Amidst the common practice of culling animals to curb the spread of diseases to humans, a study has brought to light a startling reversal: It is pets that are in more peril due to humans.
After analysing 12 million viral genomes, the scientists from University College London (UCL) found that humans pass on more viruses to domestic and wild animals than the other way around. The researchers whose study is published in the journal Nature Ecology & Evolution have called for better understanding and monitoring of viral transmission between animals and humans to prepare for future outbreaks and aid conservation efforts.
Generally speaking, the majority of emerging and re-emerging infectious diseases are attributable to animal viruses. When these pathogens transmit from animals into humans (a process called zoonosis), it leads to disease outbreaks and epidemics such as Ebola and new flu strains. Considering the tremendous impact zoonotic diseases can have on public health, humans have historically been seen as a “sink” for viruses rather than a source. In other words, human-to-animal transmission of viruses usually gets far less attention.
Moreover, as the study noted that even more animal-to-animal host jumps that didn’t involve humans at all. “We should consider humans just as one node in a vast network of hosts endlessly exchanging pathogens, rather than a sink for zoonotic bugs,” said study co-author Professor Francois Balloux (UCL Genetics Institute).
“By surveying and monitoring transmission of viruses between animals and humans, in either direction, we can better understand viral evolution and hopefully be more prepared for future outbreaks and epidemics of novel illnesses, while also aiding conservation efforts.”
On average, viral host jumps show an association with an increase in genetic changes, or mutations in viruses, relative to their continued evolution alongside just one host animal. Study authors say this reflects how viruses must adapt to better exploit new hosts.
