Resumo

Background: Cerebral babesiosis is a significant cause of mortality in calves, as it can be transmitted through the placenta during gestation and presents with hemolytic and/or neurological symptoms. However, the role of this agent as a cause of abortion is still poorly understood. In endemic areas, the disease primarily affects cattle between the ages of 1 and 12 months and occasionally neonates. This study aimed to describe the epidemiological, clinical, anatomopathological, molecular, and differential diagnostic aspects of a naturally infected newborn Nelore calf. Case: A newborn Nelore calf from Mato Grosso do Sul was discovered dead 1 h after birth and was subjected to necropsy, cytopathological and histopathological examinations by the Pathological Anatomy Laboratory (LAP) at the Federal University of Mato Grosso do Sul (UFMS), as well as complementary in situ hybridization (ISH) and polymerase chain reaction (PCR) tests. Hemoparasite research yielded negative results in all cows within the herd, including the mother of the necropsied calf, which were all clinically healthy. The clinical and hematological examination results of the cows were normal. At necropsy, the calf appeared thin, with a moderately jaundiced carcass and multiple petechiae on the pleural and pericardial surfaces. The lung was inflated until the opening of the thoracic cavity and floated when immersed in formalin, indicating that the calf was born alive and breathing. The spleen and liver were moderately enlarged with rounded edges, and the liver appeared slightly orange. The gray matter of the brain was significantly cherry red. Histologically, the central nervous system capillaries were slightly congested, with numerous punctiform and basophilic structures observed in the erythrocytes obliterating these vessels, either alone or in pairs, measuring 1 to 2 µm in diameter, which were morphologically consistent with Babesia bovis. In the cytological evaluation of the imprint slides of the brain cortex, blood capillaries filled with erythrocytes parasitized by solitary or paired punctiform basophilic structures, approximately 1 µm in diameter, morphologically compatible with B. bovis, were detected. Positive labeling for Babesia spp. was observed in the ISH ex-amination, while the PCR identified B. bovis and B. bigemina in were identified in the brain fragments. The macroscopic findings, including pale or icteric mucous membranes, yellow and enlarged liver, and splenomegaly observed in cases of anaplasmosis, may be confused with those of cerebral babesiosis when the latter does not present with hemoglobinuria. Brain congestion indicates B. bovis infection but does not rule out co-infection with Anaplasma marginale in this case, although this rickettsia was not identified in the blood smear. Discussion: The diagnosis of Babesia bovis infection was based on epidemiological and histological data, as well as the identification of the protozoan in spleen and brain smears and through PCR and ISH exams, which are highly sensitive and can aid in the diagnosis of B. bovis in cases of perinatal deaths. In situ hybridization is effective in cases where the material has autolysis, as the technique allows the genetic material of the agent to be associated with the lesion, even with tissue alterations caused by fixation in formalin. The findings of this study highlight the importance of considering this disease as a differential diagnosis among those that cause abortions or neonatal losses in cattle and emphasize the importance of conducting anatomopathological exams for definitive diagnosis.

Resumo

Babesiose cerebral é uma enfermidade causada pelo protozoário Babesia bovis. O agente faz parte do complexo Tristeza Parasitária Bovina, uma das mais importantes doenças parasitárias em bovinos. O presente estudo relata um surto causado por B. bovis em vinte bezerros de aproximadamente 7 a 25 dias de idade. O surto ocorreu entre março e junho de 2015, na região sul do Brasil, área de instabilidade enzoótica para a Tristeza Parasitária Bovina. O diagnóstico foi realizado pela epidemiologia, lesões macroscópicas e pela presença de numerosas formas parasitárias de Babesia bovis em capilares encefálicos, observados em imprints corados por Giemsa. Surtos de babesiose por B. bovis cerebral nos primeiros dias de vida de bezerros é incomum, porém não pode ser desconsiderada em surtos com alta letalidade em áreas de instabilidade enzoótica.(AU)

Cerebral babesiosis is a protozoan disease caused by Babesia bovis. This parasite belongs to the bovine parasitic complex of tick-borne diseases that affect livestock worldwide. The present study reports an outbreak caused by B. bovis affected twenty 7-25 day-old calves. Outbreak occurred from May to July 2015 in the south of Brazil, where there is an area of enzootic instability for cattle tick fever. The macroscopic lesions were anemia, hemoglobinuria, splenomegaly, hepatomegaly, yellow liver and cherry-pink discoloration of cerebral and cerebellar cortex. The diagnosis was based on epidemiology, necropsy and microscopic findings in the brain that showed B. bovis in the capillary vessels of the brain in imprints stained by Giemsa. Cases of cerebral babesiosis by Babesia bovis in such young calves are uncommon but should be considered as a diagnosis possibility when there is high mortality rate in areas ofen zootic instability.(AU)

Resumo

An outbreak of cattle mortality due to Babesia bovis infection in the county of Picada Café, Rio Grande do Sul, southern Brazil, in April 2007 is described. Twenty eight heifers (50.9%) died, out of a herd of 55 animals, in five days. The disease occurred approximately 20 days after heifers were transferred to this farm. The clinical signs included fever, anemia, aggressiveness, incoordination, petechiae in the mucous membranes and death after 1 to 2 days. The necropsy revealed pale mucous membranes, splenomegaly, enlarged and yellowish liver, congested and edematous gall bladder containing viscous granular bile. The kidneys and urine were dark red. The gray matter of cerebrum and cerebellum had a characteristic cherry-pink color. Hemorrhage was seen in the epicardium and endocardium. The histological findings consisted of hemoglobinuric nephrosis, paracentral hepatic necrosis, bile stasis, spleen congestion. The gray matter of the brain exhibited congestion with erythrocytes parasitized by Babesia bovis, which were also seen in the brain impression smear. The death of 28 heifers in 5 days was attributed to inadequate immunity against the parasite. The application of imidocarb dipropionate in animals presenting the initial stage of the disease and in all other animals of the herd was adopted as preventive treatment and no new cases of the disease happened in the next two months, when they were sent to slaughter.

Descreve-se um surto de mortalidade em bovinos por Babesia bovis em abril de 2007, no Município de Picada Café, Rio Grande do Sul. Em um rebanho com 55 novilhas, 28 (50,9%) morreram em cinco dias. A doença iniciou vinte dias após o ingresso dos bovinos na propriedade. Os sinais clínicos incluíam febre, incoordenação, agressividade, anemia, petéquias nas mucosas e morte 1 á 2 dias após. Em 4 animais necropsiados, observaram-se palidez de mucosas, hemorragias múltiplas, esplenomegalia, fígado aumentado e alaranjado, vesícula biliar com parede edemaciada e contendo bile grumosa. Os rins estavam vermelho-escuros e a bexiga continha urina cor de vinho tinto. O encéfalo apresentou cor róseo-cereja externamente e ao corte, mais marcado no córtex telencefálico, cerebelo e corpo estriado, contrastando com a cor branca da substância branca. Na histologia havia nefrose hemoglobinúrica, necrose hepática paracentral, bilestase canalicular, congestão esplênica, além de congestão com grande quantidade de eritrócitos parasitados por estruturas compatíveis com Babesia bovis na região cortical do encéfalo, também observadas em esfregaços teciduais dessas regiões. A morte de 28 bovinos em 5 dias deveu-se, provavelmente, à falta de imunidade contra o parasito. O tratamento foi realizado com dipropionato de imidocarb nos demais animais, havendo recuperação dos bovinos que apresentavam sinais iniciais leves e não ocorrência de novos casos durante um período de dois meses, quando foram enviados para abate.