Disease outbreaks and pathogen introductions can have significant effects on host populations, and the ability of pathogens to persist in the environment can exacerbate disease impacts by fueling sustained transmission, seasonal epidemics, and repeated spillover events. While theory suggests that the presence of an environmental reservoir increases the risk of host declines and threat of extinction, the influence of reservoir dynamics on transmission and population impacts remains poorly described. Here we show that the extent of the environmental reservoir explains broad patterns of host infection and the severity of disease impacts of a virulent pathogen. We examined reservoir and host infection dynamics and the resulting impacts of Pseudogymnoascus destructans, the fungal pathogen that causes white-nose syndrome, in 39 species of bats at 101 sites across the globe. Lower levels of pathogen in the environment consistently corresponded to delayed infection of hosts, fewer and less severe infections, and reduced population impacts. In contrast, an extensive and persistent environmental reservoir led to early and widespread infections and severe population declines. These results suggest that continental differences in the persistence or decay of P. destructans in the environment altered infection patterns in bats and influenced whether host populations were stable or experienced severe declines from this disease. Quantifying the impact of the environmental reservoir on disease dynamics can provide specific targets for reducing pathogen levels in the environment to prevent or control future epidemics.

We have successfully confirmed BtCoVs in numerous bat species. Furthermore, we have described new bat species harboring BtAstVs in Europe and found new species of CalVs. Further long-term investigations involving more species are needed in the Central European region for a better understanding on the host specificity, seasonality, phylogenetic relationships, and the possible zoonotic potential of these newly described viruses.

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From over 1250 extant species of the order Chiroptera, 25 and 28 are known to occur in Germany and Hungary, respectively. Close to 350 samples originating from 28 bat species (17 from Germany, 27 from Hungary) were screened for the presence of adenoviruses (AdVs) using a nested PCR that targets the DNA polymerase gene of AdVs. An additional PCR was designed and applied to amplify a fragment from the gene encoding the IVa2 protein of mastadenoviruses. All German samples originated from organs of bats found moribund or dead. The Hungarian samples were excrements collected from colonies of known bat species, throat or rectal swab samples, taken from live individuals that had been captured for faunistic surveys and migration studies, as well as internal organs of dead specimens. Overall, 51 samples (14.73%) were found positive. We detected 28 seemingly novel and six previously described bat AdVs by sequencing the PCR products. The positivity rate was the highest among the guano samples of bat colonies. In phylogeny reconstructions, the AdVs detected in bats clustered roughly, but not perfectly, according to the hosts' families (Vespertilionidae, Rhinolophidae, Hipposideridae, Phyllostomidae and Pteropodidae). In a few cases, identical sequences were derived from animals of closely related species. On the other hand, some bat species proved to harbour more than one type of AdV. The high prevalence of infection and the large number of chiropteran species worldwide make us hypothesise that hundreds of different yet unknown AdV types might circulate in bats.

BackgroundDespite the increasingly recognized eco-epidemiological significance of bats, data from molecular analyses of vector-borne bacteria in bat ectoparasites are lacking from several regions of the Old and New Worlds.MethodsDuring this study, six species of ticks (630 specimens) were collected from bats in Hungary, Romania, Italy, Kenya, South Africa, China, Vietnam and Mexico. DNA was extracted from these ticks and analyzed for vector-borne bacteria with real-time PCRs (screening), as well as conventional PCRs and sequencing (for pathogen identification), based on the amplification of various genetic markers.ResultsIn the screening assays, Rickettsia DNA was only detected in bat soft ticks, whereas Anaplasma phagocytophilum and haemoplasma DNA were present exclusively in hard ticks. Bartonella DNA was significantly more frequently amplified from hard ticks than from soft ticks of bats. In addition to Rickettsia helvetica detected by a species-specific PCR, sequencing identified four Rickettsia species in soft ticks, including a Rickettsia africae-like genotype (in association with a bat species, which is not known to migrate to Africa), three haemotropic Mycoplasma genotypes in Ixodes simplex, and Bartonella genotypes in I. ariadnae and I. vespertilionis.ConclusionsRickettsiae (from both the spotted fever and the R. felis groups) appear to be associated with soft rather than hard ticks of bats, as opposed to bartonellae. Two tick-borne zoonotic pathogens (R. helvetica and A. phagocytophilum) have been detected for the first time in bat ticks. The present findings add Asia (China) to the geographical range of R. lusitaniae, as well as indicate the occurrence of R. hoogstraalii in South Africa. This is also the first molecular evidence for the autochthonous occurrence of a R. africae-like genotype in Europe. Bat haemoplasmas, which are closely related to haemoplasmas previously identified in bats in Spain and to “Candidatus Mycoplasma haemohominis”, are reported here for the first time from Central Europe and from any bat tick.Electronic supplementary materialThe online version of this article (10.1186/s13071-019-3303-4) contains supplementary material, which is available to authorized users.