Humans pass on more viruses to domestic and wild animals than we catch from them, according to a major new analysis of viral genomes by UCL researchers.

For the new paper published in Nature Ecology & Evolution, the team analysed all publicly available viral genome sequences, to reconstruct where viruses have jumped from one host to infect another vertebrate species.

Most emerging and re-emerging infectious diseases are caused by viruses circulating in animals. When these viruses cross over from animals into humans, a process known as zoonosis, they can cause disease outbreaks, epidemics and pandemics such as Ebola, flu or Covid-19. Given the enormous impact of zoonotic diseases on public health, humans have generally been considered as a sink for viruses rather than a source, with human-to-animal transmission of viruses receiving far less attention.