Ricardo A.A. Lemos

Meningoencefalite em bovinos causada por herpesvírus bovino-5 no Mato Grosso do Sul e São Paulo

Fifteen outbreaks of bovine herpesvirus-type 5 (BHV-5) infection were diagnosed from August 1993 to December 1996. Fourteen outbreaks occurred in the State of Mato Grosso do Sul and one in the State of Sao Paulo. Cattle 6 to 60 months old were affected. Morbidity reached 0.05% to 5% and case fatality rate was nearly 100%. The disease occurred in different municipalities and at different times of the year. Clinical signs were exclusively nervous, and the clinical course varied from 1 to 15 days. The main histologic lesions were meningitis, diffuse encephalitis and necrosis of the cerebral cortex with intranuclear inclusion bodies in astrocytes and neurons. BHV-5 was isolated from 11 out of 12 brains of infected animals inoculated in calf testis cells and MDBK cells. The virus was identified by immunoperoxidase staining with use of monoclonal specific antibodies. Outbreaks of infection by BHV-5 represent 5% of the total number of bovine cases submitted for diagnosis to the Clinical Hospital of the University of Mato Grosso do Sul. These results indicate the importance of the disease in Mato Grosso do Sul and the need for its differentiation from other diseases which affect the nervous system.

Caracterização de herpesvírus bovinos tipos 1 (BHV-1) e 5 (BHV-5) com anticorpos monoclonais

The antigenic profile of 45 herpesviruses (44 viruses from cattle, including six reference BHV-1 strains and 15 putative BHV-1; three reference BHV-5 strains and 20 putative BHV-5) and one buffalo isolate (BuHV) were examined with a panel of monoclonal antibodies (Mabs) prepared against bovine herpesvirus antigens. Tests were performed by immunoperoxidase (IPX) on infected cell cultures, with the Mabs as primary antibodies. Immunostaining allowed the differentiation between types 1 and 5 viruses. All isolates from cases of encephalitis displayed BHV-5 profiles. Four BHV-5 isolates obtained from geographically distinct areas displayed different and highly variable IPX patterns of reactivity. Two viruses with BHV-5 antigenic profile were isolated from semen of asymptomatic bulls. The results showed that the antigenic characterization with the Mab panel employed here is useful for typing BHV-1 and BHV-5 isolates.

Intoxicação por Brachiaria spp. em ruminantes no Brasil

Brachiaria species are the most important grasses for cattle production in Brazil. However, a limiting factor for the use of Brachiaria spp. is their toxicity. Most outbreaks of hepatogenous photosensitization are caused by B. decumbens; however B. brizantha, B. humidicola and B. ruziziensis can also cause poisoning. The poisoning affects cattle, sheep, goats and buffalo. Sheep are more susceptible than other animal species and the young are more susceptible than adults. There are differences in susceptibility among animals of the same species and it has been suggested that this resistance is genetic. Also has been suggested that buffalo and probably some sheep are resilient, i.e. when poisoned these animals have histologic lesions and high GGT serum concentrations, but do not show clinical signs. In general, saponin concentrations are higher in growing plants, but outbreaks occur all over the year, probably due to unexplained rise in saponin concentration in the plant. A clinical syndrome of progressive weight loss and death, without photosensitization, has been reported in cattle poisoned by B. decumbens. Main preventive measures are based on the selection of resistant or resilient animals and on the development of Brachiaria species or varieties with low saponin concentration.

Colangiopatia associada a cristais em ovinos alimentados com Brachiaria decumbens que contém a saponina protodioscina

An outbreak of hepatogenous photosensitization is reported in a flock of 28 sheep grazing Brachiaria decumbens in Mato Grosso do Sul State, Central-Western Brazil. Seven lambs and an adult sheep were affected and 6 of them died. Two surviving affected lambs and one lamb without clinical signs had increased serum values of gamma glutamyltransferase, bilirubin, and cholesterol. In two adult unaffected sheep those parameters were within normal values. An adult sheep submitted to necropsy presented moderate body condition, unilateral corneal opacity, drying of the muzzle, moderate jaundice, increased lobular pattern of the liver, and a distended gallbladder. Histological lesions were epithelial degeneration, necrosis, and hyperplasia of small bile ducts. Mild amounts of foamy macrophages were observed, mainly in the centroacinar zone. Diffuse swelling and vacuolation were observed in hepatocytes. Crystal negative images were found within bile ducts, foamy macrophages, and the lumen of some renal tubules. The heart showed multifocal areas of degeneration and necrosis of the muscle fibers. Pasture samples (Brachiaria decumbens) contained 2.36% of protodioscin. No Pithomyces chartarum spores were found in the pasture. Samples from a similar neighboring B. decumbens pasture grazed by cattle without photosensitization contained 1.63% of protodioscin isomers. Outbreaks of photosensitization caused by Brachiaria spp. are common in cattle in the Brazilian Cerrado (savanna) with about 51 million hectares of Brachiaria spp pastures. Sheep farming has been recently developed in this region, and the number of sheep is increasing significantly. Because sheep are more susceptible than cattle to lithogenic saponins, poisoning by Brachiaria should be an important limiting factor for the sheep industry.

Epidemiologia, sinais clínicos e distribuição das lesões encefálicas em bovinos afetados por meningoencefalite por herpesvírus bovino-5

Seven outbreaks and an isolated case of meningoencephalitis caused by bovine herpesvirus-5 (BoHV-5) in cattle in Rio Grande do Sul, Brazil, occurring in 2002-2004, are described. From a total population at risk of 1,359 cattle, 54 1-18-month-old calves from both sexes and several breeds were affected and 50 died spontaneously or were euthanatized while moribund. The highest frequency of cases was in recently weaned calves or calves submitted to other stressing factors. General rates of morbidity, mortality and lethality were respectively 3.97, 3.67 and 92.59%. Clinical courses varied from 3-10 days and included depression, nasal and ocular discharge, grinding of teeth, circling, blindness, fever, nistagmus, trembling, anorexia, dysphagia, drooling, incoordination, head pressing, rough hair coat, tachycardia, tachypnea, abdominal pain, melena, falls, recumbency, opisthotonus, convulsions and paddling. Nineteen calves were necropsied. Necropsy findings were characterized by hyperemia of leptomeninges, swollen rostral portions of the telencephalon, and flattening of frontal lobes gyri; frequently in these frontal areas there were segmental brown-yellow discoloration and softening (malacia) of the cortex. In cases with more protracted clinical courses there were extensive swelling, softening and hemorrhaging of the telencephalic frontal lobes. Microscopically, all affected cattle had a necrotizing non-suppurative meningoencephalitis with variable distribution among the 19 cases and among the various telencephalic regions of the same case. The severity of these changes were more marked, in decreasing order of intensity, in the telencephalic frontal cortex, basal ganglia (nuclei), thalamus, brain stem, parietal telencephalic cortex, occipital telencephalic cortex and cerebellum. Perivascular inflammatory infiltrate consisted predominantly of lymphocytes, plasm cells, and less frequently of neutrophils. Additional microscopic findings included variable degrees of gliosis, edema, neuronal necrosis in the telencephalic cortex characterized by shrinking and eosinophilia of perikaria and nuclear picnosis (red neuron); basophilic intranuclear inclusion bodies in astrocytes and neurons (21.05% of the cases); sattelitosis; and neuronophagia. The areas of softening in the cortical substance consisted of necrosis of the neuroctodermal elements with maintenance of mesenchymal structures (vessels and microglia), infiltrate of Gitter cells, and, in more severe cases, extensive hemorrhages. In chronic cases, only vascular structures and a few Gitter cells remained in the cortical area leaving a cavity between white matter and leptomeninges (residual lesion).

Fotossensibilização e colangiopatia associada a cristais em ovinos em pastagem com Brachiaria decumbens

Two outbreaks of photosensitization were observed in sheep grazing Brachiaria decumbens in the state of Mato Grosso do Sul, Central Brazil. Clinical signs included swelling and dermatitis of the face, ears and eyelids, conjuntivitis. ocular discharge, blindness, and increased serum levels of AST e GT. Some sheep recoveredand others died within 3-7 days. The livers were sligthy enlarged and firm with white-yellowish or brown-yellowish discoloration. The bile ducts and gall bladder were sligthly enlarged. The main histological changes were the presence of optically active birefringent crystals in the bile ducts and within hepatocytes of periportal areas. Necrosis of the bile duct epithelium, periportal fibrosis with infiltration of inflammatory cells and bile duct proliferation were also observed. Groups of large cells with excentric nuclei and foamy eosinofilic cytoplasm werepresent in the periportal and centrilobular areas. Numerous groups of such cells were also observed in the cortex and medulla of the hepatic lymph nodes. No couhtable amounts of spores of Pithomyces chartarum were observed in the samples from the pasture where the seep grazed; from 30 cultures isolated from these samples, only one produced sporidesmin. It is concluded that the toxicosis was due the ingestion of Brachiaria decumbens.

Aspectos epidemiológicos, clínicos e distribuição das lesões histológicas no encéfalo de bovinos com raiva

The type, distribution and intensity of the histopathological changes were determined in the brain of 25 cattle which had neurological signs and were confirmed as rabies cases by direct immunofluorescent antibody or biological assay in mice. Sections of the brain examined included medulla at the obex; pons and cerebellar peduncles/ cerebellum; mesencephalon at the level of rostral colliculi; diencephalon and telencephalon through the mamillary bodies; and telencephalon at the level of frontal cortex. The cervical spinal cord was also examined in seven of those cases. The duration of clinical course averaged five days and was characterized by ascendent paresia. Specific necropsy findings were absent. Microscopically brainstem, cerebellum and cervical spinal cord were more affected than the thalamus and telencephalon, including hippocampus. The type of lesions were characteristic of viral infection and included non-suppurative encephalomyelitis with neuronal degeneration, nodular gliosis, and mononuclear perivascular infiltrate. Negri bodies were observed in 17 (68%) of the examined brains. The observed intensity and distribution of the lesions were correlated with the signs and duration of the clinical disease.

Polioencefalomalacia em bovinos nos estados de Mato Grosso do Sul e Säo Paulo

Thirty outbreaks of polioencephalomalacia (PEM) were diagnosed from August 1993 to October 1997. Twenty nine occurred in the state of Mato Grosso do Sul and one in Sao Paulo. The disease affected cattle from 4 months to 7 years of age. Morbidity rates ranged from 0.02% to 14.28% and case fatalities from 42.5 % to 100%. The disease was not seasonal. All outbreaks occurred in cattle grazing Brachiaria spp, except one affecting feedlot cattle. Only neurologic signs were observed, and the course of the disease varied from 12 hours to 4 days in untreated cattle. Most animals treated with thiamine and dexamethazone recovered. Moderate cerebral edema was observed at necropsy. Cell changes were characterized by laminar necrosis and gitter cells. In two cases moderate cortical and submeningeal hemorrhages were observed. Nine cases had perivascular and submeningeal infiltrations by eosinophils. Sodium ion concentration of the cerebrospinal fluid was elevated in one case. The cause of PEM in the region was not determined, but the results suggest that in some cases sodium chloride intoxication/water deprivation could play a role in the etiology of the disease. PEM represents 4.78% of cattle disease diagnosed at the Pathology Laboratory of the Federal University of Mato Grosso do Sul.

Polioencefalomalacia em bovinos: epidemiologia, sinais clínicos e distribuição das lesões no encéfalo

Thirty one cases of polioencephalomalacia (PEM) diagnosed from 1999-2008 in cattle from the Southern (13 cases) and Midwestern (18 cases) Brazil were studied. Morbidity (0.04%-6.66 %), mortality (0.04%-6.66 %), and lethality (50%-100%) rates were similar in both regions studied. There was no clear association between PEM cases and age, sex or seasonality. Cases occurred mainly in cattle raised at pasture; in the Southern the disease affected mainly young cattle (one-year old or less) while mainly older cattle (three-year-old or older) were affected in the Midwest. Clinical signs more frequently observed included blindness, incoordination, circling, opisthotonus, recumbence and peddling movements. Clinical course varied from 12 hours to 8 days (average three days and a half). In 11 cases no gross changes were observed in the brain. Main gross findings in the brain of remaining cases included congestion with swelling and flattening of gyri, softening and yellow discoloration of cerebral cortex, hemorrhagic foci in the brain stem, cerebellum and telencephalon, and cerebellar herniation. The main histopathological changes were in the cortex of occipital, parietal and frontal telencephalic lobes; however less prominent and less frequently found lesions occurred in the hippocampus, basal nuclei, thalamus, midbrain, and cerebellum. The type of microscopic cortical lesions was consistent in all cases and included segmentar laminar neuronal necrosis (red neurons), spongiosis, swollen of vascular endothelial nuclei, Alzheimer type II astrocytes and infiltration of gitter cells. In 20% of the cases there was mild lymphohistiocytic cellular infiltrate and in 13% of the cases there was mild infiltrate by neutrophils and eosinophils. Additionally, mild to moderate necro-hemorrhagic lesions were observed in 49% of the cases in the basal nuclei, in 39% of the cases in brain stem and in 26% of the cases in the thalamus. Brain lesions were consistently found in the cortical laminae of the occipital, parietal and frontal telencephalic lobes. In such locations, most frequently affected cortical layers both by neuronal necrosis and edema were external and internal granular layers. Both gyri and sulci were equally affected.

Bovine herpesvirus type 5 (BHV-5) in a calf with rabies

The brain of an one year old male calf which died with signs of neurological disease was submitted to the laboratory for rabies diagnosis. Microscopical findings included moderate mielitis, mild meningoencephalitis with perivascular cell cuffing and Negri inclusion bodies in Purkinje cells of the cerebellum. Rabies virus infection was further confirmed by the direct fluorescent antibody test as well as by mouse inoculation. In addition, a herpesvirus was isolated from brain tissues. The isolate was antigenic and genetically characterized as bovine herpesvirus type 5 (BHV-5). It was not possible to determine whether BHV-5 played an active role in the outcome of the infection, since, the virus might have been present in a latent form in neural tissues. This is the first report of a mixed rabies/ BHV-5 infection in calves.