Desmodus Rotundus Research Articles

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.

Phylogenetic analysis of near full-length sequences of the Desmodus rotundus genetic lineage of rabies virus

The World Health Organization (WHO), reports that rabies causes tens of thousands of deaths every year killing humans, non-human primates and other animals. Rabies continues to be a public health issue, despite the existence of effective vaccines. The dogs remain the primary reservoir and transmitter of rabies to humans globally. In the Americas, bats are regarded as the second most common source of rabies virus to humans. The vampire bat Desmodus rotundus has been identified as a natural reservoir of rabies virus (RABV) in this region. The complete genome of the RABV variant maintained by populations of vampire bats D. rotundus has rarely been reported. In this study, we sequenced and analyzed the genome of a RABV variant detected in D. rotundus. The sample, collected from an endemic area in São Paulo State, was phylogenetically compared with the genome of the standard sample for species Rabies virus as well as other samples belonging to terrestrial and bat-associated cycles of rabies transmission, available in GenBank. Distinct patterns linked to the genetic lineage were identified. These data can aid in the understanding of the molecular epidemiology of this virus and the epidemiological importance of this species in the transmission of the RABV.

Vampire bat reservoir and main transmitter of rabies, a public health problem in Mexico

Rabies is considered a re-emerging disease due to increased contact with the reservoir. The vampire bat Desmodus rotundus is the reservoir and main transmitter of this disease. Alterations in the natural environment have caused imbalances of impact on the ecology, influencing the movement of the reservoir from natural areas to rural and urban environments, where there are human settlements and the presence of domestic animals. The objective of this work has been to present the most relevant aspects about the role of the vampire bat as a natural reservoir and main transmitter of rabies in the region in order to raise awareness in the population about the risk this is to public health. Attacks by vampire bat Desmodus rotundus on livestock species are becoming more frequent, even in regions that for decades had been considered free from rabies. This represents a public health problem, because these cases can generate contacts between infected animals and people.

Relations between topography, feeding sites, and foraging behavior of the vampire bat, Desmodus rotundus

AbstractThe vampire bat (Desmodus rotundus) plays a crucial role in the maintenance and transmission of the rabies virus to humans and livestock, impacting public health and economic production. Its importance lies not only in its capacity to transmit the virus but also in its ability to adapt to anthropic changes, as expressed in its wide geographic distribution in Latin America. Deforestation, livestock intensification, and other human activities have reduced the abundance of its wild prey but have also provided new and abundant shelter and foraging resources for the vampire bats. We used radiotelemetry to evaluate relations between topography, feeding site choice, and foraging behavior in southeastern Brazil, where three occupied D. rotundus roosts, out of 11 possible, were systematically monitored throughout a 1-year period once every 2 months. Sixty-two vampire bats were captured; biometric data were collected and 44 radiotransmitters were installed in adult individuals, producing telemetry data that were recorded in VHF receptors installed in the farms. Elevation of the roosts was related to the farms attacked by the vampire bats. Understanding the use of the environment and resources by vampire bats is critical to improving rabies control aiming at the reduction of disease impacts. From the perspective of the official veterinary service, telemetry would be ineffective as a rabies surveillance system due to the costs and limitations of the available technology. However, livestock rabies control measures would be greatly improved if ecological characteristics of the vampire bat were considered.

Vampire bats.

Gerald Wilkinson introduces the blood-drinking vampire bats.

Development and evaluation of a duplex TaqMan qPCR assay for detection and quantification of Trypanosoma cruzi infection in domestic and sylvatic reservoir hosts

BackgroundA question of epidemiological relevance in Chagas disease studies is to understand Trypanosoma cruzi transmission cycles and trace the origins of (re)emerging cases in areas under vector or disease surveillance. Conventional parasitological methods lack sensitivity whereas molecular approaches can fill in this gap, provided that an adequate sample can be collected and processed and a nucleic acid amplification method can be developed and standardized. We developed a duplex qPCR assay for accurate detection and quantification of T. cruzi satellite DNA (satDNA) sequence in samples from domestic and sylvatic mammalian reservoirs. The method incorporates amplification of the gene encoding for the interphotoreceptor retinoid-binding protein (IRBP), highly conserved among mammalian species, as endogenous internal amplification control (eIAC), allowing distinction of false negative PCR findings due to inadequate sample conditions, DNA degradation and/or PCR interfering substances.ResultsThe novel TaqMan probe and corresponding primers employed in this study improved the analytical sensitivity of the assay to 0.01 par.eq/ml, greater than that attained by previous assays for Tc I and Tc IV strains. The assay was tested in 152 specimens, 35 from 15 different wild reservoir species and 117 from 7 domestic reservoir species, captured in endemic regions of Argentina, Colombia and Mexico and thus potentially infected with different parasite discrete typing units. The eIACs amplified in all samples from domestic reservoirs from Argentina and Mexico, such as Canis familiaris, Felis catus, Sus scrofa, Ovis aries, Equus caballus, Bos taurus and Capra hircus with quantification cycles (Cq’s) between 23 and 25. Additionally, the eIACs amplified from samples obtained from wild mammals, such as small rodents Akodon toba, Galea leucoblephara, Rattus rattus, the opossums Didelphis virginiana, D. marsupialis and Marmosa murina, the bats Tadarida brasiliensis, Promops nasutus and Desmodus rotundus, as well as in Conepatus chinga, Lagostomus maximus, Leopardus geoffroyi, Lepus europaeus, Mazama gouazoubira and Lycalopex gymnocercus, rendering Cq’s between 24 and 33.ConclusionsThis duplex qPCR assay provides an accurate laboratory tool for screening and quantification of T. cruzi infection in a vast repertoire of domestic and wild mammalian reservoir species, contributing to improve molecular epidemiology studies of T. cruzi transmission cycles.

The common vampire bat Desmodus rotundus (Chiroptera: Phyllostomidae) and the transmission of the rabies virus to livestock: A contact network approach and recommendations for surveillance and control

The importance of the common vampire bat Desmodus rotundus for the transmission of the rabies virus does not lie solely in its ability to transmit this disease to other mammals, but also in its capacity to adapt to environmental and climatic changes, granting them a wide geographical distribution. Control of this disease is currently based on culling of the vampire bat and vaccination of the livestock. A transmission model incorporating geographic and behavioral determinants of the vampire bat was proposed to direct and optimize the epidemiological surveillance and control of livestock rabies. This model was built using a bimodal network connecting 260 vampire bat roosts among themselves (roost-roost-network) and with 1557 farms (roost-farm network) in eastern Sao Paulo State, Brazil. These roosts were grouped in 9 communities, some very interconnected, and some not and the farms were grouped in 14 communities. From 2013 to 2017, 44 livestock rabies outbreaks occurred in the area, circulating among the farm communities during the entire period, with possible introductions from neighboring areas. Based on the network and environment parameters, it was possible to reasonably predict both the roosts’ occupation type (harem, bachelor, overnight and empty) and livestock rabies outbreak occurrence. The network approach brings light to the importance of phylogenetic studies of bats and rabies virus. Finally, the understanding of the interactions between bats and their feeding sources, influenced by the environment, allows to establish more precise surveillance and control measures and, ultimately, with a lower cost-benefit ratio of these actions.

Spatiotemporal analysis of rabies in cattle in central Mexico.

Spatial epidemiology of bat-transmitted rabies in cattle has been limited to spatial distribution of cases, an approach that does not identify hidden patterns and the spread resulting in outbreaks in endemic and susceptible areas. Therefore, the purpose of this study was to determine the relationship between the three variables average annual maximum, annual minimum temperature and precipitation in the region on the one hand, and the spatial distribution of cases on the other, using geographic information systems and co-Kriging considering that these environmental variables condition the existence of the rabies vector Desmodus rotundus. A stationary behaviour between the primary and the secondary variables was verified by basic statistics and moving window statistics. The directions of greater and lesser spatial continuity were determined by experimental cross-semivariograms. It was found that the highest risk for bovine paralytic rabies occurs in areas known as La Huasteca Potosina and La Sierra Gorda that are characterized by a maximum temperature of 29.5 °C, a minimum temperature of 16.5 °C and precipitation of 1200 mm. A risk estimation map was obtained for the presence of rabies with a determination coefficient greater than 95%, and a correlation coefficient greater than 0.95. Our conclusion is that ordinary co- Kriging provides a better estimation of risk and spatial distribution of rabies than simple Kriging, making this the method recommended for risk estimation and regional distribution of rabies.

Vampire Bats that Cooperate in the Lab Maintain Their Social Networks in the Wild.

Social bonds, maintained by mutual investments of time and energy, have greatly influenced the evolution of social cognition and cooperation in many species [e.g., 1-8]. However, there are two pitfalls regarding "social bonds" as an explanation for social structure and cooperation [1, 9-11]. First, studies often incorrectly assume that frequent association implies partner fidelity based on mutual social preference, but even seemingly complex nonrandom interaction networks can emerge solely from habitat or spatial structure [12-16]. Second, the false appearance of partner fidelity can result from stable options in the "partner market" [1, 9-11, 17]. For instance, individuals might preferentially groom the same partner, even if the decision depends entirely on the immediate costs and benefits rather than relationship history. Given these issues, a key challenge has been testing the extent to which social structure is driven by the intrinsic relationship history versus the extrinsic physical and social environment. If stable bonds exist, they should persist even if the individuals are moved to a dramatically different physical and social environment. We tested this prediction by tracking social relationships among common vampire bats (Desmodus rotundus) moved from the lab to the wild. We show that allogrooming and food sharing among female vampire bats induced in captivity over 22months predicted their assortativity and association rates when we subsequently tracked them in the wild with custom-made high-resolution proximity sensors. The persistence of many relationships across different physical and social environments suggests that social structure is caused by both extrinsic constraints and intrinsic partner fidelity.

Demographic and environmental drivers of metagenomic viral diversity in vampire bats.

Viruses infect all forms of life and play critical roles as agents of disease, drivers of biochemical cycles and sources of genetic diversity for their hosts. Our understanding of viral diversity derives primarily from comparisons among host species, precluding insight into how intraspecific variation in host ecology affects viral communities or how predictable viral communities are across populations. Here we test spatial, demographic and environmental hypotheses explaining viral richness and community composition across populations of common vampire bats, which occur in diverse habitats of North, Central and South America. We demonstrate marked variation in viral communities that was not consistently predicted by a null model of declining community similarity with increasing spatial or genetic distances separating populations. We also find no evidence that larger bat colonies host greater viral diversity. Instead, viral diversity follows an elevational gradient, is enriched by juvenile‐biased age structure, and declines with local anthropogenic food resources as measured by livestock density. Our results establish the value of linking the modern influx of metagenomic sequence data with comparative ecology, reveal that snapshot views of viral diversity are unlikely to be representative at the species level, and affirm existing ecological theories that link host ecology not only to single pathogen dynamics but also to viral communities.

Landscape and cattle management attributes associated with the incidence of Desmodus rotundus attacks on cattle

Bovine paralytic rabies, transmitted by Desmodus rotundus, causes economic losses for Latin American livestock producers. Although the total number of reported cases has decreased markedly due to vaccination campaigns, economic losses can be significant for smallholders. Identifying risk factors for vampire bat attacks on cattle could help guide preventive control efforts in specific areas. The objective of this study was to analyze the relationship between the incidence of D. rotundus attacks on cattle and various landscape features and cattle management practices in northeastern Puebla, Mexico. We visited 61 properties with cattle between May and October 2011, in which we quantified the incidence of attacks on cattle and described landscape and cattle management attributes. The following features were described within a 200-m radius around the nightly resting site of cattle: topography, percent forest cover, and number of forest fragments, rivers and streams, tree lines, buildings, roads and highways. With these variables, we built models that were assumed to describe the levels of human interference, prey availability, and movement facilitation for bats. The human interference model (number of buildings plus number of roads) best explained the incidence of attacks on cattle. According to our results, the cattle with the highest vulnerability to attacks by vampire bats are those resting at night in less confined sites, far away from human activity. Results of this study suggest that rabies vaccination campaigns on cattle should focus on fragmented areas with few livestock management practices.

Use of linear features by the common vampire bat (Desmodus rotundus) in a tropical cattle-ranching landscape

Linear landscape features are used by many species of insectivorous bats as flight routes and foraging zones, as well as for providing protection against environmental factors and predation. However, very little is known about the role that these landscape features play for non-insectivorous species. In this study, we evaluated the use of linear features by the common vampire bat (Desmodus rotundus) in a cattle-ranching landscape in the state of Tabasco, Mexico. We selected 24 sampling sites in 2014 and 24 independent sites in 2016 to 2017, all adjacent to three types of linear landscape features: forest edges, live fences and streams . We monitored each site for two non-consecutive nights between February and April 2014, and every two months from February 2016 to June 2017. We placed 24 m (2014) or 12 m (2016 to 2017) of mist nets perpendicular to the linear feature from its edge. We recorded the height and distance from the edge for each individual captured. In total we captured 50 D. rotundus individuals in 2014 and 58 in 2016 to 2017. The average flight height was 77 cm for the 2014 data and 69 cm for 2016 to 2017. According to our results, the most used linear features were forest edges, followed by live fences and streams. Overall, 52 % of the 2014 captures and 62 % of the 2016 to 2017 ones occurred in the first 2 m from the edge, with the number of captures gradually decreasing with increasing distance. This study provides information on the commuting patterns of D. rotundus in predominantly open cattle-ranching landscapes.

Do vampire bats groom others based on need?

AbstractAllogrooming provides a window into the social lives of many group-living mammals and birds. The fitness benefits of allogrooming are encouraged by proximate mechanisms that make it physiologically rewarding for both actors and receivers. However, receivers might not always benefit from allogrooming. Some allogrooming decisions might be the actor’s response to cues of the recipient’s need. Other decisions might only be caused by the actor’s motivational state. To test these ideas, we studied what triggers allogrooming in common vampire bats. In test 1, subjects that had experimentally disturbed and wetted fur were more likely to be allogroomed, even when controlling for increased self-grooming. In test 2, allogrooming rates were elevated not only by receiver self-grooming (a cue for receiver need) but also by the actor’s previous self-grooming. Both effects were significantly greater than the effect of self-grooming by third parties. Interestingly, we detected a negative interaction: the positive effect of receiver need on allogrooming was smaller when the actor was previously self-grooming. This is consistent with the hypothesis that there are “receiver-driven” allogrooming decisions, which are responses to recipient need, and “actor-driven” decisions, which are not. We predict that receiver-driven allogrooming will bestow greater benefits to recipients compared with actor-driven allogrooming.

Adaptive Evolution of C-Type Lysozyme in Vampire Bats.

In mammals, chicken-type (c-type) lysozymes are part of the innate immune system, killing bacteria by degrading peptidoglycan in their cell walls. Many of the studies on the evolution of c-type lysozymes have focused on its new digestive function, including the duplicated stomach lysozymes in ruminants. Similarly, in bats, gene duplications and subsequent adaptive evolution of c-type lysozyme have been reported in a clade of insectivorous species, which might have been driven by the need to digest chitin. However, no studies on the evolution of c-type lysozyme have been carried out in the second largest and dietary diverse bat family Phyllostomidae, which includes insectivorous, frugivorous, nectarivorous and sanguivorous species. Here, we sequenced and analyzed c-type lysozyme genes from four phyllostomid bats, the common vampire bat, the white-winged vampire bat, the lesser long-nosed bat and the big fruit-eating bat. Only a single lysozyme gene was identified in each of these species. Evidence for positive selection on mature lysozyme was found on lineages leading to vampire bats, but not other bats with single copy lysozyme genes. Moreover, several amino acid substitutions found in mature lysozymes from the sanguivorous clade are predicted to have functional impacts, adding further evidence for the adaptive evolution of lysozyme in vampire bats. Functional adaptation of vampire bat lysozymes could be associated with anti-microbial defense, possibly driven by the specialized sanguivory-related habits of vampire bats.

The role of past experience in development of feeding behavior in common vampire bats.

The life history strategy of common vampire bats (Desmodus rotundus) suggests that learning might play a role in development of their foraging skills. We took advantage of 12 captive births in a study colony of vampire bats to test the role of past experience in two aspects of feeding. First, we compared preferences for blood temperature in 32 wild-born vampire bats versus 11 captive-born vampire bats that had only previously fed on blood of ambient temperature or colder. We found no evidence for a preference in either group for blood presented at 4 °C versus 37 °C. Second, we tested whether captive-born vampire bats with no previous experience of feeding on live animals could successfully feed on a live chicken. Five of 12 naïve captive-born bats were able to bite the chicken and draw blood, but only one bat gained more than 5% of body mass. We were unable to reasonably compare their feeding performance with that of wild-born bats because only two of three wild-born, short-term captive bats fed on the chicken and none of the seven wild-born, long-term captive mothers attempted to feed. This unexpected lack of feeding might be due to a previously reported age-dependent neophobia. When six of the captive-born bats were released in the wild, they appeared to feed successfully because they survived for more than three consecutive nights. We suggest further tests that would better clarify the role of learning in the development of foraging in vampire bats.

Genetic diversity of Bartonella spp. in vampire bats from Brazil.

Recently, an increasing number of Bartonella species have been emerged to cause human diseases. Among animal reservoirs for Bartonella spp., bats stand out due to their high mobility, wide distribution, social behaviour and long-life span. Although studies on the role of vampire bats in the epidemiology of rabies have been extensively investigated in Latin America, information on the circulation and genetic diversity of Bartonella species in these bat species is scarce. In the present work, 208 vampire bats, namely Desmodus rotundus (the common vampire bat; n=167), Diphylla ecaudata (the hairy-legged vampire bat; n=32) and Diaemus youngii (the white-winged vampire bat; n=9) from 15 different states in Brazil were sampled. DNA was extracted from liver tissue samples and submitted to real-time PCR (qPCR) and conventional PCR (cPCR) assays for Bartonella spp. targeting five genetic loci, followed by phylogenetic and genotype network analyses. Fifty-one out of 208 liver samples (24.51%) were positive for Bartonella DNA in the ITS real-time PCR assay [40 (78.43%) of them were from D.rotundus from 11 states, and 11 (21.57%) samples from D.ecaudata from three states. Eleven genotypes were found for each gltA and rpoB genes. Several ITS sequences detected in the present study clustered within the lineage that includes B.bacilliformis and B.ancachensis. The Bayesian phylogenetic inference based on the gltA gene positioned the obtained sequences in six different clades, closely related to Bartonella genotypes previously detected in D.rotundus and associated ectoparasites sampled in Latin America. On the other hand, the Bartonella rpoB genotypes clustered together with the ruminant species, B.schoenbuchensis and B.chomelii. The present study describes for the first time the molecular detection of Bartonella spp. in D.ecaudata bats. It also indicates that Bartonella spp. of vampire bats are genetically diverse and geographically widespread in Brazil.

Modelo de vulnerabilidade à circulação do vírus rábico entre abrigos de morcegos hematófagos no município de São Pedro-SP

O morcego hematófago Desmodus rotundus é o principal transmissor da raiva dos herbívorosdomésticos, que causa enormes prejuízos econômicos na pecuária da América Latina. A partirda análise e combinação de determinantes que que contribuem para a exposição e a difusão dovírus da raiva (Variante 3) entre morcegos, foi possível estimar qualitativamente avulnerabilidade à circulação do vírus rábico entre abrigos de D. rotundus no Município de SãoPedro. A maioria dos abrigos mostrou-se pouco vulneráveis à circulação do vírus rábico, devidoprincipalmente a ausência do vírus no Município e ao baixo número de D. rotundus habitandoa maioria dos abrigos. O modelo apresentado possui baixo custo, podendo ser feito emsoftwares gratuitos de Sistemas de Informação Geográfica (SIG) ou utilizando somente umaparelho receptor GPS, permitindo otimizar o monitoramento e intervenções de controle daraiva dos herbívoros, com economia de tempo e recursos

Bats are unusually insensitive to brief low-frequency tones.

Bats use brief calls for echolocation, suggesting that they might be more sensitive to brief sounds than non-echolocating mammals. To investigate this possibility, absolute thresholds for brief tones were determined for four species of bats: The Commonvampire bat (Desmodus rotundus) and the Greater spear-nosed bat (Phyllostomus hastatus), both of which use frequency-modulated calls, the Egyptian fruit bat (Rousettus aegyptiacus), an echolocator that uses tongue-clicks rather than laryngeal calls, and the Dog-faced fruit bat (Cynopterus brachyotis), a non-echolocating species. Norway rats and a human were tested for comparison using the same acoustic stimuli. Contrary to expectations, the echolocating bats were not superior to non-echolocating mammals in detecting brief tones in the frequency range of their echolocation calls. Instead, all four species of bats were remarkably less sensitive than non-bats to brief sounds of 10kHz and below. This implies that temporal summation in the mammalian auditory system can show large species differences, and that the detection of brief sound is likely influenced by the selective pressures on each species as well as by the physical integration of energy in the auditory system. Such species differences in function are expected to be reflected in the physiology of their auditory systems.

Habitat fragmentation is associated with dietary shifts and microbiota variability in common vampire bats.

Host ecological factors and external environmental factors are known to influence the structure of gut microbial communities, but few studies have examined the impacts of environmental changes on microbiotas in free‐ranging animals. Rapid land‐use change has the potential to shift gut microbial communities in wildlife through exposure to novel bacteria and/or by changing the availability or quality of local food resources. The consequences of such changes to host health and fitness remain unknown and may have important implications for pathogen spillover between humans and wildlife. To better understand the consequences of land‐use change on wildlife microbiotas, we analyzed long‐term dietary trends, gut microbiota composition, and innate immune function in common vampire bats (Desmodus rotundus) in two nearby sites in Belize that vary in landscape structure. We found that vampire bats living in a small forest fragment had more homogenous diets indicative of feeding on livestock and shifts in microbiota heterogeneity, but not overall composition, compared to those living in an intact forest reserve. We also found that irrespective of sampling site, vampire bats which consumed relatively more livestock showed shifts in some core bacteria compared with vampire bats which consumed relatively less livestock. The relative abundance of some core microbiota members was associated with innate immune function, suggesting that future research should consider the role of the host microbiota in immune defense and its relationship to zoonotic infection dynamics. We suggest that subsequent homogenization of diet and habitat loss through livestock rearing in the Neotropics may lead to disruption to the microbiota that could have downstream impacts on host immunity and cross‐species pathogen transmission.

Influence of landscape structure on the abundance of Desmodus rotundus (Geoffroy 1810) in northeastern Yucatan, Mexico

Although the transformation of landscapes by human activity can negatively affect the populations of several bat species, other species may benefit from these transformations. One of such species is the vampire bat, Desmodus rotundus, which can often be found in landscapes dominated by livestock activities. Furthermore, there are certain structural landscape characteristics that could be positively influencing the abundance of the vampire bat. To assess this possibility, eight sampling sites in northeastern Yucatan, Mexico were monitored from June 2010 to February 2012. Four sites were located in forest fragments amongst a highly fragmented landscape dominated by pastures dedicated to livestock activities, and four sites were located within continuous tropical semideciduous forest with almost no fragmentation. Forest fragmentation was characterized around the sampling sites within a 2.5 km radius using SPOT images from 2010, and five landscape variables were calculated using FRAGSTATS. The results showed that landscape heterogeneity and an agricultural aggregation index both had a significant effect on the abundance of the vampire bat. Our results showed that D. rotundusabundance in northeastern Yucatan, Mexico was favored by extensive pastures as well as by landscape characteristics associated with intense forest fragmentation. However, the presence of some remnants of forest cover probably enhance the movements and persistence of this species. To reduce the negative impact of the vampire bat presence in these areas dedicated to livestock ranching activities, effective preventive vaccination campaigns could be an important strategy.