Stefan Hoby

Publications of Stefan Hoby

• Nutritional metabolic bone disease in juvenile veiled chameleons (Chamaeleo calyptratus) and its prevention.

  Authors: Stefan Hoby, Christian Wenker, Nadia Robert, Thomas Jermann, Sonja Hartnack, Helmut Segner, Claude-P Aebischer, Annette Liesegang

  The Journal of nutrition. 09/2010; 140(11):1923-31.

  Nutritional metabolic bone disease (NMBD) is one of the most frequently observed pathological conditions in herpetoculture. To develop guidelines for NMBD prevention in growing veiled chameleonsNutritional metabolic bone disease (NMBD) is one of the most frequently observed pathological conditions in herpetoculture. To develop guidelines for NMBD prevention in growing veiled chameleons (Chamaeleo calyptratus), 56 hatchlings were divided into 6 groups [group UV, with UVB exposure; group No: no supplements; group CaAUV: with calcium (Ca), vitamin A, UVB; group CaA: with Ca, vitamin A; group CaADUV: with Ca, vitamin A, cholecalciferol, UVB; and group CaAD, with Ca, vitamin A, cholecalciferol] and reared for 6 mo on locust-based diets. The nutrient composition of the locusts' diet and the locust-based diet for the chameleons was determined. The diagnosis included the detailed description of clinical findings, histopathology, measurements of serum Ca, 25-hydroxycholecalciferol (25-OHD(3)), liver 25-OHD(3), vitamin A, bone mineral density, and bone mineral concentration. Chameleons that received no dietary supplementation of Ca, vitamin A, and cholecalciferol developed NMBD. When Ca and vitamin A were supplemented, the chameleons did not develop NMBD, independently of additional UVB and dietary cholecalciferol. The best prevention for NMBD was achieved by chameleons that received locusts gut-loaded with 12% Ca and dusted with 250,000 IU/kg (75 mg/kg) vitamin A and 25,000 IU/kg (0.625 mg/kg) cholecalciferol plus provision of long (10 h/d), low irradiation exposure (3-120 μW/cm(2)) to UVB. Chameleons that were fed diets low in vitamin A, cholecalciferol, and Ca were diagnosed with fibrous osteodystrophy. We noticed an interaction of vitamin A and cholecalciferol supplementation in the storage of vitamin A in the liver and formation of colon calcifications. From these findings, recommendations for the rearing of juvenile chameleons were derived.

• Babesia capreoli infections in alpine chamois (rupicapra R. Rupicapra), roe deer (capreolus C. Capreolus) and red deer (cervus elaphus) from Switzerland.

  Authors: Stefan Hoby, Alexander Mathis, Marcus G Doherr, Nadia Robert, Marie-Pierre Ryser-Degiorgis

  Journal of wildlife diseases. 08/2009; 45(3):748-63.

  Five cases of fatal babesiosis in free-ranging chamois (Rupicapra r. rupicapra) attributed to infections with Babesia capreoli were recently recorded in two regions of the Swiss Alps. To investigateFive cases of fatal babesiosis in free-ranging chamois (Rupicapra r. rupicapra) attributed to infections with Babesia capreoli were recently recorded in two regions of the Swiss Alps. To investigate the ecologic factors that possibly lead to those fatal B. capreoli infections in chamois, blood, ticks, and demographic data of 46 roe deer (Capreolus c. capreolus), 48 chamois, and nine red deer (Cervus elaphus) were collected in 2006 and 2007 in both affected regions. Whereas no parasitic inclusions were found by microscopical examination of blood smears, B. capreoli was identified by polymerase chain reaction/sequencing in blood of 12 roe deer (26%, 95% confidence interval [CI]: 14.3-41.1), one chamois (2%, CI: 0-6.1), and one red deer (11%, CI: 0.3-48.2). Prevalence of B. capreoli was significantly higher in roe deer compared with chamois (P<0.001). All 214 ticks were identified as Ixodes ricinus, and significantly more roe deer (63%, CI: 47.5-76.8) were infested compared with chamois (21%, CI: 10.5-35.0, P<0.001). Overall, prevalences of both tick infestation and Babesia infection increased significantly (P<0.001) with decreasing altitude, and Babesia-positive samples were detected significantly more often from animals with tick infestation compared with animals without ticks (P = 0.040). Our results indicate that roe deer may play an important reservoir role for B. capreoli. It is hypothesized that the expansion of the presumed vector I. ricinus to higher elevations and its increased abundance in overlapping habitats of roe deer and chamois may favor the spillover of B. capreoli from roe deer to chamois.

• Babesia divergens-like organisms from free-ranging chamois (Rupicapra r. rupicapra) and roe deer (Capreolus c. capreolus) are distinct from B. divergens of cattle origin - an epidemiological and molecular genetic investigation.

  Authors: Nicole Schmid, Peter Deplazes, Stefan Hoby, Marie-Pierre Ryser-Degiorgis, Renate Edelhofer, Alexander Mathis

  Veterinary parasitology. 06/2008; 154(1-2):14-20.

  In 2005 and 2006, three adult female chamois (Rupicapra r. rupicapra) were found dead with signs of acute babesial infection in the eastern Swiss Alps. PCR on DNA extracted from blood or spleen ofIn 2005 and 2006, three adult female chamois (Rupicapra r. rupicapra) were found dead with signs of acute babesial infection in the eastern Swiss Alps. PCR on DNA extracted from blood or spleen of the carcasses revealed sequence identity of the amplified part of the 18S rRNA gene with GenBank entries attributed to Babesia divergens of cattle origin or B. capreoli of wild ruminant origin which have never been described before in this region. Examination of 424 blood samples from 314 head of cattle from this area by IFAT, microscopy and PCR provided no evidence for babesial infection. Six of 887 ticks collected from cattle were PCR-positive, and sequencing revealed Babesia sp. genotype EU1 in five and B. divergens/B. capreoli in one of them. A Babesia isolate of chamois, two isolates of roe deer from the same region and one isolate of a roe deer from the north-western Swiss Alps were genetically compared with two Swiss B. divergens isolates of cattle origin by analysing the genomic rDNA locus. Whereas the near full length sequences of the 18S rRNA gene were virtually identical among all six isolates (>99.4% identity), distinct differences between the two isolates from cattle on the one hand and the four isolates from free-ranging ruminants on the other hand were observed in the sequences of the internal transcribed spacers 1 and 2 (ITS1, ITS2) and part of the 28S rRNA gene. These results indicate that, albeit genetically very closely related, these babesial organisms from cattle and from free-ranging ruminants indeed are distinguishable organisms with different host specificities, and they support the use of the discrete species name B. capreoli for the B. divergens-like organisms from chamois and roe deer.

• Babesiosis in free-ranging chamois (Rupicapra r. rupicapra) from Switzerland.

  Authors: Stefan Hoby, Nadia Robert, Alexander Mathis, Nicole Schmid, Marina L Meli, Regina Hofmann-Lehmann, Hans Lutz, Peter Deplazes, Marie-Pierre Ryser-Degiorgis

  Veterinary parasitology. 10/2007; 148(3-4):341-5.

  Pathological examination of five adult chamois (Rupicapra r. rupicapra) found dead in two different regions from the Swiss Alps revealed pale mucous membranes and musculature, swollen spleen andPathological examination of five adult chamois (Rupicapra r. rupicapra) found dead in two different regions from the Swiss Alps revealed pale mucous membranes and musculature, swollen spleen and haemoglobinuria. Histologically, haemosiderosis in the spleen and centrilobular hepatic necrosis were the predominant findings. On blood smears, small (approximately 0.84-1.47 microm), round to pyriform, peripherally located inclusions were present in the erythrocytes. PCR followed by sequencing of DNA extracted from blood or spleen of the infected animals revealed 99-100% identity of the amplified part of the 18S rRNA gene with GenBank entries attributed to Babesia divergens/Babesia capreoli. This is the first report of fatal Babesia infections in chamois raising the question of an emerging disease in this species.

• Steroid hormone related male biased parasitism in chamois, Rupicapra rupicapra rupicapra.

  Authors: Stefan Hoby, Franz Schwarzenberger, Marcus G Doherr, Nadia Robert, Christian Walzer

  Veterinary parasitology. 07/2006; 138(3-4):337-48.

  Parasites are linked with their host in a trophic interaction with implications for both hosts and parasites. Interaction stretches from the host's immune response to the structuring of communitiesParasites are linked with their host in a trophic interaction with implications for both hosts and parasites. Interaction stretches from the host's immune response to the structuring of communities and the evolution of biodiversity. As in many species sex determines life history strategy, response to parasites may be sex-specific. Males of vertebrate species tend to exhibit higher rates of parasites than females. Sex-associated hormones may influence immunocompetence and are hypothesised to lead to this bias. In a field study, we tested the prediction of male biased parasitism (MBP) in free ranging chamois (Rupicapra rupicapra rupicapra), which are infested intensely by gastrointestinal and lung helminths. We further investigated sex differences in faecal androgen (testosterone and epiandrosterone), cortisol and oestrogen metabolites using enzyme immunoassays (EIA) to evaluate the impact of these hormones on sex dependent parasite susceptibility. Non-invasive methods were used and the study was conducted throughout a year to detect seasonal patterns. Hormone levels and parasite counts varied significantly throughout the year. Male chamois had a higher output of gastrointestinal eggs and lungworm larvae when compared to females. The hypothesis of MBP originating in sex related hormone levels was confirmed for the elevated output of lungworm larvae, but not for the gastrointestinal nematodes. The faecal output of lungworm larvae was significantly correlated with androgen and cortisol metabolite levels. Our study shows that sex differences in steroid levels play an important role to explain MBP, although they alone cannot fully explain the phenomenon.

• Paraparesis in an adult alpaca with discospondylitis.

  Authors: Patrik Zanolari, Martin Konar, Ales Tomek, Stefan Hoby, Mireille Meylan

  Journal of veterinary internal medicine / American College of Veterinary Internal Medicine. 20(5):1256-60.

• Steroid hormone related male biased parasitism in chamois, Rupicapra rupicapra rupicapra

  Authors: Stefan Hoby, Franz Schwarzenberger, Marcus G. Doherr, Nadia Robert, Christian Walzer

  Veterinary Parasitology.

  Parasites are linked with their host in a trophic interaction with implications for both hosts and parasites. Interaction stretches from the host's immune response to the structuring of communitiesParasites are linked with their host in a trophic interaction with implications for both hosts and parasites. Interaction stretches from the host's immune response to the structuring of communities and the evolution of biodiversity. As in many species sex determines life history strategy, response to parasites may be sex-specific. Males of vertebrate species tend to exhibit higher rates of parasites than females. Sex-associated hormones may influence immunocompetence and are hypothesised to lead to this bias. In a field study, we tested the prediction of male biased parasitism (MBP) in free ranging chamois (Rupicapra rupicapra rupicapra), which are infested intensely by gastrointestinal and lung helminths. We further investigated sex differences in faecal androgen (testosterone and epiandrosterone), cortisol and oestrogen metabolites using enzyme immunoassays (EIA) to evaluate the impact of these hormones on sex dependent parasite susceptibility. Non-invasive methods were used and the study was conducted throughout a year to detect seasonal patterns. Hormone levels and parasite counts varied significantly throughout the year. Male chamois had a higher output of gastrointestinal eggs and lungworm larvae when compared to females. The hypothesis of MBP originating in sex related hormone levels was confirmed for the elevated output of lungworm larvae, but not for the gastrointestinal nematodes. The faecal output of lungworm larvae was significantly correlated with androgen and cortisol metabolite levels. Our study shows that sex differences in steroid levels play an important role to explain MBP, although they alone cannot fully explain the phenomenon.