Granulocytic anaplasmosis in three dogs from Saskatoon,Saskatchewan

Three dogs from Saskatoon, Saskatchewan were diagnosed with acute granulocytic anaplasmosis. Fever, lethargy, inappetence, vomiting, diarrhea, and lameness were reported. Lymphopenia, thrombocytopenia, and splenomegaly were identified in all dogs. Inclusions were identified within the cytoplasm of blood neutrophils, and infection with Anaplasma phagocytophilum was confirmed by polymerase chain reaction.     

Eight-year performance of bareroot Douglas-fir and bareroot and plug western larch Seedlings following herbicide applications,northeast Oregon,USA

Plantation success in northeastern Oregon can be limited by poor survival for western larch (Larix occidentalis Nutt.) and Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco var. glauca (Beissn.) Franco) seedlings. Vegetation management treatments may increase soil moisture availability during the dry summer months, thereby increasing the probability of seedling survival. Chemical site preparation treatments were applied in spring 2007, summer 2007, and spring 2008 to determine if such treatments would improve survival and growth of bareroot Douglas-fir and bareroot and plug western larch seedlings on three sites near Elgin, Oregon. Although some herbicide treatments significantly increased survival, results were not consistent among sites. Overall, Douglas-fir had greater survival after 7–8 years than larch seedlings. Seedling size 7–8 years after planting was also highly variable among sites and treatments with larch seedlings being taller and larger than Douglas-fir seedlings, on the average. Size for all stock types was negatively correlated with vegetative cover and positively correlated with first-year soil moisture. Macro- and microclimatic conditions, including topography and soil depth, were likely contributors to differences in survival and growth.     

Reduced cerebral infection of Neospora caninum in BALB/c mice vaccinated with recombinant Brucella abortus RB51 strains expressing N. caninum SRS2 and GRA7 proteins

Neospora caninum, an obligate intracellular protozoan parasite, is the causative agent of bovine neosporosis, an important disease affecting the reproductive performance of cattle worldwide. Currently there is no effective vaccine available to prevent N. caninum infection in cattle. In this study, we examined the feasibility of developing a live, recombinant N. caninum vaccine using Brucella abortus vaccine strain RB51 as the expression and delivery vector. We generated two recombinant RB51 strains each expressing SRS2 (RB51/SRS2) or GRA7 (RB51/GRA7) antigens of N. caninum. BALB/c mice immunized by single intraperitoneal inoculation of the recombinant RB51 strains developed IgG antibodies specific to the respective N. caninum antigen. In vitro stimulation of splenocytes from the vaccinated mice with specific antigen resulted in the production of interferon-gamma, but not IL-5 or IL-10, suggesting the development of a Th1 type immune response. Upon challenge with N. caninum tachyzoites, mice vaccinated with strain RB51/SRS2, but not RB51/GRA7, showed significant resistance to cerebral infection when compared to the RB51 vaccinated mice, as determined by the tissue parasite load using a real-time quantitative TaqMan assay. Interestingly, mice vaccinated with either strain RB51 or RB51/GRA7 also contained significantly lower parasite burden in their brains compared to those inoculated with saline. Mice vaccinated with strain RB51/SRS2 or RB51/GRA7 were protected to the same extent as the strain RB51 vaccinated mice against challenge with B. abortus virulent strain 2308. These results suggest that a recombinant RB51 strain expressing an appropriate protective antigen(s), such as SRS2 of N. caninum, can confer protection against both neosporosis and brucellosis.     

Malignant catarrhal fever-like disease in sheep after intranasal inoculation with ovine herpesvirus-2.

A malignant catarrhal fever (MCF)-like disease was induced experimentally in 3 sheep after aerosol inoculation with ovine herpesvirus-2 (OvHV-2). Each of 3 OvHV-2-negative sheep was nebulized with 2 ml of nasal secretions containing approximately 3.07 X 10(9) OvHV-2 DNA copies from a sheep experiencing an intensive viral-shedding episode. Ovine herpesvirus-2 DNA became detectable by polymerase chain reaction in the peripheral blood leukocytes of all 3 sheep within 3 days, and all 3 seroconverted between 6 and 8 days postinfection (PI). The sheep developed clinical signs, with copious mucopurulent nasal discharge and fever around 14 days PI. One of the 3 clinically affected sheep was euthanized at 18 days PI. Major lesions at necropsy were multifocal linear erosions and ulcers in mucosa of the cheeks, tongue, pharynx, and proximal esophagus and mild disseminated pneumonia. Microscopically, there was extensive moderate superficial histiocytic-lymphocytic rhinitis with epithelial dissociation and degeneration. Moderate multifocal histiocytic bronchointerstitial pneumonia was associated with loss of terminal bronchiolar epithelium. Lymphocytic vasculitis was present only in the lung. The remaining 2 sheep recovered clinically, approximately 25 days PI. The study revealed that clinical signs and lesions resembling MCF can develop when uninfected sheep are exposed to a high dose of aerosolized OvHV-2.     

Development of Isospora suis from pigs in primary porcine and bovine cell cultures

Sporozoites of Isospora suis penetrated and developed by endodyogeny in primary porcine kidney (PPK) and primary fetal bovine kidney (PFBK) cell cultures. Motile merozoites and binucleate Type I meronts were observed in both types of cultured cells. Multinucleate Type II meronts developed in PPK cell cultures only. These multinucleate meronts were always found singly, were nonmotile and did not form merozoites.     

The effect of weaning method on coccidial infections in beef calves

Weaning is often cited as a stressful event that can precipitate clinical coccidiosis in cattle. Recently, two-stage weaning methods have been investigated as a means to reduce stress in calves. The objective of this study was to investigate the effect of weaning method on fecal oocyst count (FOC) and Eimeria spp. composition. A group of 108 beef calves (190-240 days of age) were allocated to three treatments on day -7: a fenceline weaned group where calves could see and hear their dams, but were physically separated from them by a fence (FL), a noseclipped group where suckling was prevented (NC), and a group left with their dams to be traditionally weaned (TW) by abrupt separation on day 0. On day 0, noseclips were removed from the NC calves and all groups were completely separated from their dams. The steers (n=50) were transported 172 km to another farm, and heifers (n=58) were taken to distant fields on the same farm. Rectal fecal samples were collected from all calves on days -7, 0, and 14. Steers were also sampled on days 7, 28, and 42. A group of steers (n=24) from each of the treatments previously described were fitted with pedometers and intensively observed on days 1-4. The Modified McMaster's test and Wisconsin sugar flotation test were used for quantification and identification of Eimeria spp. oocysts. Clinical coccidiosis was not observed during the study. Fecal oocyst counts did not differ between treatment groups on any sampling day. Differences between steer and heifer FOC were not detected. Treatment had no effect on species composition, but time effects were detected in the steers. The mean percentage of E. bovis was lower (P<0.05) on days 28 and 42 than all other sampling days. The decrease in the percentage of E. bovis was accompanied by an increase (P<0.05) in the percentage of E. canadensis on days 28 and 42. Behavioral observation showed that TW steers exhibited higher levels of stress related behavior (P<0.05) following complete separation, although this was not reflected in FOC.     

Relationships among Sarcocystis species transmitted by New World opossums (Didelphis spp.)

At least three species of Sarcocystis (S. neurona, S. falcatula, S. speeri) have recently been shown to use opossums of the genus Didelphis as their definitive host. In order to evaluate the evolutionary relationships among Sarcocystis spp. isolates from the Americas, and to determine whether organisms representing the same parasite lineages are transmitted north and south of the Panamanian isthmus, we inferred the phylogenetic relationships from nucleotide sequence variation in parasites isolated from three opossum species (D. virginiana, D. albiventris, D. marsupialis). In particular, we used variation in the 25/396 marker to compare several isolates from Brazil, Argentina, and the United States to each other and to cloned S. neurona and S. falcatula whose morphology and host affinities have been defined in the laboratory. S. neurona was identified from a Brazilian D. albiventris, as well as from North American D. virginiana. Parasites resembling the Cornell isolate of S. falcatula are transmitted both south and north of the Panamanian isthmus by D. albiventris and D. virginiana, respectively. Distinct attributes at two genetic loci differentiated a Brazilian isolate of S. falcatula from all other known parasite lineages. We confirm S. neurona as the causative agent of recently reported neurologic disease in Southern sea otters, Enhydra lutris nereis. And we found that S. speeri could not be compared to the other opossum-derived Sarcocystis isolates on the basis of nucleotide variation at the 25/396 locus. The widespread distribution of certain species of Sarcocystis may derive from their ability to parasitize migratory bird hosts in their intermediate stage.     

Prevalence of IgG Antibodies to Toxoplasma gondii in Veterinary and Undergraduate Students at Virginia Tech,Blacksburg, Virginia

Toxoplasma gondii is a globally distributed parasitic protozoan that infects humans and other warm‐blooded vertebrates. Felids are the only definitive host for T. gondii, and they excrete oocysts in their faeces. The national prevalence in humans is declining in the United States. This zoonotic organism is of particular interest due to its importance in pregnant women, in individuals with altered immune systems, and in reactivated ocular infections. Exposure to the parasite in humans is usually associated with consumption of raw or undercooked meat or by accidental ingestion of oocysts. It was hypothesized that veterinary students would have a greater chance at exposure to the parasite than an average population of undergraduate students due to increased contact with cats who are infected. A commercially available ELISA was used to examine serum samples from 336 students (252 veterinary students and 84 undergraduate students) at Virginia Polytechnic Institute and State University and the Virginia‐Maryland Regional College of Veterinary Medicine for serum IgG antibodies to T. gondii antigen. The prevalence of T. gondii in these subjects was 5.6% in veterinary school students (n = 252) and 2.4% in undergraduates (n = 84). There was no significant difference (P > 0.05) in the prevalence of T. gondii antibodies in veterinary versus undergraduate students. The overall prevalence of 4.8% in all students in this study reflects the continuing decline of antibodies to T. gondii in humans in the United States.