Endoparasite loads and the efficacy of conventional anthelmintics against gastrointestinal nematodes in captive European bison

Although little information exists on the efficacy of deworming in wild ruminants, gastrointestinal nematodes have been found to demonstrate increasing drug resistance. The spread of drug-resistant strains may be increased by transmission among livestock and susceptible wildlife species, thus posing a potential threat to endangered species, such as the European bison. The aim of the study was twofold: to identify the parasite loads in captive European bison with the use of coprological techniques, and to test the influence of other nearby ungulates on the richness of bison parasitofauna. Additionally, the efficacy of deworming procedures against gastrointestinal nematodes in bison was evaluated. The survey was based on a coprological investigation of 285 fecal samples from 156 European bison in 15 enclosures. The parasitofauna of the captive European bison was consistent with those of free-ranging populations. The highest prevalence was noted for Eimeria spp. oocysts (60.7%), strongyle eggs (50.9%), Fasciola hepatica eggs (13.1%), Dictyocaulus viviparus larvae (12.3%) and Trichuris sp. Eggs (9.47%). Moreover, the close proximity of other ungulate species resulted in a higher diversity of parasite species. In all cases, deworming with albendazole, fenbendazole and ivermectin proved to be ineffective against strongylids and Trichuris sp. The results of fecal egg count reduction test (FECRT) ranged from 37.2 to 99.6% (95% CI <90%) for albendazole; values >95% (95% CI = 41-100) were noted for fenbendazole, and FECRT ranged from 63.2 to 97.5 (95% CI = 0-99) for ivermectin. As the results of anthelmintic treatment are unsatisfactory, it seems justified to continue study in this area. Our study is the first large-scale attempt to evaluate the efficacy of anthelminthics in captive European bison. The potential sharing of parasite species between bison and other ungulates should also be further investigated from the perspective of minimizing the risk of the spread of drug-resistant parasite strains.

The occurrence and molecular identification of Thelazia spp. in European bison (Bison bonasus) in the Bieszczady Mountains

Infection with Thelazia nematodes results in eye disease in wild and domestic animals. The aim of the present study was to describe the occurrence of Thelazia nematodes in European bison, and to subject the isolated parasites to molecular identification and phylogenetical analysis. The eyeballs of 18 European bison from the Bieszczady Mountains, culled due to dysfunctional vision, were collected for study. The conjunctival sacs, tear ducts, corneal surface and nictitating membrane were rinsed with a saline solution. Any obtained nematodes were isolated under a stereoscopic microscope, and then identified as T. gulosa or T. skrjabini by molecular analysis of partial cox1 sequences. The prevalence of infection with Thelazia spp. was found to be 61%, with a 95% confidence interval (CI 95%) of 39-80%. Thelazia skrjabini was isolated from 56% (CI 95% 34-75%) of examined animals; T. gulosa was significantly less common (p = 0.038) with the prevalence of infection reaching 22% (CI 95% 9-45%). Three European bison were cross-infected with both T. gulosa and T. skrjabini. Phylogenetic analysis found the obtained sequences to be similar to those of Thelazia species from domestic ungulates in Europe. Infection intensity ranged from 1 to 16 nematodes per individual (median of three nematodes), and was significantly higher in females (6 nematodes) than in males (1 nematode; p = 0.019). A tendency for seasonal occurrence of nematodes in European bison was also observed. Our study provides further information regarding the patterns of Thelazia transmission in European bison in Poland.

Suspicion of bovine tuberculosis in sheep in the Małopolskie Voivodeship (southern Poland)

Bovine tuberculosis (BTB) in sheep (Ovis aries) is caused by Mycobacterium bovis and Mycobacterium caprae. Even though sheep have been considered less sensitive to BTB than other ruminants, they have been subject to increasing numbers of tuberculosis cases and it has been suggested that they may act as a disease reservoir in some regions. Aim of the study: Following a report of tuberculous-like gross lesions (repeated cases of purulent or caseous lymphadenitis and a single case of serosal tubercles on the peritoneum) from veterinarians working in a slaughterhouse in the Małopolskie Voivodeship, southern Poland, the aim of this study was to conduct ante-mortem BTB diagnostics in three flocks with suspected BTB. The animals for testing were selected randomly from the flocks; a blood sample for interferon-γ release assay (IGRA) and a single tuberculin skin test (TST) was performed on each sheep. All TST results were negative. The IGRA result was positive in two ewes from the same flock (four and five years of age); these two sheep were tested microbiologically using Stonebrink and Löwenstein-Jensen media. No gross lesions suggesting BTB were observed, and the culture results were negative. Based on the positive IGRA results, together with its high specificity in sheep, and the potential risk to humans posed by consuming local unpasteurized dairy products, we recommend introducing serological BTB screening in sheep from this area, and subjecting the positive results to confirmation by culture.

A comparison of detection methods of Alaria alata mesocercariae in wild boar (Sus scrofa) meat

Distomum musculorum suis (DMS), the mesocercariae of Alaria alata, is typically found accidently during examination of wild boar meat for Trichinella spp. The aim of the study was to compare DMS detection methods. Briefly, 232 wild boar meat samples were tested by mesocercariae migration technique (AMT) as a reference method; of these, 104 were found to be positive. Selected positive samples were tested again with the three other methods: compressorium method (Compressor), digestion with magnetic stirrer (Digestion) and by modified digestion with Pancreatin® bile and pancreatic enzymes (D + P). The results were analyzed by logistic regression, the non-parametric Kruskal-Wallis test and the Mann-Whitney U test. Of the 43 samples found positive by the AMT, 20 were found positive by Digestion and 25 by D + P. The Compressor identified DMS in seven of the 19 tested samples. The Digestion and D + P methods gave similar intensities (P = 0.506), i.e. 1.4 and 1.3 DMS respectively, but the AMT detected seven times higher number of parasites. The probability of detection of DMS in the meat sample by the Digestion or by D + P was higher than 0.5 when at least seven (Digestion) or five (D + P) DMS were present in the sample (AMT). The Compressor was the least sensitive method: at least 14 DMS must be present in the meat sample for detection. AMT should be considered the most accurate method of DMS detection.

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AMT appears the most sensitive method to detect Alaria alata mesocercariae.

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AMT results are seven times higher than in digestion methods in case of intensity.

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Compressor method is clearly inadequate to detect Alaria alata mesocercariae.

Rare case of presence of nematodes Dirofilaria repens in apleural cavity of a dog

Dirofilariosis, caused by nematodes Dirofilaria repens, is a parasitosis of wild and domestic carnivores. Nematodes D. repens locate in the subcutaneous and intramuscular tissue. The aim of this article is to describe rare case of pleural infection of a dog with nematodes D. repens. 12-year-old golden retriever had been treated in the veterinary clinic due to emaciation, weakness and dehydration, observed for 2 weeks. Hematologic and biochemical tests revealed reduction in the number of leukocytes and erythrocytes, significant decrease of hemoglobin, hematocrit and albumins as well as increased ALAT, urea and creatinine levels. Parasitological examination of blood smear revealed the presence of multiple microfilariae. Increased echogenicity of renal parenchyma was visible during ultrasound examination. Necropsy of euthanized animal revealed adult nematodes D. repens, located in the pleural cavity. Additionally, enlarged kidneys with subcapsular petechiae and a single cyst in the renal cortex were observed. To our best knowledge, it is the first case of finding nematodes D. repens in a pleural cavity of a dog.

Gastrointestinal Helminths of a European Moose Population in Poland

Parasitic infections have a negative impact on the fecundity and survival of wild ruminants, particularly moose; however, despite being more susceptible to parasitic diseases than other wild cervids, they remain poorly examined in this regard. Therefore, the aim of the present study was to identify gastrointestinal and liver helminth species of the moose population in central Europe, assess the factors contributing to infection intensities and examine their impact on moose health. Abomasum, small intestine, caecum and liver samples were collected from 46 moose in Poland and evaluated for helminth parasite fauna and histopathological changes. Additionally, 289 moose fecal samples were analyzed for the presence of eggs, oocysts and larvae of parasites. In total, 19 parasite taxa were identified. The most prevalent were Mazamastrongylus dagestanica and Ostertagia antipini, which are typical nematodes of moose, together with Spiculopteragia boehmi and O. leptospicularis, characteristic also of other cervids. Parasite species diversity and abomasal parasitic infection intensity were higher in adult moose than in yearlings and calves. The numbers of histopathological lesions depended on the intensity of parasitic infections, and were most severe in the livers of moose infected with Parafasciolopsis fasciolaemorpha. The analysis of fecal samples revealed several regional differences in the levels of parasite eggs, oocysts and larvae shedding. Our findings indicate an accumulation of parasite infections over time in moose, which may be related to high environmental parasite pressure, possibly connected with high moose density and the presence of wetlands; they also serve as the most comprehensive study of moose parasites in central Europe to date.

First report of a newly-described lungworm, Dictyocaulus cervi (Nematoda: Trichostrongyloidea), in moose (Alces alces) in central Europe

Lungworms from the genus Dictyocaulus are the causative agents of verminous pneumonia in domestic and wild ungulates. Recently, in 2017, a new species was isolated from red deer and described as Dictyocaulus cervi; however, little is known about its epidemiology and pathogenicity in other cervids. The aim of our study was to determine the extent of infection with Dictyocaulus nematodes in the moose population in Poland. Parasitological necropsies were performed in 18 moose and 249 faecal samples were analysed. A combination of multiplex PCR and analysis of the partial SSU, cox1 and cyt B regions revealed the presence of D. cervi infection in two of the necropsied moose. Histopathological examinations revealed changes, including multiple cross sections of larvae of nematodes in alveoli, massive pulmonary fibrosis, mononuclear cell infiltration and diffuse alveolar damage in the lungs of four animals. The lesions were more pronounced when adult Dictyocaulus nematodes were present in the bronchi and bronchioles. Some of the observed pathological changes could be attributed to co-infection by nematodes of the Protostrongylidae, whose larvae were found in all four animals with lung pathologies. In the faeces, Dictyocaulus sp. larvae only occurred together with Protostrongylidae larvae; in addition, higher numbers of Protostrongylidae larvae were excreted in the faeces of animals with dictyocaulosis. The present study is the first report of the presence of D. cervi in moose, and demonstrates the value of multiplex PCR in the identification of Dictyocaulus nematodes. Our findings indicate that co-infections with multiple species of lung nematodes in moose may be commonplace, and this should be considered as a factor aggravating the course of parasitosis.

Patterns of parasite eggs, oocysts and larvae shedding by moose in the Biebrza marshland (NE Poland)

The study analyses patterns of endoparasite eggs, oocysts and larvae shedding by moose from the relict population in the Biebrza marshland, NE Poland, which has grown to be one of the largest in Central Europe since the ban on hunting imposed in 2001. The analysis identified 10 species or groups of parasites among 230 faecal moose samples collected over 16 consequent months. The most prevalent were the eggs of Trichostrongylidae, Trichuris spp., Nematodirella alcidis, Parafasciolopsis fasciolaemorpha and the larvae of Elaphostrongylus sp. Four parasite species were more prevalent in males, indicating male-biased parasitism, and the studied moose population exhibited a female-skewed sex ratio. Nematodirella alcidis eggs and Protostrongylid larvae were more prevalent during winter, which indicated their resistance to harsh weather conditions. The prevalence of Eimeria alces and Aonchotheca sp. increased during the growing season, as did the number of eggs per gram of faeces (EPG) of P. fasciolaemorpha, possibly due to the availability of water sources. Higher mean monthly temperature was also found to have a positive effect on the excretion of Trichostrongylidae and Moniezia spp. eggs. In addition, the time of infection and the specificity of the parasite life cycle, being sensitive to certain climatic conditions, also appeared to have a strong influence on eggs, oocysts and larvae shedding in this non-harvested moose population.

Occurrence of tapeworms Moniezia benedeni (Moniez, 1879) in European bison Bison bonasus L. in Białowieża Primeval Forest

Tapeworms Moniezia benedeni are cosmopolitan parasites of wild and domestic ruminants. The aim of this study was to examine the prevalence of those tapeworms in European bison in Białowieża Primeval Forest. Parasitological necropsy of small intestine of 26 bison, aged from 3 months to 26 years was performed in years 2007–2011. Tapeworms M. benedeni were isolated from 11 examined animals and the prevalence of infection was estimated on 42.3%. Intensity of infection was ranging from 2 to 25 tapeworms and the mean intensity was estimated on 5.8 specimens. Prevalence in the group of calves reached 50% and in adult bison – 33.3%. Intensity of infection in calves was estimated on 2 to 5 tapeworms while in adult animals it was ranging from 1 to 2 parasites. High prevalence of tapeworms M. benedeni in European bison might result from poor condition or weak immunity of eliminated animals.

Ashworthius sidemi in cattle and wild ruminants in Poland - the current state of play

Ashworthius sidemi, a blood-sucking abomasal nematode, has been identified in various wild ruminants, including deer (Cervus elaphus), roe deer (Capreolus capreolus), fallow deer (Dama dama) and moose (Alces alces). Although it has been observed throughout Poland, most sightings have been in the eastern part of the country. However, more recently, A. sidemi has been confirmed in the Ruszów Forest District (Lower Silesian Wilderness). It is now possible to test the faeces of cattle for the DNA of the third-stage infectious larvae (L3) of A. sidemi. The present paper describes such a molecular study of 120 faecal samples collected from cattle grazed in the Ruszów Forest District and Biebrza Marshland, where A. sidemi had previously been detected in wildlife. In this study, no A. sidemi DNA was identified in any of the examined samples.