Egg Shedding Research Articles

Prevalence, risk factors and molecular identification of paramphistomid species in sheep from a Spanish endemic area

BackgroundParamphistomids are ruminal trematodes that cause important losses in tropical and subtropical regions. However, their presence in Europe has increased significantly in recent decades. In northwestern Spain, this trend has been confirmed in cattle, but data in sheep are scarce and not updated. Moreover, the paramphistomid species affecting sheep in the area have never been molecularly identified. To evaluate the prevalence of paramphistomid infections in sheep from northwestern Spain, 826 faecal samples from 25 sheep farms were collected and analysed via coproscopic techniques. In addition, the rumens of 85 roe deer from the same area were examined to detect adult paramphistomids. The species present were molecularly identified. Multivariate analyses for identifying the risk factors affecting the prevalence and egg shedding of rumen flukes were also performed.ResultsOverall, 14% of the animals and 44% of the flocks were positive; the mean egg count was 20.5 eggs per gram of faeces. In contrast, no adult paramphistomids were found in roe deer. Older sheep, those from farms located in the central climatic area, without water throughs available on pastures and using their own manure to fertilize, were considered significantly more susceptible to infection with paramphistomids. With respect to egg shedding, animals from 37 to 72 months of age, farms under semiextensive management, and those coinfected with Fasciola hepatica presented significantly greater egg counts. Molecular identification revealed 100% similarity with Calicophoron daubneyi sequences from other European and Mediterranean countries.ConclusionsThe present study confirms the increase in the prevalence of paramphistomid infections in sheep in the area with high dissemination of the parasite, as previously reported in cattle, and represents the first molecular identification of C. daubneyi in sheep from Spain. Our results demonstrate that special attention should be given to adult animals since they are the main carriers and are responsible for environmental contamination. In addition, detecting risk areas and applying effective control management measures such as the installation of watering points on pastures seems essential for limiting infections in livestock, especially in sheep, since they are susceptible to developing clinical paramphistomidosis at any time in their lives. The absence of adult flukes in roe deer suggests that they represent less suitable hosts for this trematode than cattle and sheep, although more robust studies monitoring the situation in sympatric areas with domestic ruminants are needed.

Year after year: Recurrent Toxocara vitulorum infections in American bison (Bison bison) calves in a zoo

Toxocara vitulorum (Nematoda: Ascaridida) is a common parasite of cattle and buffaloes in tropical and subtropical regions and the causative agent of toxocarosis in calves. In Europe, sporadic infections have been reported in cattle, but also in bovines held at zoological gardens. Here, we report T. vitulorum infections in a herd of American bison (Bison bison) kept at the Vienna Zoo, Au stria, which occurred in 2023 and 2024. After the first case in a seven-week-old calf in July 2023, another case in a five-week-old calf was diagnosed in May 2024, both of them detected by coproscopy and fecal discharge of adult worms after anthelmintic treatment. The calves originated from two different mothers imported to the zoo in 2014 from the Czech Republic and 2012 from Germany respectively. Both calves showed diarrhea and fecal soiling of the anal region prior to fecal analysis. Two intramuscular administrations of ivermectin (0.2 mg/kg bodyweight, two-week interval) caused the passing of up to 39 cm long gravid female worms, resulted in the cessation of egg shedding and improved fecal consistency. Morphological and molecular identification confirmed infections with T. vitulorum. Additionally, another calf, born in May 2024 from the mother of the calf that was T. vitulorum-positive in 2023, showed periods of diarrhea. Due to difficulties in taking individual samples, no definitive diagnosis of T. vitulorum infection could be made, however, the animal was also treated and clinically improved afterwards. Besides T. vitulorum, Eimeria spp. were detected in all samples and Giardia duodenalis genotype E in two samples in 2024. This case series highlights the possibility of unnoticed parasite introductions into zoological gardens via animals infected with resting parasite stages, and demonstrates the importance of regular individual parasitological analysis in bovine zoo animals during the first weeks after birth.

Gastrointestinal nematodes in German outdoor-reared pigs based on faecal egg count and next-generation sequencing nemabiome data

BackgroundThere is a higher risk for nematode infections associated with outdoor-reared pigs. Next to Ascaris suum, Oesophagostomum dentatum and Trichuris suis, there is the potential of infections with other nodular worm species, Hyostrongylus rubidus, Stongyloides ransomi and Metastrongylus spp. lungworms. Next-generation sequencing methods describing the nemabiome have not yet been established for porcine nematodes.MethodsFLOTAC was used for faecal egg counts of porcine gastrointestinal nematodes and lungworms in piglets, fatteners and adults individually. A nemabiome analyses based on ITS-2 gene region metabarcoding was used to differentiate strongyle species. Additionally, questionnaire data was analysed using mixed-effect regression to identify potential risk factors associated with parasite occurrences and egg shedding intensity.ResultsOn 15 of 17 farms nematode eggs were detected. Ascaris suum, strongyles and T. suis were detected on 82%, 70% and 35% of the 17 farms, respectively. Lungworms were detected on one out of four farms with access to pasture. Strongyloides ransomi was not detected. 32% (CI 28–36%), 27% (24–31%), 5% (4–7%) and 3% (0.9–8%) of the samples where tested positive for strongyles, A. suum, T. suis and lungworms, respectively. The nemabiome analysis revealed three different strongyle species, with O. dentatum being the most common (mean 93.9%), followed by O. quadrispinulatum (5.9%) and the hookworm Globocephalus urosubulatus (0.1%). The bivariate and multivariate risk factor analyses showed among others that cleaning once a week compared to twice a week increased the odds significantly for being infected with A. suum (OR 78.60) and strongyles (2077.59). Access to pasture was associated with higher odds for A. suum (43.83) and strongyles (14.21). Compared to shallow litter systems, deep litter and free range systems resulted in significant higher odds for strongyles (85.74, 215.59, respectively) and T. suis (200.33, 623.08).ConclusionsInfections with A. suum, O. dentatum, O. quadrispinulatum, T. suis, Metastrongylus spp. and G. urosubulatus are present in German outdoor-reared pigs. This is the first report of G. urosubulatus in domestic pigs in Europe. Metabarcoding based on the ITS-2 region is a suitable tool to analyse the porcine nemabiome. Furthermore, management practices have the potential of reducing the risk of parasite infections.

Temporal dynamics in gastrointestinal helminth infections of sympatric mouse lemur species (Microcebus murinus and Microcebus ravelobensis) in Northwestern Madagascar

Madagascar's lemur populations are declining in dwindling habitats due to anthropogenic expansion and changing climatic conditions. Gastrointestinal parasites can be important indicators to assess the health status of threatened species. However, parasites, hosts and the environment are connected in complex interactions. The present study aimed to disentangle the impact of seasonal and several host-specific factors (sex, species, age, reproductive status, and body mass) on endoparasitism in two small-bodied, co-occurring lemur species (Microcebus murinus and Microcebus ravelobensis) in the Ankarafantsika National Park. Helminth prevalence and egg shedding intensity was investigated via copromicroscopic examination of 810 fecal samples that were obtained from 178 individuals across an 11-month period with a longitudinal approach via repeated captures in a 30.6 ha forest area. Both mouse lemur hosts shed seven morphologically distinct egg types (assigned to Subulura baeri, unidentified Enterobiinae, Spirura sp., Lemuricola sp., two Hymenolepididae spp., one unidentified ascarid). Postmortem examination of two deceased individuals enabled assignment of adult worms to egg morphotypes of S. baeri, Spirura sp. and one Hymenolepididae sp., supported by molecular analysis. A significant seasonal variation was observed in the occurrence of the three most common helminth species S. baeri (total prevalence 71%), unidentified Enterobiinae (46%) and Spirura sp. (38%), with a higher likelihood of infection with advancing dry season. Neither host species, sex nor reproductive status had a significant effect on gastrointestinal helminth infections. Host body mass showed pronounced seasonal changes but did not differ significantly between infected and non-infected individuals. The pathogenic effects of gastrointestinal helminths therefore likely remained within compensable limits in the studied mouse lemur populations. Our findings highlight the prominent influence of seasonal changes on helminth communities. The results of combined morphologic and genetic approaches can furthermore help to overcome limitations of parasite identification via copromicroscopy by linking egg morphology to DNA sequences.

Comparison of diagnostic methods for laboratory diagnosis of the zoonotic tapeworm Dipylidium caninum in cats

The tapeworm Dipylidium caninum is the most widely distributed cestode infecting dogs, cats, and sometimes humans, worldwide. The diagnosis of the infection caused by D. caninum is achieved via the visualization of proglottids in feces or with traditional microscopic tests, but both lack sensitivity. The present study has evaluated and compared the diagnostic performance of a PCR protocol on different feline biological samples to detect D. caninum. A sample of feces, a Scotch tape test from the perianal area, and a rectal swab were collected from a total of 100 privately owned cats from Italy and Greece. All fecal samples were subjected to macroscopic examination and to floatation. Based on the results of the above tests the cats were divided in three groups, i.e. (i) cats positive for D. caninum (regardless of positivity for other endoparasites (Group A; n = 50 cats), (ii) cats negative for D. caninum but infected by other helminths (Group B; n = 25 cats), and (iii) cats negative for intestinal endoparasites (Group C; n = 25 cats). For each sample, the DNA was extracted from feces, floatation supernatant, Scotch tape test and rectal swabs and subjected to PCR. For 33 cats from Group A, at least one sample type scored positive at PCR. Of these, all were PCR-positive in the floatation aliquot, while nine and one cats were positive by PCR on feces and Scotch tape test, respectively. Swabs were negative by PCR for all the cats. None of the samples from cats of Groups B and C was positive by any PCR. Sequences obtained from amplicons generated from samples of cats enrolled in Italy had 99–100 % identity with the recently described D. caninum feline genotype. The data presented here suggest that PCR could be a useful tool for diagnosing D. caninum infections, under certain circumstances, e.g. when proglottids are unidentified, unseen or overlooked, even though it has limitations, e.g. false negative results due to fecal PCR inhibitors, uneven distribution of parasitic elements, or to intermittent proglottid and/or egg shedding. Thus, it may not be, currently, the best diagnostic choice for dipylidiosis.

POPULATION DYNAMICS OF ENTERIC PARASITES IN THE ENDANGERED VANCOUVER ISLAND MARMOT (MARMOTA VANCOUVERENSIS).

Enteric parasites can have wide-ranging effects throughout an ecosystem, often driving coevolutionary and ecological processes. Parasites have long been overlooked in conservation efforts because of the negative impact inflicted on their hosts; however, parasites make up a significant component of Earth's biodiversity and host conservation efforts need to be parasite inclusive. The Vancouver Island marmot (VIM), Marmota vancouverensis, is an endangered alpine rodent endemic to Vancouver Island, British Columbia, Canada. Captive-bred VIMs are released to augment the wild population, but their susceptibility to parasites is unknown. The objectives of this study were to describe the diversity, prevalence, severity, and temporal variation of VIM enteric parasites. Noninvasive fecal samples were collected from wild and captive marmots and analyzed using a modified McMaster fecal egg floatation technique to indicate parasite prevalence and relative mean abundance. We identified oocysts and ova from 3 parasite taxa including a protozoan coccidium not previously described in the VIM (prevalence 68%), an ascarid nematode Baylisascaris laevis (prevalence 82%), and an anoplocephalid cestode Diandrya vancouverensis (prevalence 8%). Depending on the species, comparisons revealed variation in parasite infection by sex, by colony, and between wild and captive VIMs, but not among age classes or by female reproductive status. Finally, captive VIMs displayed significant monthly variation in parasite prevalence and mean egg abundance, suggesting a seasonal influence on parasite egg shedding. This information is critically important for future research investigating the influences of these trends on the health, ecology, and conservation of VIMs and their parasites.

Clinical and Diagnostic Findings in Dogs Infected with Trichuris vulpis: A Retrospective Study.

Trichuris vulpis is a parasite of the large intestine of canids and has a global distribution. Despite its well-established epidemiology, the question of its pathogenicity in dogs remains debated. It has been suggested that younger age and concurrent infection with Ancylostoma caninum may be responsible for more severe clinical presentations. This retrospective study aimed to describe the clinical and diagnostic features of T. vulpis-infected dogs and to compare these findings with dogs infected with both T. vulpis and other intestinal parasites (poly-infected dogs). Forty-five dogs were included, with twenty-five being solely infected by T. vulpis and twenty poly-infected dogs. Only weight loss was more frequent (p = 0.006) in poly-infected dogs compared to T. vulpis mono-infected dogs. No significant differences were observed in laboratory abnormalities between mono-infected and poly-infected dogs. Only diarrhea was more frequent (p = 0.007) in younger dogs compared to adults. The egg shedding pattern was significantly higher (p = 0.04) among adult dogs compared to young ones, and there was a significant positive correlation between egg shedding and age (r = 0.41; p = 0.005). These findings suggest that T. vulpis might be responsible for both clinical signs and laboratory abnormalities in dogs, irrespective of the host's age and the presence of other intestinal parasites.

Fatal Hymenolepis nana-associated visceral larva migrans in captive juvenile white-tailed antsangies (Brachytarsomysalbicauda)

White-tailed antsangies (Brachytarsomys albicauda) are Madagascan rodents uncommonly kept in captivity. Hymenolepis nana is a cestode with an unusual life cycle, incorporating direct, indirect and autoinfective stages. This case series represents the first reported outbreak of H. nana cestodiasis in white-tailed antsangies, summarizing macroscopic and histological findings in four cases. On post-mortem examination (PME), numerous cysticerci were detected consistently throughout the intestinal serosa, liver, mesenteric lymphatic vasculature and mesenteric lymph nodes. Pancreatic cysticerci were observed in one case. Adult tapeworms, larvae and eggs were found only in the small intestine, and faecal egg shedding was a feature. Histopathological examination identified adult, larval and encysted cestodes within the respective gross lesions, with pulmonary, pancreatic and splenic involvement detected in a single case. The cestodes sampled on PME were identified by polymerase chain reaction and DNA sequencing, with H. nana confirmed in all cases. Visceral larva migrans was consistent throughout all specimens, in contrast with the natural infections of standard rodent hosts, and may be considered a likely pathological feature of H. nana infection in white-tailed antsangies.

93 Evaluating the efficacy of anthelmintics in an upper Midwest horse herd

Abstract Cyathostomins in the gastrointestinal tract are ubiquitous in horses around the world and remain a target in parasite control programs. Resistance to anthelmintics has risen in recent years with widespread resistance to benzimidazoles and pyrantels and emerging resistance to macrocyclic lactones. Thus, investigating the efficacy of anthelmintics in different locations is important to direct future parasite control programs. This 2-yr study evaluated the efficacy of three anthelmintic drugs in a university-owned equine herd in the upper Midwest using fecal egg count reduction tests (FECRT). Additionally, the effect of age group and body condition score (BCS) on fecal egg shedding was evaluated. We hypothesized that drug resistance is present in the parasite population of this equine herd. Fecal egg counts (FEC) of strongelid eggs were determined using the McMaster method. The efficacy of anthelmintics was determined by calculating the percentage of reduction in FEC between d 0 and d 14 post-treatment. Eighteen horses of various breeds were used in the study. The horses were grouped by age (< 10, 10-16, and > 16 yr; n = 6 in each group) and BCS using the Henneke system (5.0-5.5, n = 9; 6.0-6.5., n = 6; and 7.0-8.0, n = 3). In yr 1, horses within age group were randomly assigned to anthelmintic treatment: pyrantel pamoate, fenbendazole, or ivermectin. In yr 2, all horses received ivermectin. Individual FEC were performed on the day of anthelmintic treatment (d 0) using freshly voided feces. FEC were repeated 14 d after treatment. FEC were log transformed before analysis. Efficacy of the anthelmintics were compared using a mixed model ANOVA with repeated measures (SAS 9.4). Results were considered significant when P < 0.05. The FECRT was greater when treated with ivermectin and pyrantel pamoate (94.8 ± 11.6 % and 96.6 ± 14.3 %, respectively) compared with fenbendazole (54.4 ± 10.8 %; P < 0.05). The FECRT increased from 54.4% when treated with fenbendazole to 100% when the same horses were treated with ivermectin (P < 0.05). Age tended to affect egg shedding in horses (P = 0.0548). Young horses (< 10 yr) had a greater FEC compared with older horses (>16 yr; P < 0.05) but were not different from horses aged 10 to 16 yr (P > 0.05). There was no effect of BCS on strongelid egg shedding in this study (P = 0.9468). These results indicate the efficacy was within the expected range with no signs of resistance to pyrantel pamoate (93.3 to 100% reduction). There was evidence of emerging resistance to ivermectin (70.4 to 100% reduction) and significant resistance to fenbendazole (0 to 71.5% reduction) in the cyathostomin population in this horse herd. The findings of this study agree with previous research demonstrating resistance to anthelmintics. These results highlight the importance of designing improved parasite control programs to limit the spread of drug resistance with the ultimate goal of improving overall health of the horse.

The adaptive immune response to Trichuris in wild versus laboratory mice: An established model system in context.

Laboratory model organisms have provided a window into how the immune system functions. An increasing body of evidence, however, suggests that the immune responses of naive laboratory animals may differ substantially to those of their wild counterparts. Past exposure, environmental challenges and physiological condition may all impact on immune responsiveness. Chronic infections of soil-transmitted helminths, which we define as establishment of adult, fecund worms, impose significant health burdens on humans, livestock and wildlife, with limited treatment success. In laboratory mice, Th1 versus Th2 immune polarisation is the major determinant of helminth infection outcome. Here we compared antigen-specific immune responses to the soil-transmitted whipworm Trichuris muris between controlled laboratory and wild free-ranging populations of house mice (Mus musculus domesticus). Wild mice harbouring chronic, low-level infections produced lower levels of cytokines in response to Trichuris antigen than laboratory-housed C57BL/6 mice. Wild mouse effector/memory CD4+ T cell phenotype reflected the antigen-specific cytokine response across the Th1/Th2 spectrum. Increasing egg shedding was associated with body condition loss. However, local Trichuris-specific Th1/Th2 balance was positively associated with worm burden only in older wild mice. Thus, although the fundamental relationships between the CD4+ T helper cell response and resistance to T. muris infection are similar in both laboratory and wild M. m. domesticus, there are quantitative differences and age-specific effects that are analogous to human immune responses. These context-dependent immune responses demonstrate the fundamental importance of understanding the differences between model and natural systems for translating mechanistic models to 'real world' immune function.

Strongyle egg shedding and egg reappearance periods in horses with pituitary pars intermedia dysfunction

Pituitary pars intermedia dysfunction (PPID) is the most common endocrine disorder of older horses. Immune dysfunction in horses with PPID could increase susceptibility to infectious diseases, including strongyle infections; however, few data are available. The aim of this study was to determine if horses with PPID had increased strongyle faecal egg counts (FEC) compared with control horses, over a fourteen-week period in Victoria, Australia. Clinical signs and plasma adrenocorticotropic hormone (ACTH) concentrations were used to categorise horses into PPID (n=14) or control (n=31) groups. Faecal samples were collected for FEC determination prior to anthelmintic treatment, and fortnightly post-treatment for each horse. Generalised linear mixed modelling, using a gamma distribution, was used to compare differences between groups in the repeated measures study. The confounding variable of age was controlled for as a fixed effect. Following anthelmintic treatment, mean FEC was greater for the PPID group compared to the control group on day 56 (405 ± 756 eggs per gram [EPG] vs 40 ± 85 EPG, p=0.05) and day 70 (753 ±1598 EPG vs 82 ±141 EPG, p=0.04). There were no differences in mean FEC between groups on days 84 and 98. Cumulative FEC (day 14 to day 98) was significantly greater for the PPID horses than control horses (2118 ± 4016 EPG vs 798 ± 768 EPG, p<0.0001). Group egg reappearance period was shorter for PPID horses (day 56 post-anthelmintic treatment) compared to control horses (day 70) and 30% of the PPID horses reached a FEC threshold of >200 EPG on day 42, compared to 0% of control horses (p=0.02). These results suggest that the rate of a re-established patent infection between groups could be different due to a comprised immune response in PPID horses or differences in the host-parasite relationship regarding encysted stage larvae. However, despite differences between groups, some horses with PPID consistently had no detectable or low FEC (<200 EPG) during the study period. These findings highlight the importance of individual FEC monitoring to determine if anthelmintic treatment is required, in line with sustainable parasite management practices.

Blood parameters and parasite burden in cattle with chronic fascioliasis

Fascioliasis is a trematodiasis that affects domestic and wild animals as well as humans worldwide. It is a well-recognized disease in livestock, were it produces serious economic losses. Yet in cattle, there is limited information about the burden of liver flukes and its relation to the eggs per gram shed to the environment. There is also lack of knowledge on the effect of parasite load in blood parameters of infected animals, which is important to evaluate the severity and progression of the disease. The objective of this work was to gain insight in these aspects. Cattle from Mendoza province, Argentina, were inspected at a farm and at the abattoir determining the presence or absence of Fasciola hepatica. Each animal was sampled for blood and feces and in the slaughterhouse the livers were inspected. Hematology and blood chemistry parameters were determined, feces were examined for F. hepatica eggs by a quantitative sedimentation technique and livers were thoroughly inspected to determine the number of flukes. Infected cattle presented a mild burden of liver flukes per animal, strongly correlated (r = 0.72) to the number of eggs per gram of feces. The total number of eggs (X̄=35,100) shed per animal to the environment and the type of livestock management techniques in the region exacerbate the role of cattle as efficient reservoirs of this disease. Statistically significant lower red blood cell, lymphocyte and neutrophil counts were observed in infected compared to uninfected animals. All hepatic parameters tested showed highly statistically significant differences (p < 0.001) as well as proteins by cause of rise of globulins in infected cattle. The correlation between the amount of flukes in the liver and the number of eggs per gram of faces indicates coprology as a reliable and cost-effective method to infer parasite burden. The impact of fascioliasis on blood parameters can be of aid for the veterinary practitioner on the assessment of this disease on cattle.

109 Effectiveness of Fenbendazole in growing Quarter Horses using the Quantitative Modified Wisconsin Technique

Abstract Anthelmintics are commonly used in the equine industry to reduce parasite load, but there is a growing concern about anthelmintic resistance, especially in young horses where there is limited information available. Twenty-four, 2-yr-old Quarter Horses (825 ± 21 d of age, initial BW 409 ± 6 kg, 12 fillies and 12 geldings) originating from a single herd were used in a 42-d study to investigate the effectiveness of a commercial anthelmintic (fenbendazole) on fecal egg counts (FEC), hypothesizing that there would be a decrease in FEC following anthelmintic administration. Horses were housed individually (3.7m × 11m) and offered ad libitum Coastal Bermudagrass hay and water and fed a pelleted concentrate offered at 0.75% (as-fed) of their BW. During the 42-d study, BW was obtained and BCS were assigned in 21-d intervals. Fenbendazole was administered orally on d 0 and 14 dosed on BW per manufacturer label. Fresh fecal samples were collected on d 0 and 14, before anthelmintic administration, and on d 28 and 42. Fecal egg floats were conducted using the Modified Wisconsin Method, and eggs per gram (EPG) were determined in duplicate. A fecal egg count reduction test (FECRT) was calculated, beginning on d 14. Outliers were determined as values ± 2 standard deviations of the mean, and data were analyzed using PROC MIXED of SAS (v9.4) with the main effect of time. Horses increased in BW (P ≤ 0.01) over time, but BCS did not change (P = 0.25). Mean FEC increased over time (P ≤ 0.01), beginning on d 14, and remained increased to d 42 compared to baseline. However, there was a trend (P = 0.07) for mean FEC to be less on d 42 (189.70 ± 29 EPG) when compared with d 14 (251 ± 28 EPG). The calculated reduction of FEC were below the targeted 95% or greater and included d 14 (1.04%), d 28 (35%), and d 42 (41%). The increased shedding of eggs did not negatively impact BW or BCS. However, we reject the hypothesis since FEC increased following anthelmintic treatment, indicating the need for consistent monitoring of anthelmintic efficacy in young horses.

Evidence of tapeworm treatment failure on a Central Kentucky Thoroughbred farm

SummaryBackgroundEquine anoplocephalid cestodes are tapeworms that occur worldwide in horses and are known to cause pathological manifestations and clinical disease within the digestive system of horses.ObjectiveWhile these clinical manifestations and the efficacy of currently available anthelmintics against equine tapeworms have been well documented, a recent study has demonstrated treatment failure of praziquantel and pyrantel pamoate, suggesting resistance; however, this has not been heavily investigated.Study designThis case study examined 24 Thoroughbred yearlings on one Kentucky Thoroughbred horse farm to investigate the elimination of tapeworm eggs after administration of routine anticestodal anthelmintics after confirmation of positive faecal egg counts.MethodsThe Mini‐FLOTAC faecal egg counting method was used to count anoplocephalid eggs in yearlings treated with pyrantel pamoate paste (13.2 mg base/kg), moxidectin‐praziquantel (0.4 and 2.5 mg/kg) and ivermectin‐praziquantel (0.2 and 1 mg/kg) over a 6‐month period in 2022.ResultsData demonstrated that tapeworm egg shedding persisted post‐deworming with all three anthelmintic products. Out of the 24 Thoroughbred enrolled, 11/24 (45.8%) had persistent infections in the month of March and 3/24 (12.5%) had persistent infections in April after deworming with ivermectin‐praziquantel. With moxidectin‐praziquantel, 2/24 (8.3%) remained egg count positive. For pyrantel pamoate, 3/24 (12.5%) were detected with tapeworm eggs post‐treatment. During July and August, selected yearlings had faecal sampling done before and 2 weeks post‐deworming with moxidectin‐praziquantel. For July 1/6 (16.7%) horses had tapeworm eggs both before and after deworming, and one additional horse was positive in the post‐treatment sample only. For the August treatment, 4/14 (28.6%) were egg count positive both before and after deworming, with one additional horse being positive in the post‐treatment sample only.ConclusionsThis study demonstrated evidence of anthelmintic treatment failure against equine tapeworms by means of regular faecal egg count monitoring. Veterinarians should be aware of this development and implement strategies to monitor anticestodal treatment success.

Toxascaris leonina in dogs – A nematode species of high prevalence in some regions of Eurasia

A recent meta-analysis of studies from around the world had shown a global prevalence of Toxascaris leonina in stray dogs of about 7%. However, studies from Eurasian regions, where higher percentages of positive dogs were often found, were under-represented in this meta-analysis. This prompted the present study. Its main objective was to examine free-roaming dogs from the capital city of Kazakhstan to obtain information on the current occurrence of T. leonina egg shedding compared to Toxocara spp.Faecal samples from 500 free-roaming dogs from the city of Astana and its suburbs were collected 1–2 days after admission to the municipal animal shelter during three time periods (May to October 2019, September 2020, and April 2021). Samples were examined by a saline flotation method. Nematode egg-positive samples were subjected to a modified McMaster method to determine the number of eggs per gram of faeces (EPG).Toxascaris leonina eggs were found in 53.8% and Toxocara spp. eggs in 14.8% of the dogs examined. The prevalence of T. leonina egg shedding was significantly associated with age class but not with sex: dogs aged between 6 months and 2 years were more likely to be T. leonina egg positive than puppies. The intensity of T. leonina egg shedding was also age dependent: dogs aged between 6 months and 2 years had significantly higher EPGs compared to younger or older animals. In contrast, the prevalence of Toxocara spp. egg shedding was associated with both age class and sex: dogs older than 2 years were less likely to shed Toxocara spp. eggs than puppies, and females were less likely to be Toxocara spp. egg positive compared to males.The present results confirm those of other studies in Eurasian regions. It is therefore reasonable to assume that the global prevalence of T. leonina infection has been underestimated and should be revised accordingly.

Efficacy of anthelmintic drugs to control Fasciola hepatica in dairy cattle in Peru

Background: Decreasing antiparasitic efficacy of triclabendazole for controlling Fasciola hepatica in dairy cows in the Cajamarca Valley (Peru) has been reported. Objective: To determine the efficacy of four anthelmintic agents across a broader area of Cajamarca province. Methods: Four livestock farms were selected from three provinces in the Cajamarca region. Within each farm, 60 female cattle naturally infected with F. hepatica were chosen. Each farm was divided into four homogeneous groups based on individual animals and parasite burden. The groups were: triclabendazole (12 mg/kg of BW, VO), clorsulon/ivermectin (2 mg/kg and 0.2 mg/kg of BW, SC, respectively), closantel (10 mg/kg of BW, VO), and nitroxynil (10 mg/kg of BW, SC). Efficacy was determined following WAAVP guidelines by measuring the reduction in trematode egg shedding on day 30 post-dosing. Results: Triclabendazole demonstrated insufficient activity through FERCT and CPCR assessments across all four farms. The clorsulon/ivermectin and closantel groups exhibited high efficacy in all farms, while nitroxynil showed varying efficacy results in both types of analysis. Conclusions: Triclabendazole exhibited insufficient activity against F. hepatica. Clorsulon/ivermectin, closantel, and nitroxynil are viable alternatives with promising outcomes for controlling this trematode in the evaluated provinces.

Efficacy of a topical formulation containing eprinomectin, esafoxolaner and praziquantel (NexGard® Combo) in the treatment of natural respiratory capillariosis of cats.

Feline pulmonary capillariosis is a significant disorder due to its distribution and clinical impact. This study evaluated the safety and efficacy of two administrations 28 days apart of a topical solution containing esafoxolaner, eprinomectin and praziquantel (NexGard® Combo) in treating Eucoleus aerophilus (syn. Capillaria aerophila) infection in naturally infected cats. Cats were allocated to two groups: G1 cats (n=23) received two treatments at study days (SDs) 0 and 28 (±2) and were evaluated for 6 weeks, and G2 cats (n=17) served as a negative control for 6 weeks and were then treated twice on SDs 42 (±2) and 70 (±2), allowing for an additional 6-week assessment of efficacy. Each cat was subjected to McMaster coproscopy at SDs -7/0, 28 (±2) and 42 (±2) for both groups, 70 (±2) and 84 (±2) only for G2. Clinical examination and chest radiographic images were performed at SDs 0, 28 (±2) and 42 (±2) for G1 and G2, 70 (±2) and 84 (±2) only for G2. The comparison of EPG (eggs per gram of feces), clinical (CS), and radiographic scores (RS) at each time-point was used as a criterion. The efficacy based on the EPG reduction was 99.5% (G1) and 100% (G2) after two administrations of NexGard® Combo 2 weeks apart. At SD 0, no significant differences for CS and RS were recorded between G1 and G2, while a significant reduction (p<0.05) was observed post-treatment for CS, RS, oculo-nasal discharge, auscultation noises, and cough. Two doses of NexGard® Combo 28 days apart stopped egg shedding and significantly improved clinical alterations in cats infected by E. aerophilus.

The distribution of strongylid egg and lungworm (Dictyocaulus eckerti) larval counts in adult female farmed red deer (Cervus elaphus), and the implications for parasite control

Whilst healthy adult farmed red deer show little clinical indication of parasite infection, they may still be maintaining infection levels on the farm through low-level shedding of nematode eggs and lungworm larvae. This work was undertaken to establish the long-term distribution of parasite counts, to determine whether the higher counts seen in previous trials are repeatable across the same animals. All adult female red deer on a New Zealand North Island property were faecal sampled (n = 209), weighed, and body condition scored (BCS) on five sampling occasions from March – August 2021. Faecal samples were processed by modified Baermanns to recover, identify, and enumerate lungworm 1st stage larvae (FLC), and nematode faecal egg counts (FEC) were determined by mini-FLOTAC. Between animal variation for FEC was significant (p < 0.001); whilst many counts were low to zero, a few individuals were consistently shedding higher egg counts. Younger animals tended to have higher egg counts (p = 0.003), but there was no association between FEC and BCS (p = 0.22), and FEC and liveweight (p = 0.58). Modelling of the data indicated that 50% of the egg output resulted from 21% of the animals. Additionally, there was no significant association between the higher egg counts and the gastrointestinal nematode classification; ‘long tails’ (likely Oesophagostomum sp.) p = 0.76, and the Ostertagiinae complex p = 0.75. Lungworm counts tended to be very low (0 – 26 lpg); consistent with previous trials and literature in farmed adult deer. However, between animal differences were statistically significant (p < 0.001) indicating some animals were passing more larvae than others, and poorer conditioned animals (BCS 2.5) were significantly associated with higher larval count (p = 0.03). There was no relationship between larval count and age (p = 0.62) and larval count and liveweight (p = 0.22). Modelling indicates that 50% of pasture larval contamination was contributed by 15% of the animals. There was no correlation between nematode egg count and lungworm larvae count (p = 0.22). Adult deer may play an important role as a source of infection for young deer, therefore, an improved understanding of the distribution of infection is needed to improve parasite control.

Efficacy of flukicides against Fasciola hepatica and first report of triclabendazole resistance on German sheep farms

Fasciola hepatica infections lead to severe health problems and production losses in sheep farming, if not treated effectively. Triclabendazole has been used extensively over decades due to its unique efficacy range against all definitive hostfluke stages but published data about the susceptibility of F. hepatica to anthelmintics in Germany are lacking. This study aimed to identify current F. hepatica infections in German sheep flocks by coproscopic examinations and to evaluate the efficacy of anthelmintics with a focus on triclabendazole in a field study conducted from 2020 to 2022. Initial screening included 71 sheep farms, many of them with known history of fasciolosis. In this highly biased sample set, the frequency of F. hepatica infection at individual sheep and farm level were 12.8% and 35.2%, respectively. Additionally, eggs of Paramphistominae were found at frequencies of 4.8% and 15.5% at individual sheep and farm level, respectively. Due to low egg shedding intensity, faecal egg count reduction (FECR) tests could only be conducted on a few farms. The efficacy of triclabendazole was tested on 11 farms and albendazole on one farm, including 3–53 sheep/farm. Individual faecal samples were collected before and two weeks after treatment to evaluate the FECR using the sedimentation or FLUKEFINDER® or a modified FLUKEFINDER® method. On all farms a coproantigen reduction test was conducted in parallel. Lacking efficacy of triclabendazole even at double dosage was shown on one farm associated with a high number of animal losses due to acute fasciolosis. On this farm, the Fasciola miracidium development test was additionally performed, revealing a high in vitro ovicidal activity of albendazole while closantel was effective in vivo. On all other farms, sufficient efficacy of triclabendazole was observed. In conclusion, triclabendazole resistance appears not to be widespread on German sheep farms but, when present, can have serious effects on animal health.

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.