L. niloticus (34.3%, 95% CI, 19.7-52.3) compared to O. niloticus (8.6%, 95% CI, 2.2-24.2). A unit gram addition in the total weight of fish would significantly raise the risk of Contracaecum infection by 1% (p < 0.001)., Conclusions: The presence of Contracaecum, a zoonotic nematode in the fishes, which are often preferred by consumers for raw dishes, designates a high risk of possible fish-borne infections in the area. Thus, providing education and training for fishermen, visitors of the area, and local people who visit the area for fish consumption, it is inevitably important to minimize the risk. Furthermore, health workers should suspect fish-borne infections, such as anisakidosis in patients who have a history of raw fish consumption in Arba Minch, Ethiopia., (© 2024 Wiley‐VCH GmbH. Published by John Wiley & Sons Ltd.)

Background: Parascaris spp. represent a significant threat to equine health worldwide, particularly in foals. The long-term survival of parasites in the host necessitates persistent modulation of the host immune response. Intercellular communication achieved through the exchange of molecules via extracellular vesicles (EVs) released from the parasite could be a crucial factor in this regard. This study aimed to isolate and characterize EVs released by adult male and female Parascaris worms and conduct a proteomic analysis to identify sex-specific proteins and potential immunomodulatory factors., Methods: Live adult Parascaris worms were collected, and EVs were isolated from spent culture media using differential ultracentrifugation. Nanoparticle tracking analysis and transmission electron microscopy confirmed the size, concentration, and morphology of the isolated EVs. Proteins within the isolated EVs were analyzed using mass spectrometry-based proteomics (LC-MS/MS)., Results: Proteomic analysis revealed a total of 113 proteins in Parascaris EVs, with several proteins showing homology to known helminth exosome proteins and exhibiting immunomodulatory functions. Sex-specific differences in EV protein composition were observed, with a distinct abundance of C-type lectins in female EVs, suggesting potential sex-specific roles or regulation. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses revealed metabolic pathways shared between male and female Parascaris EVs, as well as differences in signal transduction, and cell growth and death pathways, indicating sex-specific variations., Conclusions: These findings imply that Parascaris EVs and their protein cargo are complex. This data potentially opens avenues for discovering innovative approaches to managing and understanding helminth infection., (© 2024. The Author(s).)

Phalacrocorax brasilianus (Gmelin, 1789) (Aves: Phalacrocoracidae) is one of the few piscivorous birds inhabiting freshwater and saline environments, being considered one of the most abundant aquatic species in Rio Grande do Sul, Brazil, especially along the state's coastline. It is known that birds are hosts to a wide variety of disease-causing agents, among them, nematodes of the Contracaecum (Anisakidae) have a large number of recognized species. However, little is still known about the occurrence of these parasites in the Southern region of Brazil. Herein we identified for the first time Contracaecum australe Garbin, Mattiucci, Paoletti, González-Acuña, and Nascetti, 2011 (Nematoda: Anisakidae) parasitizing P. brasilianus in Southern Brazil. Nematodes found in the bird's proventriculus were subjected to morphometric analyses, by optical microscopy and scanning electron microscopy, and molecular analyses. Molecular phylogeny based on the analysis of the 18S, ITS-1, 5.8S and ITS-2 genes showed our sequences identical to those of C. australe. Therefore, this is the first record of C. australe in southern Brazil, expanding the geographical distribution of the parasite species in the country. Additionally, new molecular sequences are being provided, contributing to the knowledge of Contracaecum species parasitizing cormorants., Competing Interests: Declaration of competing interest The authors declare that there is no conflict of interest., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Anthelmintic resistance is an increasing problem in many gastrointestinal parasites of grazing animals. Among these, the equine roundworm, Parascaris spp., has developed wide-spread resistance to macrocyclic lactones over the past decades. Additionally, there are recent observations of emerging treatment failure of both tetrahydropyrimidine and fenbendazole. Therefore, the aims of this study were to further investigate the occurrence of fenbendazole resistance on breeding farms and to explore potential management-related risk factors associated with resistance in Parascaris spp. in Sweden. Eleven farms with 92 foals positive for Parascaris spp. were included in a faecal egg count reduction test during the years 2021-2023. According to the clinical protocol of the guidelines of the World Association for the Advancement of Veterinary Parasitology, fenbendazole resistance was present on four farms with efficacies varying from 45 % to 96 %. Having previously reported reduced efficacy on one of these farms, we can now confirm that fenbendazole resistance in Parascaris spp. has established. Farms with more than 40 yearly born foals had a significantly higher probability of having resistant Parascaris spp. Populations compared with smaller farms, (generalized linear model (GLM), t = 70.39, p < 0.001). In addition, there was a correlation between the number of foals on the farm and the frequency of yearly treatments showing that farms with < 20 foals were notably inclined to administer treatments twice during the first year (GLM, t=2.76, p < 0.05) in contrast to larger farms with > 40 foals that were using more frequent treatment intervals. In conclusion, this study confirms the establishment of fenbendazole resistance in Parascaris spp. populations on Swedish stud farms with the number of foals on the farm identified as a risk factor for development of anthelmintic resistance., Competing Interests: Declaration of Competing Interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Frida Martin reports financial support, article publishing charges, and statistical analysis were provided by Swedish-Norwegian Foundation for Equine Research. Eva Tyden reports financial support, article publishing charges, and statistical analysis were provided by Swedish-Norwegian Foundation for Equine Research. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)

In order to know whether there is a risk of anisakiasis (or anisakidosis) by consumption of fish of the genus Mullus from the western Mediterranean Sea, which are appreciated for their quality, an epidemiological survey was carried out to evaluate the occurrence of zoonotic or potentially zoonotic nematodes in M. barbatus and M. surmuletus. Although the presence of the third larval stage (L3) of anisakids (Anisakis and Contracaecum) has been previously described in these fish, the results showed the absence of anisakids and the presence, never in muscle, of L3 and L4 of raphidascaridids of the genus Hysterothylacium, molecularly identified as H. fabri. Phylogenetic analysis groups them into the Mediterranean Sea clade, far from individuals isolated in the Pacific Ocean. Prevalence was slightly higher, but not significant, in M. barbatus versus M. surmuletus (72.3% vs 60.0%), but mean intensity (MI) and mean abundance (MA) parameters were approximately twice as high in M. barbatus as in M. surmuletus (MI 5.8 vs 2.8, p = .001; MA 4.2 vs 1.7, p < .001). The presence of the parasite seems to have different effects on these two sympatric species. In M. barbatus it seems to affect their growth, as it appreciably reduces the value of allometry coefficient in infected fish (2.78 vs. 2.18). On the other hand, in M. surmuletus the infection significantly (p < .04) affects the Fulton's condition factor, an indicator of the health status of the fish. It can be concluded that the ingestion of these fish by the people poses negligible risk of anisakiasis, but the consumer should continue to be urged to follow the rules of prevention against this illness., (© 2024 The Author(s). Journal of Fish Diseases published by John Wiley & Sons Ltd.)

Nematodes collected from the intestine of sompat grunt Pomadasys jubelini Cuvier, 1830 from Hann Bay in Dakar, Senegal represent a new species described herein as Dichelyne (Neocucullanellus) dakarensis n. sp., and investigated with the use of light and scanning electron microscopy. The new species differs from its congeners based on several characteristics, especially because the subgenus Neocucullanellus is the only 1 that has 2 ceca. In addition, the new species diagnosis is based on the number and arrangement of the caudal papillae as well as the size of the veil of spicules. Morphological data were supported by molecular analysis. Results obtained using SSU rDNA and COI distinguished the present specimens from other cucullanids. Molecular data indicated the close relatedness between the new species and Dichelyne cotylophora Ward and Magath, 1917., (© American Society of Parasitologists 2024.)

Purpose: In this study, 143 lutjanid fishes representing four different species from the Northeast coast off Brazil were analyzed for parasites. The aim of the present study is to provide a detailed redescription of R. (I.) vicentei, collected from lutjanid fishes in Brazil, including the first observation of the species using scanning electron microscopy (SEM)., Methods: Nematodes found clarified in a crescent glycerin series, were photographed and measured (in mm), and some specimens destined for SEM. The Illustrations were made using an optical microscope with a drawing tube., Results: Nematodes found were identified as Raphidascaris (Ichthyascaris) vicentei, infecting 6.29% of the examined fish. Detailed morphological analysis revealed the following characteristics observed for the first time in this species: labial papillae, narrow lateral alae and the detailed structure of male spicules. These contributions help filling the gaps in the literature and expand the knowledge of this parasite morphology., Conclusions: The presence of R. (I.) vicentei in four lutjanid species may indicates low host specificity, highlighting its adaptability to different hosts. Furthermore, new host records are given. This research provides the most comprehensive morphological description of R. (I.) vicentei to date, generating crucial insights for a better understanding of the parasitic biodiversity off the Brazilian Northeastern coast of Brazil, as well as establishing foundation for future investigations on the ecology and impacts of these parasites in fish populations from this region., (© 2024. The Author(s), under exclusive licence to Springer Nature Switzerland AG.)

The bear roundworm Baylisascaris transfuga has been identified in several host bears (Ursinae). However, limited genetic information is available on the bear roundworm in Japanese populations. This study evaluated the genetic composition of bear roundworms isolated from wild Japanese black bears indigenous to Lake Towada, Japan. First, we conducted genetic and/or molecular phylogenetic analyses based on cytochrome c oxidase subunit II and internal transcribed spacer 2 among Baylisascaris species. These analyses revealed that the identified roundworms were genetically B. transfuga. In addition, the average body size of the obtained roundworms in this study was almost the same as that previously reported for B. transfuga. This study represents an important step in genetic research on the roundworm B. transfuga in Ursinae bears not only from Japan but also from the rest of the world.

Background: Heterakis gallinarum (H. gallinarum) is a common poultry parasite that can be found in the ceca of many gallinaceous bird species, causing minor pathology and reduced weight gain. Most infections go unnoticed in commercial flocks due to the dependence on fecal egg counts, which are prone to false-negative diagnoses. Furthermore, there is a lack of research on gastrointestinal nematodes that use molecular identification methods, which could be essential for rapid diagnosis and developing efficient control approaches. As a result, the study aimed to look at the cause of mortality in layer chickens induced by H. gallinarum in Egyptian poultry farms using morphological, ultrastructural, and molecular characterization. Histopathological, immunohistochemical, and cell-mediated immune responses from damaged cecal tissues were also examined., Results: Seventy bird samples from ten-layer flocks of different breeds (Native, white, and brown layers) suffering from diarrhea, decreased egg output, and emaciation were collected. Cecal samples were collected from affected and non-affected birds and were examined for parasitic diseases using light and a scanning electron microscope. The mitochondrial cytochrome oxidase 1 (COX1) gene was used to characterize H. gallinarum. Our results showed that the collected nematodal worms were identified as H. gallinarum (male and female), further confirmed by COX1 gene amplification and sequence alignment. Gene expression analysis of the inflammatory markers in infected tissues showed a significant up-regulation of IL-2, IFN-γ, TLR-4, and IL-1β and a significant down-regulation of the anti-inflammatory IL-10. The mRNA level of the apoptotic cas-3 revealed apoptotic activity among the H. gallinarum samples compared to the control group., Conclusions: Our results implemented the use of molecular methods for the diagnosis of Heterakis, and this is the first report showing the tissue immune response following infection in layers: upregulation of IL-1β, IFN-γ, Il-2, and TLR-4, while down-regulation of anti-inflammatory IL-10 in cecal tissue, Cas-3 apoptotic activity and Nuclear factor-κB (NF-κB)activity with immunophenotyping of T-cells in Heterakis infected tissue., (© 2024. The Author(s).)

Species of the genus Hysterothylacium are aquatic roundworms (nematodes) belonging to the family Raphidascarididae. Some species in this family are known to be associated with zoonotic diseases in humans after they consume their parasitic larvae in raw or undercooked fish. The aim of this research was to report the prevalence, morphology, and molecular characteristics of Hysterothylacium species in Pagellus erythrinus. A total of Two hundred fish were purchased from the fish market in Damanhour, Beheira Province, between December 2021 and November 2022 and subjected to examination. For molecular characterization, the internal transcribed spacer (ITS) region of nuclear ribosomal DNA and the mitochondrial cytochrome oxidase subunit 2 (COX-2) gene were used. Hysterothylacium species were morphologically described and identified from the intestine of Pagellus erythrinus in Beheira Province, Egypt. The PCR amplified 1087 bp and 629 bp of the target sequences of the ITS region and COX-2 gene, respectively. Sequence analysis revealed the Hysterothylacium thalassini species. The identified species provided novel biological data for the Hysterothylacium nematode in Pagellus erythrinus. The prevalence of Hysterothylacium species recovered from the intestine was 55%. The highest prevalence of 72% has been reported in summer compared to the lowest prevalence of 38% in the winter. Females had a higher prevalence of 61.8% than males, with 44.2%. The first detection, prevalence, and molecular characterization of H. thalassini in Pagellus erythrinus from Beheira Province, Egypt, was presented in this study., Competing Interests: Declaration of competing interest The authors declare that there are no conflicts of interest., (Copyright © 2024. Published by Elsevier B.V.)

Anisakid nematodes are a globally distributed group of marine mammal parasites. Kogiid whales, including the pygmy sperm whale Kogia breviceps, host an assemblage of specific anisakid species. Currently, three species are known to be specific to kogiid hosts, i.e., Skrjabinisakis paggiae, S. brevispiculata, and the less studied Pseudoterranova ceticola. The aim of this study was to investigate the species diversity of anisakid nematodes sampled from a pygmy sperm whale stranded in 2013 at the edge of its distribution range in the Northeast Atlantic, specifically in the North of Scotland. Nematodes were assigned to genus level based on morphology and identified by sequence analysis of the mtDNA cox2 gene and the rDNA ITS region. The present finding represents the first observation of syntopic occurrence of adult stages of S. brevispiculata, S. paggiae, and P. ceticola in a pygmy sperm whale in the Northeast Atlantic, and represent the northernmost record of these species in this area. Skrjabinisakis brevispiculata was the most abundant species, accounting for 55% of the identified nematodes, predominantly in the adult stage. Anisakis simplex (s.s.) was also abundant, with most specimens in the preadult stage, followed by S. paggiae and P. ceticola. The pygmy sperm whale is rarely documented in Scottish waters, and its occurrence in the area could suggest expansion of its geographic range. The presence of S. brevispiculata, S. paggiae, and P. ceticola in this whale species in this region may indicate a shift in the whole host community involved in the life cycle of these parasites in northern waters. However, it is also plausible that these parasites were acquired while the whale was feeding in more southern regions, before migrating northbound., (© P. Cipriani et al., published by EDP Sciences, 2024.)

The microbiome plays an important role in health, where changes in microbiota composition can have significant downstream effects within the host, and host-microbiota relationships can be exploited to affect health outcomes. Parasitic helminths affect animals globally, but an exploration of their microbiota has been limited, despite the development of anti-Wolbachia drugs to help control infections with some filarial nematodes. The equine ascarids, Parascaris spp., are considered the most pathogenic nematodes affecting juvenile horses and are also the only ascarid parasite to have developed widespread anthelmintic resistance. The aim of this study was to characterize the microbiota of this helminth, focusing on the female gonad, determine a core microbiota for this organ, identify bacterial species, and show bacterial localization to the female gonad via in situ hybridization (ISH). A total of 22 gonads were isolated from female Parascaris spp. collected from three foals, and 9 female parasites were formalin-fixed and paraffin-embedded for ISH. Next-generation sequencing was performed using V3-V4 primers as well as the Swift Amplicon™ 16S+ ITS Panel. Overall, ten genera were identified as members of the Parascaris spp. female gonad and twelve bacterial species were identified. The most prevalent genus was Mycoplasma, followed by Reyranella, and there were no differences in alpha diversity between parasites from different horses. Specific eubacteria staining was identified in both the intestine and within the gonad using ISH. Overall, this study provided in-depth information regarding the female Parascaris spp. microbiota and was the first to identify the core microbiota within a specific parasite organ., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Parascaris spp. infect foals worldwide and foals typically shed eggs in the feces from about three to six months of age, upon which natural immunity is incurred. High levels of anthelmintic resistance of Parascaris spp. are a global concern, and further understanding egg shedding patterns and fecal egg counting (FEC) data variability is of high importance. The aims of this study were to monitor Parascaris spp. egg shedding in untreated foals during 12-23 weeks of age, estimate sources of data variability, and assess precision of two ascarid FEC techniques. Fecal samples were collected weekly from 11 foals born in 2022, from May through November (29 weeks). Six subsamples were extracted from each weekly sample to determine 30 FECs between two techniques: a McMaster technique and an Automated Egg Counting System (AECS). Mixed linear modeling was carried out with age, sex, birth month, seasonality, spring- or summer-born foals, and egg counting technique as explanatory variables. Ascarid FECs were associated with age (p < 0.001), seasonality (p < 0.001), and technique (p < 0.001). The McMaster technique was more precise with a mean coefficient of variation (CV) of 34.57% and a 95% confidence interval (CI) of 30.80%- 38.30% compared to the CV for the AECS, which was 42.22% (CI: 37.70%-46.70%). Seasonality accounted for the highest proportion of variance (PV) of all covariates, but differences in PVs for covariates existed between techniques with foal age and subsample contributing more variance to the McMaster, and individual foal and seasonality contributing more to the AECS. Subsamples and replicate counts accounted for less than 1% of the total data variance. The results highlighted substantial differences in PVs between the two techniques at the subsample (AECS: 57.14%; McMaster: 77.51%) and replicate count levels (AECS: 42.86%; McMaster: 22.49%). While differences in precision were observed between the two FEC techniques, they were negligible in the data set, as the overwhelming majority of the data variability in ascarid FECs was attributed to individual foal, seasonality, and foal age., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)

The raccoon roundworm (Baylisascaris procyonis), a gastrointestinal nematode of the raccoon (Procyon lotor), may cause a severe form of larva migrans in humans, which can lead to death or permanent neurological damage. Although roundworms were inadvertently introduced to Europe alongside their raccoon hosts, the parasite is not present in every raccoon population. It is important to understand the geographic distribution of B. procyonis, as early and rapid treatment can prevent severe pathologies in humans. We present evidence for the roundworm spreading into a naive raccoon population through natural dispersal of infected raccoons. We sampled 181 raccoons from Saxony-Anhalt, a German federal state containing contact zones of different raccoon populations, two of which were previously free of the parasite. We screened the raccoons for roundworms and used microsatellite-based assignment tests to determine the genetic origin of the raccoons and their parasites. We detected roundworms in 16 of 45 raccoons sampled in a previously roundworm-free area in the northern part of the state. The largest proportion of the genetic ancestry (≥ 0.5) of the 16 raccoon hosts was assigned to the previously naive raccoon population. Conversely, the genetic ancestry of almost all the roundworms was assigned to the nearest roundworm population in the southern part of the state. Infected raccoons have, therefore, spread to the north of the state, where they interbred with and infected local raccoons. It seems likely that the roundworms will continue to spread. Health authorities should consider continuous surveillance programmes of naive populations and raise public awareness., (© 2023. The Author(s).)

Raccoon roundworm (Baylisascaris procyonis) negatively affects woodrat (Neotoma spp.) populations but is not known to occur in the endemic range of endangered Key Largo woodrats (Neotoma floridana smalli). Rectal swabs from 23 raccoons (Procyon lotor) in Key Largo were screened for raccoon roundworm by PCR. All tests were negative, suggesting continued absence., (© Wildlife Disease Association 2023.)

Background: The roundworms, Parascaris spp., are important nematode parasites of foals and were historically model organisms in the field of cell biology, leading to many important discoveries. According to karyotype, ascarids in Equus are commonly divided into Parascaris univalens (2n = 2) and Parascaris equorum (2n = 4)., Methods: Here, we performed morphological identification, karyotyping and sequencing of roundworms from three different hosts (horses, zebras and donkeys). Phylogenetic analysis was performed to study the divergence of these ascarids based on cytochrome c oxidase subunit I (COI) and internal transcribed spacer (ITS) sequences., Results: Karyotyping, performed on eggs recovered from worms of three different Equus hosts in China, showed two different karyotypes (2n = 2 in P. univalens collected from horses and zebras; 2n = 6 in Parascaris sp. collected from donkeys). There are some differences in the terminal part of the spicula between P. univalens (concave) and Parascaris sp. (rounded). Additionally, it was found that the egg's chitinous layer was significantly thicker in Parascaris sp. (> 5 μm) than P. univalens (< 5 μm) (F (2537) = 1967, P < 0.01). Phylogenetic trees showed that the sequences of Parascaris from Equus hosts were divided into two distinct lineages based on sequences of the COI and ITS., Conclusions: Comparing the differences in roundworms collected from three different Equus hosts, this study describes a Parascaris species (Parascaris sp.) with six chromosomes in donkeys. It is worth noting that the thickness of the chitinous layer in the Parascaris egg may serve as a diagnostic indicator to distinguish the two roundworms (P. univalens and Parascaris sp.). The Parascaris sp. with six chromosomes in donkeys in the present study may be a species of P. trivalens described in 1934, but the possibility that it is a new Parascaris species cannot be ruled out. Both karyotyping and molecular analysis are necessary to solve the taxonomic problems in Parascaris species., (© 2023. The Author(s).)

Baylisascaris procyonis, or raccoon roundworm, is an intestinal nematode parasite of raccoons (Procyon lotor) that is important to public and wildlife health. Historically, the parasite was uncommon in the southeastern US; however, the range of B. procyonis has expanded to include Florida, US. From 2010 to 2016, we opportunistically sampled 1,030 raccoons statewide. The overall prevalence was 3.7% (95% confidence interval=2.5-4.8%) of sampled individuals, and infection intensity ranged from 1 to 48 (mean±standard deviation 9.9±4.0). We found raccoon roundworm in 9/56 (16%) counties sampled, and the percent positive ranged from 1.1% to 13.3% of specimens collected per county. Including previously published data, B. procyonis was detected in 11 Florida counties. We used logistic regression to estimate the contribution of raccoon demographic variables and the presence of the endoparasite Macracanthorhynchus ingens to B. procyonis detection in Florida. Following the model selection process we found housing density, M. ingens presence, and urbanicity to be predictive of raccoon roundworm presence. We also found substantial among-county variation. Raccoon sex and age were not useful predictors. Public health officials, wildlife rehabilitators, wildlife managers, and others should consider any Florida raccoon to be potentially infected with B. procyonis, particularly in areas where housing density is high., (© Wildlife Disease Association 2023.)

Nematodes of the genus Contracaecum Raillet & Henry, 1912 (Anisakidae, Contracaecinae) have a worldwide distribution. The taxonomy of the genus Contracaecum is well-known nowadays due to several morphometric studies, scanning electron microscopy, and molecular biology. The aim of this work was to review, clarify, and summarize the valid species of the genus Contracaecum parasitizing piscivorous sea birds and mammals from both the Neotropical and Antarctic regions reviewing all scientific available papers and electronic searching data up to date. A checklist on Neotropical and Antarctic Contracaecum spp. was organized through a revision of scientific papers and original descriptions. The systematic online search and the most updated papers were obtained through SCOPUS, Google Scholar, PubMed, Medline, World Register of Marine Species, etc. We provide information about hosts, Neotropical and Antarctic localities where worms were collected, references, molecular markers, and Genbank accession numbers. Twenty-five Neotropical and Antarctic Contracaecum species have been recorded up to date and checked out as valid ones according to the most updated data. Twenty-one species parasitize exclusively fish-eating birds, two species were reported only on marine mammals, and the other two parasitize both sea birds and mammals. A total of 20 Contracaecum species are exclusively reported for the Neotropical region, three only for Antarctic hosts, and two species were reported parasitizing both Neotropical and Antarctic hosts. Several Contracaecum species (10) have been corroborated by molecular analysis of different genetic markers. After reviewing all morphological descriptions of the Contracaecum species, and despite most of them have been characterized only by morphometric methods, we are convinced that all species listed in this work correspond to good and valid Contracaecum Neotropical and Antarctic species. Present results indicate that more taxonomic and molecular studies are needed to advance the understanding of the distribution and host specificity of the Contracaecum species.

Gastrointestinal nematodes are ubiquitous parasites of grazing equines with Parascaris spp., and strongyles being the most relevant ones regarding the prevalence and potential disease severity. Despite their importance, epidemiological data regarding the presence and egg-shedding intensities of these parasites are scarce. Data from 1067 horse samples collected on German horse farms initially to compare diagnostic methods were used for epidemiological analyses. Due to its higher sensitivity, presence/absence data were based on a combined sedimentation/flotation technique while faecal egg counts were based on Mini-FLOTAC. For strongyles, 46.5% of the samples were positive and the median egg-shedding intensity was 40 (range 5-2590). In multivariate analyses, prevalence and egg-shedding intensity were significantly influenced by season, age group and sample type. The drug used for the last treatment and the number of foals on the yard only affected prevalence while the number of horses on the yard and sex were only significant for egg-shedding intensity. For Parascaris spp., a prevalence of 4.6% and a median egg-shedding intensity of 0 (range 5-905) were observed. In multivariate analyses, the age group, the time since the last anthelmintic treatment, presence and number of foals had significant effects on ascarid prevalence whereas egg-shedding intensity was significantly influenced by age group and season only. Parascaris occurred only on yards with foals, but with an increasing number of foals, Parascaris egg-shedding intensity decreased. Prevalence and egg-shedding intensity were influenced by different but partially overlapping variables for Parascaris and strongyles., (© 2023. The Author(s).)

Background: Parasitic nematodes, including large roundworms colloquially known as ascarids, affect the health and well-being of livestock animals worldwide. The equine ascarids, Parascaris spp., are important parasites of juvenile horses and the first ascarids to develop widespread anthelmintic resistance. The microbiota has been shown to be an important factor in the fitness of many organisms, including parasitic nematodes, where endosymbiotic Wolbachia have been exploited for treatment of filariasis in humans., Methods: This study used short-read 16S rRNA sequences and Illumina sequencing to characterize and compare microbiota of whole worm small intestinal stages and microbiota of male and female intestines and gonads. Diversity metrics including alpha and beta diversity, and the differential abundance analyses DESeq2, ANCOM-BC, corncob, and metagenomeSeq were used for comparisons., Results: Alpha and beta diversity of whole worm microbiota did not differ significantly between groups, but Simpson alpha diversity was significantly different between female intestine (FI) and male gonad (MG) (P= 0.0018), and Shannon alpha diversity was significantly different between female and male gonads (P = 0.0130), FI and horse jejunum (HJ) (P = 0.0383), and FI and MG (P= 0.0001). Beta diversity (Fig. 2B) was significantly different between female and male gonads (P = 0.0006), male intestine (MI) and FG (P = 0.0093), and MG and FI (P = 0.0041). When comparing organs, Veillonella was differentially abundant for DESeq2 and ANCOM-BC (p < 0.0001), corncob (P = 0.0008), and metagenomeSeq (P = 0.0118), and Sarcina was differentially abundant across four methods (P < 0.0001). Finally, the microbiota of all individual Parascaris spp. specimens were compared to establish shared microbiota between groups., Conclusions: Overall, this study provided important information regarding the Parascaris spp. microbiota and provides a first step towards determining whether the microbiota may be a viable target for future parasite control options., (© 2022. The Author(s).)

The equine ascarids, Parascaris spp., are important nematode parasites of juvenile horses and were historically model organisms in the field of cell biology, leading to many important discoveries, and are used for the study of chromatin diminution. In veterinary parasitology, Parascaris spp. are important not only because they can cause clinical disease in young horses but also because they are the only ascarid parasites to have developed widespread anthelmintic resistance. Despite this, much of the general biology and mechanisms of anthelmintic resistance are poorly understood. This review condenses known basic biological information and knowledge on the mechanisms of anthelmintic resistance in Parascaris spp., highlighting the importance of foundational research programs. Although two variants of this parasite were recognized based on the number of chromosomes in the 1870s and suggested to be two species in 1890, one of these, P. univalens, appears to have been largely forgotten in the veterinary scientific literature over the past 100 years. We describe how this omission has had a century-long effect on nomenclature and data analysis in the field, highlighting the importance of proper specimen identification in public repositories. A summary of important basic biology, including life cycle, in vitro maintenance, and immunology, is given, and areas of future research for the improvement of knowledge and development of new systems are given. Finally, the limited knowledge regarding anthelmintic resistance in Parascaris spp. is summarized, along with caution regarding assumptions that resistance mechanisms can be applied across clades., (© 2022. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

The geographic range of the zoonotic raccoon roundworm (Baylisascaris procyonis) is expanding together with the range of its host, the raccoon (Procyon lotor). This creates a new public health risk in parts of Europe where this parasite was previously absent. In the Netherlands, a raccoon population is becoming established and incidental findings of B. procyonis have been reported. To assess the risk to public health, the prevalence of B. procyonis was determined in the province of Limburg, where currently the largest Dutch raccoon population is present, as well as in the adjoining region of southern Belgium. Furthermore, genetic methods were employed to assess invasion pathways of both the raccoon and B. procyonis to aid in the development of control measures. Macroscopic analysis of intestinal content and testing of faecal samples were performed to detect B. procyonis adults and eggs. The population genetics of both B. procyonis and its raccoon host were analysed using samples from central and northwestern Europe. B. procyonis was found in 14/23 (61%, 95% CI: 41%-78%) raccoons from Limburg, but was not detected in 50 Belgian raccoons. Genetic analyses showed that the majority of the Dutch raccoons and their roundworms were introduced through ex-captive individuals. As long as free-living raccoon populations originate from captivity, population control methods may be pursued. However, natural dispersal from the border regions will complicate prolonged population control. To reduce the public health risk posed by B. procyonis, public education to increase awareness and adapt behaviour towards raccoons is key., (© 2021 Wiley-VCH GmbH.)

Due to the recent recovery of brown bear populations in Central Europe, information about their ascarid parasite, Baylisascaris transfuga is necessary as the parasite represents a part of natural ecological networks. B. transfuga can lead to larva migrans syndrome in accidental hosts, but its zoonotic potential has not been confirmed. The resent study compares development of larva migrans in infected mice inoculated with two infectious doses (ID 200 and ID 2000) of B. transfuga embryonated eggs, and the clinical manifestation to evaluate the pathogenicity of the larvae. Histopathology revealed that the liver was the most severely infected organ. The moderately infected organs included lung, brain, skeletal muscles and jejunum and the less infected ones were the eyes, heart, kidneys and spleen. The high pathogenicity of B. transfuga to mice was reflected in high mortality (33,3%) after infection, with mortality increasing with higher infectious dose. The results extend the knowledge of the interaction of B. transfuga and its aberrant hosts and contribute to the understanding of the epidemiology and transmission of this bears roundworm., (© 2022. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Baylisascaris procyonis is a nematode parasite of the raccoon (Procyon lotor), and it can be responsible for a severe form of larva migrans in humans. This parasite has been reported from many countries all over the world, after translocation of its natural host outside its native geographic range, North America. In the period between January and August 2021, 21 raccoons were cage-trapped and euthanized in Tuscany (Central Italy), in the context of a plan aimed at eradicating a reproductive population of this non-native species. All the animals were submitted for necroscopic examination. Adult ascariids were found in the small intestine of seven raccoons (prevalence 33.3%). Parasites have been identified as B. procyonis based on both morphometric and molecular approaches. The aim of the present article is to report the first finding of this zoonotic parasite from Italy, highlighting the sanitary risks linked to the introduction of alien vertebrate species in new areas., (© 2022. The Author(s).)

Cosmocercoid nematodes are common parasites in the digestive tract of amphibians. However, our knowledge of the species diversity, genetic data and molecular phylogeny of the superfamily Cosmocercoidea are far from being well understood. In the present study, large numbers of cosmocercoid nematodes were collected from the fine-spined frog Sylvirana spinulosa (Smith) (Anura: Ranidae) and the white-spotted thigh tree-frog Polypedates megacephalus (Hallowell) (Anura: Rhacophoridae) in Guangxi Province, China. Integrated morphological and genetic evidence reveals these nematode specimens to be a new species of the genus Aplectana, A. dayaoshanensis n. sp. (Cosmocercoidea: Cosmocercidae). The molecular characterization of small ribosomal DNA (18S), internal transcribed spacer (ITS) and large ribosomal DNA (28S) of A. dayaoshanensis n. sp., together with the 28S of A. chamaeleonis (Baylis, 1929) (collected from Hyperolius kivuensis Ahl in Rwanda), were reported for the first time. Moreover, phylogenetic analyses using maximum likelihood (ML) inference based on 18S + 28S and ITS sequence data, respectively, both supported the family Cosmocercidae to be a monophyletic group and the family Kathlaniidae to be a paraphyletic group. Our phylogenetic results rejected the monophyly of the genus Aplectana. The present results contribute to the knowledge of the species diversity and genetic data of cosmocercoid nematodes, and preliminarily revealed the phylogenetic relationships of the major families and some genera in the Cosmocercoidea., (Copyright © 2021 The Authors. Published by Elsevier B.V. All rights reserved.)

Contracaecum species are economically important fish-borne larval nematodes with zoonotic significance. In June 2019, more than 100 piscivorous birds died in their habitats close to the Wild Duck Lake, located in Yanqing, northwest of Beijing, China. Post-mortem examination of Black Night Herons (Nycticorax) revealed the presence of numerous anisakid nematodes in the proventriculus. Recovered nematodes were identified as Contracaecum sp. based on morphological description. Phylogenetic analysis of the mitochondrial (mt) genome and the ITS gene showed that sequences of Contracaecum sp. Beijing isolates were grouped into a new individual cluster. Furthermore, the parasite was successfully isolated from fresh dead birds, feces of piscivorous birds, and fish and prevalence ranged from 8.0% to 81.8%. Consequently, our study demonstrated Contracaecum sp. infections in different sources from China, which might constitute a threat to wildlife, aquaculture, and public health., (© 2020 International Society of Zoological Sciences, Institute of Zoology/Chinese Academy of Sciences and John Wiley & Sons Australia, Ltd.)

Baylisascaris procyonis is a common gastrointestinal parasite of raccoons (Procyon lotor) in their native range, and both have been introduced to Europe. Humans may ingest ascarid eggs shed via the racoons' faeces, and this could lead to severe infections affecting the central nervous system. Here, we report the first occurrence of B. procyonis in Austria. The parasite was detected in a two-year-old male raccoon that was road-killed in November 2019 near Hittisau (Vorarlberg). Genetic profiling provided strong evidence that the raccoon (and its parasite) originated from the nearest German raccoon population. The first finding in Austria highlights the need for monitoring the parasite and information of the public and practitioners., (© 2020 The Authors. Transboundary and Emerging Diseases published by Wiley-VCH GmbH.)

A wild adult male giant panda that was rescued from a nature reserve in Sichuan Province, China, has died. The panda had been in poor physical condition: it was wheezing and had increased serum amylase. A pathological examination was performed in order to determine the cause of death. Gross examination revealed 1380 mL of yellowish fluid in the abdominal cavity, 356 nematodes in the digestive tract and one filling the pancreatic duct, contractions and variably-sized dark purple areas in the spleen, a collapsed right lung and consolidation of the left lung. Acute pancreatitis was confirmed histopathologically via edema, focal necrosis and hemorrhage with inflammatory cell infiltration. Other major histopathological changes included serous-hemorrhagic pneumonia, lymphocytic necrosis and depletion in the spleen, and degeneration and necrosis of renal tubular epithelial cells. The nematodes were identified as Baylisascaris schroederi via molecular assays. In conclusion, the cause of death of the giant panda was determined to be multiple organ dysfunction syndrome caused by baylisascariasis-induced acute pancreatitis. To our knowledge, this is the first report of fatal baylisascariasis-induced acute pancreatitis in the giant panda., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Background: Strongylid and ascarid parasites are omnipresent in equine stud farms, and ever-increasing levels of anthelmintic resistance are challenging the industry with finding more sustainable and yet effective parasite control programs., Objectives: To evaluate egg count levels, bodyweight and equine health under defined parasite control protocols in foals and mares at two Standardbred and two Thoroughbred stud farms., Study Design: Longitudinal randomised field trial., Methods: A total of 93 foals were enrolled and split into two treatment groups, and 99 mares were enrolled and assigned to three treatment groups. All horses underwent a health examination, and episodes of colic or diarrhoea were recorded at each faecal collection date. Bodyweights were assessed using a weight tape, and mares were body condition scored. Group A foals (FA) were dewormed at 2 and 5 months of age with a fenbendazole/ivermectin/praziquantel product, while group B foals (FB) were dewormed on a monthly basis, alternating between the above-mentioned product and an oxfendazole/pyrantel embonate product. Group A mares (MA) were dewormed twice with fenbendazole/ivermectin/praziquantel, group B mares (MB) were dewormed with the same product, when egg counts exceeded 300 strongylid eggs per gram, and group C mares (MC) were dewormed every 2 months, alternating between the two products. Health data were collected monthly for 6 months (foals) and bimonthly for 13 months (mares). Data were analysed with mixed linear models and interpreted at the α = 0.05 significance level., Results: There were no significant bodyweight differences between foal groups, but MA mares were significantly lighter than the other two groups. Very few health incidents were recorded. Foals in group FA had significantly higher ascarid and strongylid egg counts, whereas no significant differences were observed between mare groups., Main Limitations: Study duration limited to one season., Conclusions: Anthelmintic treatment intensity was lowered from the traditional intensive regimes without measurable negative health consequences for mares and foals., (© 2020 EVJ Ltd.)

Porrocaecum angusticolle is a nematode species mainly parasitic in the birds of Accipitriformes and Strigiformes. However, some aspects of the morphology of P. angusticolle remain insufficiently known. In the present study, the detailed morphology of P. angusticolle was studied using light and, for the first time, scanning electron microscopy, based on newly collected specimens from the common buzzard Buteo buteo (Linnaeus) (Accipitriformes: Accipitridae) in Czech Republic. Some previously unreported morphological features of taxonomic significance were observed. The nuclear and mitochondrial DNA markers, including partial large ribosomal DNA (28S), complete internal transcribed spacer (ITS-1 + 5.8S + ITS-2), cytochrome c oxidase subunit 1 (cox1) and subunit 2 (cox2) of P. angusticolle were sequenced for molecular identification of this species. There was no intraspecific genetic variation detected in the 28S and ITS regions among different individuals of P. angusticolle, but low level of intraspecific nucleotide divergence was found in the cox1 (0.26-0.78%) and cox2 regions (1.0%). The 28S and cox2 of P. angusticolle were sequenced for the first time. Our molecular evidence supported the validity of both P. angusticolle and P. depressum. The newly obtained genetic data are helpful for further studies of DNA-based taxonomy, population genetics and phylogeny of the genus of Porrocaecum., (Copyright © 2021 Elsevier B.V. All rights reserved.)

The scarce information on the helminth fauna in otariids from the Southeastern Pacific comes mainly from stranded individuals or killed for that purpose. In this study, we compared the abundance and composition of enteroparasitic assemblages of Otaria flavescens using coprological techniques. Three sampling localities from north to south spanning 2,200 km off the Chilean coast were considered (Iquique, Viña del Mar, and Talcahuano). In all, 60 fecal samples were collected, and eggs belonging to 5 taxa were found in 91.6% of the samples. They were the anisakid nematodes Contracaecum and Pseudoterranova, the cestode Adenocephalus (syn. Diphyllobothrium), the trematode Ogmogaster, and the acanthocephalan Corynosoma. Samples from southern Chile (Talcahuano) showed the highest prevalence. Adenocephalus eggs had the highest prevalence and abundance in Iquique and Talcahuano, whereas Ogmogaster was the less prevalent and abundant in all sampling localities. Corynosoma eggs had similar prevalence and abundance among sampling localities, and Pseudoterranova eggs were absent in Iquique and with median prevalence values in Viña del Mar and Talcahuano. Thus, the composition of parasite egg assemblages was different between sampling localities. These differences between sampling localities may help to explain differential records of some zoonotic parasitoses such as pseudoterranovosis and diphyllobothriosis in Peru and Chile, where consumption of raw or marinated fish (ceviche) is common. For example, the lower diversity of parasite egg assemblages in the northern Chilean coast may be due to the absence or lower abundance of first intermediate/paratenic hosts of Pseudoterranova., (© American Society of Parasitologists 2021.)

Background: Equine ascariosis, caused by Parascaris spp., is a worldwide endoparasitic disease affecting young horses in particular. Despite the great number of horses reared in Italy, large-scale epidemiological surveys dealing with ascariosis prevalence in the country are not reported in the current literature. For this reason, the present survey aims to describe, for the first time, the spread and infestation of Parascaris spp. in a large population of Italian horses (6896 animals) using faecal egg counts, and further to identify risk factors associated with ascarid egg shedding., Methods: Individual rectal faecal samples collected during routine veterinary examinations were used and Parascaris spp. prevalence was tested against the animal's age, sex, housing conditions, geographic provenance as well as the respective sampling season., Results: Among the examined stables, 35.8% showed at least one horse to be positive for Parascaris spp. eggs and an overall prevalence of 6.3% was found. Ascariosis rates tended to decrease significantly with age and, proportionally, 80.0% of the recorded Parascaris spp. eggs were found in 0.7% of the examined animals. Statistically significant differences among prevalence rates were found between the different geographic areas of provenance and prevalence was found to be higher in horses reared outdoors compared to those raised indoors. Analysis of data based on sex and season did not show any significant differences. Despite the lower prevalence found compared to other European countries, ascariosis was concluded to represent a significant health challenge for horses reared in Italy, especially foals. Age (foals and yearlings) and outdoor rearing were identified to be significant risk factors for Parascaris spp. egg shedding. Furthermore, the relevance of the infected horses over 6 years of age should not be underestimated as these represent a significant source of contamination for younger animals., Conclusions: The development of improved treatment protocols based on regular faecal examination combined with follow-up assessment of the efficacy of integrated action plans would prove beneficial in regard to animal health and anthelmintic resistance reduction in the field.

Sequences of the mitochondrial cytochrome c oxidase 1 (COI) gene of 115 Baylisascaris procyonis individuals from 13 U.S. states and 1 Canadian province were obtained from 44 raccoon hosts to assess genetic variation and geographic structure. The maximum genetic distance between individuals was low (1.6%), consistent with a single species. Moderate COI haplotype (h = 0.60) and nucleotide (π = 0.0053) diversity were found overall. Low haplotype diversity was found among samples east of the Mississippi River (h = 0.036), suggesting that historical growth and expansion of raccoon populations in this region could be responsible for high parasite gene flow or a selective sweep of B. procyonis mtDNA. There was low genetic structure (average Φst = 0.07) for samples east of the continental divide, but samples from Colorado showed higher diversity and differentiation from midwestern and eastern samples. There was marked genetic structure between samples from east and west of the continental divide, with no haplotypes shared between these regions. There was no significant isolation by distance among any of these geographic samples. The phylogeographic patterns for B. procyonis are similar to genetic results reported for their raccoon definitive hosts. The phylogeographic divergence of B. procyonis from east and west of the continental divide may involve vicariance resulting from Pleistocene glaciation and associated climate variation., (© American Society of Parasitologists 2021.)

Different species of the genus Ophidascaris (Baylis, 1921; Nematoda: Ascaridida, Ascaridoidea) are intestinal parasites of various snake species. More than 30 Ophidascaris species have been reported worldwide; however, few molecular genetic studies have been conducted on this genus. We sequenced the complete mitogenome of Ophidascaris wangi parasitizing two snake species of the family Colubridae, i.e., Elaphe carinata (Günther, 1864) and Dinodon rufozonatum. The mitogenome sequence of O. wangi was approximately 14,660 base pairs (bp) long and encoded 36 genes, including 12 protein-coding genes (PCGs), 2 ribosomal RNA (rRNA) genes, and 22 transfer RNA genes. Gene arrangement, genome content, and transcription direction were in line with those in Toxascaris leonina (Linstow, 1902; Ascaridida: Ascarididae). Phylogenetics of O. wangi and other ascaridoids were reconstructed based on the concatenated amino acid sequences of 12 PCGs, and on nucleotide sequences of 12 PCGs and two rRNA genes. Phylogenetic analyses were performed using maximum likelihood and Bayesian inference methods, and the results suggested that O. wangi constitutes a sister clade of Ascaris, Parascaris, Baylisascaris, and Toxascaris within the family Ascarididae, which is a sister clade of Toxocaridae. The mitogenome sequence of O. wangi obtained from the present study will be useful for future identification of the nematode worms in the genus Ophidascaris and will increase the understanding of population genetics, molecular epidemiology, and phylogenetics of ascaridoid nematodes in snakes.

This study aimed to determine the integrative characterisation of nematodes from three species of edible flathead fishes (Scorpaeniformes: Platycephalidae) in New South Wales, Australia, and describe nematode communities within three species of flatheads. Tiger (Platycephalus richardsoni (Castelnau); n = 20) and sand flatheads (Platycephalus bassensis (Cuvier); n = 20), sourced from the Nelson Bay area, and dusky flathead (Platycephalus fuscus (Cuvier); n = 20) from the Manning River, Taree, were examined for the presence of nematodes. The nematodes were initially classified morphologically as 12 different morphotypes belonging to the families Anisakidae (Anisakis types I, II, and III, Contracaecum type II, Terranova types I and II), Raphidascarididae (Hysterothylacium types IV, VI, VIII, and H. zhoushanense larva), and Gnathostomatidae (Echinocephalus sp. larva), Capillariidae (Capillaria sp.), followed by genetic identification through sequencing of the internal transcribed spacer (ITS-1, 5.8S, ITS-2) regions. Phylogenetic analyses revealed the evolutionary relationship between the identified larval specimens in the present study with available GenBank larval and adult nematodes. Sand flathead was 90% infected with nematodes followed by tiger flathead at 85% and dusky flathead at 15%. Nematodes infecting estuarine dusky and oceanic sand and tiger flatheads contrasted markedly. The analysis of similarities (ANOSIM) showed significant differences (p < 0.001) in the composition of taxa within nematode communities between the three species of flatheads (global R = 0.208) with the highest difference being between sand and dusky flatheads (R = 0.308, p < 0.001). The findings of the present study provide a foundation for future investigations of the community composition, life cycles, and distribution of nematode populations in edible fish in Australia and explore and clarify their significance to public health.

Horses in Iceland have been isolated for more than 1,000 yr but still harbor a similar range of gastrointestinal parasites as do horses across the world. The long isolation of the horses and their parasites presumably means that no resistance genes have been introduced into the Parascaris spp. population. It is therefore of particular interest to investigate the efficacy of ivermectin on Parascaris spp. infecting Icelandic foals. Potential treatment failure of ivermectin in Iceland will add substantial new information on how resistance can arise independently. This study aimed to determine the efficacy of subcutaneous injection of ivermectin for the treatment of Parascaris spp. infection in foals and to identify the Parascaris species present in the west and north of Iceland. A fecal egg count reduction (FECR) test (FECRT) was performed on 50 foals from 8 farms, including an untreated control group of 6 foals, from September to November 2019. The foals were between 3 and 5 mo of age at the start of the study and had not previously been treated with anthelmintic drugs. Each foal was treated subcutaneously with off-label use of Ivomec® injection 10 mg/ml or Noromectin® 1% at a dose of 0.2 mg/kg. The FECR for each farm was calculated in 2 ways, by the eggCounts package in R and by the Presidente formula (FECRT). Both calculation methods resulted in efficacy levels between 0% and 80.78%, indicating ivermectin resistance on all farms. We also confirmed, by karyotyping, that the species of equine ascarid present in the west and north of Iceland is Parascaris univalens. This study provides evidence for treatment failure of ivermectin against P. univalens infection in foals. Since Icelandic horses have been isolated on the island for more than 1,000 yr, this implies that resistance alleles have developed independently in the Icelandic Parascaris population. The actual clinical impact of ivermectin resistance is unknown but another drug of choice should be considered to treat Parascaris infection in foals in Iceland., (© American Society of Parasitologists 2021.)

Cryptosporidium spp. are apicomplexan parasites of public health concern. They are one of the main causes of intestinal diseases in humans and animals. Contaminated water is among the main sources of infection for humans and mammals. Raccoons are an introduced species in Germany. They are anthropogenic adapters with a natural affinity for water bodies. We collected samples from wild raccoons in the Federal States of Saxony and Thuringia, Central Germany. Through molecular genotyping, we found Cryptosporidium sp. skunk genotype in one raccoon from Saxony (1/24) and in one animal from Thuringia (1/27). Both raccoons were also infected with the zoonotic nematode Baylisascaris procyonis. This is the first report of co-infection with these two parasites in raccoons from Germany. Our study highlights the potential of these animals as carriers of zoonotic pathogens. Since raccoons can thrive in human settlements, this study provides data that can be used as a baseline for preventive programs., Competing Interests: Declaration of Competing Interest All authors declare they have no competing interests., (Copyright © 2020 Elsevier B.V. All rights reserved.)

An American white pelican migrating through Iowa, USA exhibited regurgitation and anorexia. At the time of necropsy, numerous nematodes were observed in the crop and proventriculus with evidence of proventriculitis. Nematodes were identified as Contracaecum spp. based on morphological features of the adult worms and eggs. Species level identification of C. fagerholmi were made using nucleotide sequence analysis of the partial cox2 gene. Contracaecum infections are highly prevalent in piscivorous birds that acquire the infection by ingesting fish infected with larval stages of the parasite. Considering the possible zoonotic nature of Contracaecum, humans whose diets include uncooked fresh-water and/or marine fish should handle fresh fish with care, as these may harbor immature stages of Contracaecum spp., (Copyright © 2020 Elsevier B.V. All rights reserved.)

In the spring of 2019, adult (75 wk old) brown laying hens from a commercial, pen-free, egg-laying facility (11,000 birds per house) located in northwest Arkansas were obtained for the purposes of sourcing robust and evenly dispersed cestode infections for anticipated anthelmintic evaluations. To that end, four birds from each of six discrete sites (northwest, northcentral, northeast, southwest, southcentral, and southeast) in one production barn were obtained on two occasions, 8 days apart, and necropsied for helminth counts. A definite, repeated, location-to-location variation in infection incidence and magnitude was seen for each of the two cestode parasite species present and for one of the two nematode parasite species present. Burdens of Ascaridia galli were generally similar regardless of bird location, with site-specific mean totals per bird over both sampling days between 31 and 80. For the remaining helminths, infections were greatest for birds from the southern half of the building as opposed to the northern and from the western end of the barn as opposed to the central or eastern portions. Location-specific mean worm burdens over both sample dates ranged from 340 to 1133 (Heterakis gallinarum), 14 to 277 (Raillietina cesticillus), and 1 to 35 (Choanotaenia infundibulum). The greatest individual bird infections were 299 (A. galli), 3575 (H. gallinarum), 1015 (R. cesticillus), and 102 (C. infundibulum). The above counts are for all developmental stages combined (A. galli and H. gallinarum) and for scolexes only (R. cesticillus and C. infundibulum), as determined via standard collection and quantification procedures using both intestinal contents and overnight soaks. Immediately before the mapping study outlined above, birds were obtained from the east end of the source barn and used for the nematocidal evaluation of fenbendazole in the water (5 mg/kg body weight [BW] for 1 day), levamisole in the water (8 mg/kg BW for each of 2 days), herbal mixture in the feed (1 gm/4.5 kg BW each day for 5 days), diatomaceous earth (2% of total feed for 10 days), and a nutraceutical mixture feed supplement (2% of feed for 7 days). Based on arithmetic means for adult forms, control trial efficacies for A. galli and H. gallinarum were 0% and 12% for the nutraceutical feed additive, 0% and 22% for the diatomaceous earth feed additive, 0% and 26% for dietary herbals, 87% and 63% for levamisole, and 82% and 84% for fenbendazole, respectively. Only adult burdens of A. galli and H. gallinarum for fenbendazole- and levamisole-treated birds were significantly different from control bird levels (P ≤ 0.05).

The prevalence of Heterakis infection in reproductive geese from 56 flocks was investigated between February 2015 and November 2019 by using both anatomopathologic and coproscopic examinations. The nematodes were microscopically examined, and 37.5% (21/56) of the flocks were infected with Heterakis nematodes, mostly with Heterakis dispar (35.7%). In one particular flock, a Heterakis gallinarum infection was noted. In two flocks, Heterakis infection was identified only during coproscopic examination. The infection susceptibility of the geese depended on the bird's age-in the first reproductive season, 50% of the flocks were positive; in the second season, 42% were positive; and in the third season, 30% were positive. The number of nematodes in each necropsied goose varied from 8 to 216 individuals. During the 5 years of epidemiologic analysis, the infection occurrence decreased from 66.7% to 11%.

Contracaecum sp. nematodes are important parasites of fish eating birds that can cause animal health problems. In the present study, specimens of Contracaecum rudolphii sensu lato, from the great cormorant Phalacrocorax carbo sinensis from Sardinia, were characterized based on morphological and molecular data. The morphological analysis allowed to identify all the fourth stage larvae (n = 1918) as Contracaecum sp., and adults, male (n = 5845) and female (n = 8312), as C. rudolphii sensu lato. Population genetics and phylogenetic relationships were inferred based on mitochondrial and nuclear markers. Multiple sequence alignment of the ribosomal internal transcribed spacer showed the coexistence of C. rudolphii A (n = 157), C. rudolphii B (n = 22) and a rare heterozygote of these species. Moreover, mitochondrial markers, namely NADH dehydrogenase subunits I (nad1), cytochrome c oxidase subunit (cox1 and cox2) and small subunit of rRNA (rrnS), showed that the studied C. rudolphii A populations had undergone bottleneck, or founder effect event, subsequent to a rapid population growth and expansion. The observed heterozygote is with a mitochondrial pattern of C. rudolphii B. Although, both Contracaecum species showed high genetic diversity, no genetic structure between localities was detected. Phylogenetic reconstructions supported the paraphyly of the avian Contracaecum species including C. ogmorhini (parasite of otariids).

The taxonomy of Hysterothylacium genus in Mediterranean waters remains incomplete and unresolved. The aim of the current study was to investigate the morphological and molecular identification of selected species of Hysterothylacium larvae in marine fish from the Tunisian Mediterranean coasts. A total of 192 marine fish samples were examined. In total, thirty-seven third-stage larvae of Hysterothylacium were morphologically identified as Hysterothylacium type V. In the present study, representatives of this type from the Mediterranean Sea were genetically characterized for the first time by sequencing the rDNA ITS (ITS1-5.8S-ITS2) regions and mtDNA cox2 gene. This study represents the first report of Hysterothylacium type V from the Mediterranean Sea. We also report Mullus barbatus, M. surmuletus, and Pagellus erythrinus as new hosts for this larval type. Based upon molecular and phylogenetic analyses considering the rDNA ITS regions, the Hysterothylacium type V described here was classified as a new genotype, named Genotype B. The valid genetic data of the described Hysterothylacium type V in the present study can be used to establish the phylogenetic relationships among Hysterothylacium species from the Mediterranean Sea and worldwide for future research.

Domestic dogs can function as either paratenic or definitive hosts for the zoonotic raccoon roundworm Baylisascaris procyonis. However, factors leading to development of patent infections in dogs are under-studied. Here we compared infection dynamics of B. procyonis in dogs vs the natural raccoon host. Dogs and raccoons were inoculated 5000 or 500 B. procyonis eggs (n = 3 per dose) or were fed B. procyonis-infected laboratory mice (n = 3 per dose; mice inoculated with 1000 or 250 eggs). Fecal samples were analysed via flotation and a commercial coproantigen ELISA designed for detection of Toxocara spp. Two of 12 dogs (both received low dose larvae) developed patent infections; all 12 raccoons became infected with 10 developing patent infections. Compared with dogs, prepatent periods were shorter in raccoons and maximum egg outputs were much greater. Baylisascaris procyonis coproantigens were detectable via ELISA in all raccoons and the patently infected dogs. Finally, dogs spontaneously lost infections while all patently infected raccoons shed eggs until conclusion of the study. Our results demonstrate that dogs are clearly suboptimal hosts showing limited parasite establishment and fecundity vs raccoons. Despite the low competence, patently infected dogs still pose a risk for human exposure, emphasizing the importance of control measures.

Anisakidae and Raphidascaridae are marine nematodes present in a wide range of fish hosts, which may cause gastro-intestinal complaints and/or allergy in human, in addition to economic losses for the industry. Data regarding the presence of these parasites in fish for the Belgian market is currently missing; therefore, our aim was to investigate the presence and intensity of ascaridoids in a wide range of commercially fish species. A total of 415 fish samples, belonging to 36 different fish species, were collected from a Belgian whole-sale company. Ascaridoid larvae from the viscera (if present) and the muscles were collected by enzymatic digestion and the prevalence, median intensity, mean number of larvae per 100 g infected muscle, and localisation were determined. An overall prevalence of 53% [95%-CI: 42-63%] in the viscera and 27% [95%-CI: 23-32%] in the muscles was observed. Infection in the muscles varied between the fish species; no larvae were detected in 13 fish species, while a high prevalence (>78%) was observed in pollack, halibut, and gurnard. Most samples originated from the Northeast Atlantic Ocean, with the highest prevalence in the muscles observed in the Barents & Norwegian Sea (65% [95%-CI: 38-86]). Muscle samples were, if possible, divided in an anterior region, belly flap, medial region, and posterior region, with the most infections and larvae found in the belly flaps. In all samples, a total of 2569 larvae were recovered, with 1594 larvae originating from the viscera and 975 from the muscles; with an average of two larvae per 100 g infected fillet detected. Larvae were morphologically identified, and a subgroup was further confirmed using PCR/RFLP, resulting ultimately in the identification of Anisakis simplex s.s. (1853 larvae), A. pegreffii (137), A. simplex/pegreffii hybrid genotype (38), Pseudoterranova decipiens (160) and Hysterothylacium aduncum (380). This study demonstrates that ascaridoid larvae are highly prevalent in different fish species on the Belgian market., Competing Interests: Declaration of competing interest None., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Background: Parascaris univalens is a pathogenic parasite of foals and yearlings worldwide. In recent years, Parascaris spp. worms have developed resistance to several of the commonly used anthelmintics, though currently the mechanisms behind this development are unknown. The aim of this study was to investigate the transcriptional responses in adult P. univalens worms after in vitro exposure to different concentrations of three anthelmintic drugs, focusing on drug targets and drug metabolising pathways., Methods: Adult worms were collected from the intestines of two foals at slaughter. The foals were naturally infected and had never been treated with anthelmintics. Worms were incubated in cell culture media containing different concentrations of either ivermectin (10 -9  M, 10 -11  M, 10 -13  M), pyrantel citrate (10 -6  M, 10 -8  M, 10 -10  M), thiabendazole (10 -5  M, 10 -7  M, 10 -9  M) or without anthelmintics (control) at 37 °C for 24 h. After incubation, the viability of the worms was assessed and RNA extracted from the anterior region of 36 worms and sequenced on an Illumina NovaSeq 6000 system., Results: All worms were alive at the end of the incubation but showed varying degrees of viability depending on the drug and concentration used. Differential expression (Padj < 0.05 and log2 fold change ≥ 1 or ≤ - 1) analysis showed similarities and differences in the transcriptional response after exposure to the different drug classes. Candidate genes upregulated or downregulated in drug exposed worms include members of the phase I metabolic pathway short-chain dehydrogenase/reductase superfamily (SDR), flavin containing monooxygenase superfamily (FMO) and cytochrome P450-family (CYP), as well as members of the membrane transporters major facilitator superfamily (MFS) and solute carrier superfamily (SLC). Generally, different targets of the anthelmintics used were found to be upregulated and downregulated in an unspecific pattern after drug exposure, apart from the GABA receptor subunit lgc-37, which was upregulated only in worms exposed to 10 -9  M of ivermectin., Conclusions: To our knowledge, this is the first time the expression of lgc-37 and members of the FMO, SDR, MFS and SLC superfamilies have been described in P. univalens and future work should be focused on characterising these candidate genes to further explore their potential involvement in drug metabolism and anthelmintic resistance.

Parascaris spp. are major gastro-intestinal nematodes that infect foals and can lead to respiratory symptoms, poor growth, and in some cases obstruction of the small intestine and death. Ivermectin resistance has been reported for Parascaris spp. in many countries. In Poland, the knowledge of the level of resistance against ivermectin in Parascaris spp. is limited. The aim of this study was to examine the efficacy of ivermectin against Parascaris spp. in foals from south-eastern Poland. Foals (n = 225 = reared in 7 stud farms) were treated orally with ivermectin paste. Faecal samples were collected from the rectum of each foal or from the environment straight after defaecation on 1 day prior and 2 weeks after deworming. A faecal egg count (FEC) was performed using the McMaster method with a minimum detection limit of 50 eggs/g. FEC reduction (FECR) was calculated using the Faecal Egg Count Reduction Test. The statistical analysis was limited to foals excreting more than 150 eggs/g before treatment and to stud farms with at least 6 foals excreting at or above this level. Confidence intervals were determined by 1000 bootstraps at farm level and the contribution of sex and age to FECR was quantified using a generalized equation estimation procedure. Parascaris spp. eggs were found in 40% of the foals. Following ivermectin treatment, Parascaris spp. eggs were identified in 28.4% of the foals. The mean estimated FECR ranged from 44% to 97% and average efficacy was 49.3%. FECR was more pronounced in older foals (P-values = 0. 003). The FECR was more pronounced in males than in females (P value = 0.028). This study is the first to indicate a reduced efficacy of ivermectin against Parascaris spp. in foals in Poland.

Here we report on the infection of captive crested geckos Correlophus ciliatus Guichenot (Reptilia: Diplodactylidae), with adults of the ascaridoid nematode, Hexametra angusticaecoides Chabaud & Brygoo, 1960 (Ascarididae). A population of captive crested geckoes became ill and died within a short period of time. Nematodes were recovered from the crested geckoes examined from within the coelomic cavity, penetrating various organs and migrating through subcutaneous tissues, as well as emerging through the geckos' skin. One gecko was treated with levamisole following surgical excision of nematodes from under the skin; this gecko survived. The potential source of the nematode infection in the captive geckoes is discussed. It is most likely that wild-caught Madagascan mossy geckoes, Uroplatus sikorae Boettger (Reptilia: Gekkonidae), introduced the infection to the colony. Molecular sequences of the nematodes are the first produced for the members of this genus. A redescription of the species and its genetic characterization based on the internal transcribed spacer sequence data is provided, suggesting some of the morphological criteria that have been used in the past to distinguish between Hexametra spp. may have been intraspecific morphological variations.

Gambusia affinis (western mosquitofish) serves as a host for a variety of larval and adult parasites. Gambusia affinis is also an incipient matrotroph, exhibiting adjustments in post-fertilization provisioning to some offspring within a brood using recently acquired resources. Nutrient transfer to embryos is expected to limit the loss of embryo mass during development resulting in larger offspring. Since larger offspring are more likely to survive, maternal contributions are expected to increase fitness. The presence of parasites, particularly intestinal helminths, potentially reduces body condition and resources available for developing offspring, thereby reducing host fitness. The effects of parasitism on the fitness of G. affinis were investigated in the present study. Fish were collected from 3 sites monthly from June 2015 through August 2016. All helminth parasites were collected during necropsy and identified. Brood size and embryo developmental stage were recorded for each female fish. Additionally, 10 ova/embryos of each developmental stage from each female fish collected from May through August 2016 were haphazardly selected and individually weighed. From 429 female mosquitofish, 5,072 helminths were collected. Brood size varied among collection sites and was positively influenced by maternal body condition, the number of daylight hours, water temperature, and the intensity of both plerocercoid and adult Schyzocotyle acheilognathi. However, brood size was negatively related to the intensity of Neoechinorhynchus cylindratus cystacanth and an increasing number of days between collection and dissection. Embryo weight increased with the presence of either Camallanidae or Contracaecum multipapulatum, embryo developmental stage, and relative host density. These results indicate that some parasitic helminth species negatively affect the fitness of G. affinis, while some positively affect fitness, and that effect can vary with intensity., (© American Society of Parasitologists 2020.)

The raccoon ( Procyon lotor ) roundworm, Baylisascaris procyonis , is an emerging wildlife zoonosis of public health significance in North America. Although the adult stage typically causes no disease in raccoons, the larval stage can cause significant disease in a variety of species, including humans. Raccoons often use human environments, which may increase the risk of B. procyonis exposure in people, particularly in urban settings. Because of this, our objectives were to identify host and environmental risk factors associated with the prevalence and intensity of B. procyonis infection in raccoons in Ontario, Canada. Between 2013 and 2016, 1,539 raccoons were collected and examined for the presence of B. procyonis . Thereafter, we analyzed our data for the influence of age, sex, fat stores, human population size, land use classification, season, and year of collection on the prevalence and intensity of infection. With multilevel logistic regression models, we identified significant associations between prevalence and host age, prevalence and amount of fat stores, and prevalence and season of collection; a significant two-way interaction was also identified between host sex and land use classification. Additionally, by using multilevel negative binomial regression models, we identified significant associations between the intensity of parasite infection and season of collection, as well as three significant two-way interactions: host sex and land use classification, host age and land use classification, and host sex and amount of fat stores. These findings help provide a more complete understanding of B. procyonis ecology in raccoons, including identifying associations between different environments and B. procyonis , which may assist in the development of future risk management strategies.

Thorough epidemiologic investigations of wildlife mortality events are often challenging, in part because of the dynamic variables involved. In May 2011, six fox squirrels ( Sciurus niger ) in Clinton State Park, Kansas, US were euthanized after exhibiting clinical signs of neurologic disease. Postmortem examination of two squirrels revealed that these individuals died of Baylisascaris larva migrans, which resulted in meningoencephalitis and variable pneumonia and myocarditis. Fecal flotation of raccoon ( Procyon lotor ) feces collected in the area revealed Baylisascaris sp. ova, presumably Baylisascaris procyonis , in one of nine samples. Additional fox squirrel carcasses were submitted for diagnostic evaluation from eastern Kansas for 1 yr following the Baylisascaris sp. outbreak. This monitoring unexpectedly resulted in the detection of Francisella tularensis , the zoonotic pathogen that causes tularemia, in two fox squirrels. The increased attention to fox squirrel mortalities prompted by the outbreak of Baylisascaris sp. larva migrans revealed cases of tularemia that may not have been otherwise detected. Although F. tularensis is endemic in Kansas, the current distribution and prevalence of B. procyonis in raccoons and other hosts in Kansas are poorly understood. This yearlong mortality investigation illustrated the importance of wildlife health monitoring as a means of assessing public health risks, especially during unusual wildlife mortality events.