Delayed-type hypersensitivity skin test against Neospora caninum in heifers with undetectable specific antibodies.

Delayed-type hypersensitivity (DTH) has been used in human and veterinary medicine as a skin testing for evaluating in vivo cell-mediated immune responses (CMIR). Whereas CMIR is a key process to control intracellular pathogens, its value at identifying cattle exposed to the abortigenic intracellular coccidian parasite Neospora caninum is unknown. In this work, we have evaluated a DTH skin testing in cattle exposed to N. caninum and still seronegative. Female calves were experimentally sensitized by subcutaneous (SC) inoculation with live tachyzoites of N. caninum (NC-Argentina LP1) in sterile phosphate-buffered saline (PBS) (group A; n: 8) whereas other calveswere mock-sensitized with PBS (group B; n: 6). Two DTH skin tests were performed by intradermal inoculation with a soluble lysate of N. caninum tachyzoites (NC-Argentina LP1) in the neck region at 60d and 960 d after sensitization. Skinfold thickness at the intradermal inoculation site was measured at 0, 24, 48 h post each DTH skin test and skin biopsies taken for microscopic evaluation. Specific N. caninum antibodies kinetics was evaluated all throughthe experiment. We found that whereas N. caninum specific antibodies remained below the ELISA cut-off, a distinctive skinfold thickness increase was detected in sensitized animals (group A) at the DTH skin test site, showing induration, swelling and inflammatory infiltration. Mock sensitized animals (group B) showed no skinfold thickness growth and lacked specific antibody response. Thus, N. caninum DTH skin testing could be a useful diagnostic tool for the detection of CMIR during N. caninum infection in non-humoral responders.

Bovine neosporosis in dairy cattle from the southern highlands of Ecuador.

The aim of this study was to describe bovine neosporosis in dairy cattle from the Sierra region, Ecuador. A case-control study was performed on 841 dairy cattle from 5 dairy herds. The overall seroprevalence was 23.4% having significant association between abortion and seropositivity (p < .05). Additionally, 46 fetuses were recovered from a local slaughterhouse to evaluate the frequency of vertical transmission. Seventeen and 3 fetuses were positive by PCR and had compatible histopathological lesions, respectively. N. caninum infection must be considered as a relevant cause of reproductive losses in Ecuador.

Spongy Myelinopathy in Newborn Beef Calves Associated with Consumption of Corn Infected with Stenocarpella maydis.

Stillbirth and perinatal mortality with neurological signs and lesions were diagnosed in two calves following ingestion by their dams of corn infected with Stenocarpella maydis during the third trimester of gestation. Grossly, the brain and spinal cord were unremarkable. Microscopically, diffuse severe status spongiosis of the white matter was detected in the cerebral hemispheres, brainstem, spinal cord and cerebellum. To the best of our knowledge this is the first pathological description of congenital disease in calves associated with the consumption of S. maydis-infected corn; the findings resemble those reported for the naturally occurring and experimentally induced disease in lambs.

A Descriptive Study of Lectin Histochemistry of the Placenta in Cattle following Inoculation of Neospora caninum.

The aim of this study was to describe the lectin-binding pattern in the placentas of cows infected experimentally with Neospora caninum. Four cows were inoculated intravenously with 1 × 108 tachyzoites of the NC-1 strain of N. caninum at 150 ± 7 days of pregnancy. Two control cows were administered a placebo. An indirect fluorescence antibody test (IFAT) was performed on serum samples obtained before and after the inoculation. The cows were killed at 30 and 37 days post inoculation. Samples of placenta were taken for histopathology and lectin histochemistry. Fetal tissues and fluids were collected for histopathology and IFAT, respectively. All infected cows had high antibody titres. All fetuses had characteristic histopathological lesions, including non-suppurative meningoencephalitis, myocarditis, hepatitis and myositis, suggesting N. caninum infection. Only two infected fetuses developed specific antibodies. Mild non-suppurative inflammatory infiltrates were recorded in the placentae. Differences in the lectin-binding pattern were observed between infected animals and controls in the glycocalyx (CON-A and WGA) and apical cytoplasm (RCA-I and CON-A) of the trophoblastic cells; giant trophoblastic cells (CON-A and DBA); glycocalyx (PNA, WGA) and apical cytoplasm (CON-A, WGA, PNA, DBA and RCA-I) of endometrial cells; trophoblast of the interplacentomal region (WGA); endothelium (CON-A, SBA, RCA-1 and WGA); and finally, mesenchyme (CON-A, RCA-1, SBA, PNA and DBA). These findings indicate that there is a distinctive pattern of lectin binding in the placenta of cattle infected with N. caninum. The direct effect of the presence of the protozoa as well as the altered expression of cytokines could explain these changes in the maternofetal interface.

First case report of Toxoplasma gondii-induced abortions and stillbirths in sheep in Argentina.

The aim of this study is to report an episode of reproductive losses due to toxoplasmosis in a sheep flock in Argentina. A total of 15 abortions and 9 stillbirths were recorded in a flock of 190 Texel ewes. The affected ewes were more likely to be seropositive for Toxoplasma gondii (15/24) than ewes that delivered normal lambs (5/34, OR=9.6, 95%CI=2.7-34.0, p=0.0004). A pair of aborted twins was recovered for diagnostic investigation. One of these fetuses and its dam were seropositive for T. gondii. Histological examination of the two fetuses revealed non-suppurative myocarditis and epicarditis, portal hepatitis and multifocal necrotizing encephalitis with protozoal cysts in the brain. T. gondii was detected intralesionally by immunohistochemistry in one fetus and by PCR in both. Further investigations are necessary to evaluate the economic losses due to T. gondii in the Argentinean ovine industry.

Histopathological, immunohistochemical, lectinhistochemical and molecular findings in spontaneous bovine abortions by Campylobacter fetus.

Bovine campylobacteriosis (BC) is a venereal disease caused by Campylobacter fetus characterized by temporary infertility with mild endometritis, early embryonic death and occasional abortions. The objectives of this study were to describe and identify C. fetus in spontaneous bovine abortion on the basis of histopathological, immunohistochemical, lectinhistochemical and polymerase chain reaction (PCR) techniques. The most frequent foetal lesion was neutrophilic bronchopneumonia and interstitial pneumonia. Other commonly observed lesions included non-suppurative interstitial enteritis, hepatitis, pericarditis, myositis, myocarditis, and meningitis. In this study, C. fetus fetus was phenotypically classified in all bovine foetuses from lungs and abomasal fluids. Immunohistochemistry (IHC) staining revealed positive stained Campylobacter organisms with typical morphology. Lectin binding patterns not showed great differences between the infected and the non-infected groups. The most important changes were a minor peanut agglutinin (PNA) and DBA binding in the alveolar cells of the lungs and DBA globet cells in some of the C. fetus-positive foetuses. Individual variations in each lectin binding pattern complicate the evaluation of the lectins results. All foetuses positive to IHC were positive by PCR. Better efficiency of PCR was obtained from abomasal fluids than from lung tissues. The association of culture and phenotypic techniques with histopathology, IHC and PCR allowed a better characterization and description of BC.

Retrospective study of bovine neonatal mortality: cases reported from INTA Balcarce, Argentina.

A retrospective study was performed on 169 beef and dairy calves aged from 1 to 7 days old submitted to the Diagnostic Laboratories at INTA Balcarce, Argentina. Bacterial culture was performed for aerobic and microaerophilic organisms. Samples from spleen and lymph nodes, and peripheral blood mononuclear cells were also cultured for viral isolation on cell culture. Bovine rotavirus was detected by direct-ELISA. Multiple tissue samples were fixed in 10% formalin, routinely processed and Stained with hematoxylin and eosin for microscopic examination. Etiological diagnosis was made in 70 of the 169 calves. Infectious agents were identified in 49 cases, the most common being Escherichia coli. When the histopathological examination was performed in cases with undetermined diagnosis, it was noted that 44 specimens had histological lesions, which suggested the presence of an infectious agent. In order to characterize the causes of bovine neonatal mortality, the protocols and methodology should be improved in further works.

Retrospective study of bovine neonatal mortality: cases reported from INTA Balcarce, Argentina / Estudio retrospectivo de mortalidad neonatal bovina: Casos hallados en INTA-Balcarce, Argentina

A retrospective study was performed on 169 beef and dairy calves aged from 1 to 7 days old submitted to the Diagnostic Laboratories at INTA Balcarce, Argentina. Bacterial culture was performed for aerobic and microaerophilic organisms. Samples from spleen and lymph nodes, and peripheral blood mononuclear cells were also cultured for viral isolation on cell culture. Bovine rotavirus was detected by direct-ELISA. Multiple tissue samples were fixed in 10% formalin, routinely processed and stained with hematoxylin and eosin for microscopic examination. Etiological diagnosis was made in 70 of the 169 calves. Infectious agents were identified in 49 cases, the most common being Escherichia coli. When the histopathological examination was performed in cases with undetermined diagnosis, it was noted that 44 specimens had histological lesions, which suggested the presence of an infectious agent. In order to characterize the causes of bovine neonatal mortality, the protocols and methodology should be improved in further works.

Se realizó un estudio restrospectivo en 169 terneros muertos 1 a 7 días después del nacimiento pertenecientes a rodeos para carne y leche, remitidos a los Laboratorios de Diagnóstico del INTA Balcarce, Argentina. Para detectar organismos aeróbicos y microaerófilos se realizó el cultivo bacteriano. Para el aislamiento viral sobre cultivo celular, se recolectaron muestras de bazo, ganglios linfáticos y sangre periférica. El rotavirus bovino fue identificado por ELISA directo. Se efectuó el examen microscópico de diferentes tejidos, los cuales fueron fijados en formol al 10%, procesados y teñidos con hematoxilina y eosina. Se obtuvo un diagnóstico etiológico en 70 de los 169 terneros. Se identificaron agentes infecciosos en 49 casos, siendo el más común Escherichia coli. En los casos con diagnóstico indeterminado, el examen histopatológico realizado determinó que 44 especímenes poseían lesiones compatibles con la presencia de agentes infecciosos. Es necesario mejorar los protocolos y las metodologías de trabajo a los fines de caracterizar las causas de mortalidad neonatal en bovinos.