The ecology of ebolaviruses is still poorly understood and the role of bats in outbreaks needs to be further clarified. Straw-colored fruit bats (
) are the most common fruit bats in Africa and ...antibodies to ebolaviruses have been documented in this species. Between December 2018 and November 2019, samples were collected at approximately monthly intervals in roosting and feeding sites from 820 bats from an
colony. Dried blood spots (DBS) were tested for antibodies to Zaire, Sudan, and Bundibugyo ebolaviruses. The proportion of samples reactive with GP antigens increased significantly with age from 0-9/220 (0-4.1%) in juveniles to 26-158/225 (11.6-70.2%) in immature adults and 10-225/372 (2.7-60.5%) in adult bats. Antibody responses were lower in lactating females. Viral RNA was not detected in 456 swab samples collected from 152 juvenile and 214 immature adult bats. Overall, our study shows that antibody levels increase in young bats suggesting that seroconversion to Ebola or related viruses occurs in older juvenile and immature adult bats. Multiple year monitoring would be needed to confirm this trend. Knowledge of the periods of the year with the highest risk of Ebolavirus circulation can guide the implementation of strategies to mitigate spill-over events.
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Caves house pathogenic microorganisms, some of which are transmitted by blood-sucking arthropods. In Africa, previous studies identified mosquitoes, sand flies and biting midges as the main potential ...vectors of cave-dwelling pathogens. However, to understand their involvement in pathogen spillover, it is crucial to characterize their diversity, community composition and dynamics. Using CDC light traps, we collected hematophagous Diptera in six caves of Gabon during one-shot or longitudinal sampling, and investigated their species diversity and dynamics in relation with external rainfall. Overall, we identified 68 species of mosquitoes, sand flies and biting midges, including 45 new records for Gabon. The dominant species were: Uranotaenia nigromaculata, Anopheles smithii s.l., Culex. rima group and Culex quasiguiarti for mosquitoes, Spelaeophlebotomus gigas and Spelaeomyia emilii for sand flies and the Culicoides trifasciellus group and Culicoides fulvithorax for biting midges. The survey revealed that species assemblages were cave-specific and included mainly troglophilous and trogloxenous species. Both diversity and abundance varied according to the cave and sampling time, and were significantly associated with rainfall. These associations were modulated by the cave specific environmental conditions. Moreover, the presence of trogloxenous and troglophilous species could be of high significance for pathogen transfers between cave and epigeous hosts, including humans.
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Viruses belonging to the
family have attracted a great deal of attention from scientists owing to their negative impact on agricultural economics, as well as their recent identification as potential ...aetiological agents of febrile illness in human patients. On the other hand, some Dicistroviruses are also studied for their potential biopesticide properties. To date, Dicistrovirus characterized in African mainland remain scarce. By using High-Throughput Sequencing technology on insectivorous bat faeces (
) sampled in a cave used by humans to collect bat guano (bat manure) as fertilizer in Zimbabwe, we characterized the full-length sequences of three
belonging to the
and
genus:
(
-Like),
(
), and
(
). Phylogenetic analyses of ORF-1 and ORF-2 genes showed a complex evolutionary history between
and close viruses, as well as for the
genus. Herewith, we provide the first evidence of the presence of
in Zimbabwe and highlight the need to further document the impact of such viruses on crops, as well as in beekeeping activities in Zimbabwe which represent a crucial source of income for Zimbabwean people.
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Bats are known to harbor multiple paramyxoviruses. Despite the creation of two new genera, Aquaparamyxovirus and Ferlavirus, to accommodate this increasing diversity, several recently isolated or ...characterized viruses remain unclassified beyond the subfamily level. In the present study, among 985 bats belonging to 6 species sampled in the Belinga caves of Gabon, RNA of an unclassified paramyxovirus (Belinga bat virus, BelPV) was discovered in 14 African sheath-tailed bats (Coleura afra), one of which exhibited several hemorrhagic lesions at necropsy, and viral sequence was obtained in two animals. Phylogenetically, BelPV is related to J virus and Beilong virus (BeiPV), two other unclassified paramyxoviruses isolated from rodents. In the diseased BelPV-infected C. afra individual, high viral load was detected in the heart, and the lesions were consistent with those reported in wild rodents and mice experimentally infected by J virus. BelPV was not detected in other tested bat species sharing the same roosting sites and living in very close proximity with C. afra in the two caves sampled, suggesting that this virus may be host-specific for C. afra. The mode of transmission of this paramyxovirus in bat populations remains to be discovered.
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Abstract
Background
Improved understanding of the foraging ecology of bats in the face of ongoing habitat loss and modification worldwide is essential to their conservation and maintaining the ...substantial ecosystem services they provide. It is also fundamental to assessing potential transmission risks of zoonotic pathogens in human-wildlife interfaces. We evaluated the influence of environmental and behavioral variables on the foraging patterns of
Pteropus lylei
(a reservoir of Nipah virus) in a heterogeneous landscape in Cambodia.
Methods
We employed an approach based on animal-movement modeling, which comprised a path-segmentation method (hidden Markov model) to identify individual foraging-behavior sequences in GPS data generated by eight
P. lylei
. We characterized foraging localities, foraging activity, and probability of returning to a given foraging locality over consecutive nights. Generalized linear mixed models were also applied to assess the influence of several variables including proxies for energetic costs and quality of foraging areas.
Results
Bats performed few foraging bouts (area-restricted searches) during a given night, mainly in residential areas, and the duration of these decreased during the night. The probability of a bat revisiting a given foraging area within 48 h varied according to the duration previously spent there, its distance to the roost site, and the corresponding habitat type. We interpret these fine-scale patterns in relation to global habitat quality (including food-resource quality and predictability), habitat-familiarity and experience of each individual.
Conclusions
Our study provides evidence that heterogeneous human-made environments may promote complex patterns of foraging-behavior and short-term re-visitation in fruit bat species that occur in such landscapes. This highlights the need for similarly detailed studies to understand the processes that maintain biodiversity in these environments and assess the potential for pathogen transmission in human-wildlife interfaces.
Nearly 4 years after the first report of the emergence of Middle-East respiratory syndrome Coronavirus (MERS-CoV) and nearly 1800 human cases later, the ecology of MERS-CoV, its epidemiology, and ...more than risk factors of MERS-CoV transmission between camels are poorly understood. Knowledge about the pathways and mechanisms of transmission from animals to humans is limited; as of yet, transmission risks have not been quantified. Moreover the divergent sanitary situations and exposures to animals among populations in the Arabian Peninsula, where human primary cases appear to dominate, vs. other regions in the Middle East and Africa, with no reported human clinical cases and where the virus has been detected only in dromedaries, represents huge scientific and health challenges. Here, we have used expert-opinion elicitation in order to obtain ideas on relative importance of MERS-CoV risk factors and estimates of transmission risks from various types of contact between humans and dromedaries. Fourteen experts with diverse and extensive experience in MERS-CoV relevant fields were enrolled and completed an online questionnaire that examined pathways based on several scenarios, e.g., camels-camels, camels-human, bats/other species to camels/humans, and the role of diverse biological substances (milk, urine, etc.) and potential fomites. Experts believed that dromedary camels play the largest role in MERS-CoV infection of other dromedaries; however, they also indicated a significant influence of the season (i.e. calving or weaning periods) on transmission risk. All experts thought that MERS-CoV-infected dromedaries and asymptomatic humans play the most important role in infection of humans, with bats and other species presenting a possible, but yet undefined, risk. Direct and indirect contact of humans with dromedary camels were identified as the most risky types of contact, when compared to consumption of various camel products, with estimated "most likely" incidence risks of at least 22 and 13% for direct and indirect contact, respectively. The results of our study are consistent with available, yet very limited, published data regarding the potential pathways of transmission of MERS-CoV at the animal-human interface. These results identify key knowledge gaps and highlight the need for more comprehensive, yet focused research to be conducted to better understand transmission between dromedaries and humans.
In spite of its protected status, the Ipassa Reserve (North-East Gabon) has been subject to intense hunting activities. Recent mammal surveys showed that the Reserve still shelters high mammal ...diversity, but also that densities have dramatically declined in the last two decades. We assessed the changes in diversity of duiker species within the Reserve by comparing data gathered two decades ago to data collected in 2005-2006 in the same area. The only two species currently present in the area are the blue duiker and Peter's duiker. Bay duiker was present at a density of 7.1 individuals per km2 in the 80's but seems now locally absent. As hunting for food is the only human activity carried out in the reserve during the last twenty years and Bay duiker is a favourite game species in the region, it is very likely that over hunting is the reason for this local depletion. PUBLICATION ABSTRACT
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To clarify the role of bats in the ecology of Ebola viruses, we assessed the prevalence of Ebola virus antibodies in a large-scale sample of bats collected during 2015-2017 from countries in Africa ...that have had previous Ebola outbreaks (Guinea, the Democratic Republic of the Congo) or are at high risk for outbreaks (Cameroon). We analyzed 4,022 blood samples of bats from >12 frugivorous and 27 insectivorous species; 2-37 (0.05%-0.92%) bats were seropositive for Zaire and 0-30 (0%-0.75%) bats for Sudan Ebola viruses. We observed Ebola virus antibodies in 1 insectivorous bat genus and 6 frugivorous bat species. Certain bat species widespread across Africa had serologic evidence of Zaire and Sudan Ebola viruses. No viral RNA was detected in the subset of samples tested (n = 665). Ongoing surveillance of bats and other potential animal reservoirs are required to predict and prepare for future outbreaks.
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Questions
Species defined as ecosystem engineers (e.g. elephant) are able to strongly shape their habitat. In African savannas, elephants have often been shown to reduce woody‐plant abundance and ...diversity. However, recent studies highlight more complex elephant‐induced effects on vegetation. Here, we assessed if long‐term high elephant densities (>2 km−2) in a large open landscape resulted in the depletion of savanna woodland woody communities or if it led to a new alternative equilibrium.
Location
Woodland savanna of Hwange National Park, Zimbabwe. Elephant densities at the study site have remained high for the past two decades (>2 km−²).
Methods
We measured long‐term (>15 years) elephant utilisation of woody‐plant communities and their effects on vegetation structure, species composition and functional traits (e.g. N leaf concentration, specific leaf area) in 12 vegetation plots.
Results
We observed opportunistic foraging behaviour by elephants with only a slight temporal shift in species composition, mainly explained by changes in rare species. Further, we did not observe any modification in mean functional trait values, overall height, and stem diameters of the woody‐plant communities. However, we found differential changes in woody‐plant abundance according to the height layer (decrease in the number of tall plants >200 cm and increase in the number of short plants <50 cm) and a strong reduction in crown diameter for plants in the 50–200 cm height class.
Conclusion
Our study strongly suggests that long‐term high elephant densities have led to a stable state in savanna woodland vegetation in terms of plant community composition and their functional traits. However, high elephant densities did affect vegetation structure, which would have several important indirect effects on this ecosystem (e.g. predator–prey interactions). We hope that this study stimulates more work on the long‐term effects of ecosystem engineers in large and open ecosystems.
Over the last decades, no consensus arose on the effect of high elephant densities on the African savanna ecosystems. In this long‐term study, we highlighted that this megaherbivore does not change plant species diversity, suggesting a stable state of the ecosystem. However, elephant‐induced modifications in the woodland structure at a height layer that could affect both predation and herbivory were observed.
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