Role of Brazilian bats in the epidemiological cycle of potentially zoonotic pathogens

Human cat borne rabies as the new epidemiology of the disease in the Andes mountains

BACKGROUND

Rabies virus (RABV) is the etiologic agent of rabies, a fatal brain disease in mammals. Rabies circulation has historically involved the dog has the main source of human rabies worldwide. Nevertheless, in Colombia, cats (Felis catus) have become a relevant species in the epidemiology of rabies.

AIMS

To characterize rabies cases in humans in Colombia in the last three decades in the context of the epidemiology of the aggressor animal.

MATERIALS AND METHODS

We conducted a retrospective longitudinal epidemiological study of human rabies caused by cats' aggression, collecting primary and secondary information. Variables considered included the demography of the patient, symptoms, information about the aggressor animal as the source of infection and the viral variant identified.

RESULTS

We found that the distribution of rabies incidence over the years has been constant in Colombia. Nevertheless, between 2003 and 2012 a peak of cases occurred in rural Colombia where cats were the most frequent aggressor animal reported. Most cats involved in aggression were unvaccinated against rabies. Cat's clinical signs at the time of the report of the human cases included hypersalivation and changes in behaviour. Human patients were mostly children and female and the exposure primarily corresponded to bite and puncture lacerations in hands. The RABV lineage detected in most cases corresponded to variant 3, linked to the common vampire bat (Desmodus rotundus). The geographical presentation of cat borne RABV in humans occurred along the Andes mountains, epidemiologically known as the rabies red Andean corridor.

DISCUSSION

By finding cats as the primary source of rabies spillover transmission in Colombia, this report highlights the importance of revising national rabies control and prevention protocol in countries in the Andes region.

CONCLUSION

Our results demonstrate that rabies vaccination for outdoor cats needs to prioritize to reduce the number of rabies-related human deaths.

Bartonella spp. in different species of bats from Misiones (Argentina)

The aim of this study was to detect vector-borne pathogens (Anaplasmataceae family, Rickettsia genus, and Bartonella genus) in bats from Misiones (Argentina). Thirty-three specimens were captured over 8 days using mist nets. Twenty (60.6%) blood samples were positive (11/13 Artibeus lituratus, 4/10 Desmodus rotundus, 4/8 Carollia perspicillata, and 1/2 Myotis nigricans) by PCR for the gltA gene fragment of Bartonella. All samples were negative by PCR for the Anaplasmataceae family and Rickettsia genus. The phylogenetic analysis showed seven Bartonella genotypes. The three genotypes obtained from A. lituratus, 2 from C. perspicillata, and 1 from D. rotundus were related to Bartonella spp. from New World bats, while the sequence obtained from M. nigricans was related to Old World bats. We identified a considerable diversity of Bartonella genotypes in a small number of bats, thus further research is required to better understand the complex bat-pathogen interaction.

Enterocytozoon bieneusi and Cryptosporidium bat genotype XXI and bat genotype XXII in fruit bats (Rousettus leschenaultii) inhabiting a tropical park in Hainan Province, China

Bats stand as one of the most diverse groups in the animal kingdom and are key players in the global transmission of emerging pathogens. However, their role in transmitting Enterocytozoon bieneusi and Cryptosporidium spp. remains unclear. This study aimed to evaluate the occurrence and genetic diversity of the two pathogens in fruit bats (Rousettus leschenaultii) in Hainan, China. Ten fresh fecal specimens of fruit bats were collected from Wanlvyuan Gardens, Haikou, China. The fecal samples were tested for E. bieneusi and Cryptosporidium spp. using Polymerase Chain Reaction (PCR) analysis and sequencing the internal transcribed spacer (ITS) region and partial small subunit of ribosomal RNA (SSU rRNA) gene, respectively. Genetic heterogeneity across Cryptosporidium spp. isolates was assessed by sequencing 4 microsatellite/minisatellite loci (MS1, MS2, MS3, and MS16). The findings showed that out of the ten specimens analyzed, 2 (20 %) and seven (70.0 %) were tested positive for E. bieneusi and Cryptosporidium spp., respectively. DNA sequence analysis revealed the presence of two novel Cryptosporidium genotypes with 94.4 to 98.6 % sequence similarity to C. andersoni, named as Cryptosporidium bat-genotype-XXI and bat-genotype-XXII. Three novel sequences of MS1, MS2 and MS16 loci identified here had 95.4 to 96.9 % similarity to the known sequences, which were deposited in the GenBank. Two genotypes of E. bieneusi were identified, including a novel genotype named HNB-I and a zoonotic genotype PigEbITS7. The discovery of these novel sequences provides meaningful data for epidemiological studies of the both pathogens. Meanwhile our results are also presented that the fruit bats infected with E. bieneusi, but not with Cryptosporidium, should be considered potential public health threats.

Comparative Analysis of the Gut Microbiota of Bat Species with Different Feeding Habits

Bats are a diverse and ecologically important group of mammals that exhibit remarkable diversity in their feeding habits. These diverse feeding habits are thought to be reflected in the composition and function of their gut microbiota, which plays important roles in nutrient acquisition, immune function, and overall health. Despite the rich biodiversity of bat species in South America, there is a lack of microbiome studies focusing on bats from this region. Such studies could offer major insights into conservation efforts and the preservation of biodiversity in South America. In this work, we aimed to compare the gut microbiota of four bat species with different feeding habits from Southern Brazil, including nectarivorous, frugivorous, insectivorous, and hematophagous bats. Our findings demonstrate that feeding habits can have a significant impact on the diversity and composition of bat gut microbiotas, with each species exhibiting unique metabolic potentials related to their dietary niches. In addition, the identification of potentially pathogenic bacteria suggests that the carriage of microbial pathogens by bats may vary, depending on feeding habits and host-specific factors. These findings provide novel insights into the relationship between bat feeding habits and gut microbiota composition, highlighting the need to promote diverse habitats and food sources to support these ecologically important species.

A novel hantavirus identified in bats (Carollia perspicillata) in Brazil

Bats play an essential role in maintaining ecosystems. Their unique characteristics increase the likelihood of interactions with various species, making them a potential source for the emergence and spread of infectious diseases. Hantaviruses are continuously expanding their range of hosts. This study presents the identification of a partial genome associated with Hantavirus in samples collected from neotropical bats. We conducted a metagenomic study using samples from Carollia perspicillata in Maranhão, Brazil. Tissue fragments were used for RNA extraction and subsequent sequencing. The resulting data was subjected to bioinformatic analysis. A sequence showing an identity of 72.86% with the L gene in the reference genome was obtained. The phylogenetic analysis revealed the study sequence, denoted as Buritiense, clustering within the Mobatvirus clade. The intragroup analysis showed a broader dispersion and were markedly asymmetric. This observation suggests the possibility that Buritiense could potentially represent a new species within the bat-borne hantaviruses, but further analyses are needed to provide additional insights if bats plays a role as reservoirs and the potential for transmission to human populations.

Molecular detection and characterization of Bartonella spp. in small mammals in the Amazonia and Cerrado biomes, midwestern Brazil

Although Bartonella spp. have been worldwide described in rodents and bats, few studies have reported these agents in marsupials. The present work aimed to investigate the occurrence and genetic diversity of Bartonella in small mammals (rodents, marsupials, and bats) and associated ectoparasites in two ecoregions (Amazonia and Cerrado biomes) in midwestern Brazil. For this purpose, DNA samples from 378 specimens of small mammals (128 rodents, 111 marsupials, and 139 bats) and 41 fleas (Siphonaptera) were screened for the Bartonella genus employing a quantitative real-time PCR assay (qPCR) based on the nuoG (nicotinamide adenine dinucleotide dehydrogenase gamma subunit) gene. Then, positive samples in qPCR were submitted to conventional PCR (cPCR) assays targeting the gltA, ftsZ, and rpoB genes. One (0.78 %) rodent, 23 (16.54 %) bats, and 3 (7.31 %) fleas showed positive results in the qPCR for Bartonella sp. After cPCR amplification and sequencing, 13 partial Bartonella DNA sequences of the following genes were obtained only from bats´ blood samples: 9 gltA (citrate synthase), 3 ftsZ (cell division protein), and 1 rpoB (RNA polymerase beta subunit). The maximum likelihood inference based on the gltA gene positioned the obtained sequences in three different clades, closely related to Bartonella genotypes previously detected in other bat species and bat flies sampled in Brazil and other countries from Latin America. Similarly, the ftsZ sequences clustered in two different clades with sequences described in bats from Brazil, other countries from Latin America, and Georgia (eastern Europe). Finally, the Bartonella rpoB from a specimen of Lophostoma silvicolum clustered with a Bartonella sp. sequence obtained from a Noctilio albiventris (KP715475) from French Guiana. The present study provided valuable insights into the diversity of Bartonella genotypes infecting bats from two ecoregions (Amazonia and Cerrado) in midwestern Brazil and emphasized that further studies should be conducted regarding the description and evaluation of different lineages of Bartonella in wild small mammals and their ectoparasites in different Brazilian biomes.

Metagenomic of Liver Tissue Identified at Least Two Genera of Totivirus-like Viruses in Molossus molossus Bats

The Totiviridae family of viruses has a unique genome consisting of double-stranded RNA with two open reading frames that encode the capsid protein (Cap) and the RNA-dependent RNA polymerase (RdRpol). Most virions in this family are isometric in shape, approximately 40 nm in diameter, and lack an envelope. There are five genera within this family, including Totivirus, Victorivirus, Giardiavirus, Leishmaniavirus, and Trichomonasvirus. While Totivirus and Victorivirus primarily infect fungi, Giardiavirus, Leishmaniavirus, and Trichomonasvirus infect diverse hosts, including protists, insects, and vertebrates. Recently, new totivirus-like species have been discovered in fish and plant hosts, and through metagenomic analysis, a novel totivirus-like virus (named Tianjin totivirus) has been isolated from bat guano. Interestingly, Tianjin totivirus causes cytopathic effects in insect cells but cannot grow in mammalian cells, suggesting that it infects insects consumed by insectivorous bats. In this study, we used next-generation sequencing and identified totivirus-like viruses in liver tissue from Molossus molossus bats in the Amazon region of Brazil. Comparative phylogenetic analysis based on the RNA-dependent RNA polymerase region revealed that the viruses identified in Molossus bats belong to two distinct phylogenetic clades, possibly comprising different genera within the Totiviridae family. Notably, the mean similarity between the Tianjin totivirus and the totiviruses identified in Molossus bats is less than 18%. These findings suggest that the diversity of totiviruses in bats is more extensive than previously recognized and highlight the potential for bats to serve as reservoirs for novel toti-like viruses.

Cat rabies in Brazil: a growing One Health concern

This review of human and cat rabies from 1986 to 2022 has shown mostly AgV3 variant in human cases with 29/45 (64.4%) reports including 23 from bats, four from cats, and two from unknown species, followed by 8/45 (17.8%) of AgV2 variant (all from dogs), 4/45 from marmoset variant (all from Callithrix jacchus), 2/45 samples compatible with wild canid variant (both from Cerdocyon thous), and one/45 of AgV1 variant from a domestic dog. Only one sample of human rabies was not typified, related to bat aggression. In addition, surveillance conducted in the state of São Paulo confirmed the presence of rabies in 7/23,839 cats (0.031%) and 3/106,637 dogs (0.003%) between 2003 and 2013, with a 10:1 overall cat-to-dog positivity ratio. This 10-fold higher infection rate for cat rabies may be explained by cats' hunting habits and predation. In addition, after 28 years of rabies-free status, a new cat rabies case was reported in the city of São Paulo in 2011. The rabid cat lived, along with other pets, in a household located near the largest downtown city park, whose owners presented animal hoarding behavior. Thus, animal hoarders and rescuers, public health agents, animal health professionals, and the general population with contact need to be aware of the risk of bat-borne rabies followed by spillover from cats to humans. In conclusion, cat rabies cases are becoming increasingly important in Brazil. This poses a One Health concern, given the overlapping of human, bat and cat populations within the same predisposed environment.