Field and experimental symptomless infections support wandering donkeys as healthy carriers of Trypanosoma vivax in the Brazilian Semiarid, a region of outbreaks of high mortality in cattle and sheep.

BACKGROUND: The Brazilian Semiarid is the home of the largest herd of donkeys in South America and of outbreaks of Trypanosoma vivax infection of high mortality in dairy cattle and sheep. For a comprehensive understanding of the underlying mechanisms of these outbreaks and epidemiological role of donkeys, we surveyed for T. vivax in wandering donkeys and follow the experimental infection of donkeys and sheep with a highly virulent isolate from the Semiarid. METHODS: Blood samples from 180 randomly selected wandering donkeys from the Brazilian Semiarid region were employed for PCV and parasitemia assessments and tested using the T. vivax-specific TviCATL-PCR assay. PCR-amplifed Cathepsin L (CATL) sequences were employed for genotyping and phylogenetic analysis. Four wandering donkeys were experimentally infected with a T. vivax isolate obtained during an outbreak of high mortality in the Semiarid; the control group consisted of two non-inoculated donkeys. RESULTS: We detected T. vivax in 30 of 180 wandering donkeys (16.6 %) using TviCATL-PCR. The prevalence was higher during the dry (15.5 %) than the wet season (1.1 %) and more females (23.1 %) than males (8.9 %) were infected. All the PCR-positive donkeys lacked patent parasitemia and showed normal values of body condition score (BCS) and packed cell volume (PCV). To evaluate the probable tolerance of donkeys to T. vivax, we inoculated five donkeys with a highly virulent isolate (TviBrRp) from the Semiarid. All inoculated donkeys became PCR-positive, but their parasitemia was always subpatent. A control goat inoculated with TviBrRp showed increasing parasitemia concurrently with fever, declining PCV, tachycardia, mucous membrane pallor, enlarged lymph nodes and anorexia. None of these signs were observed in donkeys. However, T. vivax from wandering donkeys shared identical or highly similar genotypes (identified by Cathepsin L sequences) with isolates from cattle and sheep outbreaks of acute disease in the Semiarid. CONCLUSIONS: This is the first report of T. vivax in donkeys in Brazil and, to our knowledge, the first experimental infection of donkeys with T. vivax. The symptomless field and experimental infections corroborated that donkeys are more tolerant to T. vivax than other livestock species as shown in African countries. Therefore, farmers, veterinaries and control programmes should be aware of healthy carrier donkeys as a possible source of T. vivax for susceptible livestock species in the Brazilian Semiarid.

Evaluation of hematologic, blood gas, and select biochemical variables in ovine whole blood stored in CPDA-1 bags.

BACKGROUND: The economic consequences from mortality of sheep after blood loss can be considerable. To date there are no reports addressing hematologic, blood gas, and biochemical changes in ovine blood stored in CPDA-1 bags. OBJECTIVES: The aim of this study was to investigate hematologic, blood gas, and biochemical alterations resulting from storage of ovine blood in CPDA-1 bags to establish transfusion protocols in sheep. METHODS: From each of 7 healthy 8-month-old sheep 450 mL of blood were collected into CPDA-1 bags and stored for 35 days in at 3-6°C. Samples were taken from the bags at days 0, 7, 14, 21, and 35. Whole blood was used to assess PCV, MCV, RBC count, pH, pO2 , pCO2 , and concentrations of bicarbonate, sodium, and lactate. Plasma was used to measure potassium, hemoglobin, and glucose concentrations. RESULTS: The PCV remained stable throughout the storage period, while plasma hemoglobin and MCV began to increase on days 7 and 21, respectively. The RBC count began to decrease on day 21. Blood pH decreased and pCO2 increased steadily throughout the storage period. Potassium concentration increased from 3.8 to 18.3 mmol/L on day 7 and remained high thereafter. In contrast, sodium concentration began to decrease on day 7. CONCLUSIONS: The results show that ovine blood undergoes hematologic, blood gas, and biochemical changes during storage. Further studies are required to establish RBC viability in CPDA-1 bags after a storage period of 35 days.

Molecular confirmation of ovine herpesvirus 2-induced malignant catarrhal fever lesions in cattle from Rio Grande do Norte, Brazil / Diagnóstico molecular de herpesvírus ovino tipo 2 em surto de febre catarral malígna em bovinos do Rio Grande do Norte

Molecular findings that confirmed the participation of ovine herpesvirus 2 (OVH-2) in the lesions that were consistent with those observed in malignant catarrhal fever of cattle are described. Three mixed-breed cattle from Rio Grande do Norte state demonstrated clinical manifestations that included mucopurulent nasal discharge, corneal opacity and motor incoordination. Routine necropsy examination demonstrated ulcerations and hemorrhage of the oral cavity, corneal opacity, and lymph node enlargement. Significant histopathological findings included widespread necrotizing vasculitis, non-suppurative meningoencephalitis, lymphocytic interstitial nephritis and hepatitis, and thrombosis. PCR assay performed on DNA extracted from kidney and mesenteric lymph node of one animal amplified a product of 423 base pairs corresponding to a target sequence within the ovine herpesvirus 2 (OVH-2) tegument protein gene. Direct sequencing of the PCR products, from extracted DNA of the kidney and mesenteric lymph node of one cow, amplified the partial nucleotide sequences (423 base pairs) of OVH-2 tegument protein gene. Blast analysis confirmed that these sequences have 98-100% identity with similar OVH-2 sequences deposited in GenBank. Phylogenetic analyses, based on the deduced amino acid sequences, demonstrated that the strain of OVH-2 circulating in ruminants from the Brazilian states of Rio Grande do Norte and Minas Gerais are similar to that identified in other geographical locations. These findings confirmed the active participation of OVH-2 in the classical manifestations of sheep associated malignant catarrhal fever.

Os achados moleculares confirmaram a participação do herpesvírus ovino tipo 2 (OVH-2) nas lesões observadas em um surto de febre catarral malígna em bovinos. Três bovinos oriundos de propriedade rural de Mossoró, Rio Grande do Norte apresentaram manifestações clínicas, que incluíram secreção nasal mucopurulenta, opacidade da córnea e incoordenação motora. A necropsia revelou ulcerações e hemorragias da cavidade oral, opacidade da córnea e linfonodomegalia. Os achados histopatológicos significativos incluíam vasculite necrosante generalizada, meningoencefalite não supurativa, nefrite intersticial linfocítica, hepatite linfocítica e trombose. A PCR, realizada a partir de DNA extraído do rim e do linfonodo mesentérico de um dos animais, amplificou um produto com 423 pares de base do gene da proteína do tegumento do herpesvírus ovino 2 (OVH-2). O sequenciamento direto dos produtos da PCR e a análise pelo Blast demonstraram que o produto amplificado apresentava 98-100% de identidade com sequências do OVH-2 depositadas no GenBank. As análises filogenéticas, baseadas nas sequências deduzidas de aminoácidos demonstraram que a cepa de OVH-2 circulando em ruminantes nos estados de Rio Grande do Norte e Minas Gerais são semelhantes àquelas identificadas em outras regiões geográficas. Esses achados confirmam a participação ativa de OVH-2 nas manifestações clássicas de febre catarral maligna em ovinos.