European bat Lyssavirus Type 1 exhibits active circulation across multispecies bat colonies in the Iberian Peninsula, with seroprevalence peaking above 70% in specific species during 2007, according to an active surveillance study conducted between 2004 and 2012 that evaluated 406 sera from nine different bat species sharing common refuges. Meanwhile, a landmark global study published in Nature by the international Bat1K consortium reveals that bats—the world’s only mammals capable of true powered flight—actually originated in Europe approximately 65 million years ago, overturning decades of assumptions placing their origins in Africa, Asia, or North America.
Active Surveillance of Lyssavirus in Multispecies Bat Colonies
Wildlife reservoirs remain a central focus in the study of emerging infectious diseases, particularly given that zoonotic pathogens account for approximately 60% of all pathogens capable of infecting humans. Among these reservoir hosts, bats have drawn intensive scientific scrutiny. Accounting for roughly 21% of all mammalian species across about 1200 recognized varieties worldwide (with theguardian.com noting they account for one-fifth of all mammals and comprise the second most diverse mammal species in the world, featuring forms ranging to the hammer-headed fruit bats investigated by Wildlife Conservation Society director of health research Sarah Olson), bats possess unique biological characteristics—including powered flight, long lifespans, high survival rates, and gregarious roosting habits—that facilitate the rapid and wide geographic spread of viruses like Ebola, Nipah, and Marburg, which bats host without getting sick themselves.
To better understand how these pathogens circulate, researchers undertook an active surveillance study from 2004 to 2012 examining the occurrence of specific antibodies to European Bat Lyssavirus Type 1. Investigators obtained 406 sera samples from nine distinct bat species sharing common refuges on the Iberian Peninsula. Using a modified fluorescent antibody virus neutralization test, the team detected EBLV-1-neutralizing antibodies in six of the nine analyzed species: Pipistrellus pipistrellus, Pipistrellus kuhlii, Hypsugo savii, Plecotus austriacus, Eptesicus serotinus, and Tadarida teniotis.
Seroprevalence Dynamics and Temporal Variation
When examining demographic breakdowns among the sampled mammals, researchers found that female seroprevalence reached 20.21% (with a 95% confidence interval spanning from 14.78% to 26.57%), while male seroprevalence stood at 15.02% (with a 95% confidence interval between 10.51% and 20.54%). The data indicated that female seroprevalence was not significantly higher than that observed in males.
Significant inter-annual variations emerged when tracking the number of seropositive bats over time. Specifically, the temporal patterns of Tadarida teniotis and Plecotus austriacus revealed a pronounced peak in 2007, during which seroprevalence exceeded 70% for both species. However, mathematical modeling of these temporal patterns showed significant differences between the two types.
Scientists attribute these divergent annual fluctuations to the distinct behavioral ecology of each participating species. Expanding on these deep evolutionary timelines, the Bat1K study—incorporating 103 bat genomes spanning all 21 recognized families and 44 fossil bats from across the globe, including teeth and specimens like the 47–48-million-year-old fossil from the Messel oil shale in Germany—revealed via a team of 137 researchers from 64 countries that the earliest bat ancestors dispersed from Europe into Africa, then onward to Asia, the Americas, and Australia. This landmark work provides a robust phylogenetic tree showing that echolocation evolved near the dawn of bat evolution alongside flight, while UNSW Sydney palaeontologist Professor Suzanne Hand pointed out that despite European origins, Australia holds an extraordinarily old bat fossil in Australonycteris at 55 million years old found in Murgon, South East Queensland, alongside younger New Zealand fossils like those at St Bathans, Central Otago dating to 16–18 million years old.