Meningoencefalite necrosante em bovinos associada ao herpesvírus bovino-5 em Pernambuco - Brasil

Background: Bovine Herpesvirus-5 (BoHV-5) is the most important cause of encephalopathy in cattle in Brazil. Necrotizing meningoencephalitis is an acute or subacute infectious disease that has low morbidity, higher fatal outcome and affects animals of all age groups, but especially young cattle under stress situations. The disease may occur like outbreaks or affect cattle alone. The mortality and morbidity varies from 75-100% and 0.05 to 22% respectively. This study aims to report the occurrence of two outbreaks of meningoencephalitis caused by bovine herpesvirus-5 diagnosed in the state of Pernambuco in the years 2011-2012. Cases: The epidemiological data and clinical signs were obtained with the veterinarians of two properties where the outbreaks occurred. Necropsies in two cattle were performed and samples of brain, spinal cord and tissue’s fragments from thoracic and abdominal cavities were collected. The material fi xed in 10% buffered formalin was processed routinely for histopathological examination. After fi xation of the brain, fragments of cerebral cortex, basal ganglia, thalamus, midbrain, cerebellar peduncles, cerebellum, bridge, medulla oblongata and cervical spinal cord were immunohistochemically processed for rabies. CNS samples were subjected to the technique of PCR for detection of BoHV-5. In affected cattle, the main clinical signs consisted of circling, blindness, nasal and ocular discharge, head pressing, muscle tremors, incoordination, and permanent lateral recumbence followed by death. At necropsy, no significant changes observed. After cutting the brain previously fixed in formaldehyde solution, softened grayish areas of granular appearance and cavitations in the cerebral cortex, midbrain, hippocampus, thalamus, basal ganglia and cerebellum were observed. Microscopically there was nonsuppurative meningitis and diffuse encephalitis with perivascular cuffs, mononuclear or undifferentiated cells and neuronal necrosis. In areas of polioencefalomalacia there was neuronophagia and the presence of Gitter cells. In the samples submitted to PCR had amplifi cation of DNA from BoHV-5. Discussion: The diagnosis of necrotizing meningoencephalitis by BoHV-5 was based on the epidemiology, clinical signs, characteristic histological lesions and especially in molecular detection of viral DNA, similar to those described in other cases of disease. In Pernambuco the disease had not yet been described. In the State of Paraiba, three cases with characteristic lesions of meningoencephalitis by BoHV-5 were diagnosed. However, in these cases the diagnosis was only based on clinical signs and lesions in the CNS of affected cattle. Despite the apparent low prevalence in northeastern Brazil, the disease has seems to be more frequent and many other outbreaks are not probably diagnosed, especially outside of areas covered by veterinary diagnostic laboratories. In CNS samples of this study no intranuclear eosinophilic inclusion bodies in astrocytes were observed. In those cases, the IHC for rabies becomes an important methodology in differential diagnosis of disease, especially in tissues embedded in paraffi n and fi xed in formalin with non-suppurative meningoencephalitis in which inclusion bodies are observed. The results of this study confi rmed BoHV-5 infection in cattle in Pernambuco in which the technique of PCR using primers that encode protein C (gC) was used.