Bat Rabies Research Articles

Bat rabies surveillance and risk factors for rabies spillover in an urban area of Southern Brazil

BackgroundBat rabies surveillance data and risk factors for rabies spillover without human cases have been evaluated in Curitiba, the ninth biggest city in Brazil, during a 6-year period (2010–2015). A retrospective analysis of bat complaints, bat species identification and rabies testing of bats, dogs and cats has been performed using methodologies of seasonal decomposition, spatial distribution and kernel density analysis.ResultsOverall, a total of 1003 requests for bat removal have been attended to, and 806 bats were collected in 606 city locations. Bat species were identified among 13 genera of three families, with a higher frequency of Nyctinomops in the central-northern region and Molossidae scattered throughout city limits. Out of the bats captured alive, 419/806 (52.0%) healthy bats were released due to absence of human or animal contacts. The remaining 387/806 (48.0%) bats were sent for euthanasia and rabies testing, which resulted in 9/387 (2.32%) positives. Linear regression has shown an increase on sample numbers tested over time (regression: y = 2.02 + 0.17×; p < 0.001 and r2 = 0.29), as well as significant seasonal variation, which increases in January and decreases in May, June and July. The Kernel density analysis showed the center-northern city area to be statistically important, and the southern region had no tested samples within the period. In addition, a total of 4769 random and suspicious samples were sent for rabies diagnosis including those from dogs, cats, bats and others from 2007 to 2015. While all 2676 dog brains tested negative, only 1/1136 (0.088%) cat brains tested positive for rabies.ConclusionOnly non-hematophagous bats were collected during the study, and the highest frequency of collections occurred in the center-northern region of the city. Rabies spillover from bats to cats may be more likely due to the registered exposure associated with cats’ innate hunting habits, predisposing them to even closer contact with potentially infected bats. Although associated with a very low frequency of rabies, cats should always be included in rabies surveillance and vaccination programs.

Combination drug treatment prolongs survival of experimentally infected mice with silver-haired bat rabies virus

Rabies is a lethal disease in humans and animals, killing approximately 60,000 people every year. Currently, there is no treatment available, except post-exposure prophylaxis (PEP) that can be administered whenever exposure to a rabid animal took place. Here we describe the beneficial effects of a combination treatment initiated at day 4 post infection, containing anti-viral drugs and immune modulators in infected mice. Combination therapy resulted in significant increase in survival time (P < 0.05) and significantly lowers viral RNA in the brain and spinal cord (P < 0.05). Furthermore, treatment influenced markers of pyroptosis and apoptosis and early inflammatory response as measured by the levels of TNF-α. Morphological lesions were absent in rabies virus infected mice with few signs of inflammation. However, these were not significant between the different groups.

Combination therapy of rabies-infected mice with inhibitors of pro-inflammatory host response, antiviral compounds and human rabies immunoglobulin

Recent studies demonstrated that inhibitors of pro-inflammatory molecular cascades triggered by rabies infection in the central nervous system (CNS) can enhance survival in mouse model and that certain antiviral compounds interfere with rabies virus replication in vitro. In this study different combinations of therapeutics were tested to evaluate their effect on survival in rabies-infected mice, as well as on viral load in the CNS. C57Bl/6 mice were infected with Silver-haired bat rabies virus (SHBRV)-18 at virus dose approaching LD50 and LD100. In one experimental group daily treatments were initiated 4 h before-, in other groups 48 or 96 h after challenge. In the first experiment therapeutic combination contained inhibitors of tumour necrosis factor-α (infliximab), caspase-1 (Ac-YVAD-cmk), and a multikinase inhibitor (sorafenib). In the treated groups there was a notable but not significant increase of survival compared to the virus infected, non-treated mice. The addition of human rabies immunoglobulins (HRIG) to the combination in the second experiment almost completely prevented mortality in the pre-exposure treatment group along with a significant reduction of viral titres in the CNS. Post-exposure treatments also greatly improved survival rates. As part of the combination with immunomodulatory compounds, HRIG had a higher impact on survival than alone. In the third experiment the combination was further supplemented with type-I interferons, ribavirin and favipiravir (T-705). As a blood-brain barrier opener, mannitol was also administered. This treatment was unable to prevent lethal consequences of SHBRV-18 infection; furthermore, it caused toxicity in treated mice, presumably due to interaction among the components. In all experiments, viral loads in the CNS were similar in mice that succumbed to rabies regardless of treatment. According to the findings, inhibitors of detrimental host response to rabies combined with antibodies can be considered among the possible therapeutic and post-exposure options in human rabies cases.

First cases of European bat lyssavirus type 1 in Iberian serotine bats: Implications for the molecular epidemiology of bat rabies in Europe

Previous studies have shown that EBLV-1 strains exclusively hosted by Eptesicus isabellinus bats in the Iberian Peninsula cluster in a specific monophyletic group that is related to the EBLV-1b lineage found in the rest of Europe. More recently, enhanced passive surveillance has allowed the detection of the first EBLV-1 strains associated to Eptesicus serotinus south of the Pyrenees. The aim of this study is the reconstruction of the EBLV-1 phylogeny and phylodynamics in the Iberian Peninsula in the context of the European continent. We have sequenced 23 EBLV-1 strains detected on nine E. serotinus and 14 E. isabellinus. Phylogenetic analyses were performed on the first 400-bp-5’ fragment of the Nucleoprotein (N) gene together with other 162 sequences from Europe. Besides, fragments of the variable region of the phosphoprotein (P) gene and the glycoprotein-polymerase (G-L) intergenic region were studied on Spanish samples. Phylogenies show that two of the new EBLV-1a strains from Iberian E. serotinus clustered together with French strains from the North of the Pyrenees, suggesting a recent expansion southwards of this subtype. The remaining seven Iberian strains from E. serotinus grouped, instead, within the cluster linked, so far, to E. isabellinus, indicating that spatial distribution prevails over species specificity in explaining rabies distribution and supporting interspecific transmission. The structure found within the Iberian Peninsula for EBLV-1b is in concordance with that described previously for E. isabellinus. Finally, we have found that the current EBLV-1 European strains could have emerged only 175 years ago according to our evolutionary dynamics analyses.

Canine rabies in Rio Grande do Sul caused by an insectivorous bat rabies virus variant

Rabies is caused by rabies virus (RV), a RNA virus member of the Lyssavirus genus, family Rhabdoviridae . The aim of this study was to determine antigenic characteristics of a rabies virus isolate (RV183-07) recovered from a stray bitch that died of rabies and to infer the most likely source of contamination, since no urban rabies has been reported in the area in more than 20 years. The virus was identified by direct immunofluorescence and multiplied by one passage in mice. The antigenic profile of the isolate was determined with a panel of monoclonal antibodies to lyssavirus antigens on infected brain tissues. A fragment of the viral genome corresponding to the nucleoprotein (N) gene was submitted to reverse transcription/polymerase chain reaction and the amplicon obtained was subjected to restriction enzyme analysis. A 303 base pair fragment of the N gene was cloned, sequenced and compared to other RV sequences available at Genbank. The isolate RV183-07 displayed antigenic and genomic characteristics of rabies virus variants whose natural reservoir is the non-hematophagous bat Tadarida brasiliensis . Therefore, the most likely source of contamination of the bitch was an incidental contact with an infected bat of that species, common inhabitants of the area. In view of that, the status of “urban rabies-free” of the area was not compromised.

Pathogenesis of bat rabies in a natural reservoir: Comparative susceptibility of the straw-colored fruit bat (Eidolon helvum) to three strains of Lagos bat virus.

Rabies is a fatal neurologic disease caused by lyssavirus infection. People are infected through contact with infected animals. The relative increase of human rabies acquired from bats calls for a better understanding of lyssavirus infections in their natural hosts. So far, there is no experimental model that mimics natural lyssavirus infection in the reservoir bat species. Lagos bat virus is a lyssavirus that is endemic in straw-colored fruit bats (Eidolon helvum) in Africa. Here we compared the susceptibility of these bats to three strains of Lagos bat virus (from Senegal, Nigeria, and Ghana) by intracranial inoculation. To allow comparison between strains, we ensured the same titer of virus was inoculated in the same location of the brain of each bat. All bats (n = 3 per strain) were infected, and developed neurological signs, and fatal meningoencephalitis with lyssavirus antigen expression in neurons. There were three main differences among the groups. First, time to death was substantially shorter in the Senegal and Ghana groups (4 to 6 days) than in the Nigeria group (8 days). Second, each virus strain produced a distinct clinical syndrome. Third, the spread of virus to peripheral tissues, tested by hemi-nested reverse transcriptase PCR, was frequent (3 of 3 bats) and widespread (8 to 10 tissues positive of 11 tissues examined) in the Ghana group, was frequent and less widespread in the Senegal group (3/3 bats, 3 to 6 tissues positive), and was rare and restricted in the Nigeria group (1/3 bats, 2 tissues positive). Centrifugal spread of virus from brain to tissue of excretion in the oral cavity is required to enable lyssavirus transmission. Therefore, the Senegal and Ghana strains seem most suitable for further pathogenesis, and for transmission, studies in the straw-colored fruit bat.

Molecular Epidemiology and Evolution of European Bat Lyssavirus 2.

Bat rabies cases in Europe are mainly attributed to two lyssaviruses, namely European Bat Lyssavirus 1 (EBLV-1) and European Bat Lyssavirus 2 (EBLV-2). Prior to the death of a bat worker in Finland in 1985, very few bat rabies cases were reported. Enhanced surveillance in the two subsequent years (1986–1987) identified 263 cases (more than a fifth of all reported cases to date). Between 1977 and 2016, 1183 cases of bat rabies were reported, with the vast majority (>97%) being attributed to EBLV-1. In contrast, there have been only 39 suspected cases of EBLV-2, of which 34 have been confirmed by virus typing and presently restricted to just two bat species; Myotis daubentonii and Myotis dasycneme. The limited number of EBLV-2 cases in Europe prompted the establishment of a network of European reference laboratories to collate all available viruses and data. Despite the relatively low number of EBLV-2 cases, a large amount of anomalous data has been published in the scientific literature, which we have here reviewed and clarified. In this review, 29 EBLV-2 full genome sequences have been analysed to further our understanding of the diversity and molecular evolution of EBLV-2 in Europe. Analysis of the 29 complete EBLV-2 genome sequences clearly corroborated geographical relationships with all EBLV-2 sequences clustering at the country level irrespective of the gene studied. Further geographical clustering was also observed at a local level. There are high levels of homogeneity within the EBLV-2 species with nucleotide identities ranging from 95.5–100% and amino acid identities between 98.7% and 100%, despite the widespread distribution of the isolates both geographically and chronologically. The mean substitution rate for EBLV-2 across the five concatenated genes was 1.65 × 10−5, and evolutionary clock analysis confirms the slow evolution of EBLV-2 both between and within countries in Europe. This is further supported by the first detailed EBLV-2 intra-roost genomic analysis whereby a relatively high sequence homogeneity was found across the genomes of three EBLV-2 isolates obtained several years apart (2007, 2008, and 2014) from M. daubentonii at the same site (Stokesay Castle, Shropshire, UK).

Quantifying the burden of vampire bat rabies in Peruvian livestock.

BackgroundKnowledge of infectious disease burden is necessary to appropriately allocate resources for prevention and control. In Latin America, rabies is among the most important zoonoses for human health and agriculture, but the burden of disease attributed to its main reservoir, the common vampire bat (Desmodus rotundus), remains uncertain.Methodology/Principal findingsWe used questionnaires to quantify under-reporting of livestock deaths across 40 agricultural communities with differing access to health resources and epidemiological histories of vampire bat rabies (VBR) in the regions of Apurimac, Ayacucho and Cusco in southern Peru. Farmers who believed VBR was absent from their communities were one third as likely to report livestock deaths from disease as those who believed VBR was present, and under-reporting increased with distance from reporting offices. Using generalized mixed-effect models that captured spatial autocorrelation in reporting, we project 4.6 (95% CI: 4.4–8.2) rabies cases per reported case and identify geographic areas with potentially greater VBR burden than indicated by official reports. Spatially-corrected models estimate 505–724 cattle deaths from VBR in our study area during 2014 (421–444 deaths/100,000 cattle), costing US$121,797–171,992. Cost benefit analysis favoured vaccinating all cattle over the current practice of partial vaccination or halting vaccination all together.ConclusionsOur study represents the first estimate of the burden of VBR in Latin America to incorporate data on reporting rates. We confirm the long-suspected cost of VBR to small-scale farmers and show that vaccinating livestock is a cost-effective solution to mitigate the burden of VBR. More generally, results highlight that ignoring geographic variation in access to health resources can bias estimates of disease burden and risk.

Mannitol treatment is not effective in therapy of rabies virus infection in mice

Rabies is a deadly viral disease with an extremely high fatality rate in humans. Previously, it was suggested that an enhancement of the blood–brain barrier (BBB) permeability, which allows immune cells and/or antibodies to enter the central nervous system (CNS) tissue, is critical to clear the infection. In this study, we utilised mannitol to increase BBB permeability in mice infected with highly pathogenic silver-haired bat rabies virus (SHBRV). We found that intraperitoneal injection of mannitol causes a slight, transient increase of BBB permeability in the treated mice. SHBRV-infected mice were treated with intraperitoneally administered mannitol daily from day 3 or day 4 post-infection, but no effect of this treatment on the time of disease onset, clinical signs or survival was observed. This data indicates that the increase of BBB permeability by mannitol is not efficient in promoting CNS virus clearance in SHBRV-infected mice.

Bat rabies surveillance in France: first report of unusual mortality among serotine bats

BackgroundRabies is a fatal viral encephalitic disease that is caused by lyssaviruses which can affect all mammals, including human and bats. In Europe, bat rabies cases are attributed to five different lyssavirus species, the majority of rabid bats being attributed to European bat 1 lyssavirus (EBLV-1), circulating mainly in serotine bats (Eptesicus serotinus). In France, rabies in bats is under surveillance since 1989, with 77 positive cases reported between 1989 and 2016.Case presentationIn the frame of the bat rabies surveillance, an unusual mortality of serotine bats was reported in 2009 in a village in North-East France. Six juvenile bats from an E. serotinus maternity colony counting ~200 individuals were found to be infected with EBLV-1. The active surveillance of the colony by capture sessions of bats from July to September 2009 showed a high detection rate of neutralising EBLV-1 antibodies (≈ 50%) in the colony. Moreover, one out of 111 animals tested was found to shed viable virus in saliva, while lyssavirus RNA was detected by RT-PCR for five individuals.ConclusionThis study demonstrated that the lyssavirus infection in the serotine maternity colony was followed by a high rate of bat rabies immunity after circulation of the virus in the colony. The ratio of seropositive bats is probably indicative of an efficient virus transmission coupled to a rapid circulation of EBLV-1 in the colony.

Longitudinal survey of two serotine bat (Eptesicus serotinus) maternity colonies exposed to EBLV-1 (European Bat Lyssavirus type 1): Assessment of survival and serological status variations using capture-recapture models.

This study describes two longitudinal serological surveys of European Bat Lyssavirus type 1 (EBLV-1) antibodies in serotine bat (Eptesicus serotinus) maternity colonies located in the North-East of France. This species is currently considered as the main EBLV-1 reservoir. Multievent capture-recapture models were used to determine the factors influencing bat rabies transmission as this method accounts for imperfect detection and uncertainty in disease states. Considering the period of study, analyses revealed that survival and recapture probabilities were not affected by the serological status of individuals, confirming the capacity of bats to be exposed to lyssaviruses without dying. Five bats have been found with EBLV-1 RNA in the saliva at the start of the study, suggesting they were caught during virus excretion period. Among these bats, one was interestingly recaptured one year later and harbored a seropositive status. Along the survey, some others bats have been observed to both seroconvert (i.e. move from a negative to a positive serological status) and serorevert (i.e. move from a positive to a negative serological status). Peak of seroprevalence reached 34% and 70% in site A and B respectively. On one of the 2 sites, global decrease of seroprevalence was observed all along the study period nuanced by oscillation intervals of approximately 2–3 years supporting the oscillation infection dynamics hypothesized during a previous EBLV-1 study in a Myotis myotis colony. Seroprevalence were affected by significantly higher seroprevalence in summer than in spring. The maximum time observed between successive positive serological statuses of a bat demonstrated the potential persistence of neutralizing antibodies for at least 4 years. At last, EBLV-1 serological status transitions have been shown driven by age category with higher seroreversion frequencies in adults than in juvenile. Juveniles and female adults seemed indeed acting as distinct drivers of the rabies virus dynamics, hypothesis have been addressed but their exact role in the EBLV-1 transmission still need to be specified.

Host Genetic Variation Does Not Determine Spatio-Temporal Patterns of European Bat 1 Lyssavirus.

The majority of bat rabies cases in Europe are attributed to European bat 1 lyssavirus (EBLV-1), circulating mainly in serotine bats (Eptesicus serotinus). Two subtypes have been defined (EBLV-1a and EBLV-1b), each associated with a different geographical distribution. In this study, we undertake a comprehensive sequence analysis based on 80 newly obtained EBLV-1 nearly complete genome sequences from nine European countries over a 45-year period to infer selection pressures, rates of nucleotide substitution, and evolutionary time scale of these two subtypes in Europe. Our results suggest that the current lineage of EBLV-1 arose in Europe ∼600 years ago and the virus has evolved at an estimated average substitution rate of ∼4.19×10−5 subs/site/year, which is among the lowest recorded for RNA viruses. In parallel, we investigate the genetic structure of French serotine bats at both the nuclear and mitochondrial level and find that they constitute a single genetic cluster. Furthermore, Mantel tests based on interindividual distances reveal the absence of correlation between genetic distances estimated between viruses and between host individuals. Taken together, this indicates that the genetic diversity observed in our E. serotinus samples does not account for EBLV-1a and -1b segregation and dispersal in Europe.

The Imperative of Palliation in the Management of Rabies Encephalomyelitis.

The aim of this review is to guide clinicians in the practical management of patients suffering from rabies encephalomyelitis. This condition is eminently preventable by modern post-exposure vaccination, but is virtually always fatal in unvaccinated people. In the absence of any proven effective antiviral or other treatment, palliative care is an imperative to minimise suffering. Suspicion of rabies encephalomyelitis depends on recognising the classic symptomatology and eliciting a history of exposure to a possibly rabid mammal. Potentially treatable differential diagnoses must be eliminated, notably other infective encephalopathies. Laboratory confirmation of suspected rabies is not usually possible in many endemic areas, but is essential for public health surveillance. In a disease as agonising and terrifying as rabies encephalomyelitis, alleviation of distressing symptoms is the primary concern and overriding responsibility of medical staff. Calm, quiet conditions should be created, allowing relatives to communicate with the dying patient in safety and privacy. Palliative management must address thirst and dehydration, fever, anxiety, fear, restlessness, agitation, seizures, hypersecretion, and pain. As the infection progresses, coma and respiratory, cardiovascular, neurological, endocrine, or gastrointestinal complications will eventually ensue. When the facilities exist, the possibility of intensive care may arise, but although some patients may survive, they will be left with severe neurological sequelae. Recovery from rabies is extremely rare, and heroic measures with intensive care should be considered only in patients who have been previously vaccinated, develop rabies antibody within the first week of illness, or were infected by an American bat rabies virus. However, in most cases, clinicians must have the courage to offer compassionate palliation whenever the diagnosis of rabies encephalomyelitis is inescapable.

First detection of European bat lyssavirus type 2 (EBLV-2) in Norway

BackgroundIn Europe, bat rabies is primarily attributed to European bat lyssavirus type 1 (EBLV-1) and European bat lyssavirus type 2 (EBLV-2) which are both strongly host-specific. Approximately thirty cases of infection with EBLV-2 in Daubenton’s bats (Myotis daubentonii) and pond bats (M. dasycneme) have been reported. Two human cases of rabies caused by EBLV-2 have also been confirmed during the last thirty years, while natural spill-over to other non-flying mammals has never been reported. Rabies has never been diagnosed in mainland Norway previously.Case presentationIn late September 2015, a subadult male Daubenton’s bat was found in a poor condition 800 m above sea level in the southern part of Norway. The bat was brought to the national Bat Care Centre where it eventually displayed signs of neurological disease and died after two days. EBLV-2 was detected in brain tissues by polymerase chain reaction (PCR) followed by sequencing of a part of the nucleoprotein gene, and lyssavirus was isolated in neuroblastoma cells.ConclusionsThe detection of EBLV-2 in a bat in Norway broadens the knowledge on the occurrence of this zoonotic agent. Since Norway is considered free of rabies, adequate information to the general public regarding the possibility of human cases of bat-associated rabies should be given. No extensive surveillance of lyssavirus infections in bats has been conducted in the country, and a passive surveillance network to assess rabies prevalence and bat epidemiology is highly desired.

Rabies Virus in Bats, State of Pará, Brazil, 2005-2011.

Rabies is an acute, progressive zoonotic viral infection that in general produces a fatal outcome. This disease is responsible for deaths in humans and animals worldwide and, because it can affect all mammals, is considered one of the most important viral infections for public health. This study aimed to determine the prevalence of rabies in bats of different species found in municipalities of the state of Pará from 2005 to 2011. The rabies virus was detected in 12 (0.39%) bats in a total of 3100 analyzed, including hematophagous, frugivorous, and insectivorous bats. Of these, eleven were characterized as AgV3, which is characteristic of the hematophagous bat Desmodus rotundus (E. Geoffroy 1810); one insectivorous animal showed a different profile compatible with the Eptesicus pattern and may therefore be a new antigenic variant. This study identified the need for greater intensification of epidemiological surveillance in municipalities lacking rabies surveillance (silent areas); studies of rabies virus in bats with different alimentary habits, studies investigating the prevalence of AgV3, and prophylactic measures in areas where humans may be infected are also needed.

Rabies vaccination campaigns in dogs and cats, and rabies positivity in bats, from 2004 to 2014, in Campinas, São Paulo, Brazil.

to describe the results of rabies vaccination campaigns in dogs and cats from 2004 to 2009 and from 2012 to 2014, and the positivity for rabies in bats from 2004 to 2014, in Campinas-SP, Brazil. a descriptive study was carried out with secondary data from the Zoonoses Surveillance Unit. there was a marked reduction in the number of vaccinated dogs, from 105,764 (2004) to 65,561 (2014), with vaccine coverage below 80%, except in 2004; there was little oscillation in the number of vaccinated cats, from 10,212 (2004) to 9,522 (2014), with vaccine coverage below 80%, except in 2014; 4,464 bats were collected by passive surveillance, 2.17% of them were positive for rabies. the low vaccine coverage in dogs and cats and the circulation of the virus in bats imposes the need for improvement in surveillance actions, in order to prevent cases of human rabies.

Experimental infection of Artibeus intermedius with a vampire bat rabies virus.

Experimental infection of Artibeus intermedius, the great fruit-eating bat, was performed with vampire bat rabies isolates. Bats (n=35) were captured in the wild and quarantined prior to experimental infection. No rabies antibodies were detected by rapid fluorescent focus inhibition test (RFFIT) prior to infection. Three doses of rabies virus (RV) and three different routes of infection were used. One out of 35 bats died without showing any clinical signs at day 14 and was positive for rabies. None of the 34 other bats showed clinical signs for rabies, but high antibody titers were detected post-inoculation, suggesting either innate immune response to the vampire bat rabies virus or possible pre-exposure to RV and inoculation leading to a booster effect. Rabies virus was detected by hemi-nested RT-PCR (hnRT-PCR) in the brain (n=3), stomach (n=1) of bats that were negative by immunofluorescence and that survived rabies infection. The bat that died on day 14 was positive by hnRT-PCR on the brain, heart and liver. These results suggest that either previous non-lethal exposure to RV or natural low susceptibility to vampire bat viruses somehow protected Artibeus intermedius from clinical rabies infection leading to a marginal lethality effect on this bats species population in the wild.

Characterization of the epidemiology of bat-borne rabies in Chile between 2003 and 2013

Rabies is a zoonotic disease of great impact to public health. According to the World Health Organization, the country of Chile is currently declared free from human rabies transmitted by dogs. An epidemiological characterization and description was conducted using rabies data from 2003 to 2013 held by the National Program for Prevention and Control of Rabies from the Ministry of Health, consisting of bats samples reported as suspect and samples taken by active surveillance (bats brain tissue). Spatial autocorrelation analysis was performed using Local Indicators of Spatial Association (LISA) statistics, particularly Moran’s I index, for the detection of spatial clusters. Temporal descriptive analysis was also carried out. Nine hundred and twenty-seven positive cases were reported, presenting an average of 84 cases per year, mainly originated from passive surveillance (98.5%), whilst only 1.5% of cases were reported by active surveillance. Global positivity for the study period was 7.02% and 0.1% in passive and active surveillance respectively. Most of the cases were reported in the central zone of Chile (88.1%), followed by south zone (9.1%) and north zone (2.8%). At a regional level, Metropolitana (40.6%), Valparaíso (19.1%) and Maule (11.8%) regions reported the majority of the cases. Tadarida brasiliensis (92%) presented the majority of the cases reported, with viral variant 4 (82%) being most commonly diagnosed. Only two cases were detected in companion animals. The central zone presented a positive spatial autocorrelation (Moran’s I index=0.1537, 95% CI=0.1141–0.1933; p-value=0.02); north and south zones returned non-significant results (Moran’s I index=0.0517 and −0.0117, 95% CI=−0.0358–0.1392 and −0.0780–0.0546, and p-values=0.21 and 0.34 respectively). The number of rabies cases decreased between May and August (late fall and winter) and tended to increase during the hot season (December to March), confirmed with the evidence from Autocorrelation analysis and the Ljun-Box test (X2=234.85 and p-value<0.0001). Knowledge of animal rabies epidemiologic behaviour becomes relevant when designing prevention and control measures and surveillance programs. This is especially important considering the high impact to Public Health of this disease and that wildlife rabies in bats remains endemic in Chile.

What do we know about the behavior of animal rabies in Chile through the last years?

ObjectiveThis study aims to analyze the evolution of the epidemiologicalbehavior of rabies in Chile during the period 2003 to 2013, throughthe epidemiological characterization of a number of variables anddescription of spatial and temporal patterns of animal cases.IntroductionRabies is a zoonotic disease caused by an RNA virus from thefamily Rhabdoviridae, genus Lyssavirus. Worldwide distributed,control of rabies has been considered to be particularly amenable toa “One Health” strategy (1). In Chile, rabies was considered endemicin domestic dog population until the late 1960s, when a surveillanceprogram was established, decreasing the number of human casesrelated to canine variants until the year 1972 (2). Rabies is recognizedas a endemic infection in chiropterans of Chile and prompted thesurveillance of the agent in this and other species (3).MethodsAn epidemiological characterization of the registered cases fromthe National Program for Prevention and Control of Rabies wascarried. During the period 2003-2013, 927 cases were reported.Descriptive statistics and descriptive mapping, recording origin of thesample, number of cases per region, animal reservoir implicated andviral variant were performed. A spatial autocorrelation analysis wascarried using Moran’s I indicator for the detection of spatial clusters(4), using the Local Indicators of Spatial Association (LISA) statistics(5), at national and regional level of aggrupation (north, central andsouth zone). Temporal descriptive analysis was carried.Results927 positive cases were recorded. 920 (99.2%) cases came frompassive surveillance, while 7 (0.8%) cases by active surveillance, totalpositivity was 77.02% and 1.37% respectively. Positivity was reportedmainly in the central zone (88.1%), mainly in Valparaiso (19.1%),Metropolitana (40.6%) (Figure 1), Maule (11.8%) regions concentratedin urban centers. Main positive reservoirs were bats (99.8%),specificallyTadarida brasiliensisand viral variant 4 was the mostcommonly diagnosed. LISA test gives a Moran’s I indicator of 0.1537(p-value = 0.02) for the central zone (Table 1). Rabies tend to decreasein fall and winter season (2.9 cases vs 13 cases during summer).ConclusionsWildlife rabies in bats remains endemic in Chile, concentrated inurban areas. The main reservoirs are insectivorous bats. There is asignificant spatial autocorrelation of animal rabies cases in the centralzone of Chile. Results are relevant to the design of preventive andcontrol measures.

Serological Evidence of Lyssavirus Infection among Bats in Nagaland, a North-Eastern State in India.

Bats are known to be reservoirs of several medically important viruses including lyssaviruses. However, no systematic surveillance for bat rabies has been carried out in India, a canine rabies endemic country with a high burden of human rabies. Surveillance for rabies virus (RABV) infection in bats was therefore carried out in Nagaland, a north-eastern state in India at sites with intense human-bat interfaces during traditional bat harvests. Brain tissues and sera from bats were tested for evidence of infection due to RABV. Brain tissues were subjected to the fluorescent antibody test for detection of viral antigen and real-time reverse transcriptase PCR for presence of viral RNA. Bat sera were tested for the presence of rabies neutralizing antibodies by the rapid fluorescent focus inhibition test. None of the bat brains tested (n = 164) were positive for viral antigen or viral RNA. However, rabies neutralizing antibodies were detected in 4/78 (5·1%) bat sera tested, suggesting prior exposure to RABV or related lyssaviruses. The serological evidence of lyssaviral infection in Indian bats may have important implications in disease transmission and rabies control measures, and warrant extensive bat surveillance to better define the prevalence of lyssaviral infection in bats.