Biology subjects

Fenton, M. B.

Publications and source records attributed to Fenton, M. B..

8 recordsLinked to original sources

bioRxiv2025

Vampire bats in Belize harbor multiple Trypanosoma cruzi genotypes: implications for parasite transmission at the wildlife-domestic-human interface

BackgroundChagas disease, caused by Trypanosoma cruzi, is a neglected tropical disease with complex sylvatic and domestic transmission cycles involving vectors, mammalian hosts, and humans. The common vampire bat (Desmodus rotundus) is an obligate blood-feeding species that frequently interacts with livestock and humans, yet their role in parasite maintenance in Central America remains poorly characterized. Methodology/Principal FindingsWe analyzed 205 blood samples from vampire bats collected at two sites in northern Belize over three years (2019, 2021, 2022). PCR screening revealed an overall T. cruzi prevalence of 41.5% and increasing infection risks over time. The amplicon-based next-generation sequencing of the parasite mini-exon locus identified 36 unique haplotypes belonging to five DTUs: TcI, TcIV, TcV, TcVI, and TcBat. TcBat was present in half of the samples sequenced. TcBat and TcVI, were detected in Belize for the first time. Belizean TcBat haplotypes clustered closely with Colombian reference sequences, and a subset formed a Belize-specific clade, indicating previously unrecognized TcBat diversity in the region; in contrast, Brazilian TcBat sequences were more distantly related. Conclusions/SignificanceVampire bats in Belize harbor diverse T. cruzi genotypes, including DTUs with established roles in human disease. Given their obligate blood diet, frequent feeding on livestock, and occasional biting of humans, vampire bats may serve as bridge hosts linking sylvatic, domestic, and human transmission cycles. Together with a recent report of an acute human Chagas disease case in northern Belize, these results underscore the need for integrated One Health surveillance of bats, vectors, livestock, and humans to better evaluate and mitigate the risk of Chagas disease in Central America. Author SummaryChagas disease, caused by the parasite Trypanosoma cruzi, is a major public health concern in the Americas but remains neglected in many regions, including Central America. The parasite is typically transmitted by kissing bugs, but wild mammals also serve as important hosts. Vampire bats (Desmodus rotundus) are unique because they feed exclusively blood and frequently bite livestock, and occasionally humans, creating opportunities for parasite transmission across different environments. In this study, we screened 205 vampire bats from northern Belize and found that over 40% were infected with T. cruzi. By sequencing parasite DNA, we discovered a surprising diversity of DTUs, including TcI, TcIV, TcV, TcVI, and TcBat. The detection of TcVI is particularly important, because this DTU, associated with human infections in South America, had not been previously reported in Belize. TcBat haplotypes were highly prevalent and genetically diverse. Our results show that vampire bats are important hosts of diverse T. cruzi genotypes in Belize and may act as bridge hosts between wildlife, livestock, human transmission cycles. Enhanced One Health surveillance across vectors, bats, domestic animals, and humans will be critical for understanding and preventing Chagas disease emergence in Central America.

molecular biology↗

bioRxiv2025

Neotropical bats as bioindicators for emerging zoonoses in Central America: A case study identifying Trypanosoma cruzi in bats from Belize using metagenomic next-generation sequencing

Emerging zoonoses remain a global public health concern. Surveillance of infectious and vector-borne diseases is vital for predicting and mitigating detrimental effects of zoonotic spillover events. Beyond assessing what microorganisms are circulating in specific environments, it is important to understand how potential reservoir hosts, especially animals such as bats, participate in pathogen transmission. Bats can host and potentially spread infections caused by bacteria, viruses, fungi, and protozoa. However, bats can also act as bioindicators that test positive for pathogenic microorganisms without necessarily contributing to the pathogen replication cycle. Metagenomic next-generation sequencing (mNGS) provides an efficient means to broadly screen for pathogens, although microorganism selectivity can sometimes be lower than targeted approaches. Pairing mNGS results with higher-sensitivity tests such as quantitative PCR (qPCR) can validate results and together these tools provide a relatively fast and reliable method for conducting surveillance. To test this approach, we surveyed the types of microorganisms circulating in Belize by collecting 263 blood samples from 20 different bat species captured in the Orange Walk District in 2019, 2022, and 2023. We used mNGS to initially characterize the microbial communities and qPCR to confirm presence and intensity of human pathogens of interest. We detected 1,430 different microorganisms with some relevance to human or animal health, including the protozoan Trypanosoma cruzi which was detected in the phyllostomid bats Desmodus rotundus and Artibeus jamaicensis. qPCR confirmed the presence and intensity of Trypanosoma cruzi in mNGS-positive bat samples. We documented the types of pathogenic microorganisms circulating throughout the bat community in northern Belize to demonstrate the capacity for bats to serve as bioindicators. Author SummaryTracking the spread of new and emerging zoonotic diseases is a major component of global health research. Pathogen surveillance is a vital part of predicting and reducing the consequences of disease outbreaks. Bats are a diverse group of mammals that can host and potentially transmit many pathogens that pose potential risks to human and environmental health. Our study surveyed blood samples (n=263) from 20 bat species collected from the Orange Walk District of Belize in 2019, 2022, and 2023. Metagenomic next-generation sequencing identified 1,430 different microorganisms that are considered potentially relevant to human or animal health. Among the microorganisms detected was Trypanosoma cruzi (T. cruzi), the protozoan causative agent of Chagas disease. T. cruzi was of particular interest due to its presence throughout the Americas and relevance to public health. We surveyed the types of microorganisms circulating throughout bat populations in northern Belize to demonstrate the ability of bats to act as bioindicators.

microbiology↗

bioRxiv2025

Longitudinal impacts of habitat fragmentation on Bartonella and hemotropic Mycoplasma dynamics in vampire bats

Habitat fragmentation can have negative impacts on wildlife including increased risk of infectious disease. To assess spatiotemporal changes in pathogen dynamics in vampire bats (Desmodus rotundus) in response to habitat fragmentation, we used general linear mixed models to investigate the influence of site, year, and tree cover on the prevalence of Bartonella and hemotropic Mycoplasma (hemoplasma) in bats in one large and one small forest fragment in northern Belize across seven years. Bartonella was marginally more prevalent in later years, while year and site differences in hemoplasma infections were driven by a peak in prevalence in the third year of the study in the small fragment. Bartonella prevalence increased with forest loss, but only in the large fragment, whereas hemoplasma prevalence showed a marginal negative response to forest loss. The effects of site, year, and forest loss on infection likelihood varied by pathogen genotype. Neither site nor year affected Bartonella genotypes, but one genotype was positively associated with tree cover. Two hemoplasma genotypes were influenced by year, but with differing trends. One genotype increased with tree cover regardless of site while another increased with forest loss at the small fragment only. Our work demonstrates that the effects of habitat fragmentation on infection prevalence depended on both the pathogen and specific genotype. Our findings complicate expectations of how habitat fragmentation affects infectious disease dynamics in bats. As such, management practices aimed at mitigating the impacts of infectious diseases in fragmented systems should be tailored to specific pathogens of concern.

ecology↗

bioRxiv2023

Bat cellular immunity varies by year and dietary habit in an increasingly fragmented landscape

Monitoring the health of wildlife populations is essential in the face of increased agricultural expansion and forest fragmentation. Loss of habitat and habitat degradation can negatively affect an animals physiological state, possibly resulting in immunosuppression and increased morbidity or mortality. We sought to determine how fragmentation may differentially impact cellular immunity and infection risk in Neotropical bats species regularly infected with bloodborne pathogens, and to evaluate how effects may vary over time and by dietary habit. We studied common vampire bats (Desmodus rotundus), northern yellow-shouldered bats (Sturnira parvidens), and Mesoamerican mustached bats (Pteronotus mesoamericanus), representing the dietary habits of sanguinivory, frugivory, and insectivory respectively, in northern Belize. We compared estimated total white blood cell counts, leukocyte differentials, and infection status with two blood-borne bacterial pathogens (Bartonella spp. and hemoplasmas) of 118 bats captured in a broadleaf, secondary forest over a three-year period (2017-2019) of increasing habitat fragmentation. We found evidence for bat species-specific responses of cellular immunity between years, with neutrophil counts increasing in D. rotundus, but decreasing in S. parvidens and P. mesoamericanus from 2018 to 2019. However, the odds of infection with Bartonella spp. and hemoplasma spp. between 2017 and 2019 did not differ between bat species, contrary to our prediction that pathogen prevalence may increase with increased fragmentation. We conclude that each bat species invested differently in cellular immunity in ways that changed over years of increasing fragmentation. We recommend further research on the interactions between habitat fragmentation, cellular immunity, and infection across dietary habits of Neotropical bats for informed management and conservation.

ecology↗

bioRxiv2020

Body size affects immune cell proportions in birds and non-volant mammals, but not bats

Powered flight has evolved several times in vertebrates and constrains morphology and physiology in ways that likely have shaped how organisms cope with infections. Some of these constraints likely have impacts on aspects of immunology, such that larger fliers might prioritize risk reduction and safety. Addressing how the evolution of flight may have driven relationships between body size and immunity could be particularly informative for understanding the propensity of some taxa to harbor many virulent and sometimes zoonotic pathogens without showing clinical disease. Here, we used a scaling framework to quantify scaling relationships between body mass and the proportions of two types of white blood cells--lymphocytes, and granulocytes (neutr-/heterophils)--across 60 bat species, 414 bird species, and 256 non-volant mammal species. By using phylogenetically-informed statistical models on field-collected data from wild Neotropical bats, data gleaned from other wild bats available in the literature, and data from captive non-volant mammals and birds, we show that lymphocyte and neutrophil proportions do not vary systematically with body mass among bats. In contrast, larger birds and non-volant mammals have disproportionately higher granulocyte proportions than expected for their body size. Future comparative studies of wild bats, birds, and non-volant mammals of similar body mass should aim to further differentiate evolutionary effects and other aspects of life history on immune defense. Summary statementPowered flight might constrain morphology such that certain immunological features are prioritized. We show that bats largely have similar cell proportions across body mass compared to strong allometric scaling relationships in birds and non-flying mammals.

physiology↗

bioRxiv2020

Temporal patterns of vampire bat rabies and host connectivity in Belize

In the Neotropics, vampire bats (Desmodus rotundus) are the main reservoir host for rabies, a highly fatal encephalitis caused by viruses in the genus Lyssavirus. Although patterns of rabies virus exposure and infection have been well-studied for vampire bats in South America and Mexico, exploring the ecology of vampire bat rabies in other regions is crucial for predicting risks to livestock and humans. In Belize, rabies outbreaks in livestock have increased in recent years, underscoring the need for systematic data on viral dynamics in vampire bats. In this study, we examine the first three years of a longitudinal study on the ecology of vampire bat rabies in northern Belize. Rabies seroprevalence in bats was high across years (29-80%), suggesting active and endemic virus circulation. Across two locations, the seroprevalence time series per site were inversely related and out of phase by at least a year. Microsatellite data demonstrated historic panmixia of vampire bats, and mark-recapture detected rare but contemporary inter-site dispersal. This degree of movement could facilitate spatial spread of rabies virus but is likely insufficient to synchronize infection dynamics, which offers one explanation for the observed phase lag in seroprevalence. More broadly, our analyses suggest frequent transmission of rabies virus within and among vampire bat roosts in northern Belize and highlight the need for future spatiotemporal, phylogenetic, and ecological studies of vampire bat rabies in Central America.

ecology↗

bioRxiv2020

Disentangling interactions between mercury, immunity, and infection in a Neotropical bat community

O_LIContaminants such as mercury are pervasive and can have immunosuppressive effects on wildlife. Impaired immunity could be important for forecasting pathogen spillover risks, as many land-use changes that generate mercury contamination also bring wildlife into close contact with humans and domestic animals. However, the interactions among contaminants, immunity, and infection are difficult to study in natural systems, and empirical tests of possible directional relationships remain rare. C_LIO_LIWe capitalized on extreme mercury variation in a diverse bat community in Belize to test association among contaminants, immunity, and infection. By comparing a previous dataset of bats sampled in 2014 with new data from 2017, representing a period of rapid agricultural land conversion, we first confirmed bat species more reliant on aquatic prey had higher fur mercury. Bats in the agricultural habitat also had higher mercury in recent years. We then tested covariation between mercury and cellular immunity and determined if such relationships mediated associations between mercury and common bacterial pathogens. As bat ecology can dictate exposure to mercury and pathogens, we also assessed species-specific patterns in mercury-infection relationships. C_LIO_LIAcross the bat community, individuals with higher mercury had fewer neutrophils but not lymphocytes, suggesting stronger associations with innate immunity. However, the odds of infection for hemoplasmas and Bartonella spp. were generally lowest in bats with high mercury, and relationships between mercury and immunity did not mediate infection patterns. Mercury also showed species- and clade-specific relationships with infection, being associated with especially low odds for hemoplasmas in Pteronotus mesoamericanus and Dermanura phaeotis. For Bartonella spp., mercury was associated with particularly low odds in the genus Pteronotus but high odds in the Stenodermatinae. C_LIO_LISynthesis and application: Lower general infection risk in bats with high mercury despite weaker innate defense suggests contaminant-driven loss of pathogen habitat (i.e., anemia) or vector mortality as possible causes. Greater attention to these potential pathways could help disentangle relationships among contaminants, immunity, and infection in anthropogenic habitats and help forecast disease risks. Our results also suggest contaminants may increase infection risk in some taxa but not others, emphasizing the importance of considering surveillance and management at different phylogenetic scales. C_LI

ecology↗

bioRxiv2019

Ecological and evolutionary drivers of hemoplasma infection and bacterial genotype sharing in a Neotropical bat community

Most emerging pathogens can infect multiple species, underscoring the importance of understanding the ecological and evolutionary factors that allow some hosts to harbor greater infection prevalence and share pathogens with other species. However, our understanding of pathogen jumps is primarily based around viruses, despite bacteria accounting for the greatest proportion of zoonoses. Because bacterial pathogens in bats (Order: Chiroptera) can have conservation and human health consequences, studies that examine the ecological and evolutionary drivers of bacterial prevalence and barriers to pathogen sharing are crucially needed. We here studied hemotropic Mycoplasma spp. (i.e., hemoplasmas) across a species-rich bat community in Belize over two years. Across 469 bats spanning 33 species, half of individuals and two-thirds of species were hemoplasma positive. Infection prevalence was higher for males and for species with larger body mass and colony sizes. Hemoplasmas displayed high genetic diversity (21 novel genotypes) and strong host specificity. Evolutionary patterns supported co-divergence of bats and bacterial genotypes alongside phylogenetically constrained host shifts. Bat species centrality to the network of shared hemoplasma genotypes was phylogenetically clustered and unrelated to prevalence, further suggesting rare--but detectable--bacterial sharing between species. Our study highlights the importance of using fine phylogenetic scales when assessing host specificity and suggests phylogenetic similarity may play a key role in host shifts for not only viruses but also bacteria. Such work more broadly contributes to increasing efforts to understand cross-species transmission and epidemiological consequences of bacterial pathogens.

ecology↗