Epidemiology of canine heartworm in its southern distribution limit in South America: Risk factors, inter-annual trend and spatial patterns

This study was aimed at understanding some aspects of the canine heartworm epidemiology in the southern distribution limit of the parasite in South America. With this objective, 19,298 blood samples of owned dogs from 65 localities of 13 municipalities of Buenos Aires Province were tested for Dirofilaria immitis circulating microfilariae and/or female antigens. The overall heartworm prevalence was 1.63% by microhematocrit tube technique (n=19,136), 3.65% by modified Knott (n=713), and 14.41% by antigen test kit (n=118). Microfilaremic dogs showed a median of 1933 microfilariae per millilitre (q1=375, q3=5625, n=100). Male dogs belonging to breeds of short hair and large size recorded significantly higher prevalences than the other categories. Also, the prevalence increased significantly with the age and only dogs younger than 12 months were not found infected. A clear decreasing trend of the annual prevalence was observed during the whole study period, from 3.91% in 2001 to 1.17% in 2006. D. immitis-infected dogs were detected in 32 localities of 9 municipalities (prevalence range: 0.2-6.7%). Generalized linear models were used to assess associations between heartworm prevalence and environmental variables. The resulting significant models were univariate and included variables related with soil cover and human population density. The best model predicted maximum heartworm prevalences around middle values of bare soil cover, and lower at high and low covers. According to our analyses, canine heartworm infection in urban temperate Argentina could be described as relatively low, endemic, and spatially heterogeneous. Host and environmental factors affecting heartworm transmission at local level were identified and discussed.     

Seroprevalence of Neospora spp. in asymptomatic horses in Italy

One hundred and fifty horses from Italy were tested for serum antibodies to Neospora caninum by indirect fluorescence antibody test (IFAT). Antibodies were present in 42 horses (28%). The positive titres were: 1:50 (16/150-10.5%), 1:100 (26/150-17%), 1:200 (8/150-5.3%) and 1:800 (1/150-0.6%). No neurological anomalies were observed in the seropositive horses. This is the first serologic survey for Neospora spp. antibodies performed on horses born and raised in Italy.     

Comparison of a radioimmunoprecipitation assay to immunoblotting and ELISA for detection of antibody to African swine fever virus

A radioimmunoprecipitation assay (RIPA) has been developed for detection of antibody to African swine fever virus (ASFV) and compared with the immunoblot assay with regard to sensitivity and specificity. Two hundred seven field sera, obtained from pigs in Spain from different geographic areas between 1975 and 1986, that were positive by ASFV enzyme-linked immunosorbent assay (ELISA) were also analysed by immunoblot assay and RIPA. By serum dilution experiments, the RIPA appeared at least as sensitive as the ELISA and immunoblotting tests, although ELISA and RIPA detected antibodies to ASFV earlier in natural infection than did the immunoblot assay, as disclosed by animal inoculation studies. The most antigenic ASFV-induced proteins in natural infection detected by RIPA were the viral proteins p243, p172, p73, p25.5, p15, and p12 and the infection proteins p30 and p23.5. In the immunoblot assay, the proteins that were most reactive with the same sera were the viral protein p25.5 and the infection proteins p30, p25, and p21.5. Only 1 serum, from an animal infected with ASFV, was negative by immunoblot assay but showed a positive result by RIPA. A modification of conventional RIPA was performed using a dot transference of immunoprecipitated proteins to a nitrocellulose filter. This modification simplified the conventional RIPA procedures by eliminating the electrophoresis of immunoprecipitated proteins without affecting sensitivity and specificity. The ease of use, specificity, and the sensitivity comparable to that of the immunoblot assay make the RIPA a useful confirmatory assay for sera that yield conflicting results in other ASFV antibody assays.     

Genetic parameter estimation for pre- and post-weaning traits in Brahman cattle in Brazil

Beef cattle producers in Brazil use body weight traits as breeding program selection criteria due to their great economic importance. The objectives of this study were to evaluate different animal models, estimate genetic parameters, and define the most fitting model for Brahman cattle body weight standardized at 120 (BW120), 210 (BW210), 365 (BW365), 450 (BW450), and 550 (BW550) days of age. To estimate genetic parameters, single-, two-, and multi-trait analyses were performed using the animal model. The likelihood ratio test was verified between all models. For BW120 and BW210, additive direct genetic, maternal genetic, maternal permanent environment, and residual effects were considered, while for BW365 and BW450, additive direct genetic, maternal genetic, and residual effects were considered. Finally, for BW550, additive direct genetic and residual effects were considered. Estimates of direct heritability for BW120 were similar in all analyses; however, for the other traits, multi-trait analysis resulted in higher estimates. The maternal heritability and proportion of maternal permanent environmental variance to total variance were minimal in multi-trait analyses. Genetic, environmental, and phenotypic correlations were of high magnitude between all traits. Multi-trait analyses would aid in the parameter estimation for body weight at older ages because they are usually affected by a lower number of animals with phenotypic information due to culling and mortality.     

Nasal bacterial microbiota during an outbreak of equine herpesvirus 1 at a farm in southern Ontario

The objective of this study was to investigate the nasal bacterial microbiota of healthy horses and horses infected with equine herpesvirus 1 (EHV-1). The nasal bacterial microbiota of 10 horses infected with EHV-1 and 11 control horses from a farm experiencing an outbreak was characterized using the Illumina MiSeq platform targeting the V4 region of the 16S ribosomal RNA gene. The nasal bacterial microbiota of healthy horses and EHV-1 horses was significantly different in community membership and structure. Horses shedding EHV-1 had lower bacterial richness (P = 0.002), evenness (P = 0.008), and diversity (P = 0.026) than healthy horses. Healthy horses had a higher relative abundance of Firmicutes and Bacteroidetes, but lower Proteobacteria than horses with EHV-1 (P < 0.05). This study provides the basis for generating hypotheses and investigations on the role of bacterial-viral interactions in the health and diseases of adult horses.     

A sensitive dot immunobinding assay for serodiagnosis of African swine fever virus with application in field conditions.

The present work describes a simple dot immunobinding assay (DIA) for African swine fever virus (ASFV) antibody detection that can be used under field conditions. The assay uses nitrocellulose strips dotted with a cytoplasmic soluble antigen (CS-P) of ASFV. The nitrocellulose strips are adhered to a plastic handle. The test serum samples react with the CS-P, and antibodies are detected using a protein A-peroxidase conjugate. Both incubations are carried out at 20 C. The efficacy of the DIA as a screening test for ASFV was compared to an enzyme-linked immunosorbent assay (ELISA) and an immunoblotting (IB) test using 343 sera collected from natural African swine fever epizootics and from inapparent ASFV carriers. The DIA had comparable sensitivity to both reference techniques, and all samples positive in the ELISA and IB test were also positive in the DIA. False-positive reactions were not detected when whole blood or poorly preserved serum samples were tested by DIA. Some poorly preserved sera that were positive initially by the ELISA were no longer ELISA positive in a later run, although they were positive in IB and DIA. These positive DIA and IB test results could be caused by the differences in antibody epitope binding.     

Coelioscopic-assisted prefemoral ovariosalpingectomy in a d`Orbigny slider (Trachemys dorbigni) using a digital otoscope

The purpose of this study was to assess the unilateral prefemoral coelioscopic-assisted approach for ovariosalpingectomy in a d`Orbigny slider (Trachemys dorbigni) using a digital otoscope. Twenty healthy turtles were randomly assigned to one of two groups, for right (GR; n=10) or left (GL; n=10) prefemoral access, for coelioscopic-assisted ovariosalpingectomy. Anesthesia and surgery times, body weight, and ovary/oviduct weight data were recorded. Anesthesia and surgery times did not differ significantly between the groups. Wound closure was the most time-consuming surgical step. Ovary and body weights significantly affected the exposure time of the ipsilateral and contralateral ovaries, respectively. Two intraoperative complications were reported. All the animals recovered uneventfully. The digital otoscope can be safely and effectively used for coelioscopic-assisted single-access, unilateral prefemoral ovariosalpingectomy in d`Orbigny slider.