Ban on wild bird importation accelerated the spread of global viral outbreaks in parrots.

Since the isolation of the first parrot bornavirus (PaBV), which causes slow-onset, fatal neurological disease in various parrot species, in the United States in 2008, PaBVs have spread rapidly worldwide; however, the reason remains unknown. In this study, we show that the most dominant lethal genotype, PaBV-4, spread via the global trade of captive birds. Analyses of traded parrot numbers in the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) database and PaBV-4 phylodynamics suggested that the ban of wild imported birds in the European Union (EU) in 2007 facilitated the international trade of captive parrots, which resulted in an increase in the effective population size of PaBV-4. This change coincided with a historical PaBV-4 epidemic. These data suggest that due to the low transmission efficiency and long incubation period of PaBV-4, the majority of PaBV-4 transmission occurred in breeding facilities and the increased trade of captive parrots accelerated the global spread of PaBV-4 infection. Our results indicate that interventions for the protection of wild animals and prevention of infectious diseases may conversely cause epidemics of infectious diseases in the global system. Conservation of ecosystems requires not only the establishment of importation restrictions and maintenance of the diversity of wild animals but also the implementation of multifaceted management measures, such as quarantine policies and breeding control in captive animals.