The effects of climate change on ovine parasitic gastroenteritis determined using veterinary surveillance and meteorological data for Northern Ireland over the period 1999-2009

Occurrence of gastrointestinal nematodes in lambs in Norway, as assessed by copromicroscopy and droplet digital polymerase chain reaction

BACKGROUND

Gastrointestinal nematodes (GINs) have a major impact on sheep production, health, and welfare worldwide. Norway is no exception, but there are only a few studies on the prevalence of GINs in Norwegian sheep. The aim of this study was to investigate the current occurrence of the most important nematodes in sheep flocks in Norway. Faecal samples were collected from flocks in 2021/2022, mainly from three geographical regions in Norway, i.e., northern, eastern, and western. In each of 134 flocks included, individual samples from 10 lambs (autumn) were pooled. Third stage larvae (L3) were cultivated and harvested (Baermann method) from the pooled samples. The DNA was then extracted and further analysed using droplet digital PCR (ddPCR). This enables assessment of the proportions of the three most important nematode species/genera, i.e., H. contortus, T. circumcincta, and Trichostrongylus. The fractional abundance/relative proportion of each species/genus was assessed by performing duplex assays with universal strongyle and species/genus-specific primers and probe sets. In addition, the occurrence of Nematodirus eggs was assessed by standard faecal egg counts (i.e., McMaster method).

RESULTS

Of the 134 flocks sampled, 24 were from the northern region, 31 from eastern, and 71 from western Norway. In addition, some flocks from central (n = 7), and southern (n = 1) Norway were included. Among the sampled flocks, T. circumcincta occurred most commonly (94%), followed by H. contortus (60%) and Trichostrongylus (55%), and Nematodirus (51%). In general, mixed infections were observed, with 38% and 18% of flocks infected with three or all four genera, respectively.

CONCLUSIONS

The results of this study indicate that GINs are widespread in Norway. Teladorsagia circumcincta seems to be present in most flocks based on this screening. Moreover, the results show that Nematodirus spp. infect lambs throughout the country, predominantly N. battus, and indicate that this nematode has become more abundant, which could lead to an increase in nematodirosis.

An alien parasite in a changing world - Ashworthius sidemi has lost its traditional seasonal dynamics

A non-native nematode Ashworthius sidemi has emerged in captive fallow deer in Central and Eastern Europe over the last decade. Although this parasite has been spreading in the wild outside it's native distributional range and colonising local European host species since the middle of the last century, limited information has been published on the seasonality of A. sidemi and its susceptibility to anthelmintics. To address this knowledge gap, we conducted a study to investigate seasonal dynamics of the non-native parasite in the current Central European climate conditions. We collected freshly voided faecal pellets at four-week intervals from February 2018 to February 2020 at a fallow deer reserve with a known history of A. sidemi presence. The faecal pellets obtained were pooled after each site visit (n = 25) and coprocultured to obtain the third stage larvae of trichostrongylid nematodes at monthly intervals. Total genomic DNA was extracted from the recovered larvae. Using real-time multiplex PCR, A. sidemi DNA was detected in 17 out of 25 larval samples (68% prevalence). During the monitoring period, the annual administration of ivermectin based premix (Cermix) took place in January 2018, 2019, and 2020, and additionally a mixture of rafoxanide and mebendazole (Rafendazol) was administered once in spring 2019. The probability of parasite presence was significantly influenced by the time since the drug administration (p = 0.048) and the mean temperature at the location (p = 0.013). Larval samples negative for A. sidemi were always identified shortly after the drug administration. However, rapid pasture contamination by the parasite eggs from two to three months after Cermix administration and within one month after Rafendazol administration suggest only a short-lived efficacy of both administered drugs. The abundance of A. sidemi DNA was positively affected by mean temperature (p = 0.044) and remained relatively stable throughout the monitoring period, with the highest peak in August 2018 and 2019. Pasture contamination with A. sidemi eggs occurred almost all year round, with the exception of the beginning of 2018, 2019, and 2020. These findings indicate adaptation of a non-native parasite to the current climatic conditions of the Czech Republic resulted in negligible seasonal patterns of parasite egg shedding.

Influence of breed and parasite challenge on the immune response to naturally acquired intestinal nematode infection in sheep

Natural infection by intestinal nematodes was assessed in Santa Ines and Ile de France sheep breeds, over a five-month grazing period, with emphasis on the development of the immune response in lambs under two anthelmintic treatment regimens. Nineteen Santa Ines and 19 Ile de France male lambs were allocated into two treatment groups: animals under suppressive treatment with anthelmintics; and animals under targeted selective treatment (TST). The nematodes Trichostrongylus colubriformis and Strongyloides papillosus showed the highest infection intensity in the TST animals in both breeds. Parasite-specific immunoglobulin G levels were significantly higher and more rapidly induced in Santa Ines lambs. Additionally, these lambs had higher levels of parasite-specific immunoglobulin A in intestinal mucus. Animals under TST had higher means of mast cells and globule leukocytes in the intestinal mucosa due to longer and greater parasite challenge in comparison with the suppressive group. A breed effect (P < 0.05) was recorded for mast cells, with Santa Ines lambs presenting the highest counts. Although Santa Ines lambs had lower intestinal nematode counts than Ile de France lambs, they had shown a large variation in T. colubriformis burden, with most of them presenting a marked worm burden, despite showing an earlier and more intense immune response to intestinal nematode infection.

A 4 year observation of gastrointestinal nematode egg counts, nemabiomes and the benzimidazole resistance genotypes of Teladorsagia circumcincta on a Scottish sheep farm

Anthelmintic resistance threatens the sustainability of sheep production globally. Advice regarding strategies to reduce the development of anthelmintic resistance incorporates the outcomes of modelling exercises. Further understanding of gastrointestinal nematode species diversity, and population dynamics and genetics (which may vary between species) is required to refine these models; and field studies combining faecal egg outputs, species composition and resistance genetics are needed to calibrate them. In this study, faecal samples were taken from ewes and lambs on a commercial farm in south-eastern Scotland at approximately 3 t-4 week intervals between spring and autumn over a period of 4 years. Faecal egg counts were performed on these samples, and L₃ were collected from pooled coprocultures. Deep amplicon sequencing was used to determine both the species composition of these L₃ and the proportions of benzimidazole-resistant single nucleotide polymorphisms in the isotype-1 β-tubulin locus of the predominant species, Teladorsagia circumcincta L₃. Despite consistent management throughout the study, the results show variation in gastrointestinal nematode species composition with time and between age groups, that was potentially associated with weather conditions. The F200Y benzimidazole resistance mutation is close to genetic fixation in the T. circumcincta population on this farm. There was no evidence of variation in isotype-1 β-tubulin single nucleotide polymorphisms frequency between age groups, and no genetic evidence of reversion to benzimidazole susceptibility, despite targeted benzimidazole usage. This study highlights the need to include speciation when investigating gastrointestinal nematode epidemiology and anthelmintic resistance, and serves as an example of how genetic data may be analysed alongside species diversity and faecal egg counts, when markers for other anthelmintic classes are identified.

Brain diseases in changing climate

Climate change is one of the biggest and most urgent challenges for the 21st century. Rising average temperatures and ocean levels, altered precipitation patterns and increased occurrence of extreme weather events affect not only the global landscape and ecosystem, but also human health. Multiple environmental factors influence the onset and severity of human diseases and changing climate may have a great impact on these factors. Climate shifts disrupt the quantity and quality of water, increase environmental pollution, change the distribution of pathogens and severely impacts food production - all of which are important regarding public health. This paper focuses on brain health and provides an overview of climate change impacts on risk factors specific to brain diseases and disorders. We also discuss emerging hazards in brain health due to mitigation and adaptation strategies in response to climate changes.

The dynamics of ovine gastrointestinal nematode infections within ewe and lamb cohorts on three Scottish sheep farms

Gastrointestinal nematodes (GIN) are a serious concern for sheep producers worldwide. However, there is a paucity of evidence describing the epidemiology of GIN on modern UK sheep farms. The aim of this paper was to understand whether expected seasonal variations of infection are still found in ewes and lambs under varying management strategies in temperate climates. Faecal egg counts (FEC) were conducted on freshly voided samples collected from groups of ewes and lambs every third week for twelve months on three farms in southeast Scotland. The patterns of egg output have been described here in relation to management practices undertaken on the farms. Despite changes in farming practice and climatic conditions, the findings complement historical studies detailing the epidemiology of GIN. Findings include a periparturient rise in ewe FEC on two of the farms, while lambing time treatment appeared to suppress this on the third farm. On the same two farms lamb FEC increased during the summer, reaching a peak in the autumn. The work also highlights how the ad hoc use of anthelmintics does little to impact these patterns.

Control of Nematodirus spp. infection by sheep flock owners in Northern Ireland

BACKGROUND

To address a lack of information on the control of ovine helminth parasites in Northern Ireland (NI), a number of research projects have been undertaken, dealing with gastrointestinal nematodes, tapeworms and liver fluke. This investigation concerns Nematodirus and concentrates on three aspects of disease: farm management strategies for its control, derived from the results of a Questionnaire; the efficacy of treatment used by farmers, as determined by a coprological survey; and the hatching requirements of Nematodirus eggs, that is, whether prolonged chilling is a pre-requisite for hatching.

RESULTS

A Questionnaire was sent to 252 sheep farmers in NI in March 2012 (covering the years 2009-2012) and replies were received from 228 farmers. Under-dosing, inaccurate calibration of equipment and inappropriate product choice were poor practices identified. Following this survey, the efficacy of treatment of Nematodirus spp. in sheep flocks was evaluated in April and May 2012. Sampling kits were sent to 51 flock owners, all of whom returned pre- and post-anthelmintic dosing faecal samples to the laboratory for analysis. At the time of treatment, 41 flocks were positive for Nematodirus (as diagnosed by the presence of eggs). Reduced benzimidazole efficacy was detected in 35.7% of flocks tested (n = 28). Although only involving a small number of flocks, reduced efficacy of levamisole treatment was detected in 50%, of avermectins in 33% and of moxidectin in 75% of flocks tested (n = 2, 6 and 4, respectively). In the egg hatch experiment, carried out under "chilled" and "non-chilled" conditions, 43% of the eggs in the "non-chilled" group were able to hatch, compared to 100% in the "chilled" group.

CONCLUSIONS

The identification of inefficient control strategies argues for continued education of stockholders, in order to improve their management programmes. This is particularly important where the practices might impact on the development of anthelmintic resistance, which has been shown to exist on NI farms. The appropriate choice of anthelmintic is a vital part of this plan. The ability of eggs to hatch under non-chilled conditions demonstrates a flexibility in hatching behaviour. This may represent an adaptation to climate change and account for the recent emergence of a second, autumnal peak of infection.

Autumn nematodirosis in lambs reported in Scotland

Autumn nematodirosis in lambsRespiratory disease in calvesLouping ill in calvesOedema disease in pigsMycoplasmosis in pheasantsThese are among matters discussed in the disease surveillance report for October 2016 from SAC Consulting: Veterinary Services (SAC C VS).

Opportunities and challenges for the application of microfluidic technologies in point-of-care veterinary diagnostics

There is a growing need for low-cost, rapid and reliable diagnostic results in veterinary medicine. Point-of-care (POC) tests have tremendous advantages over existing laboratory-based tests, due to their intrinsic low-cost and rapidity. A considerable number of POC tests are presently available, mostly in dipstick or lateral flow formats, allowing cost-effective and decentralised diagnosis of a wide range of infectious diseases and public health related threats. Although, extremely useful, these tests come with some limitations. Recent advances in the field of microfluidics have brought about new and exciting opportunities for human health diagnostics, and there is now great potential for these new technologies to be applied in the field of veterinary diagnostics. This review appraises currently available POC tests in veterinary medicine, taking into consideration their usefulness and limitations, whilst exploring possible applications for new and emerging technologies, in order to widen and improve the range of POC tests available.

Asynchrony in host and parasite phenology may decrease disease risk in livestock under climate warming: Nematodirus battus in lambs as a case study

Mismatch in the phenology of trophically linked species as a result of climate warming has been shown to have far-reaching effects on animal communities, but implications for disease have so far received limited attention. This paper presents evidence suggestive of phenological asynchrony in a host-parasite system arising from climate change, with impacts on transmission. Diagnostic laboratory data on outbreaks of infection with the pathogenic nematode Nematodirus battus in sheep flocks in the UK were used to validate region-specific models of the effect of spring temperature on parasite transmission. The hatching of parasite eggs to produce infective larvae is driven by temperature, while the availability of susceptible hosts depends on lambing date, which is relatively insensitive to inter-annual variation in spring temperature. In southern areas and in warmer years, earlier emergence of infective larvae in spring was predicted, with decline through mortality before peak availability of susceptible lambs. Data confirmed model predictions, with fewer outbreaks recorded in those years and regions. Overlap between larval peaks and lamb availability was not reduced in northern areas, which experienced no decreases in the number of reported outbreaks. Results suggest that phenological asynchrony arising from climate warming may affect parasite transmission, with non-linear but predictable impacts on disease burden. Improved understanding of complex responses of host-parasite systems to climate change can contribute to effective adaptation of parasite control strategies.

Seasonal changes of diagnostic potential in the detection of Anoplocephala perfoliata equine infections in the climate of Central Europe

For this study, 724 gastrointestinal tracts of slaughter horses were investigated to determine the prevalence, intensity of Anoplocephala perfoliata and tapeworm development stages over the second, third and fourth quarter of 2012 and the first quarter of 2013. For each positive horse, faecal samples were collected from the rectum or small colon for coproscopic examinations. The samples were analysed using dedicated modified sedimentation-flotation methods. In total, 52 horses were infected with A. perfoliata in the course of the study, with an overall prevalence of 7.2 %. The prevalence changed over the study period; however, not markedly. The overall mean of A. perfoliata abundance was 12.3 (3.23) and did not differ significantly between the quarters. Mean invasion intensity did not differ significantly between the quarters. The quantity of mature tapeworms did not differ significantly over the study period; however, there was a significant difference in the number of immature tapeworms. The highest number of mature tapeworms was found in the first quarter of 2013. The number of detected tapeworm eggs rose significantly over the study period. The total number of tapeworms did not have a significant influence on the presence/absence of detected eggs. However, there was a noticeable difference between the number of mature tapeworms and presence/absence of eggs in faeces. This clearly indicates that the efficacy of the modified sedimentation-flotation method is influenced by seasonality, and therefore the most effective and reliable time for detection of A. perfoliata in equines is the first quarter of the year.

Differences in prevalence of parasites in stool samples between three distinct ethnic pediatric populations in southern Israel, 2007-2011

Intestinal parasites cause significant morbidity worldwide, particularly in developing populations. At least three pediatric populations reside in southern Israel: the Bedouin population, the general Jewish population and Jewish children of Ethiopian origin. Our aim was to compare intestinal parasite prevalence between the three pediatric populations in southern Israel. This is a retrospective, laboratory, population-based surveillance. Most ova and parasite (O&P) tests in southern Israel (hospital and community obtained) are performed by the hospital parasitology laboratory. All pediatric stool O&P tests examined by the hospital laboratory between 2007 and 2011 were included. Overall, 45,978 samples were examined; 27,354, 16,969 and 1655 from Bedouin, non-Ethiopian Jewish and Ethiopian children, respectively. 16,317 parasites were identified in 12,325 (26.8%) positive samples. Total prevalences were 36%, 11% and 46% for Bedouin, non-Ethiopian Jewish and Ethiopian children, respectively. Blastocystis hominis, Giardia lamblia and Entamoeba species were the most common parasites identified, constituting ≥80% of positive samples in all groups. Hymenolepis nana was rarely identified in non-Ethiopian Jewish children (0.04% of isolates compared with 2.6% and 0.5% in Bedouin and Ethiopian children, respectively). Other helminths, excluding H. nana and Enterobius vermicularis, were identified almost exclusively in Ethiopian children ≥5years of age. In conclusion, the Bedouin and Ethiopian children were characterized by higher parasite prevalence in stool, compared with the non-Ethiopian Jewish children, probably reflecting higher intestinal parasitic disease rates. Certain helminthic infections were identified almost exclusively in the Ethiopian children. These differences may be associated with lifestyle differences between the three populations.

Anthelmintic resistance in Northern Ireland (I): prevalence of resistance in ovine gastrointestinal nematodes, as determined through faecal egg count reduction testing

The prevalence of anthelmintic resistance in Northern Ireland sheep flocks was evaluated between July and October 2011. Sampling kits were sent to 172 flock owners and returns were received from 91. Within this survey population, 27 flock owners used benzimidazole products, 10 used levamisole products, 15 used avermectin products, 26 used milbemycin products and 4 flock owners used the amino acetonitrile derivative, Monepantel. The remaining 9 flock owners used combination drenches (broad spectrum wormer plus fasciolicide). However, 15 sets of samples were ineligible for faecal egg count reduction testing due to either too low an egg count or insufficient faecal volume. Treatment efficacy below 95%, indicating significant resistance, was detected in 81% (n=24) of flocks tested for benzimidazole resistance; in 14% (n=1) of flocks tested for levamisole resistance; and in 50% (n=7) and 62% (n=13) of flocks tested for avermectin and milbemycin resistance, respectively. Monepantel resistance was absent in all (n=3) flocks tested. Combination products (broad spectrum nematocide plus flukicide) containing levamisole were entirely effective, while treatment efficacy below 95% was detected in 60% (n=3) of flocks where the nematocide in the combination product was a benzimidazole. Where parasite identification based on coproculture was completed, Trichostrongylus was the dominant genus detected in all cases post-treatment, indicating the occurrence of anthelmintic-resistant Trichostrongylus spp. populations. Benzimidazole efficacy was highest in treating Trichostrongylus spp. (51%) and lowest when treating Teladorsagia spp. Levamisole was 100% effective in treating Cooperia, but ineffective (0%) in treating Trichostrongylus spp. Avermectin efficacy was highest when treating Haemonchus contortus (100%) and Teladorsagia spp. (73%), with a marginally lower efficacy against Trichostrongylus spp. (71%). Moxidectin efficacy was 33% against Trichostrongylus spp., 68% against Teladorsagia spp., 97% against Cooperia spp. and 100% against Haemonchus contortus infections.