Non-hematophagous Bats Research Articles

Rabies virus circulation in a highly diverse bat assemblage from a high-risk area for zoonoses outbreaks in the Brazilian Amazon

Bats are the second most diverse order of mammals and play a central role in ecosystem dynamics. They are also important reservoirs of potentially zoonotic microorganisms, of which rabies virus is the most lethal among the bat-transmitted zoonotic pathogens. Importantly, recent outbreaks of human rabies have been reported from the Brazilian Amazon. Here we present a survey of bat species and rabies virus (RABV) circulation in a bat assemblage in the Marajó region, northern Brazil. Using data from mist-net captures and bioacoustic sampling, 56 bat species were recorded along the Jacundá River basin over a 10-day expedition in November 2022. For the investigation of RABV, we used the direct fluorescent antibody test (DFAT) and the rapid fluorescent focus inhibition test (RFFIT). In total, 159 bat individuals from 22 species were investigated for RABV. Five adults of the common vampire bat, Desmodus rotundus, showed RABV-specific antibodies in serum samples. Additionally, we report on local residents with injuries caused by D. rotundus bites and the occurrence of colonies of non-hematophagous bats from different species roosting inside human residences. This scenario raises concerns about the risks of new cases of human rabies and other zoonotic diseases associated with bats in the region and highlights the need for epidemiological surveillance and mitigation measures to prevent outbreaks of emerging infectious diseases.

Presencia del virus de la rabia en murciélagos no hematófagos en México

The presence of the rabies virus and antibodyes in bats from the Americas is mainly associated with hematophagous species; however, this virus has also been detected with low frequency in bats with other feeding habits. The same thing happens in Mexico, although there is no updated information on the species that have been infected by this virus. Due to the public health implications of the subject, in this study we explore how the presence of the rabies virus is related to eating habits, the family to which they belong, the size of the distribution area and the type of refuge used by bats. Based on a review of the scientific literature published from 1954 to 2015, seven families, 24 genera, and 40 species of non-hematophagous bats that have been detected with rabies virus in Mexico. Most are insectivorous (63%) and belong to the Phyllostomidae and Vespertilionidae families (68%). The presence of rabies is positively and significantly related to the number of species per family (r = 0.9, p < 0.005) and type of feeding habit (r = 0.97, p < 0.002) but is not related to the size of its distribution area (r = 0.2, p = 0.2). Cases of rabies in non-hematophagous species in Mexico are rare, and do not represent a risk of transmission to humans.

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.

Characterization of the bacterial microbiome of non-hematophagous bats and associated ectoparasites from Brazil.

Bats, along with their ectoparasites, harbor a wide diversity of symbiotic and potential pathogenic bacteria. Despite the enormous diversity of bats (181 species), few studies aimed to investigate the bacterial microbiome of Brazilian chiropterans and associated ectoparasites. This study aimed to characterize the bacterial microbiome of non-hematophagous bats and associated Streblidae flies and Macronyssidae and Spinturnicidae mites in the state of Mato Grosso do Sul, midwestern Brazil. Oral and rectal swabs were collected from 30 bats (Artibeus lituratus [n = 13], Artibeus planirostris [n = 9], Eptesicus furinalis [n = 5], Carollia perspicillata [n = 2], and Platyrrhinus lineatus [n = 1]). In addition, a total of 58 mites (15 Macronyssidae and 43 Spinturnicidae) and 48 Streblidae bat flies were collected from the captured bats. After DNA extraction and purification, each sample's bacterial composition was analyzed with metagenomic sequencing. The microbiome composition of both oral and rectal bat swab samples showed that Gammaproteobacteria was the most abundant bacterial class. Spiroplasma, Wolbachia and Bartonella represented the most abundant genera in Streblidae flies. While Wolbachia (Alphaproteobacteria) was the most abundant genus found in Spinturnicidae, Arsenophonus (Gammaproteobacteria) was found in high abundance in Macronyssidae mites. In addition to characterizing the microbiome of each sample at the class and genus taxonomic levels, we identified medically significant bacteria able to infect both animals and humans in oral (Streptococcus and Anaplasma) and rectal swabs (Enterobacter, Klebsiella, Escherichia, Enterococcus, Streptococcus), Macronyssidae (Anaplasma, Bartonella, Ehrlichia) and Spinturnicidae (Anaplasma, Bartonella) mites as well as Streblidae flies (Spiroplasma, Bartonella). Besides expanding the knowledge on the bacterial microbiome of non-hematophagous bats and Streblidae flies from Brazil, the present work showed, for the first time, the bacterial community of bat-associated Macronyssidae and Spinturnicidae mites.

Rabies in chozna ‘Potus flavus’: a warning of a potential threat to public and animal health

We reported an outbreak of wild rabies in Potus flavus (choznas), a carnivorous mammal associated with insectivorous bats in Kosñipata, Cusco, Peru, from February 2021 to October 2022. Eight human exposures were reported, with aggressive attacks resulting in injuries. The outbreak prompted a public health response and raised concerns about zoonotic diseases due to habitat fragmentation and urbanization. The study involved antigenic and genetic characterization of the virus in the affected animals, revealing similarities with variants in non-hematophagous bats. This outbreak marked the first time rabies had been reported in choznas in the region, highlighting the need for early intervention programs and wildlife protection. Pre-exposure rabies vaccinations were administered to residents, and community surveillance was established to control the outbreak. The study emphasizes the importance of continuous surveillance and education to prevent rabies transmission from choznas to humans and other animals, as their role as potential secondary transmitters of the virus warrants further investigation.

Molecular detection of blood-borne agents in vampire bats from Brazil, with the first molecular evidence of Neorickettsia sp. in Desmodus rotundus and Diphylla ecaudata

Bats (Mammalia, Chiroptera) represent the second largest group of mammals. Due to their ability to fly and adapt and colonize different niches, bats act as reservoirs of several potentially zoonotic pathogens. In this context, the present work aimed to investigate, using molecular techniques, the occurrence of blood-borne agents (Anaplasmataceae, Coxiella burnetii, hemoplasmas, hemosporidians and piroplasmids) in 198 vampire bats sampled in different regions of Brazil and belonging to the species Desmodus rotundus (n = 159), Diphylla ecaudata (n = 31) and Diaemus youngii (n = 8). All vampire bats liver samples were negative in PCR assays for Ehrlichia spp., Anaplasma spp., piroplasmids, hemosporidians and Coxiella burnetii. However, Neorickettsia sp. was detected in liver samples of 1.51% (3/198) through nested PCR based on the 16S rRNA gene in D. rotundus and D. ecaudata. This is the first study to report Neorickettsia sp. in vampire bats. Hemoplasmas were detected in 6.06% (12/198) of the liver samples using a PCR based on the 16S rRNA gene. The two 16S rRNA sequences obtained from hemoplasmas were closely related to sequences previously identified in vampire and non-hematophagous bats from Belize, Peru and Brazil. The genotypic analysis identified a high diversity of bat-associated hemoplasma genotypes from different regions of the world, emphasizing the need for studies on this subject, in order to better understand the mechanisms of co-evolution between this group of bacteria and their vertebrate hosts. The role of neotropical bat-associated Neorickettsia sp. and bats from Brazil in the biological cycle of such agent warrant further investigation.

No molecular evidence for influenza A virus and coronavirus in bats belonging to the families Phyllostomidae, Vespertilionidae, and Molossidae in the state of São Paulo, Brazil.

This study aimed to evaluate, by molecular methods, the presence of influenza A virus (IAV) and coronavirus in non-hematophagous bats collected in the state of São Paulo, Brazil. Samples of lung tissue and small intestine from 105 bats belonging to three families (Phyllostomidae, Vespertilionidae, and Molossidae) were collected in 22 municipalities in the state of São Paulo. Genetic identification of bats species was performed by amplification and sequencing of a fragment of 710bp of the mitochondrial COI gene. In the detection of IAV, genomes were performed by RT-PCR, aiming at the amplification of a 245-bp fragment of the IAV matrix (M) protein gene. For coronaviruses, two fragments of 602 and 440bp corresponding to segments along the gene encoding the RNA-dependent RNA polymerase (RdRp) were targeted. The detection limit for each of the PCRs was also determined. All samples analyzed here were negative for both viruses, and the lower limit of detection of the PCRs for the amplification of influenza virus A and coronavirus was estimated at 3.5 × 103 and 4.59 genomic copies per microliter, respectively. Although bats have been shown to harbor a large number of pathogens, the results of the present study support the theory that virus circulation in bats in the wild often occurs at low viral loads and that our understanding of the complex infectious dynamics of these viruses in wild conditions is still limited.

Molecular detection and genotype diversity of hemoplasmas in non-hematophagous bats and associated ectoparasites sampled in peri-urban areas from Brazil

Hemoplasmas have already been detected in bats in the United States of America, Spain, Australia, Chile, Brazil, Peru, Belize, Nigeria, Costa Rica, Germany, Switzerland and New Caledonia. The recent detection of hemoplasmas closely related to Mycoplasma haematohominis, an agent causing disease in humans, emphasizes the need for additional studies on the diversity of hemoplasmas in bats. The present work aimed to investigate the occurrence and assess the phylogenetic positioning and genetic diversity of hemoplasmas in bats and associated ectoparasites sampled in central-western Brazil. Overall, 43% (58/135) sampled bats and 1.56% (1/64) bat flies (Megistopoda aranea) were positive for hemoplasmas, however, twenty-four and two hemoplasma sequences were obtained from PCR assays targeting 16S and 23S rRNA genes, respectively, since the majority of the obtained amplicons showed faint bands in agarose gel electrophoresis. The obtained 16S rRNA sequences showed to be broadly distributed along the phylogenetic tree, albeit positioned within the ‘Haemofelis group’ and clustering with other bat-associated hemoplasmas. Twelve 16S rRNA hemoplasma genotypes were found among the 24 obtained sequences. When compared to other bat-related hemoplasmas sequences retrieved from the Genbank, 52 genotypes were found. The two 23S rRNA sequences obtained were positioned as a sister clade to “Candidatus Mycoplasma haematohydrochaerus”, M. haemofelis and M. haemocanis. High genetic diversity was found among 16S rRNA hemoplasma sequences detected in non-hematophagous bats from central-western Brazil and previously detected in other regions of the world. Even though the genotype analysis showed that hemoplasmas from the same genus tend to group together, the results from the unipartite and bipartite analyses did not robustly support the hypothesis. Further studies addressing the specificity of hemoplasma genotypes according to bat species and genera should be performed.

Molecular Survey of Anaplasmataceae Agents and Coxiellaceae in Non-Hematophagous Bats and Associated Ectoparasites from Brazil

The Anaplasmataceae family (order Rickettsiales) encompasses obligately intracellular bacteria of the genera Anaplasma, Ehrlichia, and Neorickettsia. Together with Coxiella burnetii (Coxiellaceae family, order Legionellales), these bacteria represent important causative agents of diseases in humans and animals. The scarcity of studies that investigated the occurrence of these agents in bats and their associated ectoparasites, emphasizes the need to achieve a better understanding of the role of these animals in the maintenance of such bacteria. Herein, 418 samples (133 blood, 135 spleen, and 150 ectoparasites) are collected from 135 non-hematophagous bats belonging to 12 species in a periurban area of Campo Grande city, Mato Grosso do Sul state, midwestern Brazil. In the results, 1.65% (7/418), 12.04% (50/418), and 13.63% (57/418) of samples are positive in PCR assays for Anaplasma spp. (16S rRNA gene), Ehrlichia spp. (dsb gene), and Neorickettsia spp. (16S rRNA gene), respectively. Anaplasma spp. and Neorickettsia spp. are detected in one (5.26%) Ornithodoros hasei tick larva. Ehrlichia spp. is detected in 14% of bat flies (represented by Megistopoda aranea, Trichobius costalimai, and Strebla hertigi), 6% of tick larvae (O. hasei), 12% of Spinturnicidae mites (represented by Periglischrus sp., P. torrealbai, and P. acutisternus), and 38% of Macronyssidae mites (Steatonyssuss sp.). The obtained sequences are observed to be similar to Anaplasma phagocytophilum (97.42–97.6% identified), Ehrlichia minasensis (96.73–100% identified), Neorickettsia risticii (96.7–100% identified), and Neorickettsia findlayensis (95.07–100% identified) by BLASTn analyses, and closely related to Ehrlichia ruminantium by phylogenetic analyses based on the gltA gene. No bat samples (blood/spleen) are positive in the qPCR assay for C. burnetii based on the IS1111 gene. The present work shows, for the first time, the occurrence of Anaplasmataceae in bats and associated ectoparasites (ticks, mites, and bat flies) from Brazil.

Genetic identification of a rabies virus from an insectivorous bat in an urban area of Rio Grande do Sul, Brazil.

In Latin America, hematophagous bats are the main reservoirs of rabies virus (RABV) to livestock, to other mammals and, occasionally, to human. Nonetheless, reports of exposure of human and pets to RABV upon aggression by non-hematophagous bats are increasing, possibly facilitated by the synanthropic habits of these bats. We, herein, report the detection and genetic identification of a RABV recovered from an insectivorous bat found sick in a student housing building at the Federal University of Santa Maria, Southern Brazil. Taxonomic characterization identified the captured bat as a member of the genus Nyctinomops, family Molossidae, the group of insectivorous bats. Brain fragments of the bat were positive for RABV antigens by fluorescent antibody test (FAT) and for sequences of the nucleoprotein (N) gene by RT-PCR. The N amplicon was submitted to nucleotide sequencing and analysis, showing that the consensus sequences (SV 33/19) had high identity with RABV sequences of insectivorous bats deposited in GenBank. At phylogenetic tree, the N gene sequences of SV 33/19 clustered with RABV recovered from Nyctinomops laticaudatus, Molossus molossus, and Tadarida lauticaudata bats, and a part of RABV variant 3, 4, and 6, that correspond to Desmodus rotundus, Tadarida brasiliensis, and Lasiurus cinereus, respectively. Although no direct human or domestic animal exposure has been reported, this case strengthens the need for a continuous rabies vaccination in pets in the surrounding areas, since non-hematophagous bats may serve as source of infection for these animals. These findings also call attention for continuous monitoring of populations of synanthropic bats to avoid/prevent human exposure.

First molecular detection of piroplasmids in non-hematophagous bats from Brazil, with evidence of putative novel species.

Piroplasmida is an order of the phylum Apicomplexa that comprises the Babesia, Cytauxzoon, and Theileria genera. These hemoparasites infect vertebrate blood cells and may cause serious diseases in animals and humans. Even though previous studies have shown that bats are infected by different species of piroplasmids, the occurrence and diversity of these hemoparasites have not been investigated in this group of mammals in Brazil. Therefore, the present work aimed to investigate the occurrence and assess the phylogenetic placement of piroplasmids infecting bats sampled in a peri-urban area from Central-Western Brazil. Seventeen (12.6%) out of 135 animals were positive by nested PCR assay for the detection of Babesia/Theileria targeting the 18S rRNA gene. Eleven sequences of the 17 positive samples could be analyzed and showed an identity of 91.8-100% with Theileria bicornis, Babesia vogeli, a Babesia sp. identified in a small rodent (Thrichomys pachyurus) from the Brazilian Pantanal and a Babesia sp. identified in a dog from Thailand as assessed by nBLAST. A phylogenetic tree was constructed from an alignment of 1399bp length using analyzed and known piroplasmid 18S rRNA sequences. In this tree, piroplasmid 18S rRNA sequences detected in three specimens of Phyllostomus discolor (Piroplasmid n. sp., P. discolor) were placed as a sister taxon to Theileria sensu stricto (Clade V) and Babesia sensu stricto (Clade VI). An additional phylogenetic tree was generated from a shorter alignment of 524bp length including analyzed piroplasmid 18S rRNA sequences of bat species Artibeus planirostris and A. lituratus (Piroplasmid sp., Artibeus spp.). The two 18S rRNA sequences detected in Artibeus spp. (Piroplasmid n. sp., Artibeus spp.) were placed within Babesia sensu stricto (Clade VI) into a strongly supported clade (bootstrap: 100) that included Babesia vogeli. The two 18S rRNA sequences of Piroplasmid sp., Artibeus spp. showed a single and a two-nucleotide differences, respectively, with respect to B. vogeli in a 709pb length alignment. For the first time, the present study shows the occurrence of putative new piroplasmid species in non-hematophagous bats from Brazil.

Intra- and Inter-Host Assessment of Bartonella Diversity with Focus on Non-Hematophagous Bats and Associated Ectoparasites from Brazil.

The relationship among bats, ectoparasites and associated microorganisms is important to investigate how humans can become exposed to zoonotic agents. Even though the diversity of Bartonella spp. in bats and ectoparasites has been previously reported, the occurrence of gltA genotypes within hosts has not been assessed so far. We aimed to investigate the genetic diversity of Bartonella spp. in non-hematophagous bats and associated ectoparasites by assessing cloned gltA Bartonella genotypes in intra- and inter-hosts levels, as well as by using three additional molecular markers. Overall, 13.5% (18/133) bat blood samples, 17.18% bat flies (11/64) and 23.8% (5/21) Macronyssidae mite pools showed to be positive for Bartonella spp. Seventeen positive samples were submitted to gltA-cloning and three clones were sequenced for each sample. We also obtained 11, seven and three sequences for nuoG, rpoB and ftsZ genes, respectively. None were positive for the other target genes. We found at least two genotypes among the three gltA-cloned sequences from each sample, and 13 between all the 51 sequences. Among the nuoG, rpoB and ftsZ sequences we found eight, five and three genotypes, respectively. In the phylogenetic analysis, the sequences were positioned mainly in groups related to Bartonella identified in rodents, bats and bat flies. Herein, we showed the genetic diversity of Bartonella in bat’s blood and associated ectoparasites samples at both intra- and inter-host levels.

The Serological Prevalence of Rabies Virus-Neutralizing Antibodies in the Bat Population on the Caribbean Island of Trinidad.

Rabies virus (RABV) is the only lyssavirus known to be present within the Caribbean. The island of Trinidad, is richly diverse in chiropteran fauna and endemic for bat-transmitted rabies with low RABV isolation rates observed in this population. We aimed to determine the seroprevalence of rabies virus neutralizing antibodies (RVNA) in light of spatio-temporal and bat demographic factors to infer the extent of natural exposure to RABV in the Trinidadian bat population. RVNA titers were determined by the RABV micro-neutralization test on 383 bat samples representing 21 species, comprising 30.9% of local bat diversity, from 31 locations across the island over 5 years. RVNA was positively detected in 33 samples (8.6%) representing 6 bat species (mainly frugivorous) with titers ranging from 0.1 to 19 IU/mL (mean 1.66 IU/mL). The analyses based on a multivariable binomial generalised linear mixed-effects model showed that bat age and year of capture were significant predictors of seropositivity. Thus, juvenile bats were more likely to be seropositive when compared to adults (estimate 1.13; p = 0.04) which may suggest early exposure to the RABV with possible implications for viral amplification in this population. Temporal variation in rabies seropositivity, 2012–2014 versus 2015–2017 (estimate 1.07; p = 0.03) may have been related to the prevailing rabies epizootic situation. Regarding other factors investigated, RVNA was found in bats from both rural and non-rural areas, as well as in both hematophagous and non-hematophagous bat species. The most common seropositive species, Artibeus jamaicensis planirostris is ubiquitous throughout the island which may potentially facilitate human exposure. The findings of this study should be factored into public health assessments on the potential for rabies transmission by non-hematophagous bats in Trinidad.

Molecular detection of Hepatozoon spp. in non-hematophagous bats in Brazil

Even though Hepatozoon spp. has been molecularly detected in several wild animals in Brazil, there is no report on the occurrence of Hepatozoon spp. DNA in bats in Brazil. This study aimed at detecting Hepatozoon, in addition to ectoparasites, in non-hematophagous bats sampled in central-western Brazil using blood smears, hematoxylin-eosin (HE)-staining liver/spleen preparations and molecular and phylogenetic techniques. A total of 135 spleen, 127 liver, and 133 blood samples were collected from 135 non-hematophagous bats from 12 different species in two different sites in Campo Grande, Mato Grosso do Sul state, in the Brazilian Cerrado region. Spleen and blood DNA samples were submitted to two conventional PCR protocols for Hepatozoon spp. based on 18S rRNA. No Hepatozoon spp. gamonts or meronts were observed in blood smears and HE-stained-liver preparations, respectively. While none of the spleen samples was positive for Hepatozoon spp. in the PCR assays, 5 (3 %) blood samples contained 18S rRNA Hepatozoon DNA, including 2/37 (5 %) Artibeus lituratus, 2/32 (6 %) A. planirostris, and 1/23 (4 %) Platyrrhinus lineatus. Out of 5 bats positive for Hepatozoon spp., 3 were parasitized by either Macronyssidae/Spinturnicidae mites or Streblidae flies. BLAST analysis showed that the sequences detected in bats had >99 % identity with Hepatozoon sequences detected in amphibians and reptiles from Brazil, including Hepatozoon caimani detected in Caiman crocodilus. The phylogenetic inferences estimated by the Maximum Likelihood and Bayesian methods clustered the Hepatozoon sequences detected in Brazilian bats with those detected in reptiles and amphibians.

Hemotropic mycoplasmas (hemoplasmas) in free-ranging bats from Southern Brazil

Hemotropic mycoplasmas (hemoplasmas) are bacteria distributed worldwide and affect domestic and wildlife animals and human beings. Hemoplasmas have been described infecting hematophagous and non-hematophagous bats; however, transmission risk and zoonotic potential in vampire bats remain to be fully established. This study aimed to evaluate the presence of hemotropic mycoplasma species in free-ranging bats from this area using a universal PCR protocol for hemoplasmas. Accordingly, ten blood samples were collected from six male common vampire bats (Desmodus rotundus), two male hairy-legged vampire bats (Diphylla ecaudata), and two female non-hematophagous Pallas's mastiff bats (Molossus sp.) from the Curitiba’s region, Paraná State, Southern Brazil. A total of eight (8/10) blood samples were positive byconventional PCR; five (5/6) Desmodus rotundus, two (2/2) Diphylla ecaudata, and one (1/2) Molossus sp. bats. The analyses of the partial sequence of the 16S rDNA gene suggest that the hemoplasma detected in Desmodus rotundus in South Brazil has a high identity compared to the hemoplasma circulating in vampire bats from Central and South America.

Dengue Virus in Bats from Córdoba and Sucre, Colombia.

Natural infection of dengue virus (DENV) in bats is an unexplored field in Colombia. To detect the presence of DENV in bats, a descriptive prospective study using a nonprobabilistic sampling was carried out; 286 bats in 12 sites were caught. Sample tissues of different animals were obtained; the RNA was obtained from tissues and a nested-RT-PCR was carried out and detected amplicons of 143 fragment of the NS5 gene were sequenced by the Sanger method. In nonhematophagous bats Carollia perspicillata and Phyllostomus discolor captured in Ayapel and San Carlos (Córdoba), respectively, an amplicon corresponding to NS5 was detected. The amplicons showed a high similarity with serotype-2 dengue virus (DENV-2). This is the first evidence of the DENV-2 genome in bats in from the Colombian Caribbean.

First Report of Trypanosoma cruzi Infection in Salivary Gland of Bats from the Peruvian Amazon.

.In the Americas, 8 million people are infected with Chagas disease, and an additional 90 million people are at risk for infection. Little is known about the role bats play in the sylvatic transmission cycle of Trypanosoma cruzi, the parasite causing Chagas disease. Here, we captured bats in the villages of Palmiche, Pachacutec, Nuevo San Martin, and Mayuriaga located in the Datem del Marañon Province in Loreto, Peru. Venous blood samples were collected by cardiac puncture or from the upper extremities, and trypanosomatids were identified by microscopy and molecularly. We collected blood samples from 121 bats on filter paper for molecular studies and 111 slides for microscopic examination of thin and thick blood smears from 16 different bat species. The prevalence of trypanosomatids in all bats species was 34.7% (42/121) and the prevalence of T. cruzi was 4.1% (5/121). In hematophagous bat species, the prevalence of trypanosomatids and T. cruzi was 36.9% (27/73) and 2.7% (2/73), respectively. In non-hematophagous bats, the prevalences of trypanosomatids and T. cruzi were 31.2% (15/48) and 6.2% (3/48), respectively. Also, we confirm the presence of T. cruzi in salivary glands of hematophagous bats Diaemus youngi. These results suggest a sylvatic cycle of trypanosomatid transmission in which bats may harbor infectious T. cruzi parasites that could be transmitted to humans via hematophagous bat bites or salivary contamination by non-hematophagous bats of vegetables consumed by humans.

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.

Antigenic and genotypic characterization of rabies virus isolated from bats (Mammalia: Chiroptera) from municipalities in São Paulo State, Southeastern Brazil.

Bats have aroused growing attention in the publichealth sphere because they are considered the main reservoir of rabies virus (RABV) in the Americas, in places where canine rabies is under control. Antigenic and genetic studies of RABV isolates have been used to describe the epidemiological profile of rabies and to identify possible hosts/reservoirs for different epidemiological cycles. This study describes the antigenic and genotypic characterization of 19 RABV isolates from central nervous system samples of non-hematophagous bats (Mammalia: Chiroptera). These bats were diagnosed as RABV positive by direct fluorescent antibody and mouse inoculation tests. Antigenic characterization using a panel of eight monoclonal antibodies revealed that 7 of 19 RABV isolates from these bats belonged to variant 3, for which the hematophagous bat species Desmodus rotundus is the main reservoir, and 1 of 19 RABV isolates from an insectivorous bat belonged to variant 4, which is characteristic of these bats. The remaining 11 RABV samples were divided into six non-compatible profiles. The isolates were subjected to reverse transcription polymerase chain reaction for the N gene and partially sequenced. Genetic characterization of these isolates was performed by grouping the sequences obtained with known RABV lineages. The sequences were grouped in clusters by the phylogenetic inference neighbor-joining method, together with another 89 homologous sequences obtained from GenBank. This analysis grouped the isolates into four known lineages: Nyctinomops Brazil, Myotis Brazil, Eptesicus Brazil and D. rotundus Brazil, as well as another cluster that may define a RABV lineage not yet characterized, here named Myotis Brazil II, for which bats of the genus Myotis apparently act as reservoirs. This assumption of a new lineage is also based on the observation of amino acid substitutions, with an average intraspecific identity of 99.8%, varying from 99.6 to 100.0% for nucleotides and 100.0% for amino acids.

Monoclonal antibodies for characterization of rabies virus isolated from non-hematophagous bats in Brazil.

In Brazil, various isolates of rabies virus (RABV) show antigenic profiles distinct from those established by the reduced panel of eight monoclonal antibodies (MAbs) determined by the Centers for Disease Control and Prevention (CDC), utilized for the antigenic characterization of RABV in the Americas. The objective of this study was to produce MAbs from RABV isolates from insectivorous bats with an antigenic profile incompatible with the pre-established one. An isolate of RABV from the species Eptesicus furinalis that showed an antigenic profile incompatible with the panel utilized was selected. Hybridomas were produced utilizing the popliteal lymph nodes of mice immunized with ribonucleoproteins purified from the isolate. Two MAbs-producing clones were obtained, BR/IP1-3A7 and BR/IP2-4E10. Fifty-seven isolates of RABV from different species of animals and different regions of Brazil were analyzed utilizing the MAbs obtained. In the analysis of 23 RABV isolates from non-hematophagous bats, the MAbs cross-reacted with ten isolates, of which four were of the species Nyctinomops laticaudatus, one of the species Eptesicus furinalis, and five of the genus Artibeus. Of the nine isolates of non-hematophagous isolates that displayed an incompatible profile analyzed, characteristic of insectivorous bats, BR/IP1-3A7 reacted with five (55.55%) and BR/IP2-4E10 with four (44.44%). The MAbs obtained were able to recognize epitopes common between the three genera, Artibeus, Eptesicus, and Nyctinomops, thereby allowing the antigenic characterization of RABV isolates in Brazil.