Parasitological and molecular investigation of consequences of raw meat feeding (BARF) in dogs and cats: implications for other pets living nearby

Considering the original nature of carnivorism among dogs and cats, nowadays these pets are increasingly fed BARF (Biologically Appropriate Raw Food/Bone And Raw Food) diet to improve their health conditions. However, this diet may also carry health risks, such as vitamin or mineral deficiencies, and infection with pathogens including parasites. In our study, fecal samples of 89 pet animals kept on BARF diet were subjected to coprological examination followed by molecular analyses. Six of them shed eggs of Dicrocoelium dendriticum. This result was confirmed with PCR and sequencing, and in one case, the DNA of Fasciola hepatica was also demonstrated. In addition, oocysts of Cystoisospora canis, a Cystoisospora ohioensis-like sp. and Eimeria stiedai, as well as sporocysts of a Sarcocystis sp. were also detected. All samples were negative for Neospora caninum and Toxoplasma gondii. In conclusion, no evidence was found for the infection of BARF-fed dogs and cats with parasites that are usually associated with this diet and considered as clinico-pathological risk factors for these pets themselves (e.g., N. caninum, T. gondii). However, fluke eggs (probably originating from ruminants) and oocysts of E. stiedai (from rabbit liver in the food) were demonstrated as pseudoparasites. These species are usually not considered among parasite-associated risks of BARF-feeding, implying that other animals living near BARF-fed pets are neglected in this context. However, where intermediate hosts of D. dendriticum occur in urban areas, BARF-feeding may indirectly affect later other dogs and cats. It was also shown here that BARF-feeding may contribute to the contamination of the environment with E. stiedai oocysts, thus increasing the risks of biliary coccidiosis in nearby living pet rabbits that would otherwise not have access to oocysts of E. stiedai.

Pivotal role of permeability-glycoprotein in absorption of praziquantel into Dicrocoelium dendriticum parasite

Dicrocoelium dendriticum affects the livers of ruminants and causes several deleterious effects on animal health status. The aim of this study was to investigate the role of permeability-glycoprotein (P-gp) in absorption of praziquantel (PZQ) into D. dendriticum flukes by co-incubation with verapamil (VPL), an inhibitor of P-gp, under in vitro conditions. Mature flukes of D. dendriticum were collected from naturally infected sheep livers. The flukes were incubated with different concentrations of PZQ and VPL (50 and 100 μg/ml) in culture media and after several times of exposure (2, 6, 12, and 24 h), the concentration of PZQ absorbed in the parasites was measured by high-performance liquid chromatography. At 2-h post-incubation, the highest concentration of PZQ was noted as 0.92 µg/ml in the flukes treated with 100 μg/ml of each PZQ and VPL. After 24-h of exposure, VPL at all tested concentrations resulted in significant increase in absorption of PZQ into the parasite. Co-incubation of lancet flukes with VPL and PZQ roughly doubled the absorption of PZQ into them. Results of tegumental structures analysis by light microscopy confirmed higher efficacy of combination of VPL and PZQ. In conclusion, co-administration of VPL, especially at the concentration of 100 μg/ml, was able to increase PZQ uptake in Dicrocoelium flukes at all time points of the study.

Case report: Infection with Dicrocoelium dendriticum in a Japanese Chin dog

Dicrocoelium dendriticum is a trematode colonising the bile ducts of herbivores. Coproscopic findings in dogs are usually considered gastrointestinal passages of eggs after ingestion of unheated liver tissue or infected ruminant faeces. Here, a Japanese Chin presented with diarrhoea and weight loss. Eggs comparable to D. dendriticum were detected in faeces and infection was confirmed via PCR and by ruling out differential diagnoses. Egg excretion continued for a period of 10 months. Praziquantel (50 mg/kg body weight [BW]) was administered orally for four consecutive days. Egg excretion 10 days after treatment entailed further treatments with 100 mg/kg BW, again for four days. Faecal samples were negative ten days and four weeks afterwards, diarrhoea resolved, and the dog gained weight. In cases of repeated coproscopic positivity for D. dendriticum, an infection with dogs acting as definitive hosts should be considered. Treatment with praziquantel at a higher dosage may be required.

Neuromuscular system of the causative agent of dicrocoeliosis, Dicrocoelium lanceatum. I. 5-Hydroxytryptamine in the nervous system

The trematode Dicrocoelium lanceatum known as lancet fluke, is a causative agent of dicrocoeliosis, a widespread parasitic disease of the grazing ruminants. The investigation of the major neurotransmitters and their functions are an important step in the development of a new pharmacological strategy of the struggle against the dicrocoeliosis affecting the neuronal signal substances and the functions of its nervous system. The aim of this work was to study the presence and localization of the neurotransmitter serotonin (5-HT, 5-Hydroxytryptamine) in the nervous system of D. lanceatum using immunocytochemical technique and confocal laser scanning microscopy. For the first time the data on the presence and distribution of serotonin-immunopositive components in the central and peripheral compartments of the nervous system of D. lanceatum has been obtained. Serotonin-immunopositive neurons and neurites were identified in paired brain ganglia, in the brain commissure, longitudinal nerve cords and connective nerve commissures. The innervation of the oral and ventral suckers by serotonergic nerve structures was revealed. The distal part of the reproductive system and the region of the reproductive pore were intensively innervated by serotonergic neurites. Serotonin-immunopositive neurons and neurites were also revealed in the proximal region of the reproductive system. The data obtained suggest that the serotonergic nervous system is involved in the regulation of the attachment organs and the reproductive system functions in D. lanceatum. The new results on the morphological and functional organization of the D. lanceatum nervous system increase our knowledge of the structure and function of nervous system of trematodes of various taxonomic groups and support the possibility of the exploitation of the serotonergic system of the parasite as a target for anthelmintic drugs.

Prevalence of hydatid cyst, Fasciola spp. and Dicrocoelium dendriticum in cattle and sheep slaughtered in Sabzevar abattoir, Iran

Hydatid cyst, Dicrocoelium dendriticum, and Fasciola spp. are common parasites among ruminants. The current study was conducted to assess the prevalence of these parasites in cattle and sheep slaughtered in Sabzevar abattoir, from April 2014 to March 2016. Total of 1653 cattle and 26720 sheep were inspected for helminthic infections of liver and lung in different seasons. The prevalence rates were found to be 684 (2.55%) and 235 (14.21%) in sheep and cattle, respectively. The infection rate of liver in cattle was estimated to be 5.86%, 0.84% and 5.68% for hydatid cysts, Fasciola spp. and D. dendriticum, respectively and lung infection with hydatid cyst in cattle was 1.81%. Moreover, the liver infection rate of sheep was estimated to be 0.87%, 0.06% and 2.13% with hydatid cysts, Fasciola spp. and D. dendriticum, respectively and lung infection with hydatid cyst was 0.35%. The rate of infection with D. dendriticum was higher in the both animals than the other parasites. The results of this study indicated that the prevalence of the aforementioned parasites was high, which caused high economic losses. Therefore, sanitary and preventive measures should be taken.

Assessment of climatic and orographic conditions on the infection by Calicophoron daubneyi and Dicrocoelium dendriticum in grazing beef cattle (NW Spain)

From February 2003 to March 2004, 1148 faecal samples from autochthonous Rubia Gallega cattle breed were collected in 170 farms from Lugo (NW Spain), in order to find out the prevalence and intensity of egg-excretion by Calicophoron daubneyi and Dicrocoelium dendriticum, and the possible influence of external factors as annual mean temperature and rainfall, altitude and mean slope. Twenty-six percent (95% CI 19%, 33%) and the 18% (12, 24) of the farms were infected with rumen and lancet flukes. C. daubneyi egg-output (Me=24) was found in 13% (11, 15) of the individual samples. Six percent (5, 7) of the animals in the study had low D. dendriticum eggs (Me=8). By estimating the odds ratio values it was shown that the highest probability of infection by C. daubneyi was in pastures with a mean slope of less than 13% (OR=1.9) and situated under 600 m (OR=1.6). Annual mean rainfall and temperature were not identified as risk factors for the infection with rumen flukes. Mountainous pastures with a mean slope of higher than 25% (OR=5.8) and situated over 600 m (OR=24.6) where precipitation was high (>1000 mm; OR=7) and temperature low (<11 degrees C; 2.8) had involved the highest risk of infection by D. dendriticum. Because of the prevalences found in this study, employment of suitable management practices with strategic treatments with efficacious anthelmintics are needed to reduce the presence of both trematodes and to increase the health status of grazing beef cattle.

[The incidence of Dicrocoelium dendriticum in Emmental]

A cross-sectional field study on the prevalence of Dicrocoelium dendriticum was performed in the Emmental. The study included 211 bovines, 170 equines, 20 ovines, 46 caprines and 23 rabbits (from 119 farms). In addition, laboratory routine diagnostic data obtained from 2.840 animals--all originating from the same area of investigation--were assessed in the same way. The infection extent concerning the different animal species were the following: bovines 46%, equines 12%, ovines 30%, caprines 48% and rabbits 9%. Univariate analyses of baseline epidemiological data identified no significant risk factors, with the exception of the type of stable used. Bovines kept in a modern free ranging stable had a significantly lower chance of infection with D. dendriticum than cattle in conventional tie stalls. The epidemiological data characterizing the area of investigation suggest the following procedure to reduce the problem of dicrocoeliosis: Pasturing animals of all ages should be regularly dewormed (e.g. every six week during pasture) using a compound effective against D. dendriticum. A treatment is especially indicated at the time after pasture in autumn or before housing the animals in winter. In spring, only animals having pastured the year before need to be treated prior to pasture in the new year. However, it is recommended to perform an economic analysis comparing costs of treatment versus putative costs of damage prior to the initiation of a strategic campaign: animal welfare aspects have to be considered. The laboratory routine diagnostic data showed infection extent similar to those of the cross-sectional study: bovines 60%, equines 24%, ovines 26%, caprines 31%, rabbits 32%. Atypical hosts such as dogs and cats exhibited low infection extent (3% and 1%, respectively), rather reflecting a gastro-intestinal passage of parasite eggs ingested by consumption of infected livers or by coprophagy of ruminant faeces.

[Human infection with Dicrocoelium dendriticum]

MEDICAL HISTORY AND PHYSICAL EXAMINATION: A 36-year-old German reported having had chronic-relapsing diarrhea, right upper abdominal pain and weight-loss for about two years. His last journey had taken him to Morocco three and a half years ago. The physical examination was unremarkable except for an abdominal tenderness to palpation in the right upper quadrant. LABORATORY: The serum level of bilirubin was slightly raised to 1.13 mg/dl (<1.10 mg/dl) and the level of IgE was raised to 253 U/ml (<100 U/ml). All other laboratory findings were within normal limits. Stool examinations showed eggs of Dicrocoelium dendriticum. The abdominal ultrasound was unremarkable except for mild steatosis.

TREATMENT AND COURSE

The patient denied consumption of liver or liver-products within the past weeks. Spurious infection due to eating infected liver could thus be excluded. The patient was treated for dicrocoeliasis with praziquantel (3 x 600 mg/day for three days). Further stool examinations for parasites were negative. Since the patient still had gastrointestinal discomfort, we decided to give a further therapy with triclabendazole (700 mg, single dose). Five weeks after the second treatment the patient was almost free of symptoms and stool examinations for parasites remained negative.

CONCLUSION

Dicrocoeliasis can be associated with chronic diarrhea. Stool examinations for parasites are very important in patients with gastrointestinal symptoms.

Structural and electronic properties of the liver fluke heme cavity by nuclear magnetic resonance and optical spectroscopy. Evidence for a distal tyrosine residue in a normally functioning hemoglobin

Structural features of the heme and the heme cavity of the monomeric hemoglobin (Hb) from the platyhelminth Dicrocoelium dendriticum were investigated by optical and proton nuclear magnetic resonance spectroscopy. Using nuclear Overhauser effects (NOEs) from resonances assigned previously through isotope labeling, most hyperfine-shifted resonances could be attributed to individual heme and protein protons in the cyano-metHb complex. It was observed that the heme 2-vinyl group is held in the trans orientation by nearby residues, whereas the 4-vinyl group exhibits an equilibrium between cis and trans orientations. NOE experiments in 1H2O allowed the identification of exchangeable protons belonging to the proximal histidine residue (F8) and to a distal residue. Detailed analysis of the NOE patterns obtained from the distal labile proton to non-labile protons and among these latter protons leads to the conclusion that a tyrosine side-chain occupies the distal site E7. Optical spectra of the alkaline-metHb also lead to this view, in that they are not typical of a hydroxy-metHb complex but instead resemble that of a hemin-phenolate or human mutant (M-type) Hb with a tyrosine residue linked to the iron atom. Further evidence for a distal tyrosine residue stems from the occurrence of an unusually stable transient ferrous Hb-cyanide complex, formed upon reduction of cyano-metHb to deoxy-Hb with dithionite. We suggest that the stability of this intermediate is due to a slow re-orientation of a large distal side-chain prior to cyanide dissociation. The sequence of the E-helix, known from the partially determined primary structure, was realigned to accommodate these findings. A frame-shift by one residue now positions a tyrosine at the distal site E7 instead of the originally proposed glycine residue.

Acid Bohr effect of a monomeric haemoglobin from Dicrocoelium dendriticum. Mechanism of the allosteric conformation transition

The dioxygen affinity of Dicrocoelium dendriticum haemoglobin was determined as a function of pH with a thin-layer diffusion technique. From the oxygen dissociation and association curves Hill coefficients h equal 1 were obtained throughout. Ultracentrifugation studies prove this haemoglobin to be monomeric irrespective of pH and ligation state. Thus, Dicrocoelium haemoglobin is a non-cooperative monomer. It has the highest O2 affinity so far known for any monomeric haemoglobin: its half-saturation pressure, p50 value, ranges at 25 degrees C from 0.016 mm Hg to 0.15 mm Hg (2.13-20.0 Pa) dependent on pH. Dicrocoelium haemoglobin shows an acid Bohr effect only and as such it constitutes a new class of haemoglobins. Its log p50 versus pH plot (Bohr effect curve) is characterized by a large amplitude, delta log p50 = 0.96, and an inflection point (Bohr effect pK) at pH 5.0. A model for the acid Bohr effect of D. dendriticum haemoglobin is proposed. By generalization, both the alkaline and the acid Bohr effect in various monomeric haemoglobins may arise from a single Bohr group complex (salt bridge).

Continuous gas-depletion technique for measuring O2-dissociation curves of high-affinity hemoglobins

The O2-depletion technique allows a continuous measurement of the complete O2-dissociation curve of high-affinity hemoglobins in the O2-partial pressure range of 700 to 10(-4) mm Hg. With this technique p50 values greater than or equal to 0.01 mm Hg (approximately equal to 1.3 Pa) can be determined for 3-microliter hemoglobin samples. As examples, O2-dissociation curves of sperm whale myoglobin (p50 = 0.9 mm Hg, 25 degrees C, pH 8.0) and Dicrocoelium hemoglobin (p50 = 0.06 mm Hg, 25 degrees C, pH 4.9) are demonstrated which show Hill coefficients of n = 1.0 over the complete O2-saturation range.

Endoparasites of hares (Lepus timidus L. and L. europaeus Pallas) in Finland

Intestinal and lung parasites of 85 mountain hares (Lepus timidus) and 24 European hares (L. europaeus) were examined. The species of parasites found in both hare species were Trichostrongylus retortaeformis Zeder, 1800; Mosgovoyia pectinata Goeze, 1782 and Protostrongylus pulmonalis Froelich, 1802. Eimeria semisculpta Madsen, 1938 and E. townsendi Carvalho, 1943 were found only in the European hares and Eimeria leporis Nieschulz, 1923 and Dicrocoelium dendriticum Rudolphi, 1819 only in the mountain hares. Ninety-five percent of the mountain hares and 88% of the European hares were infected with parasites. Mountain hares were more commonly infected with P. pulmonalis and D. dendriticum while European hares were more commonly infected with Eimeria spp. and T. retortaeformis. Young mountain hares were more often infected with M. pectinata and adult mountain hares with P. pulmonalis. The management technique of winter-feeding did not increase significantly the percentage of infected animals. Dicrocoelium dendriticum was found only in hares from islands where sheep had grazed during the summers. The absence of cysticerci of Taenia pisiformis Bloch, 1780 in this survey may be a reflection of improved hygiene practices instituted by hunters.

Spectral properties and reactivity towards azide of Dicrocoelium dendriticum met-hemoglobin

The spectroscopic properties of Dicrocoelium dendriticum met-hemoglobin, investigated between pH 3.8 and 10.5, display two proton-induced transitions with apparent pK values of 8.1 and 4.7. The spectral changes, over the pH region 6.5 to 10.5, correspond to the high to low spin transition usually observed in ferric hemoproteins. The relaxation time (tau = 3.2 ms at the pK) associated with this transition is closely similar to that observed in Aplysia limacina met-myoglobin, but approximately 1000-fold slower than that of sperm whale met-myoglobin. The spectral changes associated with the more acid transition are in the opposite direction and have not been resolved by the temperature jump method. The rate constants for the reaction of azide with Dicrocoelium dendriticum met-hemoglobin were measured between pH 3.8 and 6.7 by the temperature jump method. Two kinetic schemes, both consistent with the pH dependence of the apparent rate constant for binding of azide, were identified. No objective way of discriminating between the two models is available. However, one of them is amenable to a physical interpretation based on a comparison with the structural, kinetic and spectral properties of other monomeric hemoproteins.

The serodiagnosis of chronic fascioliasis (Fasciola gigantica) using a fluorescent-antibody technique with single and multiple whole-fluke antigens

Sera from cattle with single or mixed infections of Fasciola gigantica. Dicrocoelium hospes, Schistosoma bovis and paramphistomes were examined for fluorescent antibodies. Cross-reacting antibodies of the heterologous flukes were easily detected by using cryostat sections with whole-fluke-antigen of all three flukes. The presence of F. gigantica antibodies in a cattle herd was tested at two monthly intervals in order to establish the occurrence of chronic fascioliasis. The lack of significant differences in antibody levels of infected, treated and uninfected cattle however showed that herd antibody levels are not very useful to detect chronic Fasciola infections.

[Share to the Cionella lubrica Müller biological cycle, intermediate host of Dicrocoelium lanceolatum (Rudolphi, 1803) in Limousin (author's transl)]

Description of the habitat and biological cycle of Cionella lubrica in Limousin and surroundings. The species reaches its adult size in a five to six months' period and its longevity may go beyond one year. In spite of existence of young adult individuals for a whole twelve-month, we may notice two generations: the first one in spring and the second one from the outset of autumn.

Evolution-oriented ethology, kin selection, and altruistic parasites

The genetic theory of social behaviour challenges ethology to incorporate the study of invertebrates and lower animals; to search for behaviour mechanisms that contribute to the maximization of "inclusive fitness" (rather than to the maintenance of the individual and the species); and to intensify the study of social consequences and interindividual differences in species-specific behaviour.

[Studies on the hatching of miracidia of Dicrocoelium dendriticum (author's transl)]

The eggs of Dicrocoelium dendriticum were induced to open by solutions of formic acid and caproic acid (Table 1). The miracidia hatched in O2-free water after the eggs had been dried with N2 or in vacuum. The miracidia were able to live for 3 hours if water contained 20 mM NaCl, 10 mM KCl, and 1 mM CaCl2. Ca++-ions are obviously necessary for the mobility of miracidia. The experimental use of intestinal juice of the Roman snail Helix pomatia gave hatching results which were dependent on the absence of O2 (exposure to N2) and the presence of bacteria with a still unknown function. The dependence on pH seems to be indirect (Abb. 2). Studies on the permeabilities of the egg shell and the embryonic membrane ("vitelline membrane"), the evidence of an oligosaccharide (Abb. 3) liberated from the "spaltraum" (Abb. 1) during egg-opening, and the determination of the osmotic pressure of the hatching process (50% hatching in 1.2--14. Osmols sucrose/1000 ml H2O; Abb. 4) led to the following hypothesis of hatching mechanism: After the activation of the granular gland of the miracidium an enzyme is released into the extra-embryonic "spaltraum". A polysaccharide is digested to an oligosaccharide which cannot permeate the egg shell and the embryonic membrane. The rising osmotic pressure bursts off the operculum.