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

Comparison of 4 laboratory tests for the detection of bovine rabies viral infection in Paraguay: fluorescent antibody test, rapid detection test, histologic lesions, and RT-PCR

Rabies virus (RABV; Lyssavirus rabies) is a neurotropic virus that can be transmitted to mammals by the hematophagous bat Desmodus rotundus. An accurate, accessible method for the detection of RABV in cattle is necessary in Paraguay; thus, we evaluated the detection of RABV using 4 techniques: fluorescent antibody test (FAT), immunochromatography rapid detection test (RDT; Anigen Rapid Rabies Ag test kit; Bionote), a reverse-transcription PCR (RT-PCR) assay, and histologic lesions in different portions of the CNS of 49 Paraguayan cattle to determine the most sensitive and specific technique. By FAT and RDT, 15 of 49 (31%) samples were positive. By RT-PCR amplification of N and G genes, 13 of 49 (27%) and 12 of 49 (25%) were positive, respectively. RDT had high agreement with FAT (kappa = 1); sensitivity was 100% (95% CI: 97-100%) and specificity was 100% (95% CI: 99-100%). The amplification of the N and G genes resulted in substantial agreement (kappa of 0.9 and 0.8, respectively) compared with FAT, and the sensitivity and specificity of the N gene were 87% (95% CI: 66-100%) and 100% (95% CI: 98-100%), respectively, and those of the G gene were 80% (95% CI: 56-100%) and 100% (95% CI: 98-100%), respectively. Histologic lesions observed were lymphoplasmacytic meningoencephalitis, gliosis, and neuronophagia. The agreement observed between the FAT and RDT tests suggests that RDT is an accurate tool for the detection of RABV. Histopathology can be used to confirm lesions caused by RABV and to rule out other conditions; the RT-PCR assay is useful for molecular epidemiology studies.

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

Post-exposure prophylaxis (PEP) is necessary to prevent the fatal onset of rabies but requires optimization to avoid overuse in populations at risk of rabies. In Brazil, the incidence of dog bites remains high, with almost half of dog-bite patients not receiving the PEP recommended by the Ministry of Health guidelines between 2008 and 2017. In this study, we aimed to identify the factors that limit the appropriate prescribing of PEP by interviewing health professionals responsible for PEP administration and completion of the ‘Information System on Diseases of Compulsory Declaration’ (SINAN) form reporting human anti-rabies care for patients seeking health care after a dog bite. We conducted 147 questionnaires (45 questions each) in three Brazilian states (i.e., Rio Grande do Sul, Santa Catarina, Rio Grande do Norte) including questions related to the criteria used by professionals to classify a dog as “suspect” or “rabid”, knowledge on PEP prescription guidelines, SINAN and communication with veterinarians. Our analyses showed that most health professionals delivering PEP in these three states struggle to identify a rabies “suspect” dog according to the Ministry of Health guidelines, and to indicate the adequate PEP regimen, with only 11% of professionals prescribing the appropriate PEP under various dog-bite patient scenarios. PEP knowledge score was higher among professionals trained on PEP guidelines and working in facilities with the highest incidence of dog bites. In contrast, PEP knowledge scores did not vary significantly between states, and were not correlated to the professional's level of experience, the number of colleagues available at the health unit or the professional's confidence on prescribing appropriate PEP. Our results suggest that knowledge gaps in PEP administration among health professionals of Brazil can be reduced by implementing training programs to differentiate among rabies risk scenarios, prescribe the corresponding appropriate PEP and improve communication between health and veterinary authorities.

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

Brain samples were collected from 33 animals of different species, including buffalo, cattle, dog, donkey, fox and wolf, that had been suspected to be infected by rabies virus (RABV) in different geographical regions of Aswan and Luxor governorates in Egypt. The samples were submitted for histopathological examination and the presence of the nucleic acid and antigens of RABV was tested by RT-PCR and indirect fluorescent antibody technique (IFAT), respectively. Sixteen samples were found positive by all the three examinations. Three samples were selected for further study from animals in which the highest virus loads were detected. The partial sequence of the RABV N gene was determined and analysed from the samples of a buffalo, a cow and a donkey. The viruses in the samples were found to share 95-98% and 95-97% nucleotide and amino acid sequence identities, respectively. In comparison to reference sequences, a few amino acid substitutions occurred in the N protein antigenic sites I and IV in the immunodominant epitopes of the viruses detected in the cow and the donkey but not in the one from the buffalo. The phylogenetic analysis revealed that the RABVs sequenced from the samples belonged to genotype 1, Africa-4 clade, and formed two distinct sub-clades within the Egyptian clade. These findings indicate the circulation of RABV among livestock animals in the southern part of Egypt and raise public health concerns. The amino acid changes detected in this work may contribute to the antigenic diversification of RABVs.