Equine tapeworm infections: Disease, diagnosis and control

Prevalence and seasonal dynamic of gastrointestinal parasites in equids in France during two years

Grazing equids are constantly exposed to three clinically important gastrointestinal parasites (small strongyles/cyathostomins, Anoplocephala spp. and Parascaris spp.). Knowledge of the local seasonal dynamic of these parasitic infections is important for constructing a sustainable parasite control program with a rational number of anthelmintic treatments. However, studies describing these patterns are sparse in France. In this context, a two-year study was carried out to assess i) the seasonal dynamic and variability of strongyle faecal egg counts (FEC) and infective larvae (L3) counts on pastures, and ii) the prevalence of Anoplocephala spp. and Parascaris spp. and the dynamic evolution of their presence. During 2021 and 2022 grazing seasons, monthly individual faecal egg counts (FEC) and diarrhea scores (DS) were determined on 428 equids divided into 33 groups. A monthly body condition score (BCS) was also attributed to animals ≥3 years old and a monthly bodyweight was estimated for each animal <3 years old. At the group level, the strongyle L3 counts on grazed pastures were carried out at least in spring, summer and autumn. Eggs of strongyles were observed in 97% of equids. In 64% of the groups, the peaks of FEC were noted in September and October. At the individual level, the maximum strongyle FEC was related to age, group of breeds, number of grazed plots and number of anthelmintic treatments. No negative association was observed between strongyle FEC and BCS or average daily weight gain. In the pastures, cyathostomin larvae were found almost exclusively. Over the two years, the peaks of cyathostomin L3 counts occurred in 87% of the groups between September and November and ranged from 635 to 87,500 L3 kg-1 dry herbage. The variability of the maximum cyathostomin L3 count in each group was explained by the year and the number of grazed plots. Eggs of Anoplocephala spp. were observed in 12% of equids. Eggs of Parascaris spp. were noted in 34% of one year-old animals, 9% of two years-olds and 2% of olders. Anoplocephala spp. and Parascaris spp. eggs were observed every month with a peak in the percentage of shedders in groups in October for Anoplocephala spp. and May-June for Parascaris spp.This study highlights the prevalence of each parasite, the variability in cyathostomin egg excretion and L3 counts amongst groups and individuals and the factors involved in this variation These local epidemiological data will help us to re-think a newer strategy against these parasites.

Equine tapeworm (Anoplocephala spp.) infection: evaluation of saliva- and serum-based antibody detection methods and risk factor analysis in Slovak horse populations

A lack of accurate information on the prevalence and distribution of Anoplocephala spp. infections on horse farms has led to insufficient attention to tapeworm control and increasing horse anoplocephaloses in Europe. Our study aimed to examine the occurrence of Anoplocephala spp. infection using coprological, serum- and saliva-based antibody detection methods and to analyze the risk factors associated with tapeworm infection in domestic horses in Slovakia. Fecal, serum, and saliva samples were collected from 427 horses from 31 farms in Slovakia. Additionally, a questionnaire study was conducted to collect information on tapeworm distribution on horse farms and analyze risk factors associated with infection. Fecal samples were examined by the mini-FLOTAC and the double centrifugation/combined sedimentation-flotation techniques. Serum and saliva samples were analyzed by ELISA to determine antibody levels against Anoplocephala spp. The effects of variables associated with an individual horse were tested for the positive result of the saliva ELISA test on Anoplocephala spp. Cestode eggs were detected in 1.99% of fecal samples (farm prevalence 12.90%), with no differences between the two coprological methods. Serum-based tapeworm ELISA results revealed that 39.39% of horses tested positive (farm prevalence 83.87%); while saliva-based tapeworm ELISA results revealed 56.95% positive horses (farm prevalence 96.77%). Binary logistic regression analysis revealed four meaningful predictors that significantly impacted the likelihood of detecting tapeworm infection in horses: horse age, pasture size, anthelmintic treatment scheme, and access to pasture. The influences of other variables associated with an individual horse were not significantly associated with detecting tapeworm infection.

The Use of Innovative Diagnostics to Inform Sustainable Control of Equine Helminth Infections

Helminths are commonly found in grazing equids, with cyathostomin nematodes and the cestode Anoplocephala perfoliata being the most prevalent. Most horses harbour low burdens of these parasites and do not develop signs of infection; however, in a small number of animals, high burdens can accumulate and cause disease. Cyathostomins are associated with a syndrome known as larval cyathostominosis. This occurs when large numbers of larvae emerge from the large intestinal wall. This disease has a case fatality rate of up to 50%. A. perfoliata infection has been associated with various types of colic, with burdens of >20 worms associated with pathogenicity. Anthelmintic resistance is a serious problem in cyathostomins and is emerging in A. perfoliata. Control methods that reduce reliance on anthelmintics now need to be applied, especially as no new dewormer compounds are on the horizon. Sustainable control methods must employ diagnostics to identify horses that require treatment. Coprological tests (faecal egg counts, FECs) have been used for several decades to inform treatment decisions to reduce helminth egg shedding. These tests cannot be used to assess host burdens as FECs do not correlate with cyathostomin or A. perfoliata burdens. In the last decade, new tests have become available that measure parasite-specific antibodies, the levels of which have been shown to correlate with parasite burden. These tests measure antigen-specific IgG(T) and are available in serum (cyathostomin, A. perfoliata) or saliva (A. perfoliata) formats. Tests for other helminths have been developed as research tools and need to be translated to support equine clinicians in practice. A key element of sustainable control strategies is that diagnostics must be used in combination with management approaches to reduce environmental transmission of helminths; this will help limit the proportion of horses harbouring parasite burdens that need to be targeted by treatment. This manuscript provides a review of the development, performance and general utility of various diagnostic methods for informing equine helminth management decisions.

Horse and donkey parasitology: differences and analogies for a correct diagnostic and management of major helminth infections

In June 2022, at the XXXII Conference of the Italian Society of Parasitology, the parallels of the main endoparasitic infections of horses and donkeys were discussed. Although these 2 species are genetically different, they can be challenged by a similar range of parasites (i.e. small and large strongyles, and Parascaris spp.). Although equids can demonstrate some level of resilience to parasites, they have quite distinct helminth biodiversity, distribution and intensity among different geographical locations and breeds. Heavily infected donkeys may show fewer clinical signs than horses. Although parasite control is primarily provided to horses, we consider that there may be a risk of drug-resistance parasitic infection through passive infection in donkeys when sharing the same pasture areas. Knowing the possible lack of drug efficacy (<90 or 80%), it is advocated the use of selective treatment for both species based on fecal egg counts. Adult horses should receive treatment when the threshold exceeds 200–500 eggs per gram (EPG) of small strongyles. Moreover, considering that there are no precise indications in donkeys, a value >300 EPG may be a safe recommendation. We have highlighted the main points of the discussion including the dynamics of helminth infections between the 2 species.

Apparent treatment failure of praziquantel and pyrantel pamoate against anoplocephalid tapeworms

Anoplocephalid tapeworms are commonly occurring in grazing horses around the world. Two currently available anthelmintics have documented high efficacy against Anoplocephala perfoliata; praziquantel in various dosages ranging from 1.0 to 2.5 mg/kg and pyrantel pamoate administered at 13.2 mg base/kg. Anthelmintic resistance has not been reported in A. perfoliata, but anecdotal reports made during 2022 have suggested a possible loss of efficacy for both actives. This paper reports fecal egg count data from a Thoroughbred operation in Central Kentucky in 2023. Fifty-six yearlings were first dewormed with a combination of ivermectin (200 μg/kg) and praziquantel (1.5 mg/kg) and subsequently treated with pyrantel pamoate (13.2 mg base/kg). Fecal egg counts were determined at the day of treatment and again 14 days post-treatment. Two groups of mares (n = 39 and 45) were also treated with ivermectin/praziquantel and examined pre- and post-treatment. Low efficacy of ivermectin and pyrantel pamoate was demonstrated against strongylid parasites in the yearlings with mean Fecal Egg Count Reductions (FECRs) at 75.6% or below and upper 95% credible interval (CI) limits below 90% in all cases. Overall anti-cestodal FECR levels in the yearlings were 23.5% (95% CI: 11.2-48.0) for praziquantel and 50.9% (20.5-72.0) for pyrantel pamoate. Praziquantel eliminated anoplocephalid eggs from three of 17 yearlings, but another 5 yearlings went from negative to positive status following treatment. Pyrantel pamoate failed to eliminate anoplocephalid eggs from any of 14 treated tapeworm-positive yearlings. Nine of 84 mares tested positive for anoplocephalid eggs, and seven of these were still positive post praziquantel treatment. These findings sharply contrast data from historic field efficacy studies conducted for both actives and raise concern about anthelmintic resistance having possibly developed. This emphasizes the need for developing and refining antemortem methodologies for evaluating anti-cestodal treatment efficacy and for searching for possible alternative treatment options.

What about the Cytoskeletal and Related Proteins of Tapeworms in the Host's Immune Response? An Integrative Overview

Recent advances have increased our understanding of the molecular machinery in the cytoskeleton of mammalian cells, in contrast to the case of tapeworm parasites, where cytoskeleton remains poorly characterized. The pertinence of a better knowledge of the tapeworm cytoskeleton is linked to the medical importance of these parasitic diseases in humans and animal stock. Moreover, its study could offer new possibilities for the development of more effective anti-parasitic drugs, as well as better strategies for their surveillance, prevention, and control. In the present review, we compile the results of recent experiments on the cytoskeleton of these parasites and analyze how these novel findings might trigger the development of new drugs or the redesign of those currently used in addition to supporting their use as biomarkers in cutting-edge diagnostic tests.

Moringa oleifera as a Natural Alternative for the Control of Gastrointestinal Parasites in Equines: A Review

Studies have shown a wide variety of parasites that infect horses, causing major gastrointestinal damage that can lead to death, and although the main method of control has been synthetic anthelmintics, there are parasites that have developed resistance to these drugs. For generations, plants have been used throughout the world as a cure or treatment for countless diseases and their symptoms, as is the case of Moringa oleifera, a plant native to the western region. In all its organs, mainly in leaves, M. oleifera presents a diversity of bioactive compounds, including flavonoids, tannins, phenolic acids, saponins, and vitamins, which provide antioxidant power to the plant. The compounds with the greatest antiparasitic activity are tannins and saponins, and they affect both the larvae and the oocytes of various equine gastrointestinal parasites. Therefore, M. oleifera is a promising source for the natural control of gastrointestinal parasites in horses.

Gastrointestinal Helminths in Horses in Serbia and Various Factors Affecting the Prevalence

PURPOSE

Data on gastrointestinal infections in horses in Southeastern Europe are limited; thus, this study aimed to add to the existing knowledge on this topic by reporting on the prevalence of intestinal parasites of horses in the territory of the Republic of Serbia.

METHODS

In the period from April 2017 to December 2018, parasitological examination of 548 samples from horses of different breed, age and sex from four regions and 18 districts of the country was performed. Coprological diagnostic was done by using qualitative methods without concentration and qualitative methods with concentration of parasitic elements. Quantification of the obtained results was performed using semi-qualitative faecal egg count.

RESULTS

Four helminthoses were detected in the examined samples: P. equorum (8.57%), O. equi (3.65%), strongylid eggs (71.17%) and Anoplocephala spp. (0.91%). The total prevalence of helminthoses was 77.19%. Monoinfections were significantly more present 70.07% compared to coinfections (7.12%). The highest prevalence of helminthoses was detected in free-ranging horses (93.10%-27/29), in autumn 86.67% (117/135) and winter 79.71% (165/207), in Šumadija and West Serbia region (100%), and in the youngest category (100%). Significant difference (p < 0.001) was detected in the prevalence of monoinfections by strongylids and O. equi and also coinfections by strongylid/P. equorum between horses of different age categories.

CONCLUSION

Obtained results are of great contribution to clinical parasitology and pathology, especially from the aspect of animal health, welfare and preservation of horse population.

Label-free quantitative proteomics and immunoblotting identifies immunoreactive and other excretory-secretory (E/S) proteins of Anoplocephala perfoliata

Anoplocephala perfoliata is a common tapeworm in horses causing colic and even mortalities. Current diagnostic tests to detect A. perfoliata infections have their limitations and an improved method is needed. Immunoreactive excretory/secretory proteins (E/S proteome) of this parasite can provide promising candidates for diagnostic tests. We compared E/S proteins produced by small (length < 20 mm, width < 5 mm) and large (length 20 to 40 mm, width 5 to 10 mm) A. perfoliata worms in vitro by label-free quantitative proteomics using a database composed of related Hymenolepis diminuta, Echinococcus multilocularis/granulosus and Taenia aseatica proteins for protein identifications. Altogether, 509 E/S proteins were identified after incubating the worms in vitro for three and eight hours. The greatest E/S proteome changes suggested both worm size- and time-dependent changes in cytoskeleton remodeling, apoptosis, and production of antigens/immunogens. The E/S proteins collected at the three-hour time point represented the natural conditions better than those collected at the eight-hour time point, and thereby contained the most relevant diagnostic targets. Immunoblotting using antibodies from horses tested positive/negative for A. perfoliata indicated strongest antigenicity/immunogenicity with 13-, 30- and 100-kDa proteins, involving a thioredoxin, heat-shock chaperone 90 (Hsp90), dynein light chain component (DYNLL), tubulin-specific chaperone A (TBCA) and signaling pathway modulators (14-3-3 and Sj-Ts4). This is among the first studies identifying new diagnostic targets and A. perfoliata antigens eliciting a IgG-response in horses.

Evidence of Immune Modulators in the Secretome of the Equine Tapeworm Anoplocephala perfoliata

Anoplocephala perfoliata is a neglected gastro-intestinal tapeworm, commonly infecting horses worldwide. Molecular investigation of A. perfoliata is hampered by a lack of tools to better understand the host-parasite interface. This interface is likely influenced by parasite derived immune modulators released in the secretome as free proteins or components of extracellular vesicles (EVs). Therefore, adult RNA was sequenced and de novo assembled to generate the first A. perfoliata transcriptome. In addition, excretory secretory products (ESP) from adult A. perfoliata were collected and EVs isolated using size exclusion chromatography, prior to proteomic analysis of the EVs, the EV surface and EV depleted ESP. Transcriptome analysis revealed 454 sequences homologous to known helminth immune modulators including two novel Sigma class GSTs, five α-HSP90s, and three α-enolases with isoforms of all three observed within the proteomic analysis of the secretome. Furthermore, secretome proteomics identified common helminth proteins across each sample with known EV markers, such as annexins and tetraspanins, observed in EV fractions. Importantly, 49 of the 454 putative immune modulators were identified across the secretome proteomics contained within and on the surface of EVs in addition to those identified in free ESP. This work provides the molecular tools for A. perfoliata to reveal key players in the host-parasite interaction within the horse host.

Using worm egg count data to detect and counter trends in equine helminth abundance

Jan van Dijk, RCVS specialist in veterinary parasitology, describes how data can be used to both increase understanding of trends in equine helminth abundance and drive better treatment of individual horses.

A Comparison of the Colonic Microbiome and Volatile Organic Compound Metabolome of Anoplocephala perfoliata Infected and Non-Infected Horses: A Pilot Study

Simple Summary

In horses, tapeworm infection is associated with specific forms of colic (abdominal pain) that can be life-threatening without surgical treatment. There is growing evidence that intestinal parasites interact with the gut bacteria, and the consequences of these interactions may influence the ability of the host to resist infection and parasite-associated disease. We aimed to compare the intestinal bacteria and the gases produced by metabolic processes in the gut between horses that had varying levels of tapeworms and those with no tapeworm present. Overall, the diversity of gut bacteria was similar in horses with and without tapeworms. There were some decreases in beneficial bacteria in horses with tapeworms, indicating a possible negative consequence of infection. Intestinal gases correlated with some bacteria indicating their functionality and use as potential markers of active bacteria. Our study validates further research investigating tapeworm and gut bacteria interactions in the horse.

Abstract

Anoplocephala perfoliata is a common equine tapeworm associated with an increased risk of colic (abdominal pain) in horses. Identification of parasite and intestinal microbiota interactions have consequences for understanding the mechanisms behind parasite-associated colic and potential new methods for parasite control. A. perfoliata was diagnosed by counting of worms in the caecum post-mortem. Bacterial DNA was extracted from colonic contents and sequenced targeting of the 16S rRNA gene (V4 region). The volatile organic compound (VOC) metabolome of colonic contents was characterised using gas chromatography mass spectrometry. Bacterial diversity (alpha and beta) was similar between tapeworm infected and non-infected controls. Some compositional differences were apparent with down-regulation of operational taxonomic units (OTUs) belonging to the symbiotic families of Ruminococcaceae and Lachnospiraceae in the tapeworm-infected group. Overall tapeworm burden accounted for 7–8% of variation in the VOC profile (permutational multivariate analysis of variance). Integration of bacterial OTUs and VOCs demonstrated moderate to strong correlations indicating the potential of VOCs as markers for bacterial OTUs in equine colonic contents. This study has shown potential differences in the intestinal microbiome and metabolome of A. perfoliata infected and non-infected horses. This pilot study did not control for extrinsic factors including diet, disease history and stage of infection.

Paleoparasitology and archaeoparasitology in Iran: A retrospective in differential diagnosis

OBJECTIVE

This paper reviews paleo- and archaeoparasitology publications to date, from Iran. The primary focus is the importance of differential diagnosis and the crucial role of interdisciplinary collaborations among parasitologists and other specialists.

METHODS

All relevant articles and theses published in Iran through October 2020 are included and evaluated, with particular emphasis on the diagnostic process.

RESULTS

Archaeoparasitic studies in Iran have identified a number of parasites that provide insight into the past. Misidentification, however, due to incomplete differential diagnosis, remains an issue, as does incomplete description and problematic images.

CONCLUSIONS

Identification of paleoparasites to the species level must be supported with accurate morphology and morphometry. Rigorous differential diagnosis is essential. Caution must be exercised when interpreting observations of ova recovered from coprolites. In these instances, precise identification of host animals and aligning parasite ranges with host specificity is critical. The possibility of incidental parasite presence must be evaluated, including non-specificity of parasite tropisms, transport hosting, or contamination. Lastly, differential diagnosis must include consideration of intentional consumption of parasites. Thus, parasitological findings must be placed in geographical, historical, and cultural contexts.

SIGNIFICANCE

Archaeoparasitological research in Iran has elucidated the presence of faunal and human disease in the past and has, through this reevaluation of the published works, contributed to precise description and diagnosis of ova of roundworms, tapeworms, thorny-headed worms, and recognition of larval stages of tapeworms in recovered remains of mites.

Monitoring equine ascarid and cyathostomin parasites: Evaluating health parameters under different treatment regimens

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.

Parasitic diseases of equids in Iran (1931-2020): a literature review

Parasitic infections can cause many respiratory, digestive and other diseases and contribute to some performance conditions in equids. However, knowledge on the biodiversity of parasites of equids in Iran is still limited. The present review covers all the information about parasitic diseases of horses, donkeys, mules and wild asses in Iran published as articles in Iranian and international journals, dissertations and congress papers from 1931 to July 2020. Parasites so far described in Iranian equids include species of 9 genera of the Protozoa (Trypanosoma, Giardia, Eimeria, Klossiella, Cryptosporidium, Toxoplasma, Neospora, Theileria and Babesia), 50 helminth species from the digestive system (i.e., 2 trematodes, 3 cestodes and 37 nematodes) and from other organs (i.e., Schistosoma turkestanica, Echinococcus granulosus, Dictyocaulus arnfieldi, Parafilaria multipapillosa, Setaria equina and 3 Onchocerca spp.). Furthermore, 16 species of hard ticks, 3 mite species causing mange, 2 lice species, and larvae of 4 Gastrophilus species and Hippobosca equina have been reported from equids in Iran. Archeoparasitological findings in coprolites of equids include Fasciola hepatica, Oxyuris equi, Anoplocephala spp. and intestinal strongyles. Parasitic diseases are important issues in terms of animal welfare, economics and public health; however, parasites and parasitic diseases of equines have not received adequate attention compared with ruminants and camels in Iran. The present review highlights the knowledge gaps related to equines about the presence, species, genotypes and subtypes of Neospora hughesi, Sarcocystis spp., Trichinella spp., Cryptosporidium spp., Giardia duodenalis, Blastocystis and microsporidia. Identification of ticks vectoring pathogenic parasites, bacteria and viruses has received little attention, too. The efficacy of common horse wormers also needs to be evaluated systematically.

Comparative Analysis of Intestinal Helminth Infections in Colic and Non-Colic Control Equine Patients

All around the world, intestinal helminths constitute one of the most prevalent life-long occurring infections and re-infections affecting all horse age groups. A range of parasite species among strongyles, ascarids, and tapeworms is known to have the potential to cause colic in horses. However, there is a lack of current scientific evidence on the actual relevance of helminth infection levels in the context of colic in horses kept during prevailing epidemiological conditions. Thus, a prospective case-control study on the occurrence of intestinal helminths in a total of 620 mainly adult equine clinic patients was conducted to investigate the association between colic and helminth infection. For each horse, a range of copromicroscopic, serological, and clinical data was obtained, in addition to a questionnaire on relevant anamnestic data, including previous anthelmintic treatment and husbandry. Using a FLOTAC-based copromicroscopic diagnosis, the highest infection rates were seen for strongyles (41.8%), followed by Anoplocephala perfoliata and Parascaris spp. (both 0.8%), with no significant difference between the two study groups. Employing a real-time PCR a 1.1% S. vulgaris DNA prevalence was found. Considerably higher seroprevalences were observed using S. vulgaris and A. perfoliata ELISAs, with 32.3% and 10.7%, respectively. It was noteworthy that no association concerning either serologic status was encountered with colic status. The shedding of strongyle eggs was associated with a 1.8-times increased risk of S. vulgaris seropositivity. Recent anthelmintic treatment was associated with the onset of colic, as animals who had received an anthelmintic during the previous week had a 2.4-times higher risk of signs of colic compared to those who had been treated at least eight weeks prior. Another noteworthy observation was that ponies were significantly less often affected by colic than warmbloods. The high S. vulgaris and considerable A. perfoliata seroprevalences encountered in this investigation should prompt veterinarians, farm managers, and horse owners to maintain consequent and effective worm control measures.

Effects of life history stage and climatic conditions on fecal egg counts in plains zebras (Equus quagga) in the Serengeti National Park

In wildlife, endoparasite burden can be affected by host life history stage, environmental conditions, host abundance, and parasite co-infections. We tested the effects of these factors on gastrointestinal parasite infection in plains zebras (Equus quagga) in the Serengeti ecosystem, Tanzania, using fecal egg counts of two nematode families (Strongylidae and Ascarididae) and the presence/absence of cestode (Anoplocephalidae) eggs. We predicted higher egg counts of Strongylidae and Ascarididae, and increased likelihood of Anoplocephalidae infection in individuals (1) during energetically costly life history stages when resource allocation to immune processes may decrease and in young zebras after weaning because of increased uptake of infective stages with forage, (2) when climatic conditions facilitate survival of infective stages, (3) when large zebra aggregations increase forage contamination with infective stages, and (4) in individuals co-infected with more than one parasite group as this may indicate reduced immune competence. Strongylidae egg counts were higher, and the occurrence of Anoplocephalidae eggs was more likely in bachelors than in band stallions, whereas Ascarididae egg counts were higher in band stallions. Strongylidae and Ascarididae egg counts were not increased in lactating females. Strongylidae egg counts were higher in subadults than in foals. Regardless of sex and age, Ascarididae infections were more likely under wet conditions. Co-infections did not affect Strongylidae egg counts. Ascarididae egg counts in adult females were higher when individuals were co-infected with Anoplocephalidae. We present evidence that parasite burdens in plains zebras are affected by life history stage, environmental conditions, and co-infection.

Parasite Occurrence and Parasite Management in Swedish Horses Presenting with Gastrointestinal Disease-A Case-Control Study

All grazing horses are exposed to intestinal parasites, which have the potential to cause gastrointestinal disease. In Sweden, there is a concern about an increase in parasite-related equine gastrointestinal disease, in particular Strongylus vulgaris, since the implementation of prescription-only anthelmintics approximately 10 years ago. In a prospective case-control study, parasitological status, using fecal analyses for strongyle egg counts, the presence of Anoplocephala perfoliata eggs and S. vulgaris Polymerase chain reaction (PCR) as well as serology for S. vulgaris, were compared between horses presenting with or without gastrointestinal disease at a University hospital during a one-year period. Information regarding anthelmintic routines and pasture management was gathered with an owner-filled questionnaire. Although the prevalence of S. vulgaris PCR was 5.5%, 62% of horses were positive in the enzyme-linked immunosorbent assay (ELISA) test and horses with peritonitis showed higher antibody levels for S. vulgaris, as compared to other diagnoses or controls. Overall, 36% of the horse owners used only fecal egg counts (FEC), 32% used FEC combined with specific diagnostics for S. vulgaris or A. perfoliata, and 29% dewormed routinely without prior parasite diagnostics. Effective management methods to reduce the parasitic burden on pastures were rare and considering exposure to S. vulgaris appears high; the study indicates a need for education in specific fecal diagnostics and pasture management.

Equine helminth prevalence and management practices on Australian properties as shown by coprological survey and written questionnaire

Context Parasite control is an essential part of a broader equine health-management strategy and is often completely administered by the horse owner, with little or no supporting evidence on which to base decisions. Practical and sound advice relies on knowledge of the resident parasite species, the anthelmintic resistance status of important species, and the strategies currently being utilised by owners and managers of horses. Much of this farm-level information is lacking in the Australian literature. Aims The present study aimed to gather both farm- and horse-level prevalence data for four important equine helminth species and to gather information on the current worm-management practices conducted on Australian horse farms. Methods We conducted a coprological survey of cyathostomins, Strongylus vulgaris, Parascaris spp. and equine tapeworm on 102 horse properties, using a combination of classical and molecular parasitological methods, including a tapeworm polymerase chain reaction developed as part of the study. A questionnaire canvasing horse owners on internal parasite-control practices was also distributed. Key results Cyathostomin were present on all farms surveyed and S. vulgaris, despite being considered rare, was present on 7.8% (95% CI: 3.9–15.0) of farms. The prevalence of Parascaris spp. and equine tapeworm was 33.3% (95% CI: 19.6–50.6) and 3.9% (95% CI: 1.5–10.1) respectively. Questionnaire responses showed that the majority (85.0%) of horse owners administer anthelmintics at regular intervals of 12 weeks or less, and only 2.6% utilise faecal egg counts to inform treatment decisions. Conclusions Prevalence data confirmed the endemic nature of cyathostomin and P. equorum infections, as well as low levels of tapeworm and S. vulgaris infections on Australian horse farms. Worm-management practices were reminiscent of traditional interval-style treatment regimens that rely heavily on macrocyclic lactone anthelmintics. Implications These results suggest a need for more strategic approaches to internal-parasite control in horses to slow the development of anthelmintic resistance. Such programs need to consider the risk of re-establishment of the pathogenic S. vulgaris in significant numbers.

Pixel by pixel: real-time observation and quantification of passive flotation speeds of three common equine endoparasite egg types

The efficacy of anthelmintic treatments against populations of endoparasites infecting livestock throughout the world is decreasing. To mitigate this, the use of fecal egg counts is recommended to determine both the necessity, and to ensure the appropriate choice, of anthelmintic treatment. Traditionally, and in order to facilitate easier identification and/or enumeration, samples are analysed after separating eggs from other fecal particulates by exposing them to a solution with a density higher than that of the eggs, but lower than the remaining fecal contents. While many parasite egg flotation protocols exist, little is known about the characteristics of these eggs with respect to their movement through a flotation solution. In this study, we have demonstrated a novel method for the observation and quantification of microscopic (65-100 µm) objects as they experience unassisted flotation. This also represents, to our knowledge for the first time, that the flotation of parasite eggs has been observed and their movement characteristics quantified as they float through solution. Particle tracking and video analysis software were utilised to automatically detect and track the movement of individual eggs as they floated. Three 30 s videos and one 2 min video of each egg type were analysed. If the first 30 s of video were discounted, the differences in mean flotation speed among all videos was statistically significant between egg types (P = 0.0004). Strongyle type eggs (n = 201) moved the fastest with a mean 51.08 µm/s (95% confidence interval: 47.54-54.62). This was followed by Parascaris spp. (n = 131) and Anoplocephala perfoliata eggs (n = 322), with mean speeds of 44.43 µm/s (95% confidence interval: 39.47-49.4) and 31.11 µm/s (95% confidence interval: 29.6-32.61), respectively. This method for evaluating the mean speed of passive flotation may represent a first step towards further optimizing fecal egg flotation and be of interest to parasitologists and veterinary practitioners.

Gastrointestinal and pulmonary parasites of working horses from Colombia

Working equids are used in different countries for numerous purposes and regularly are crucial for multiple communities' income and profit. Historically, in Bogotá D.C. they were used as animal-powered vehicles but in 2013 it was initiated a substitution and adoption program as a result of society pressure and lawful processes. Infectious diseases and mainly parasitic diseases, poses a threat in the health and productivity of these animals. Our aim was to identify, by coproparasitological methods, the gastrointestinal and pulmonary parasite species infecting working horses submitted to the mentioned substitution and adoption program. Between May and December 2013 and February and July 2014, fresh faecal samples were obtained from 1004 and 648 horses from Bogotá D.C. and other Colombian municipalities, respectively. They were processed by flotation and Baermann tests in order to visualize faecal parasitic forms (eggs, oocysts, and larvae). Prevalences were calculated for each gastrointestinal parasite at origin and one year after, at destination, and analysed by age group and coinfection. At origin (Bogotá D.C.), prevalence for at least one parasite species was 87.5% and one year later, at destination (other municipalities), was 89.5%. The most prevalent species were strongyles (86.4-89.4%) followed by Parascaris spp. (0.7-6.2%), cestodes (Anoplocephalidae) (3.7-4.9%) and Oxyuris sp. (2.8-4.3%). Other species detected were Eimeria sp., Strongyloides sp. and Dictyocaulus sp. Coinfection by two or more species ranged between 14.4 and 38.3% being strongyle, Parascaris spp., Oxyuris sp. and cestodes (Anoplocephalidae) the most common species involved. Some parasitic infections commonly associated with younger animals (e.g. Parascaris spp.) were detected in all age groups. Flow patterns of parasites linking Bogotá D.C. and other municipalities are presented. Finally, these results support the widespread distribution of most of species and the plausible health and welfare impact of this infections in working equids submitted to particular epidemiological risks.