Alphavirus Identification in Neotropical Bats.

Alphaviruses (Togaviridae) are arthropod-borne viruses responsible for several emerging diseases, maintained in nature through transmission between hematophagous arthropod vectors and susceptible vertebrate hosts. Although bats harbor many species of viruses, their role as reservoir hosts in emergent zoonoses has been verified only in a few cases. With bats being the second most diverse order of mammals, their implication in arbovirus infections needs to be elucidated. Reports on arbovirus infections in bats are scarce, especially in South American indigenous species. In this work, we report the genomic detection and identification of two different alphaviruses in oral swabs from bats captured in Northern Uruguay. Phylogenetic analysis identified Río Negro virus (RNV) in two different species: Tadarida brasiliensis (n = 6) and Myotis spp. (n = 1) and eastern equine encephalitis virus (EEEV) in Myotis spp. (n = 2). Previous studies of our group identified RNV and EEEV in mosquitoes and horse serology, suggesting that they may be circulating in enzootic cycles in our country. Our findings reveal that bats can be infected by these arboviruses and that chiropterans could participate in the viral natural cycle as virus amplifiers or dead-end hosts. Further studies are warranted to elucidate the role of these mammals in the biological cycle of these alphaviruses in Uruguay.

Ecological and Conservation Significance of Herpesvirus Infection in Neotropical Bats.

Bats are the second most diverse order of mammals and key species for ecosystem functioning, providing a wide range of ecosystem services, from pest control to seed dispersal. Chiropterans are known for hosting a large diversity of viruses, in some cases with little or no effect to their health. Here, we report on the results of a screening for DNA (Herpesviridae) and RNA viruses (Rhabdovirus and Pneumovirus), finding a high prevalence and wide diversity of both Beta- and Gamma-Herpesvirus in insectivorous and hematophagous bats of the southern cone of South America. Our findings suggest that bats in the southern neotropics harbor a high diversity of herpesviruses and, at least in some cases, the viral community in the bat species is more strongly associated with ecological traits of the hosts, rather than their taxonomy. The presence of a separate clade into the Gammaherpesvirinae subfamily in the common vampire bat suggests the independent circulation of herpesviruses in hematophagous and insectivorous bats and highlights the properness of these viruses to track vampire bats' population structure for rabies studies. Hence, we suggest that as other pathogens viruses may be used to track the population dynamics of their hosts, including movement and demographics.

Synergistic Effects of Grassland Fragmentation and Temperature on Bovine Rabies Emergence.

In 2007, common vampire bats were the source of the first outbreak of paralytic bovine rabies in Uruguay. The outbreak coincided in space and time with the fragmentation of native grasslands for monospecific forestry for wood and cellulose production. Using spatial analyses, we show that the increase in grassland fragmentation, together with the minimum temperature in the winter, accounts for the spatial pattern of outbreaks in the country. We propose that fragmentation may increase the connectivity of vampire bat colonies by promoting the sharing of feeding areas, while temperature modulates their home range plasticity. While a recent introduction of the virus from neighboring Brazil could have had an effect on outbreak occurrence, we show here that the distribution of rabies cases is unlikely to be explained by only an invasion process from Brazil. In accordance with previous modeling efforts, an increase in connectivity may promote spatial persistence of rabies virus within vampire bat populations. Our results suggest that land use planning might help to reduce grassland fragmentation and thus reduce risk of rabies transmission to livestock. This will be especially important in the context of climatic changes and increasing minimum temperatures in the winter.