Deforestation and Bovine Rabies Outbreaks in Costa Rica, 1985-2020

In Latin America, rabies virus has persisted in a cycle between Desmodus rotundus vampire bats and cattle, potentially enhanced by deforestation. We modeled bovine rabies virus outbreaks in Costa Rica relative to land-use indicators and found spatial-temporal relationships among rabies virus outbreaks with deforestation as a predictor.

Naturally Acquired Rabies in White-Eared Opossum, Brazil

Opossums are considered resistant to rabies. Nonhematophagous bats are reservoirs of rabies in urban areas of South America. We analyzed bats and opossums tested for rabies during 2021 in a highly urbanized city in Brazil to understand spillover in an urban setting. Wildlife surveillance is necessary to prevent rabies in humans and domestic animals.

No Evidence of Rabies Exposure in Wild Marmosets (Callithrix jacchus) of Northeast Brazil

Rabies transmitted by wildlife is the main source of human rabies mortality in Latin America and considered an emerging disease. The common marmoset Callithrix jacchus of Brazil is the only known primate reservoir of rabies worldwide. We tested whether alive free-ranging C. jacchus were exposed to rabies in four northeast states that have previously reported rabies-positive dead C. jacchus (Pernambuco and Bahia) or not (Paraíba and Rio Grande do Norte). Our results show no evidence of rabies antibodies or infection in the sampled C. jacchus, suggesting that apparently healthy marmosets are not widely exposed to rabies over their natural range.

A rabies-related lyssavirus from a Nycticeinops schlieffeni bat with neurological signs, South Africa

We report the coding-complete sequence of a lyssavirus, provisionally designated Phala bat lyssavirus (PBLV), characterized using a metagenomics approach. PBLV was identified in a Nycticeinops schlieffeni bat that exhibited neurological signs and died within 24 hours of admission to a wildlife rehabilitation center in Phalaborwa, South Africa.

Human rabies encephalomyelitis in the background of rabies outbreak in animals in Gelephu, Bhutan, 2023: a case report

BACKGROUND

Rabies continues to pose significant public health challenges in many developing countries including Bhutan. A probable case of rabies was admitted to our hospital and its reporting led to the uncovering of an outbreak in domestic and wild animals. We discuss the challenges in the diagnosis and management of rabies in a resource-limited setting.

CASE PRESENTATION

A 35-year-old male presented with intermittent fever, bilateral lower limb weakness that was rapidly progressive, urinary incontinence with episodes of palpitations and sweating. He had sustained a Category III bite on the right lower thigh with four bite marks, inflicted by a stray dog. He had received post-exposure prophylaxis with intra-dermal anti-rabies vaccine. On initial examination, the patient was in distress but cooperative for the interview. He had pulse rate ranging from 60 to 100/min with episodes of diaphoresis and palpitations, but with normal capillary blood glucose. In the lower limb, the muscle power was zero with absent tendon reflexes in the lower limb and impaired abdominal reflex below T10 level. He had hyperaesthesia below T8, hydrophobia, aerophobia and photophobia. He had multiple spontaneous fasciculations in both the thighs and right deltoid and these later involved the intercostal muscles, neck and face muscles. He had altered sensorium and desaturation for which he required mechanical ventilation. Polymerase chain reaction for rabies virus was negative in cerebrospinal fluid and saliva. Rabies virus neutralizing antibody was negative in cerebrospinal fluid but had high titres in the serum. He received Human Rabies Immunoglobulin after admission. He was managed in the intensive care unit and died 23 days later. After this case was notified, a rapid response team was deployed in the field, and uncovered rabies outbreak in animals in the locality.

CONCLUSIONS

This case called for a serious evaluation of the country's efforts in achieving zero rabies deaths by 2030. The management of this case identified several critical areas of context-specific interventions in Bhutan. There is also an urgent need to improve diagnostic capabilities at the national reference laboratory and enhance the technical competencies of healthcare workers in the management of dog bite cases.

Phylogenetic analysis of rabies surveillance samples from north and northeast Brazil

Viruses of the Lyssavirus genus are classified into several genotypes (GT1 to GT7), of which only GT1 (classic rabies virus-RABV) has a cosmopolitan distribution and circulates in Brazil. GT1 is subdivided into several antigenic variants (AgV) maintained in independent cycles with a narrow host range and distinct geographic distributions, namely, AgV1 and AgV2 found in dogs, AgV3 in the vampire bats Desmodus rotundus, and AgV4 and AgV6 in bats non-hematophagous Tadarida brasiliensis and Lasiurus cinereus, a common variant of marmoset (Callithrix jacchus), and crab-eating fox (Cerdocyon thous). In this study, we performed phylogenetic analysis to identify at the antigenic variant level; six RABV genomes derived from the Rabies Surveillance in the north and northeast regions of Brazil. The analysis resulted in the formation of 11 monophyletic clusters, each corresponding to a particular variant, with high bootstrap support values. The samples were positioned inside the AgV3, AgV6, and Callithrix variant clades. This is the first report of the AgV6 variant found in northern Brazil, which provides valuable information for rabies surveillance in the country. The possibility of viral spillover has been much debated, as it deals with the risk of shifting transmission from a primary to a secondary host. However, more genomic surveillance studies should be performed, with a greater number and diversity of samples to better understand the transmission dynamics of each variant to detect changes in its geographic distribution and spillover events.

Epidemiology and Control of Rabies in Cattle and Equines in Rondônia State, a Brazilian's Legal Amazon Area

Rabies is a fatal neglected tropical zoonosis, and its significance for domestic herbivores in the rural cycle is probably associated with rainforest deforestation, livestock, and agricultural expansion. This epidemiological survey aimed to study the occurrence of rabies in bovines and equines in the state of Rondônia, located in the Brazilian's Legal Amazon, between the years 2002 and 2021, correlating these findings with the prophylactic strategies adopted by the local sanitary agency for rabies control. During this period, 201 cases were observed in bovines and 23 in equines. A downward trend in rabies incidence was observed for both domestic herbivores. Rabies did not show a higher occurrence in any specific time of the year, and epidemic periods varied during some years for bovines and equines. Using the Generalized estimating equations (GEE) method, a multiple model approach was obtained with the explanatory variables significantly associated with the decrease in rabies incidence in cattle and horses during the study period: the ratio of treated bats and ratio of vaccine doses sold. Furthermore, the ratio of printed educative material was positively associated with rabies incidence. Despite a decreasing trend in rabies occurrences in this Amazon rainforest area, likely due to the actions taken by the animal sanitary agency, rabies remains endemic and requires monitoring, as well as prophylactic strategies to control this disease.

Sequencing and Partial Molecular Characterization of BAB-TMP, the Babeș Strain of the Fixed Rabies Virus Adapted for Multiplication in Cell Lines

The rabies virus is a major zoonosis that causes severe nervous disease in humans, leading to paralysis and death. The world's second anti-rabies center was established in 1888 by Victor Babeș, in Bucharest, where an eponymous strain of rabies was isolated and used to develop a method for immunization. The Babeș strain of the rabies virus was used for over 100 years in Romania to produce a rabies vaccine for human use, based on animal nerve tissue, thus having a proven history of prophylactic use. The present study aimed to sequence the whole genome of the Babeș strain and to explore its genetic relationships with other vaccine strains as well as to characterize its relevant molecular traits. After being adapted for multiplication in cell lines and designated BAB-TMP, 99% of the viral genome was sequenced. The overall organization of the genome is similar to that of other rabies vaccine strains. Phylogenetic analysis indicated that the BAB-TMP strain is closely related to the Russian RV-97 vaccine strain, and both seem to have a common ancestor. The nucleoprotein gene of the investigated genome was the most conserved, and the glycoprotein showed several unique amino acid substitutions within the major antigenic sites and linear epitopes.

Rabies in a postpandemic world: resilient reservoirs, redoubtable riposte, recurrent roadblocks, and resolute recidivism

Rabies is an ancient disease. Two centuries since Pasteur, fundamental progress occurred in virology, vaccinology, and diagnostics-and an understanding of pathobiology and epizootiology of rabies in testament to One Health-before common terminological coinage. Prevention, control, selective elimination, and even the unthinkable-occasional treatment-of this zoonosis dawned by the twenty-first century. However, in contrast to smallpox and rinderpest, eradication is a wishful misnomer applied to rabies, particularly post-COVID-19 pandemic. Reasons are minion. Polyhostality encompasses bats and mesocarnivores, but other mammals represent a diverse spectrum of potential hosts. While rabies virus is the classical member of the genus, other species of lyssaviruses also cause the disease. Some reservoirs remain cryptic. Although global, this viral encephalitis is untreatable and often ignored. As with other neglected diseases, laboratory-based surveillance falls short of the notifiable ideal, especially in lower- and middle-income countries. Calculation of actual burden defaults to a flux within broad health economic models. Competing priorities, lack of defined, long-term international donors, and shrinking local champions challenge human prophylaxis and mass dog vaccination toward targets of 2030 for even canine rabies impacts. For prevention, all licensed vaccines are delivered to the individual, whether parenteral or oral-essentially 'one and done'. Exploiting mammalian social behaviors, future 'spreadable vaccines' might increase the proportion of immunized hosts per unit effort. However, the release of replication-competent, genetically modified organisms selectively engineered to spread intentionally throughout a population raises significant biological, ethical, and regulatory issues in need of broader, transdisciplinary discourse. How this rather curious idea will evolve toward actual unconventional prevention, control, or elimination in the near term remains debatable. In the interim, more precise terminology and realistic expectations serve as the norm for diverse, collective constituents to maintain progress in the field.

Progress towards dog-mediated rabies elimination in PR China: a scoping review

BACKGROUND

Rabies continues to be a serious threat to global public health endangering people's health and public health safety. In the People's Republic of China, multi-sectoral and comprehensive prevention and control strategies have aimed to extensively curb human rabies transmission. Here, we examine the current state of rabies infection in China, explore strategic interventions put in place in response to WHO's ambition of "Zero rabies deaths by 2030" and critically assess the constraints and feasibility of dog-mediated rabies elimination in China.

METHODS

This study analyzed and evaluated the process towards dog-mediated rabies elimination in China from five perspectives: namely, human, dog, policy, challenge, and prospects. Evidence-based data on progress of dog-mediated rabies elimination in China was derived from a number of sources; a literature search was undertaken using PubMed, Web of Science and CNKI databases, distribution data for human rabies cases as derived from the Data-center of the China Public Health Science and policy and document data were obtained from official websites of the relevant China ministries and commissions.

RESULTS

The incidence of human rabies cases in China have shown a downward trend year-on-year since 2007. Implementation of a government-led, multi-sectoral "One Health" approach to combating rabies has driven down the total number of rabies deaths nationwide to around 200 in 2020. The number of provincial-level administrative divisions (PLADs) reporting human cases of rabies has also decreased to 21 in 2020, 13 of which reported less than 10 cases. Furthermore, the number of outpatient visits seeking rabies post-exposure prophylaxis has risen dramatically over the past two decades, with demand being 15 times higher than it was initially. There remain however, significant gaps in rabies elimination outcomes across the different regions of China. To date the target of achieving a canine rabies vaccination rate of > 75% has not been met. The challenges of rabies immunization of dogs and dog management in underdeveloped cities and rural areas need to be addressed together with more effective animal surveillance and rabies risk from and too wildlife and livestock.

CONCLUSIONS

The Chinese government-led, multi-sectoral "One Health" approach to combating rabies and has made significant progress over the past decade. Development and adoption of more cost-effective One Health strategies can achieve more nationally beneficial rabies elimination outcomes. The ambitious target of "Zero rabies deaths by 2030" can be met through establishment of long-lasting herd immunity in dogs by means of dog mass vaccination campaigns, dog population management, epidemiological surveillance and the application of large-scale oral rabies vaccine to eliminate rabies in wild animals coupled with deployment of cost-effective human post-exposure prophylaxis, and community education.

Rabies virus uniquely reprograms the transcriptome of human monocyte-derived macrophages

Macrophages are amongst the first immune cells that encounter rabies virus (RABV) at virus entry sites. Activation of macrophages is essential for the onset of a potent immune response, but insights into the effects of RABV on macrophage activation are scarce. In this study we performed high-throughput sequencing on RNA extracted from macrophages that were exposed to RABV for 48 hours, and compared their transcriptional profiles to that of non-polarized macrophages (M0), and macrophages polarized towards the canonical M1, M2a and M2c phenotypes. Our analysis revealed that RABV-stimulated macrophages show high expression of several M1, M2a and M2c signature genes. Apart from their partial resemblance to these phenotypes, unbiased clustering analysis revealed that RABV induces a unique and distinct polarization program. Closer examination revealed that RABV induced multiple pathways related to the interferon- and antiviral response, which were not induced under other classical polarization strategies. Surprisingly, our data show that RABV induces an activated rather than a fully suppressed macrophage phenotype, triggering virus-induced activation and polarization. This includes multiple genes with known antiviral (e.g. APOBEC3A, IFIT/OAS/TRIM genes), which may play a role in anti-RABV immunity.

Pseudotyped Viruses for Lyssavirus

Lyssaviruses, which belong to the family Rhabdoviridae, are enveloped and bullet-shaped ssRNA viruses with genetic diversity. All members of Lyssavirus genus are known to infect warm-blooded animals and cause the fatal disease rabies. The rabies virus (RABV) in lyssavirus is the major pathogen to cause fatal rabies. The pseudotyped RABV is constructed to study the biological functions of G protein and evaluation of anti-RABV products including vaccine-induced antisera, rabies immunoglobulins (RIG), neutralizing mAbs, and other antiviral inhibitors. In this chapter, we focus on RABV as a representative and describe the construction of RABV G protein bearing pseudotyped virus and its applications. Other non-RABV lyssaviruses are also included.

Mapping the Spatiotemporal Distribution of Bovine Rabies in Colombia, 2005-2019

Introduction: Rabies is caused by a virus belonging to the genus Lyssavirus and family Rhabdoviridae, which can infect any mammal including humans. Hematophagous, fructivorous, and insectivorous bats have become the main reservoir of sylvatic rabies in Latin America. In the sylvatic cycle, hematophagous bats are usually the main reservoir. In contrast, dogs and cats fulfil this critical role in the urban cycle. However, in rural areas, the most affected animals are bovines. They show clinical signs such as behavioural changes, hypersalivation, muscle tremors, spasms caused by extensive damage to the central nervous system, and death from respiratory paralysis. Objective: To describe the spatiotemporal distribution of bovine rabies in Colombia from 2005 to 2019. Methods: Retrospective cross-sectional descriptive observational study, based on the monthly reports of the Colombian Agricultural Institute (ICA) on the surveillance of bovine rabies in Colombia from 2005 to 2019, retrieved from its official website. The data were converted to databases in Microsoft Access 365®. Multiple epidemiological maps were developed with the GIS software Kosmo RC1® 3.0 coupled to the shape files (.shp) of all the country’s municipalities. Results: During the study period, 4888 cases of rabies were confirmed in cattle, ranging from a peak of 542 cases (11.1%) in 2014 to 43 in 2019 (0.88%). From 2014 to 2019, there has been a significant reduction in the annual national number of cases (r2 = 0.9509, p < 0.05). In 2019, 32.6% of the cases occurred in January, and 48.8% occurred in the department of Sucre. In 2009, the maximum number of spatial clusters (13) occurred in the Orinoquia region, where other clusters were also identified in 2005, 2006 and 2008. In 2018, 98 outbreaks were identified that led to the death of cattle and other animals, 28.6% of them in the department of Sucre. In the first half of 2019, of 38 outbreaks, 55.2% were identified in Sucre. Conclusions: It is necessary to review the current national program for the prevention and control of rabies in cattle, incorporating concepts from the ecology of bats, as well as the prediction of contagion waves of geographical and temporal spread in the context of the OneHealth Approach. Sylvatic rabies remains a threat in Colombia that requires further study.

Genotyping of rabies positive samples isolated from animals in Mato Grosso and Rondônia - Brazil

Lyssavirus is a genus that causes infectious disease transmit by bats transmit, which results in economic losses in livestock and public health problems. From 2005 to 2019, more than 49 thousand cases of the disease were registered in animals in Brazil, with 3418 registered in Mato Grosso (MT). The lack of information on the genetic diversity and distribution of the rabies virus in MT was the motivation for carrying out this study. A total of 117 samples of brain tissue from cattle, horses, donkeys, mules and sheep from 29 municipalities in the state of MT and one municipality in Rondônia were used. Direct immunofluorescence and/or biological tests performed from 2014 to 2021 indicated that all samples were positive for the disease. RNA was extracted and molecular analysis was performed using RT-PCR for the N gene. Of the 117 samples analyzed, 50 were amplified by RT-PCR, purified and sequenced. The samples showed 93.13%-100% identity with the rabies virus. The sequences were submitted to phylogenetic analysis that resulted in a tree of four clades; these were genetically grouped into distinct regions within the Desmodus rotundus lineage. The results of the geolocation of clades will be useful to guide monitoring, control and health surveillance programs in MT.

Longitudinal Tracing of Lyssavirus Infection in Mice via In Vivo Bioluminescence Imaging

Bioluminescence imaging (BLI) is a technique that can be employed to quantify biological processes in living cells. When used in small animal models such as mice, BLI can provide both longitudinal and positional information regarding the biological process under investigation. Although perhaps best known for its utility in non-invasively quantifying tumor burden over time in experimental animals, BLI has also been applied in many pathogenesis models to track pathogen burden and responses to therapeutic interventions. In this chapter, we present a BLI-based method for tracing anatomical progression of lyssavirus infection in a mouse model. We also include validation methods to ensure that semiquantitative BLI data correlate well with viral load. Due to the longitudinal nature of this approach, lyssavirus pathogenesis and therapeutic intervention studies can be performed with far fewer animals than more traditional approaches, which typically require euthanasia of large animal groups at every data collection time point.

Understanding the incidence and timing of rabies cases in domestic animals and wildlife in south-east Tanzania in the presence of widespread domestic dog vaccination campaigns

The "Zero by 30" strategic plan aims to eliminate human deaths from dog-mediated rabies by 2030 and domestic dog vaccination is a vital component of this strategic plan. In areas where domestic dog vaccination has been implemented, it is important to assess the impact of this intervention. Additionally, understanding temporal and seasonal trends in the incidence of animal rabies cases may assist in optimizing such interventions. Data on the incidence of probable rabies cases in domestic and wild animals were collected between January 2011 and December 2018 in thirteen districts of south-east Tanzania where jackals comprise over 40% of reported rabies cases. Vaccination coverage was estimated over this period, as five domestic dog vaccination campaigns took place in all thirteen districts between 2011 and 2016. Negative binomial generalized linear models were used to explore the impact of domestic dog vaccination on the annual incidence of animal rabies cases, whilst generalized additive models were used to investigate the presence of temporal and/or seasonal trends. Increases in domestic dog vaccination coverage were significantly associated with a decreased incidence of rabies cases in both domestic dogs and jackals. A 35% increase in vaccination coverage was associated with a reduction in the incidence of probable dog rabies cases of between 78.0 and 85.5% (95% confidence intervals ranged from 61.2 to 92.2%) and a reduction in the incidence of probable jackal rabies cases of between 75.3 and 91.2% (95% confidence intervals ranged from 53.0 to 96.1%). A statistically significant common seasonality was identified in the monthly incidence of probable rabies cases in both domestic dogs and jackals with the highest incidence from February to August and lowest incidence from September to January. These results align with evidence supporting the use of domestic dog vaccination as part of control strategies aimed at reducing animal rabies cases in both domestic dogs and jackals in this region. The presence of a common seasonal trend requires further investigation but may have implications for the timing of future vaccination campaigns.

Rabies Infection: An Overview of Lyssavirus-Host Protein Interactions

Viruses are obligatory intracellular parasites that use cell proteins to take the control of the cell functions in order to accomplish their life cycle. Studying the viral-host interactions would increase our knowledge of the viral biology and mechanisms of pathogenesis. Studies on pathogenesis mechanisms of lyssaviruses, which are the causative agents of rabies, have revealed some important host protein partners for viral proteins, especially for most studied species, i.e. RABV. In this review article, the key physical lyssavirus-host protein interactions, their contributions to rabies infection, and their exploitation are discussed to improve the knowledge about rabies pathogenesis.

RELATEDNESS AND GENETIC STRUCTURE OF BIG BROWN BAT (EPTESICUS FUSCUS) MATERNITY COLONIES IN AN URBAN-WILDLAND INTERFACE WITH PERIODIC RABIES VIRUS OUTBREAKS

Big brown bats (Eptesicus fuscus) are the bat species in North America most frequently found to be rabid because of their high rate of human contact and thus submissions for rabies testing, of which, 4-5% are positive. The social behavior of big brown bats during the summer months may drive space use and potential viral exposure to conspecifics and mesocarnivores. We collected 88 unique genetic samples via buccal swabs from big brown bats captured at four maternity roosts surrounding a golf course during the summer of 2013. We used seven microsatellite loci to estimate genetic relatedness among individuals and genetic structure within and among colonies to infer whether females selected roosts based on kinship and used genetics and radio telemetry to determine the frequency of roost switching. We found roost switching through genetics and telemetry, and no evidence of elevated genetic relatedness within colonies or genetic structure among colonies. Social cohesion based on relatedness may not act to constrain the pathogen to a particular roost area, and thus, geographic mobility may increase viral exposure of bats in neighboring areas.

Bat and Lyssavirus Exposure among Humans in Area that Celebrates Bat Festival, Nigeria, 2010 and 2013

Using questionnaires and serologic testing, we evaluated bat and lyssavirus exposure among persons in an area of Nigeria that celebrates a bat festival. Bats from festival caves underwent serologic testing for phylogroup II lyssaviruses (Lagos bat virus, Shimoni bat virus, Mokola virus). The enrolled households consisted of 2,112 persons, among whom 213 (10%) were reported to have ever had bat contact (having touched a bat, having been bitten by a bat, or having been scratched by a bat) and 52 (2%) to have ever been bitten by a bat. Of 203 participants with bat contact, 3 (1%) had received rabies vaccination. No participant had neutralizing antibodies to phylogroup II lyssaviruses, but >50% of bats had neutralizing antibodies to these lyssaviruses. Even though we found no evidence of phylogroup II lyssavirus exposure among humans, persons interacting with bats in the area could benefit from practicing bat-related health precautions.

First case of lethal encephalitis in Western Europe due to European bat lyssavirus type 1

BACKGROUND

Inaccurate diagnosis of encephalitis is a major issue as immunosuppressive treatments can be deleterious in case of viral infection. The European bat lyssavirus type 1, a virus related to rabies virus, is endemic in European bats. No human case has yet been reported in Western Europe. A 59 year-old patient without specific past medical history died from encephalitis. A colony of bats lived in an outbuilding of his house. No diagnosis was made using standard procedures.

METHODS

We used a Next Generation Sequencing (NGS) based transcriptomic protocol to search for pathogens in autopsy samples (meninges and brain frontal lobe). Results were confirmed by PCR and by antibody testing in serum. Immunochemistry was used to characterize inflammatory cells and viral antigens in brain lesions. Cells and mice were inoculated with brain extracts for virus isolation.

RESULTS

The patient's brain lesions were severe and diffuse in white and gray matter. Perivascular inflammatory infiltrates were abundant and rich in plasma cells. NGS identified European bat lyssavirus type 1a in brain, which was confirmed by PCR. A high titer of neutralizing antibodies was found in serum. No viral antigen was detected and the virus could not be isolated by cell culture or by mouse inoculation.

CONCLUSIONS

The patient died from European bat lyssavirus type 1a infection. NGS was key to identifying this unexpected viral etiology in an epidemiological context that did not suggest rabies. People exposed to bats should be strongly advised to be vaccinated with rabies vaccines, which are effective against EBLV-1.

Rabies: Presentation, case management and therapy

Several Lyssaviruses are known to be a causative agent of rabies and rabies like syndrome. There are no proven effective treatment strategies for symptomatic rabies patient. Risk of infection from dog variant of rabies virus is highest with deep bite reaching muscular layer and much higher when compared to scratch. Failure of viral eradication at the central nervous system (CNS) is partly due to inadequate immune response. Favipiravir selectively inhibit viral RNA polymerase and has been shown to reduce rabies replication in neuronal cell and mouse model system. Endocannabinoid system has emerged as an important regulator for CNS integrity, cell fate and may serve as an important novel neuroprotective agent. Cannabinoid may be able to regulate the impaired homeostasis induced by rabies virus by promoting infected cell survival and promote complete autophagy in infected cell.

Tackling the Threat of Rabies Reintroduction in Europe

Rabies is one of the oldest, most important zoonoses worldwide due to its extreme and inevitably lethal nature, causing one death every 9 min worldwide. Recent reports have demonstrated that the Lyssavirus continues more alive than ever, despite the control carried out against the virus throughout Europe. In this context, this work reviews the main immunological implications, transmission risk factors and current prevention measures for virus control in Europe, and especially in Spain.

Update on lyssaviruses and rabies: will past progress play as prologue in the near term towards future elimination?

Rabies is an ancient, much-feared, and neglected infectious disease. Caused by pathogens in the family Rhabdoviridae, genus Lyssavirus, and distributed globally, this viral zoonosis results in tens of thousands of human fatalities and millions of exposures annually. All mammals are believed susceptible, but only certain taxa act as reservoirs. Dependence upon direct routing to, replication within, and passage from the central nervous system serves as a basic viral strategy for perpetuation. By a combination of stealth and subversion, lyssaviruses are quintessential neurotropic agents and cause an acute, progressive encephalitis. No treatment exists, so prevention is the key. Although not a disease considered for eradication, something of a modern rebirth has been occurring within the field as of late with regard to detection, prevention, and management as well as applied research. For example, within the past decade, new lyssaviruses have been characterized; sensitive and specific diagnostics have been optimized; pure, potent, safe, and efficacious human biologics have improved human prophylaxis; regional efforts have controlled canine rabies by mass immunization; wildlife rabies has been controlled by oral rabies vaccination over large geographic areas in Europe and North America; and debate has resumed over the controversial topic of therapy. Based upon such progress to date, there are certain expectations for the next 10 years. These include pathogen discovery, to uncover additional lyssaviruses in the Old World; laboratory-based surveillance enhancement by simplified, rapid testing; anti-viral drug appearance, based upon an improved appreciation of viral pathobiology and host response; and improvements to canine rabies elimination regionally throughout Africa, Asia, and the Americas by application of the best technical, organizational, economic, and socio-political practices. Significantly, anticipated Gavi support will enable improved access of human rabies vaccines in lesser developed countries at a national level, with integrated bite management, dose-sparing regimens, and a 1 week vaccination schedule.

Identification of a reptile lyssavirus in Anolis allogus provided novel insights into lyssavirus evolution

Lyssaviruses (genus Lyssavirus) are negative-strand RNA viruses belonging to the family Rhabdoviridae. Although a lyssa-like virus (frog lyssa-like virus 1 [FLLV-1]), which is distantly related to lyssaviruses, was recently identified in frogs, a large phylogenetic gap exists between those viruses, and thus the evolution of lyssaviruses is unclear. In this study, we detected a lyssa-like virus from publicly available RNA-seq data obtained using the brain and skin of Anolis allogus (Spanish flag anole), which was designated anole lyssa-like virus 1 (ALLV-1), and determined its complete coding sequence. Via mapping analysis, we demonstrated that ALLV-1 was actively replicating in the original brain and skin samples. Phylogenetic analyses revealed that ALLV-1 is more closely related to lyssaviruses than FLLV-1. Overall, the topology of the tree is compatible with that of hosts, suggesting the long-term co-divergence of lyssa-like and lyssaviruses and vertebrates. The ψ region, which is a long 3' untranslated region of unknown origin present in the G mRNA of lyssaviruses (approximately 400-700 nucleotides), is also present in the genome of ALLV-1, but it is much shorter (approximately 180 nucleotides) than those of lyssaviruses. Interestingly, FLLV-1 lacks the ψ region, suggesting that the ψ region was acquired after the divergence of the FLLV-1 and ALLV-1/lyssavirus lineages. To the best of our knowledge, this is the first report to identify a lyssa-like virus in reptiles, and thus, our findings provide novel insights into the evolution of lyssaviruses.

Molecular characterization of rabies viruses from two western provinces of the Democratic Republic of the Congo (2008-2017)

Although rabies is enzootic in the Democratic Republic of the Congo, there is very little molecular epidemiological information about the viruses circulating in animals. In this study, a fragment of the rabies virus (RABV) nucleoprotein gene was amplified and sequenced from 21 animal brain samples collected in two western provinces of the country between 2008 and 2017. The samples tested were from cat (n = 1), dog (n = 17), goat (n = 2), and sheep (n = 1). Phylogenetic analysis revealed that the sequences generated were highly similar to each other and belonged to lineage Africa 1b clustering with a single sample identified in a canine in the Republic of Congo in 2014. This is the first molecular epidemiological study of RABV in the DRC and the data generated will assist authorities in the development of effective control strategies for rabies in the country.

Structural comparison of the C-terminal domain of functionally divergent lyssavirus P proteins

Lyssavirus P protein is a multifunctional protein that interacts with numerous host-cell proteins. The C-terminal domain (CTD) of P is important for inhibition of JAK-STAT signaling enabling the virus to evade host immunity. Several regions on the surface of rabies virus P are reported to interact with host factors. Among them, an extended, discrete hydrophobic patch of P CTD is notable. Although structures of P CTD of two strains of rabies virus, and of mokola virus have been solved, the structure of P CTD for Duvenhage virus, which is functionally divergent from these species for immune evasion function, is not known. Here, we analyze the structures of P CTD of Duvenhage and of a distinct rabies virus strain to gain further insight on the nature and potential function of the hydrophobic surface. Molecular contacts in crystals suggest that the hydrophobic patch is important to intermolecular interactions with other proteins, which differ between the lyssavirus species.

Establishment of a longitudinal pre-clinical model of lyssavirus infection

Traditional mouse models of lyssavirus pathogenesis rely on euthanizing large groups of animals at various time points post-infection, processing infected tissues, and performing histological and molecular analyses to determine anatomical sites of infection. While powerful by some measures, this approach is limited by the inability to monitor disease progression in the same mice over time. In this study, we established a novel non-invasive mouse model of lyssavirus pathogenesis, which consists of longitudinal imaging of a luciferase-expressing Australian bat lyssavirus (ABLV) reporter virus. In vivo bioluminescence imaging (BLI) in mice revealed viral spread from a peripheral site of inoculation into the central nervous system (CNS), with kinetically and spatially distinct foci of replication in the footpad, spinal cord, and hindbrain. Detection of virus within the CNS was associated with onset of clinical disease. Quantification of virus-derived luminescent signal in the brain was found to be a reliable measure of viral replication, when compared to traditional molecular methods. Furthermore, we demonstrate that in vivo imaging of ABLV infection is not restricted to the use of albino strains of mice, but rather strong BLI signal output can be achieved by shaving the hair from the heads and spines of pigmented strains, such as C57BL/6. Overall, our data show that in vivo BLI can be used to rapidly and non-invasively identify sites of lyssavirus replication and to semi-quantitatively determine viral load without the need to sacrifice mice at multiple time points.

Rabies in Uganda: rabies knowledge, attitude and practice and molecular characterization of circulating virus strains

Background

Rabies is a deadly preventable viral disease that affects all warm-blooded animals and widespread in many regions including Africa. The disease remains of major public health importance in Uganda.

The purpose of this study was to establish Knowledge, Attitude, Practice (KAP) of Rabies in Moyo and Ntoroko districts and to characterize Rabies virus (RABV) strains from seven districts of Uganda with consistent prevalence of rabies.

Methods

KAP survey data were collected based on animal biting history by interviewing the head of the veterinary departments, the medical centers and selected households from the study sites. Data were obtained from 84 households in Ntoroko and Moyo districts. Thirty-five (35) brain samples were collected from bovine, dogs, goats, foxes, jackals ad sheep between 2011 and 2013. Samples were tested using fluorescent antibody test (FAT), One step RT-PCR (following RNA extraction) and partial RABV N gene was sequenced by Sanger method before phylogenetic and phylogeographic analyses of sequences.

Results

Scarcity of post-exposure prophylaxis services in the health centers was noted. Poor attitude of wound washing and deficiency of knowledge on how to handle wounds related to dog bites and the significance among household participants lacked. There is a high risk of rabies infection due to a limited dog’s vaccination. Dog biting episodes in humans were of 75.00 and 62.50% in Moyo and Ntoroko districts respectively. Twenty-seven (27) samples tested positive for rabies by FAT and PCR. Ugandan sequences were closely related (97% nucleotide id) to the rabies virus sequences from Tanzania, Rwanda, Burundi, Nigeria, Central African Republic and Sudan with both the “Africa 1A” and “Africa 1B” RABV clades represented. A putative new clade 1D was also detected.

Conclusions

Rabies remains a public health hazard in Uganda. There is urgent need to establish advocacy programs in both schools and communities to curtail the spread of rabies. Increasing the knowledge regarding wound washing, post-exposure prophylaxis and dogs vaccination would enhance prevention of rabies. A strong collaboration between medical and veterinary sectors under a one health platform is required to ensure sufficient preventative services to the communities.

Towards rabies elimination in the Asia-Pacific region: From theory to practice

Rabies is a major neglected zoonotic disease and causes a substantial burden in the Asian region. Currently, Pacific Oceania is free of rabies but enzootic areas throughout southeast Asia represent a major risk of disease introduction to this region. On September 25-26, 2019, researchers, government officials and related stakeholders met at an IABS conference in Bangkok, Thailand to engage on the topic of human rabies mediated by dogs. The objective of the meeting was focused upon snowballing efforts towards achieving substantial progress in rabies prevention, control and elimination within Asia by 2030, and thereby to safeguard the Pacific region. Individual sessions focused upon domestic animal, wildlife and human vaccination; the production and evaluation of quality, safety and efficacy of existing rabies biologics; and the future development of new products. Participants reviewed the progress to date in eliminating canine rabies by mass vaccination, described supportive methods to parenteral administration by oral vaccine application, considered updated global and local approaches at human prophylaxis and discussed the considerable challenges ahead. Such opportunities provide continuous engagement on disease management among professionals at a trans-disciplinary level and promote new applied research collaborations in a modern One Health context.

[Expert consensus on rabies exposure prophylaxis]

Rabies is a zoonotic infectious disease caused by lyssavirus and characterized by central nervous system symptoms. The fatality rate of rabies is almost 100%. About 59 000 cases die of rabies worldwide every year, mainly in Asia and Africa. China is an epidemic country of rabies. Grade II and III exposures are the main types of rabies exposures in China. Standardized post-exposure prophylaxis (PEP) can prevent rabies almost 100%. Human Rabies Vaccine Technical Working Group, National Immunization Advisory Committee and invited experts reached an expert consensus on PEP by referring to the World Health Organization's position paper on rabies vaccine in 2018 and related research progress in recent.

[Expert consensus on rabies exposure prophylaxis]

Rabies is a zoonotic infectious disease caused by lyssavirus and characterized by central nervous system symptoms. The fatality rate of rabies is almost 100%. About 59 000 cases die of rabies worldwide every year, mainly in Asia and Africa. China is an epidemic country of rabies. Grade II and III exposures are the main types of rabies exposures in China. Standardized post-exposure prophylaxis (PEP) can prevent rabies almost 100%. Human Rabies Vaccine Technical Working Group, National Immunization Advisory Committee and invited experts reached an expert consensus on PEP by referring to the World Health Organization's position paper on rabies vaccine in 2018 and related research progress in recent.

1H, 15N and 13C resonance assignments of the C-terminal domain of the P protein of the Nishigahara strain of rabies virus

The C-terminal domain of the P protein of rabies virus is a multifunctional domain that interacts with both viral and host cell proteins. Here we report the ¹H, ¹³C and ¹⁵N chemical shift assignments of this domain from P protein of the Nishigahara strain of rabies virus, a pathogenic laboratory strain well established for studies of virulence functions of rabies virus proteins, including P protein. The data and secondary structure analysis are in good agreement with the reported predominantly helical structure of the same domain from the CVS strain of rabies solved by crystallography. These assignments will enable future solution studies of the interactions of the P protein with viral and host proteins, and the effects of post-translational modifications.

Global rabies management: perspectives on regional strategies for prevention and control

Rabies is a major neglected zoonotic disease, despite the availability of highly sensitive diagnostic tests and efficacious human and animal vaccines. Perpetuation of rabies among multiple species of bats and wild carnivores, together with the presence of diverse lyssaviruses, remains a challenge for the prevention and control of this disease. However, most of the global burden may be reduced by mass vaccination of dogs, the major reservoir. Elimination of human rabies mediated by dogs may be feasible, based upon the elicitation of herd immunity, the application of sound health economic principles for appropriate disease management and technology transfer to those developing countries where rabies is hyper-endemic. Global canine rabies elimination has clear benefits for public health, veterinary medicine and conservation biology, so these sectors must collaborate using a transdisciplinary 'One Health' approach that allows the creation of long-term regional strategies for enhanced surveillance and practical intervention.

Rabies pathogenesis and immunology

Once clinical disease is manifest, the rabies virus is one of the few pathogens known to science with a near 100% fatality rate and, as such, this zoonotic pathogen has shaped both humanity and the history of science. However, today rabies is still considered to be a neglected tropical disease, despite the fact that it causes more than 59,000 human deaths each year. Although effective vaccines are available to combat the disease, the underlying mechanisms of its pathogenicity and immunology remain poorly defined. In this paper, the existing knowledge of the pathogenesis and immunological response to the rabies virus in infected hosts is described.

New developments in rabies vaccination

Current rabies vaccines are safe and, when administered properly, they are highly effective. In addition, they elicit long-lasting immunity, with virus-neutralising antibody titres persisting for years after vaccination. However, current regimens require multiple doses to achieve high neutralising titres and they are costly, which means that it is difficult for developing countries, where rabies deaths are highest, to implement widespread vaccination. New innovations are the only way to reduce rabies disease to acceptable rates. Numerous preclinical and clinical studies are under way, testing novel vaccines, adjuvants and injection methods. Research into the use of live vaccines and alternative vaccine vectors is ongoing, while attempts to develop DNA vaccines have so far failed to match the immunogenicity and neutralising capability of traditional vaccines. The development of molecular adjuvants that induce faster, stronger immune responses with less antigen has yielded exciting preclinical results and appears to edge us closer to a better rabies vaccine. However, steep challenges remain: molecular adjuvants require administration with live vaccines, and differences in species specificity of immune molecules complicate development. Over all, the array of research undertaken over the past decade is impressive and encouraging, but most new vaccines have yet to be tested in clinical trials, and the viability of such experimental vaccines in the global market remains to be seen. Only a vaccine that outperforms currently available vaccines in every area will have a chance at widespread adoption. Nevertheless, the authors are confident that some vaccine candidates will meet these criteria.

Bat lyssaviruses

Bats (order Chiroptera) are the principal reservoir host for 14 of the 16 officially recognised lyssavirus species. Rabies virus is the only lyssavirus that is well established in terrestrial carnivores (worldwide), as well as bats (but only in the Americas). The other bat lyssaviruses occur only outside the Americas. They have a distinct geographical distribution and association with specific bat species, with limited cross-species transmission to other animals and humans, resulting in deadend infections. The nucleoprotein gene is well conserved between all lyssavirus species. Therefore, gold-standard diagnostic techniques detect all lyssaviruses but do not discriminate between viral species. Lyssaviruses are divided into at least three phylogroups, based on their immunogenic and phylogenic properties. Owing to the diversity of glycoproteins among phylogroups, rabies vaccines and immunoglobulins only provide protection against phylogroup I, excluding several of the bat lyssaviruses. Africa hosts a high diversity of lyssaviruses, leading to the hypothesis that this region was the site of emergence; however, this has been challenged by more recent phylogenetic analysis, suggesting a Palearctic origin. Serological evidence indicates a more widespread and even higher diversity of lyssaviruses in bats, suggesting that the incidence of known lyssaviruses is underestimated and several new lyssavirus species are yet to be discovered. Most bats are, however, not able to transmit the virus and therefore pose a low risk to human and animal populations.

Assessment of naturally acquired neutralizing antibodies against rabies Lyssavirus in a subset of Nunavik's Inuit population considered most at risk of being exposed to rabid animals

Contact with infected saliva through the bite of a rabid animal is the main route of infection with the rabies Lyssavirus in humans. Although a few individuals have survived the infection, rabies remains the most lethal zoonotic infection worldwide. Over the last century, the dogma that rabies is invariably fatal has been challenged by the survival and recovery of infected animals. In humans, 11 studies have found rabies virus-specific antibodies in unvaccinated individuals exposed to rabies virus reservoir species, suggesting the possibility of asymptomatic rabies virus infection, contact with non-infectious virus or exposure to the virus without viral replication. Two of these studies were conducted in Arctic hunters. Considering the extensive exposure of Nunavik's Inuit to potentially infected animals through hunting, trapping, skinning and the preparation of Arctic carnivores, we analysed archived serum samples from the 2004 Nunavik Inuit Health Survey for the presence of rabies virus-neutralizing antibodies (rVNA) in this sub-population. A total of 196 participants who were considered at highest risk for exposure to rabies virus were targeted. Serum samples were tested for the presence of rVNA using a variation of the fluorescent antibody virus neutralization test, an assay recommended for the quantification of neutralizing antibody titres following vaccination. Our study identified two seropositive individuals among the 196 participants but a review of their medical record and a phone interview revealed previous vaccination. Our results do not provide evidence for naturally acquired rVNA in Nunavik's Inuit population.

Priorities in applied research to ensure programmatic success in the global elimination of canine rabies

The elimination of human rabies mediated by dogs is attainable in concept, based upon current sensitive and specific diagnostic methods, existing safe and effective human and veterinary vaccines and a sound virological, pathological and epidemiological understanding of the disease. Globally, all developed countries achieved this goal. Regionally, major progress occurred throughout the Americas. However, less advancement is evident in Africa and Asia. Our objective was to concentrate upon those salient improvements to extant tools and methods over the next five years which could assist and simplify the task for both those developing countries that have already begun the process, as well as other localities in the earlier stages of consideration. We considered several categories of applied research which could be accomplished in the short term, based upon the available scientific evidence and recent recommendations from subject matter experts and key opinion leaders, focused upon perceived major limitations to prior program success. Areas of concentration included: laboratory-based surveillance, pathogen detection and characterization; human rabies prophylaxis; veterinary biologics; implementation of canine vaccination; and oral vaccination of free-ranging community dogs. Further real-time application in these core areas with proven techniques and technology would simplify attaining not only the global goal focused subtly upon human mortality, but the actual elimination of canine rabies as well.

Detection of lyssavirus antigen and antibody levels among apparently healthy and suspected rabid dogs in South-Eastern Nigeria

OBJECTIVES

Domestic dogs are the main reservoir of rabies virus (RABV) infection in Nigeria, thus surveillance of rabies in dog populations is crucial in order to understand the patterns of spread of infection and ultimately devise an appropriate rabies control strategy. This study determined the presence of lyssavirus antigen in brain tissues and anti-rabies antibodies in sera of apparently healthy and suspected-rabid dogs slaughtered for human consumption at local markets in South-Eastern Nigeria.

RESULTS

Our findings demonstrated that 8.3% (n = 23) of brain tissues were lyssavirus positive and 2.5% (n = 25) of sera had rabies antibody levels as percentage blocking of 70% and above correlating with a cut-off value ≥ 0.5 IU/mL in the fluorescent antibody neutralization test. There was an inverse correlation between lyssavirus positivity and rabies antibody levels confirming that infected individuals most often do not develop virus neutralizing antibodies to the disease. The low percentage of rabies antibodies in this dog population suggests a susceptible population at high risk to RABV infection. These findings highlight a huge challenge to national rabies programs and subsequent elimination of the disease from Nigeria, considering that majority of dogs are confined to rural communal areas, where parenteral dog vaccination is not routinely undertaken.

Evaluation of six TaqMan RT-rtPCR kits on two thermocyclers for the reliable detection of rabies virus RNA

Rabies is diagnosed postmortem in animals, based on tests prescribed by the World Organization for Animal Health (OIE), such as the fluorescent antibody test, the direct rapid immunohistochemistry test, or pan-lyssavirus PCR assays. Several reverse-transcription real-time PCR (RT-rtPCR) methods have been developed and validated for rapid and accurate detection of lyssaviruses. We evaluated the performance of 6 TaqMan RT-rtPCR kits using different commercial master mixes and 2 real-time thermocyclers. Changing the master mix overall did not influence the TaqMan RT-rtPCR performance, regardless of the thermocycler used. The limits of detection at the 95% confidence level were 18.1-25.8 copies/µL for the Rotor-Gene Q MDx thermocycler and 16.7-21.5 for the Mx3005P thermocycler. Excellent repeatability was demonstrated for rabies virus (RABV) RNA samples of 100, 50, and 25 copies/µL regardless of the thermocycler used. RABV field samples ( n = 35) isolated worldwide gave positive results using the most efficient of the 6 kits tested, with a copy number of 6.03 × 10² to 6.78 × 10⁷ RNA copies per reaction. The TaqMan RT-rtPCR assay provides sensitive and rapid amplification of RABV RNA.

Paralytic rabies in a goat

Background

Paralytic form of rabies is frequent in cattle in Latin America, but it is uncommon in goats. There are few clinical reports on furious rabies affecting goats, and the sporadic cases of rabid goats from surveillance programs worldwide lack clinical data. Furthermore, few studies reported the cerebrospinal fluid findings in rabid livestock.

Case presentation

On a farm in Midwestern Brazil, six of 47 Saanen goats died within one week. No vaccination protocols were implemented on the farm and the owner stated bat bites history on the livestock. Although rabies is endemic in Brazil, livestock vaccination is not mandatory. One 1-year-old buck was evaluated and showed non-specific clinical signs evolving within 12-h to nervous signs. Cerebrospinal fluid analysis revealed mononuclear pleocytosis, hyperproteinemia and high glucose levels. At necropsy, no gross lesions were present. Microscopically, discrete to moderate perivascular lymphoplasmacytic cuffing in gray and white matter, neuronal necrosis, neuronophagia, and mononuclear ganglioneuritis was observed in the brainstem and cervical spinal cord. Immunohistochemistry revealed strong anti-rabies virus immunostaining. Fresh central nervous system samples were positive for rabies in direct fluorescent antibody test (dFAT) and mouse intracerebral inoculation test (MIT). Exposed livestock recommendations included immediate vaccination, a strict isolation period of 90 days, and booster vaccinations during the third and eighth weeks.

Conclusion

IHC revealed the widespread distribution of rabies virus antigen in the goat’s CNS, contrasting the discrete pathological changes. In this goat, definitive diagnosis of paralytic rabies was obtained through the association of epidemiological, clinical, laboratorial, pathological findings (histology and IHC) and gold standard confirmatory tests (dFAT and MIT).

Molecular and serological survey of lyssaviruses in Croatian bat populations

BACKGROUND

Rabies is the only known zoonotic disease of bat origin in Europe. The disease is caused by species belonging to the genus Lyssavirus. Five Lyssavirus species, i.e., European bat lyssavirus (EBLV)-1, EBLV-2, Bokeloh bat lyssavirus, Lleida bat lyssavirus, and West Caucasian bat virus, have been identified in European bats. More recently, a proposed sixth species, Kotalahti bat lyssavirus, was detected. Thus, in this study, active surveillance was initiated in order to obtain insights into the prevalence of lyssaviruses in Croatian bat populations and to improve our understanding of the public health threat of infected bats.

RESULTS

In total, 455 bats were caught throughout Continental and Mediterranean Croatia. Antibodies were found in 20 of 350 bats (5.71%, 95% confidence interval 3.73-8.66). The majority of seropositive bats were found in Trbušnjak cave (Continental Croatia, Eastern part), and most seropositive bats belonged to Myotis myotis (13/20). All oropharyngeal swabs were negative for the presence of Lyssavirus.

CONCLUSIONS

The presence of lyssaviruses in bat populations was confirmed for the first time in Croatia and Southeastern Europe. The results of this study suggest the need for further comprehensive analyses of lyssaviruses in bats in this part of Europe.

Rabies in the Caribbean: A Situational Analysis and Historic Review

Rabies virus is the only Lyssavirus species found in the Americas. In discussions about rabies, Latin America and the Caribbean are often grouped together. Our study aimed to independently analyse the rabies situation in the Caribbean and examine changes in rabies spatiotemporal epidemiology. A questionnaire was administered to the 33 member countries and territories of the Caribbean Animal Health Network (CaribVET) to collect current data, which was collated with a literature review. Rabies was endemic in ten Caribbean localities, with the dog, mongoose, and vampire bat identified as enzootic reservoirs. The majority of animal cases occurred in Puerto Rico, the Dominican Republic, and Haiti, while human cases only consistently occurred in the latter two areas. Rabies vaccination was conducted for high-risk animal populations with variable coverage, and rabies diagnostic capacities varied widely throughout the region. Illegal importation and natural migration of animals may facilitate the introduction of rabies virus variants into virus-naïve areas. Passive surveillance, together with enhanced methods and serological screening techniques, can therefore be of value. The insularity of the Caribbean makes it ideal for conducting pilot studies on reservoir host population management. Best practice guidelines developed for these reservoir hosts can be individually modified to the epidemiological status and available resources within each locality.

Efficacy of rabies vaccines in dogs and cats and protection in a mouse model against European bat lyssavirus type 2

BACKGROUND

Rabies is preventable by pre- and/or post-exposure prophylaxis consisting of series of rabies vaccinations and in some cases the use of immunoglobulins. The success of vaccination can be estimated either by measuring virus neutralising antibodies or by challenge experiment. Vaccines based on rabies virus offer cross-protection against other lyssaviruses closely related to rabies virus. The aim was to assess the success of rabies vaccination measured by the antibody response in dogs (n = 10,071) and cats (n = 722), as well as to investigate the factors influencing the response to vaccination when animals failed to reach a rabies antibody titre of ≥ 0.5 IU/ml. Another aim was to assess the level of protection afforded by a commercial veterinary rabies vaccine against intracerebral challenge in mice with European bat lyssavirus type 2 (EBLV-2) and classical rabies virus (RABV), and to compare this with the protection offered by a vaccine for humans.

RESULTS

A significantly higher proportion of dogs (10.7%, 95% confidence interval CI 10.1-11.3) than cats (3.5%; 95% CI 2.3-5.0) had a vaccination antibody titre of < 0.5 IU/ml. In dogs, vaccination with certain vaccines, vaccination over 6 months prior the time of antibody determination and vaccination of dogs with a size of > 60 cm or larger resulted in a higher risk of failing to reach an antibody level of at least 0.5 IU/ml. When challenged with EBLV-2 and RABV, 80 and 100% of mice vaccinated with the veterinary rabies vaccine survived, respectively. When mice were vaccinated with the human rabies vaccine and challenged with EBLV-2, 75-80% survived, depending on the booster. All vaccinated mice developed sufficient to high titres of virus-neutralising antibodies (VNA) against RABV 21-22 days post-vaccination, ranging from 0.5 to 128 IU/ml. However, there was significant difference between antibody titres after vaccinating once in comparison to vaccinating twice (P < 0.05).

CONCLUSIONS

There was a significant difference between dogs and cats in their ability to reach a post vaccination antibody titre of ≥ 0.5 IU/ml. Mice vaccinated with RABV-based rabies vaccines were partly cross-protected against EBLV-2, but there was no clear correlation between VNA titres and cross-protection against EBLV-2. Measurement of the RABV VNA titre can only be seen as a partial tool to estimate the cross-protection against other lyssaviruses. Booster vaccination is recommended for dogs and cats if exposed to infected bats.

Comparison of G protein sequences of South African street rabies viruses showing distinct progression of the disease in a mouse model of experimental rabies

Rabies is a fatal zoonotic disease and infections generally lead to a fatal encephalomyelitis in both humans and animals. In South Africa, domestic (dogs) and the wildlife (yellow mongoose) host species maintain the canid and mongoose rabies variants respectively. In this study, pathogenicity differences of South African canid and mongoose rabies viruses were investigated in a murine model, by assessing the progression of clinical signs and survivorship. Comparison of glycoprotein gene sequences revealed amino acid differences that may underpin the observed pathogenicity differences. Cumulatively, our results suggest that the canid rabies virus may be more neurovirulent in mice than the mongoose rabies variant.

New isolations of the rabies-related Mokola virus from South Africa

BACKGROUND

Mokola virus (MOKV) is a rabies-related lyssavirus and appears to be exclusive to the African continent. Only 24 cases of MOKV, which includes two human cases, have been reported since its identification in 1968. MOKV has an unknown reservoir host and current commercial vaccines do not confer protection against MOKV.

RESULTS

We describe three new isolations of MOKV from domestic cats in South Africa. Two cases were retrospectively identified from 2012 and an additional one in 2014.

CONCLUSIONS

These cases emphasize the generally poor surveillance for rabies-related lyssaviruses and our inadequate comprehension of the epidemiology and ecology of Mokola lyssavirus per se.

Lyssavirus-reactive antibodies in Swedish bats

Introduction

To study the presence of European bat lyssavirus (EBLV) infections in bat reservoirs in Sweden, active surveillance was performed during the summers from 2008 to 2013.

Material and methods

Bat specimens were collected at >20 bat colonies in the central, southeastern, and southern parts of Sweden. In total, blood and saliva of 452 bats were examined by a virus neutralization test and by reverse transcription polymerase chain reactions (RT-PCRs).

Results and discussion

EBLV neutralizing antibodies were detected in 14 Daubenton's bats (Myotis daubentonii), all trapped in Skåne or Småland (south and southeast of Sweden). The result was not unexpected since EBLV has been shown to be present in many neighboring countries, for example, Denmark, Finland, Germany, and Norway. However, Sweden has been regarded free of rabies in terrestrial mammals since 1896. Although very rare, spillover of EBLV into other animals and humans have occurred, and the risk of EBLV infection to other species including humans should not be ignored. This is the first report of lyssavirus infection in Swedish bats.

Isolation and complete genome sequencing of rabies virus strain isolated from a brown bear (Ursus arctos) that attacked a human in Primorsky krai (November, 2014)

An attack of a brown bear (Ursus arctos) on human was detected in November, 2014 in the Barabash village (Khasan region of the Primorski krai) located in close proximity to the national park Land of the Leopard. The bear was shot. The deviant behavior of the bear indicated the possibility of rabies. The diagnosis was confirmed by means of laboratory methods. The strain RABV/Ursus arctos/Russia/Primorye/PO 01/2014 (further PO 01) was isolated from the brain of the bear. PO 01 is the first completely sequenced Far Eastern strain of RABV. It can be considered as topotypic. PO 01 considerably differs from the vaccine strain RV 97 (GenBank EF542830) that is the basis of attenuated vaccine applied in the Land of the Leopard. At the same time, the immunodominant sites in PO 01 and RV 97 proteins differ slightly. It can be recommended to continue application of the vaccine. The analysis of the PO 01 genome (GenBank KP997032) revealed its belonging to the Eurasian genetic subgroup of the genotype 1 (street rage). Thus, this genetic subgroup stretches to the East. Expansion of the cross-border protected territories of Russia and China in the Far East demands the correct statistics of circulation of the lyssaviruses to be kept.

Paediatric Australian bat lyssavirus encephalomyelitis - sequential MRI appearances from symptom onset to death

Human infection with Australian bat lyssavirus is extremely rare. Here we present the craniospinal findings in a fatal case of Australian bat lyssavirus infection in an 8-year-old child. MRI plays a very important role, not only in the diagnostic work-up of Australian bat lyssavirus infection but also in the prognostic assessment.

Rabies: Rare Human Infection - Common Questions

Rabies is an acute, rapidly progressive encephalitis that is almost always fatal. Prophylaxis is highly effective but economics limits disease control. The mechanism of death from rabies is unclear. It is poorly cytopathic and poorly inflammatory. Rabies behaves like an acquired metabolic disorder. There may be a continuum of disease severity. History of animal bite is rare. The diagnosis is often missed. Intermittent encephalopathy, dysphagia, hydrophobia and aerophobia, and focal paresthesias or myoclonic jerks suggest rabies. Laboratory diagnosis is cumbersome but sensitive. Treatment is controversial but survivors are increasingly reported, with good outcomes in 4 of 8 survivors.