Elias Jorge Facury-Filho

Protection in the absence of exclusion between two Brazilian isolates of Anaplasma marginale in experimentally infected calves.

This study investigated whether a low pathogenicity isolate of Anaplasma marginale with an appendage (UFMG1) could protect calves from infection with a pathogenic A. marginale isolate (UFMG2). Two groups of five Friesian calves were each inoculated with UFMG1 by intravenous injections of either A. marginale-infected tick cell cultures (group 1) or blood stabilates (group 2); a third (control) group was injected with saline. All animals were inoculated with a blood stabilate containing a high pathogenicity A. marginale isolate (UFMG2) 75 days after the UFMG1 inoculation. After infection with UFMG2, animals in groups 1 and 2 presented low rickettsaemia, but no clinical signs and no reduction in packed cell volume (PCV). Control animals became sick, with high rickettsaemia (16% infected erythrocytes) and a reduction in PCV (71%), resulting in 60% deaths. Up to 2 weeks after the UFMG2 inoculation, msp1α UFMG1 sequences were detected in groups 1 and 2. Four weeks after UFMG2 inoculation, UFMG2 sequences were detected in these animals, along with a new msp1α genotype sequence, closely related to that of the UFMG2 isolate. Control animals had UFMG2 msp1α sequences up to 4weeks after inoculation with UFMG2 and the new msp1α genotype sequence could be detected on the sixth week. The origin of the new A. marginale genotype was unknown, but may represent the first example of MSP1a antigenic variation in infected cattle. The results confirmed the low pathogenicity of the UFMG1 isolate, which provided clinical protection against the highly pathogenic A. marginale UFMG2. Infection with UFMG1 did not prevent the establishment of a second isolate, suggesting protection without infection-exclusion among A. marginale isolates.

Pancreatite crônica intersticial e caquexia causada por Eurytrema coelomaticum em vaca Nelore

A euritrematose bovina, causada por Eurytrema coelomaticum, tem sido relatada no Brasil. A doenca pode afetar animais domesticos, incluindo ruminantes. Estes parasitos geralmente vivem nos ductos pancreaticos e ocasionalmente nos ductos biliares. Este estudo relata um quadro de caquexia em um bovino parasitado por E. coelomaticum proveniente de um rebanho de gado de corte localizado no Estado de Minas Gerais. O animal acometido apresentou perda progressiva de peso, glicosuria e cetonuria. Na necropsia o pâncreas apresentava-se diminuido de tamanho, brancacento, intensa e difusamente firme (fibrose). Varios ductos apresentavam-se dilatados e repletos de Eurytrema. Microscopicamente foi observada destruicao extensa do parenquima pancreatico e fibrose, ovos e parasitas intralesionais, hiperplasia ductal e inflamacao multifocal cronica. Este relato descreve a perda progressiva de peso e pancreatite cronica associada a E. coelomaticum em bovino de corte no Estado de Minas Gerais.

Natural infection of calves by Anaplasma marginale in dairy herds of the Metalúrgica Region, Minas Gerais

The dynamic of natural infections by Anaplasma marginale in calves was evaluated during a period of one year on two farms located in the Metalurgica Region, State of Minas Gerais, Brazil. Blood samples were collected weekly for rickettsemia and packed cell volume (PCV) determination. The animals born from March to July suffered the infection in October and November, independently of their age, whilst calves born from September to December acquired the infection during the first days of life. These animals presented patent rickettsemia from 30 days of life. During the patent period PCV decreased after one week of infection, ranging from 20 to 23%. It was concluded, that in the region studied, the transmission of A. marginale is influenced by climatic conditions, and that calves born during the dry season are more likely to acquire the infection when they are exposed to high transmission levels during the subsequent raining season.

Identification of a vertically transmitted strain from Anaplasma marginale (UFMG3): Molecular and phylogenetic characterization, and evaluation of virulence.

Bovine anaplasmosis is a disease caused by the intraerythrocytic rickettsia species Anaplasma marginale and results in great economic losses in tropical and subtropical regions. Vertical transmission is an important phenomenon that contributes to the persistence of different strains of the agent within the same herd. The identification of new strains and genetic characterization studies are essential to understanding their epidemiology and virulence and for vaccine development. The aim of this study was to perform molecular and phylogenetic characterizations of a new vertically transmitted strain from A. marginale and to evaluate its virulence by experimental inoculation of rickettsia-free calves. Thirty newborn Holstein calves were subjected to molecular tests for the detection of A. marginale, Babesia bovis and Babesia bigemina. Calves positive for A. marginale (n=3) were splenectomized and monitored for the clinical manifestations of anaplasmosis. Blood samples from one of the calves that presented rickettsemia of 42.8% and spontaneous recovery of clinical parameters were used for molecular and phylogenetic characterization (msp1a gene), and inoculum production was used for the evaluation of virulence. This strain was identified as UFMG3. Three tandem repeat forms (13 and MGI19) were identified from the analysis of the msp1a gene, in which the form MGI19 appeared twice. Analysis of these repeats revealed the presence of the sequences QASTSS and SSASGQQQESS and of aspartic acid (D) at position 20 of both repeats. Phylogenetic analysis showed a close relationship among the UFMG3, MGI19 and UFMG2 strains. For virulence evaluation, six Holstein calves were inoculated intravenously with 2×10(7)A. marginale UFMG3-infected erythrocytes. The calves showed maximum rickettsemia of 5.1%, a moderate decrease in packed cell volume and spontaneous recovery of clinical parameters without the need for treatment. The results of experimental inoculation suggest that the strain A. marginale UFMG3 has low virulence and potential application for use as a live vaccine against A. marginale.

Effectiveness of enrofloxacin for the treatment of experimentally-induced bovine anaplasmosis

Four groups of six Holstein calves were inoculated with 3.6 × 10(7) erythrocytes parasitized with Anaplasma marginale. The criteria for treatment of calves were increasing A. marginale rickettsemia and 30% reduction of baseline packed cell volume (PCV) of each animal. Group 1 (G1) received 7.5 mg.kg(-1) of enrofloxacin in a single dose; Group 2 (G2) 7.5 mg.kg(-1) of enrofloxacin twice every three days; Group 3 (G3) 20 mg.kg(-1) of long-acting oxytetracycline in a single dose; and Group 4 (G4) a single dose of PBS. Physical examinations, blood smears and PCV were performed daily. On day treatment, G1, G2 and G3 animals had a mean rickettsemia of 17, 23 and 12%, respectively. At 2 days after treatment (DAT) G1 and G2 animals showed a significant reduction of rickettsemia (p < 0.05) compared to G3. G3 animals had high rates of rickettsemia in the first 2 DAT and a slow decrease until stabilization on 9 DAT. The mean PCV in G1 and G2 increased and stabilized after 7 and 8 DAT, respectively. PCV stabilization was achieved in G3 at 13 DAT. Both enrofloxacin and oxytetracycline were effective for the treatment of anaplasmosis, but enrofloxacin was faster reduction of rickettsemia and PCV recuperation (p < 0.05) compared to oxytetracycline.

Uso de inóculo padronizado de Anaplasma marginale e da quimioprofilaxia no controle da anaplasmose bovina

The use of a homologous standardized inoculum of Anaplasma marginale was compared to a chemoprophylatic method, using dihydrate oxytetracycline, considering reduction of rickttsemia and packed cell volume (PCV), during A. marginale infections in calves. The animals that had received the inoculum (107 A. marginale infected erythrocytes) showed a 1.2% reduction of rickettsemia and the PCV decreased 23.0%, when challenged in the field. These values were statistically lower than those obtained from animals in the control group. As far as chemoprophylaxis is concerned, the animals that had been treated three times with dihydrate oxytetracycline (20 mg/kg) showed a 2.7% reduction of rickettsemia and the PCV decreased 36.3%. These values were also statistically lower than those obtained from animals in the control group. Both preventive measures proved to be efficient in reducing rickettsemia and decrease of PCV.

Natural infection by Eimeria spp. in a cohort of lambs raised extensively in Northeast Brazil

The aim of the study was to examine and describe the changes in the course of Eimeria infection in a cohort of lambs of the mixed breed Santa Inês raised extensively on a farm in the State of Rio Grande do Norte, northeastern Brazil. The study was carried out between April and August 2008, during which period fecal samples were collected on a weekly basis from each of the 27 male lambs starting from the day after birth until the age of 90 days. Samples were analyzed under optical microscope a nd those testing positive for Eimeria oocysts were submitted to a quantitative analysis. Oocysts were detected in 17% of the lambs by week 3, but by week 6 100% of the animals were infected. Eight species of Eimeria were identified in the fecal samples, namely, in decreasing order of prevalence, E. crandallis, E. parva, E. granulosa, E. ovinoidalis, E. ahsata, E. ovina, E. faurei and E. intricata. Of the 191 fecal samples that contained Eimeria oocysts, only 32 (16.8%) were infected with a single species whereas 23 (12.0%) were infected with at least two species and 136 (71.2%) harbored three or more species. Although Eimeria coccidiosis is a complex disease owing to the mixed nature of the infective agents, an ongoing prevention program should be implemented to reduce production losses.