Use of stable isotope ratio analysis to investigate the biology and clinical significance of seal parasites.

Stranded seals are often infected with a broad range of parasites, although whether they are the cause of significant morbidity or an incidental finding is usually unclear. In this study we used stable isotope ratio analysis, a method frequently used to investigate food webs, to explore the extent to which common seal parasites feed directly on host tissue and fluids or absorb host-derived metabolites, which in turn may give an indication of their potential impact on the host's health. The trophic discrimination factor Δ15N for the nasal mite, Halarachne halichoeri, was mostly positive, ranging between −0.015 and 3.2‰ (n = 6), while for the Acanthocephalan worm, Corynosoma strumosum and the anisakid nematode, Pseudoterranova decipiens, Δ15N ranged between −4.2 and −2.0‰ (n = 7), and between −6.7 and −0.8‰ (n = 5) respectively. In the case of the lungworm, Otostrongylus circumlitus, Δ15N measured between −5.6 and 0‰ for worms collected in the stomach (n = 5), between −1.1 and 0.2‰ for worms collected from the heart (n = 3), between −0.7 and 1.9‰ for worms situated in the lungs (n = 4). Based on Δ15N, parasites could be clearly divided into those that were on a higher trophic level than their host suggesting a predator­prey-like relationship, and those that were not. It is hypothesized that Δ15N may be indicative of the clinical significance of parasite­host associations.

Evaluation of Student Engagement, Communication, and Collaboration during Online Group Work: Experiences of Fourth Year Veterinary Medicine Students.

Accelerated by the COVID-19 pandemic, online teaching has become widely established in higher education in recent years. However, little is known about the influence of the online environment on collaborative student activities which are an integral part of veterinary education. This study explored engagement, collaboration, and communication among fourth-year veterinary students working in groups on online case-based learning (CBL) activities. Data were collected by questionnaire (93/135) and anonymous peer assessment (98/135) at the end of the trimester. While most students (67%) enjoyed group work and 75% considered it of benefit to their learning, the results indicated that the students' interaction was mainly limited to task management and collating individual answers on shared documents. Rather than meeting online, students communicated by chat and messenger apps. Agreement of roles, rules, and the group contract were largely treated as box-ticking exercises. The conflict was the only factor that affected group work satisfaction and was largely avoided rather than addressed. Interestingly lack of student engagement in group work was not related to overall academic performance and had no impact on their end-of-term exam results. This study highlights high student satisfaction and engagement with online group CBL activities even when collaboration and communication was limited. Achieving higher levels of collaborative learning involving co-regulation of learning and metacognitive processing of learning content may require more specific, formal training in relevant skill sets from an early stage of the veterinary curriculum.

Apoptosis levels in bovine Johne's disease ileal lesions and association with bacterial numbers.

Johne's disease (JD) is a chronic granulomatous enteritis caused by Mycobacterium avium subsp. paratuberculosis (MAP). While it is generally accepted that MAP employs immune subversion mechanisms, aspects of the host-pathogen relationship are not fully understood. We sampled 3 ileal tissue sections from 17 naturally infected cattle (n = 51 sections) to analyze differences in cell types, apoptosis, and phagocytic cells. Diffuse multibacillary (DM) was the most common lesion type (n = 17) followed by diffuse intermediate (DI; n = 15). DM lesions had significantly greater proportion of Treg cells (CD3+ FoxP3+) relative to all CD3+ T cells as compared to DI forms (P < .05). CD68+ individual cell size was significantly smaller in DM than in diffuse lymphocytic (DL) forms (P < .05). Area of caspase-3 positivity (apoptosis) was greater in DM lesions than DL (P < .05) and DI (P < .0001), and was linked to higher numbers of MAP within the macrophage.

Fasciola hepatica products can alter the response of bovine immune cells to Mycobacterium avium subsp. paratuberculosis.

BACKGROUND: Fasciola hepatica causes economically important disease in livestock worldwide. The relevance of this parasitic infection extends beyond its direct consequences due to its immunoregulatory properties. OBJECTIVES: Given the importance of the T helper 1 (Th1) immune response in controlling infections with Mycobacterium avium subspecies paratuberculosis (MAP) in cattle, we aimed to establish the immunological consequences that co-infection with F. hepatica might have on the course of Johne's disease (JD). METHODS: This study compared the in vitro response of bovine immune cells to infection with MAP or exposure to MAP antigens following F. hepatica infection or stimulation with F. hepatica products. RESULTS: We found a decreased proliferation of peripheral blood mononuclear cells (PBMCs) after infection with F. hepatica. This reduction was inversely correlated with fluke burden. Pre-stimulation with F. hepatica molecules produced a significant reduction of ileocaecal lymph node leucocyte proliferation in response to MAP antigens. Additionally,F. hepatica products reduced expression of the CD14 receptor by macrophages and increased levels of apoptosis and bacterial (MAP) uptake. CONCLUSIONS: Overall, F. hepatica infection had little impact on the in vitro response of immune cells to MAP, whereas in vitro co-stimulation with F. hepatica molecules had a measurable effect. Whether this is likely to affect JD progression during in vivo chronic conditions remains unclear.

Vectors of Babesiosis.

Babesiosis, caused by piroplasmid protozoans in the genus Babesia, is arguably the most important vector-borne disease of livestock and companion animals and is growing in importance as a zoonosis. Ixodid ticks were identified as vectors more than a hundred years ago, but the particular tick species transmitting some significant pathogens are still unknown. Moreover, it is only recently that the complexity of the pathogen-tick relationship has been revealed as a result of studies enabled by gene expression and RNA interference methodology. In this article, we provide details of demonstrated and incriminated vectors, maps of the current knowledge of vector distribution, a summary of established features of the pathogen life cycle in the vector, and an outline of molecular research on pathogen-tick relationships. The article concludes with a discussion of vector ecology and disease epidemiology in a global-change context and with suggestions for future research.

Identification and epidemiological analysis of Perostrongylus falciformis infestation in Irish badgers.

BACKGROUND: The lungworm, Perostrongylus falciformis (fomerly known as Aelurostrongylus falciformis) has been identified in badgers (Meles meles) in Britain, the Russian Federation, Italy, Norway, Poland, Ukraine, Bosnia Herzegovina and Romania, while Aelurostrongylus pridhami has been reported from badgers in Spain. RESULTS: Pulmonary tissue from 1580 Irish badgers was examined and an estimated prevalence of 32.09% (95% CI: 29.79-34.45%) of this parasite was detected. Confirmation of its occurrence was made by PCR analysis on a subset of the population. CONCLUSION: Infestation was widely distributed throughout the Republic of Ireland, with a trend towards higher infestation risk in western versus eastern counties. In addition males were at a higher risk of infestation than females and juveniles were at a significantly higher risk than adult badgers.

Epidemiological investigation of a severe rumen fluke outbreak on an Irish dairy farm.

Although the rumen fluke, Calicophoron daubneyi is now very common and widespread throughout Western Europe, reports of clinical cases are still rare. This study explores the epidemiological background to a severe rumen fluke outbreak in 6-month-old heifers on a dairy farm in Ireland. Sequence analysis of the cytochrome oxidase subunit 1 (Cox1) gene of the rumen fluke metacercariae on pasture failed to identify predominant, possibly pathogenic subtypes. However, estimates of metacercarial load indicated that the animals were exposed to a daily dose of about 5334 C. daubneyi metacercariae for a period of 3 weeks resulting in the build-up of very large numbers of immature worms in the small intestine. It is hypothesized that specific environmental conditions may favour this parasite over its competitor, the liver fluke, Fasciola hepatica, possibly by allowing it to emerge earlier. The possibility that C. daubneyi may be better adapted to the Irish climate than F. hepatica together with the fact that selective treatment against F. hepatica effectively frees the niche for C. daubneyi, may result in the gradual replacement of F. hepatica by C. daubneyi.

Comparison of in vitro viability methods for Cryptosporidium oocysts.

The water-borne protozoan parasite Cryptosporidium parvum forms oocysts that can persist for long periods of time in the environment, even though the sporozoites inside the oocysts may no longer be viable, making it difficult to assess the associated risk of infection. In this study, we compared the ability of various in vitro methods to discriminate viable from non-viable oocysts, including excystation, DAPI/PI staining, RNA FISH, PMA-qPCR and a novel polymer slide adhesion method. With the notable exception of our in vitro excystation protocol, all methods were found to be useful for identifying viable oocysts.

Agricultural anaerobic digestion power plants in Ireland and Germany: policy and practice.

The process of anaerobic digestion (AD) is valued as a carbon-neutral energy source, while simultaneously treating organic waste, making it safer for disposal or use as a fertilizer on agricultural land. The AD process in many European nations, such as Germany, has grown from use of small, localized digesters to the operation of large-scale treatment facilities, which contribute significantly to national renewable energy quotas. However, these large AD plants are costly to run and demand intensive farming of energy crops for feedstock. Current policy in Germany has transitioned to support funding for smaller digesters, while also limiting the use of energy crops. AD within Ireland, as a new technology, is affected by ambiguous governmental policies concerning waste and energy. A clear governmental strategy supporting on-site AD processing of agricultural waste will significantly reduce Ireland's carbon footprint, improve the safety and bioavailability of agricultural waste, and provide an indigenous renewable energy source. © 2016 Society of Chemical Industry.

Ticks and Tick-borne diseases in Ireland.

Throughout Europe interest in tick-borne agents is increasing, particularly with regard to those that can cause human disease. The reason for this is the apparent rise in the incidence of many tick-borne diseases (TBD's). While there has never been a national survey of ticks or TBD's in Ireland, the trend here appears to be the reverse with a decline in the incidence of some agents seemingly associated with decreasing tick numbers particularly on agricultural land. In the absence of robust baseline data, however, this development cannot be confirmed. This review collates the limited information available from several dated published records on tick species and a small number of studies focused on certain TBD's. Some pilot data on tick density and TBD agents collected in 2016 are also presented. The aim is to explore the particular situation in Ireland with regard to ticks and TBD's and to provide a reference for future workers in the field.

Comparison of diagnostic techniques for the detection of Cryptosporidium oocysts in animal samples.

While a large number of laboratory methods for the detection of Cryptosporidium oocysts in faecal samples are now available, their efficacy for identifying asymptomatic cases of cryptosporidiosis is poorly understood. This study was carried out to determine a reliable screening test for epidemiological studies in livestock. In addition, three molecular tests were compared to identify Cryptosporidium species responsible for the infection in cattle, sheep and horses. A variety of diagnostic tests including microscopic (Kinyoun's staining), immunological (Direct Fluorescence Antibody tests or DFAT), enzyme-linked immunosorbent assay (ELISA), and molecular methods (nested PCR) were compared to assess their ability to detect Cryptosporidium in cattle, horse and sheep faecal samples. The results indicate that the sensitivity and specificity of each test is highly dependent on the input samples; while Kinyoun's and DFAT proved to be reliable screening tools for cattle samples, DFAT and PCR analysis (targeted at the 18S rRNA gene fragment) were more sensitive for screening sheep and horse samples. Finally different PCR primer sets targetedat the same region resulted in the preferential amplification of certain Cryptosporidium species when multiple species were present in the sample. Therefore, for identification of Cryptosporidium spp. in the event of asymptomatic cryptosporidiosis, the combination of different 18S rRNA nested PCR primer sets is recommended for further epidemiological applications and also tracking the sources of infection.

Identity of rumen fluke in deer.

As evidence is growing that in many temperate areas paramphistome infections are becoming more common and widespread, this study was undertaken to determine the role of deer as reservoirs for rumen fluke infections in livestock. A total of 144 deer faecal samples (88 from fallow deer, 32 from red deer and 24 samples from sika, sika/red deer hybrids) were screened for the presence of fluke eggs. Based on the ITS-2 rDNA locus plus flanking 5.8S and 28S sequences (ITS-2+), fluke eggs were identified to species level. Our results indicate that, of the 3 deer species, fallow deer had the highest fluke infection rates. Two rumen fluke species, Calicophoron daubneyi and Paramphistomum leydeni, with morphologically distinct eggs, were identified. Concurrent infections of the two paramphistome species and liver fluke, Fasciola hepatica, were common. Considering the comparatively low egg burdens observed in this study, it is unlikely that deer represent a significant source of infection for Irish livestock.

Changing incidence of bovine babesiosis in Ireland.

BACKGROUND: In Ireland bovine babesiosis is caused by the tick-borne blood parasite, Babesia divergens. A survey of veterinary practitioners and farmers in the 1980's revealed an annual incidence of 1.7% associated with considerable economic losses. However, two subsequent surveys in the 1990's indicated a decline in clinical babesiosis. Recent evidence from continental Europe suggests that, probably due to climate change, the distribution of the tick vector of B. divergens, Ixodes ricinus is extending to more northerly regions and higher altitudes. In addition, milder winters are thought to widen the window of tick activity. In order to determine whether any such changes have affected the incidence of bovine babesiosis in Ireland, a questionnaire survey of farmers and veterinarians was carried out and compared with data from previous surveys. RESULTS: Our survey indicates that while the incidence of clinical disease has continued to decline, cases can occur at any time of year. In contrast to previous surveys, affected farms were the same size as unaffected ones. There was no correlation between disease risk and the presence of deer on the land. Disease severity and mortality rates were increased because many infections were advanced by the time they were detected and treated. CONCLUSION: While the precise reasons for the decline in the incidence of redwater are unknown, changes in agricultural practice are likely to be of importance. A reversal of the trend could be devastating, as vigilance among farmers and veterinarians is flagging and the national herd is losing its protective immunity to disease.

Pathogens transmitted by Ixodes ricinus.

Ixodes ricinus is the most important tick vector in central and western Europe and one of the most researched parasites. However, in the published literature on the tick and the pathogens it transmits, conjecture about specific transmission cycles and the clinical significance of certain microbes is not always clearly separated from confirmed facts. This article aims to present up-to-date, evidence-based information about the well-researched human pathogens tick-borne encephalitis virus, louping-ill virus, Anaplasma phagocytophilum, Borrelia burgdorferi sensu lato and several Babesia species, with a focus on their development in the tick, transmission dynamics and the competent reservoir hosts that support their circulation in the environment. Borrelia miyamotoi, Neoehrlichia mikurensis, Rickettsia helvetica and Rickettsia monacensis, which are much less common causes of disease but may affect immunocompromised patients, are also briefly discussed. Finally, the possible role of I. ricinus in the transmission of Coxiella burnetii, Francisella tularensis, Bartonella spp. and Spiroplasma ixodetis is reviewed.

Molecular species determination of cyathostomins from horses in Ireland.

Cyathostomins are globally important equine parasites, responsible for both chronic and acute pathogenic effects. The occurrence of mixed infections with numerous cyathostomin species hinders our understanding of parasite epidemiology, host-parasite dynamics, and species pathogenicity. There have been few studies of cyathostomin species occurring in horses in Ireland, where temperate climatic conditions with year-round rainfall provide suitable conditions for infection of grazing animals with bursate nematodes. Here, we amplified and sequenced the ITS-2 region of adult worms harvested at post-mortem from eleven adult horses between August 2018 and June 2020, and recorded species prevalence and abundance of worms recovered from the caecum, right ventral colon and left dorsal colon, using both BLAST and IDTAXA for taxonomic attribution. Phylogenetic relationships and community composition were also recorded and compared with other relevant studies, including a global meta-analysis. Overall, our results agree with previous studies that there does not seem to be a major difference in cyathostomin species occurrence in equids in different geographical regions. We confirmed the results of other workers in relation to the difficulties in discriminating between Cylicostephanus calicatus and Coronocyclus coronatus on the basis of ITS-2 sequences.

Investigating the role of wild carnivores in the epidemiology of bovine neosporosis.

Neospora caninum is a protozoan parasite, primarily associated with bovine abortion. The only definitive hosts discovered to date are carnivores. This study aimed to identify the role of mammalian carnivores in the epidemiology of bovine neosporosis. A sample bank of serum, fecal and brain samples was established: American mink (Mustela vison), red foxes (Vulpes vulpes), pine martens (Martes martes), badgers (Meles meles), stoats (Mustela erminea), otters (Lutra lutra) and feral ferrets (Mustela putorius). Approximately 1% of mink and 1% of fox samples were positive by IFAT. According to PCR analysis of DNA extracted from brain tissue, 3% of the mink, 4% of the otters and 6% of the foxes examined were infected with N. caninum. All fecal samples tested negative for N. caninum DNA (n = 311), suggesting that the species that tested positive were intermediate not definitive hosts. This is the first time that tissues from mustelids have tested positive for N. caninum. The need to test 2 relatively large (~200 mg) targeted parts of the brain to avoid false negatives was also identified. The relatively low prevalence of N. caninum in Irish carnivores suggests that the local ecology of a species has an important influence on its epidemiological role.

A coprological survey of parasites of wild carnivores in Ireland.

The increasing movement of people to wilderness areas, shrinking of wildlife habitats and the resulting urbanisation of wildlife has led to growing concerns about the transfer of parasitic diseases, particularly from contaminated faeces. Faecal samples from wild carnivores in Ireland were examined for the presence of protozoan and nematode parasites. Red fox (Vulpes vulpes) samples (n = 91) were positive for Uncinaria stenocephala (38%), Eucoleus aerophilus (26%), Toxocara canis (20%), Trichuris vulpis (4%) and Isospora-like oocysts (9%). Badger (Meles meles) samples (n = 50) were positive for Uncinaria criniformis (40%), E. aerophilus (6%) and Isospora-like oocysts (16%). No parasites were observed in pine marten (n = 48; Martes martes) faeces. Approximately 5% of American mink (Mustela vison) samples were positive for Cryptosporidium by polymerase chain reaction (identified as Cryptosporidium andersoni (n = 3) and 'mink' genotype (n = 1)). The results suggest that wild carnivores in Ireland have a range of parasites, although it is unclear from the present study to what extent these infections are associated with morbidity. While it can be expected that, via their faeces, wild carnivores contribute to the spread of these parasites, they are unlikely the primary source of environmental contamination. Therefore, they should not always be the principal target of control measures.

Bulk milk ELISA and the diagnosis of parasite infections in dairy herds: a review.

The bulk milk enzyme-linked immune sorbent assay (ELISA) is a rapid and inexpensive method of assessing herd exposure to pathogens that is increasingly being used for the diagnosis of parasite infections in dairy herds. In this paper, with the dairy herd health veterinarian in mind, we review the principles of the assay and the recent literature on the potential role of bulk milk ELISA for the diagnosis of ostertagiosis, fasciolosis, parasitic bronchitis due to cattle lung worm and neosporosis. It is generally accepted that assay results reflect exposure to the parasite rather than the presence of active infection. Bulk milk ELISA can be a useful tool for the veterinary practitioner as a component of a herd health monitoring programme or in the context of a herd health investigation. It can also play a role in regional or national surveillance programmes. However, the results need to be interpreted within the context of the herd-specific health management, the milk production pattern and the parasite life cycle.

The Prevalence and Genetic Diversity of Babesia divergens in Ixodes ricinus Nymphs Collected from Farm- and Woodland Sites in Ireland.

The parasite, Babesia divergens causes redwater fever in cattle and a rare, albeit life-threatening disease in humans. In Ireland, B. divergens has always been considered an important pathogen as the high incidence of redwater fever precluded areas of the country from cattle farming. Moreover a relatively large proportion of human cases were reported here. Red deer (Cervus elaphus), which often harbour babesias that are genetically very similar (if not identical) to B. divergens, are quite widespread. In this study 1369 nymphal Ixodes ricinus ticks collected from various habitats were screened for the presence of B. divergens using TaqMan followed by conventional nested PCR. Fragments of the 18S rRNA gene locus (560 bp) were compared against published Irish B. divergens isolates from cattle, humans and red deer. Overall just 1% of I. ricinus nymphs were infected with B. divergens, with similar infection rates in ticks collected from farm- and woodland. Most (90%) 18S rRNA gene fragments derived from woodland ticks were 100% identical to published sequences from cattle and humans. One differed by a single nucleotide polymorphism (SNP) as did two isolates from ticks collected in bogland. Two isolates derived from nymphs collected in farmland differed by 2 and 4 SNPs respectively.

Babesia and Theileria Identification in Adult Ixodid Ticks from Tapada Nature Reserve, Portugal.

This study, conducted in a nature reserve in southern Portugal, investigated the frequency and diversity of tick-borne piroplasms in six species of adult ixodid ticks removed from 71 fallow deer (Dama dama) and 12 red deer (Cervus elaphus), collected over the period 2012-2019. The majority of 520 ticks were Ixodes ricinus (78.5%), followed by Rhipicephalus sanguineus sensu lato, Hyalomma lusitanicum, Haemaphysalis punctata, Dermacentor marginatus, and Ixodes hexagonus. The R. sanguineus ticks collected from the deer were clearly exophilic, in contrast to the endophilic species usually associated with dogs. Four tick-borne piroplasms, including Theileria spp., and the zoonotic species, Babesia divergens and Babesia microti, were detected. B. divergens 18S rDNA, identical to that of the bovine reference strain U16370 and to certain strains from red deer, was detected in I. ricinus ticks removed from fallow deer. The sporadic detection of infections in ticks removed from the same individual hosts suggests that the piroplasms were present in the ticks rather than the hosts. Theileria sp. OT3 was found in I. ricinus and, along with T. capreoli, was also detected in some of the other tick species. The natural vector and pathogenic significance of this piroplasm are unknown.