Cattle rabies: the effect of clinical evolution, viral genetic lineage, and viral load on the severity of histological lesions

Abstract

<jats:p>ABSTRACT: Our objective was the characterization and staging of histological lesions in different anatomical sites of the central nervous system (CNS) of rabid cattle. The severity of the lesions was compared with the clinical stages of the disease, the variants of viral isolates, and with the load of virus. Thirty-one spontaneously affected rabid cattle the state of Santa Catarina underwent clinical follow-up and were eventually necropsied. CNS tissues were sampled and submitted to direct fluorescent antibody technique (DFAT), immunohistochemistry (IHC), routine histopathology with hematoxylin and eosin stain (HE), reverse transcriptase polymerase chain reaction (RT-PCR), and polymerase chain reaction in quantitative reverse transcriptase in real time (qRT-PCR). Affected cattle were allotted in four groups according to their clinical stage when euthanized: G1, euthanized while standing; G2, euthanized when in sternal recumbence; G3, euthanized when in lateral recumbence; and G4, affected cattle with natural death. In order to evaluate the degree of severity of the lesions and the presence of Negri bodies (NBs), the brain was sectioned at 9 sites. Additionally, spinal cord and trigeminal ganglion sections were examined. The intensity of the lesions was graded as either absent, mild, moderate, or marked, and the presence or absence of the NBs was noted. Histological lesions were characterized by lymphocytic and monocytic meningoencephalitis with NBs in 28 cases. In all analyzed groups, intensities of histological lesions ranging from mild to severe were observed. Brain regions with the highest inflammatory lesion intensity were the medulla at the level of obex, followed by the colliculus and thalamus. NBs were observed in a higher percentage in the cerebellum, followed by medulla at the obex level, striatum complex, and frontal telencephalon. The duration of the clinical course of the disease did not influence the intensity of the inflammatory lesion, but it did influence the presence of NBs, with a higher percentage of these inclusions in cattle that died naturally than in euthanized cattle. All isolated rhabdovirus included in this study were genetically compatible with samples from hematophagous bats Desmodus rotundus. The evaluation by qRT-PCR did not demonstrate a correlation between lesion intensity and the amount of virus.</jats:p>

Molecular characterisation of rabies virus detected in livestock animals in the southern part of Egypt during 2018 and 2019

“…The brain specimen of one donkey with biting history that had been euthanised three days later before the appearance of any clinical signs was found negative. The intensity of the IFAT detection of RABV antigen and the number of Negri bodies in the brain tissue were affected by the duration of the clinical course of rabies and spontaneous animal death as it has been described previously (Wisser et al, 2020).…”

“…Many diagnostic techniques have been developed for the identification of rabies, including the fluorescent antibody test (FAT) for the detection of rabies virus antigen, RT-PCR for the detection of RABV RNA and histopathological examination for the demonstration of the characteristic intracytoplasmic inclusion bodies (Negri bodies) in the brain tissues of animals (Johnson et al, 2002;Bordignon et al, 2005;Fooks et al, 2009;Zhang et al, 2011;Wisser et al, 2020).…”

Phylogenetic relationship of rabies virus (Rabies lyssavirus) in two different host species

“…Rabies lyssavirus (RABV) is one of seventeen members belonging to the genus Lyssavirus, fteen of which have members of Chiroptera as exclusive reservoirs, showing the importance of this order as a reservoir for the genus [1,[11][12]. In addition to bats, the virus affects several species of mammalian, some with economic importance, such as cattle [1,[13][14].…”

Factors Limiting the Appropriate Use of Rabies Post-exposure Prophylaxis by Health Professionals in Brazil

“…Additionally, 11 cases in dogs were reported between 2011 and 2016, and 6 cases of the rabies canine variant (AgV2) were detected in the wild crab-eating fox Cerdocyon thous between 2015 and 2020 (17,18). Other wildlife reservoirs of rabies (e.g., bats, the common marmoset Callithrix jacchus or foxes) are present in all three states (16)(17)(18)(19). We aimed to determine (i) the criteria used by health professionals to identify a dog as rabid or suspicious for rabies, (ii) the factors correlated with prescribing appropriate PEP by health professionals, and (iii) describe how the SINAN form is completed by health professionals.…”