Viruses: Humans responsible for their spread

According to a new study, pandemics caused by pathogenic viruses that originally come from animals may occur more frequently in the future — and humans themselves are responsible.

Through hobby hunting of wild animals, trading in them, and the increasing destruction of their natural habitats, animals are being forced into ever closer proximity to humans. The closer the contact becomes, the greater the danger that pathogens will jump from animals to humans.

Around 70 percent of human pathogens are zoonotic, meaning that — as in the case of the new coronavirus SARS-CoV-2 — they make the leap, known as “spillover,” from animal to human at some point.

For their study, published on Wednesday in the journal «Proceedings of the Royal Society B», US researchers led by Christine Johnson from the School of Veterinary Medicine at the University of California examined more than 140 viruses known to have been transmitted from animals to humans.

A comparison with the IUCN Red List of Threatened Species revealed that domesticated animals, primates, bats, and rats carried the most zoonotic viruses — around 75 percent. It also showed that the risk of transmission is greatest when a species is threatened by excessive human consumption and habitat loss.

Bats or pangolins as a source of viruses

«We are changing the landscape through deforestation, agriculture or livestock farming, as well as through the construction or expansion of our settlements», Johnson told the news agency AFP. «This also increases the frequency and intensity of contact between humans and wildlife – and that creates the perfect conditions for viral spillover.»

Scientists are still searching for the exact transmission routes of the pathogen behind the lung disease Covid-19. They suspect it was transmitted by bats or pangolins – both considered delicacies in China. The first infections were recorded there at an animal market in Wuhan.

In the wake of the pandemic, conservationists have called for a global ban on wildlife trade, and China has banned the consumption of wild animals. The environmental organisation Greenpeace appealed on Wednesday to the EU to push for a global ban in order to protect the «health of all and biodiversity».

According to the WWF, however, the wildlife trade continues to boom. The environmental organisation stated on Wednesday that, according to authorities, six tonnes of «smuggled goods from African pangolins» had been seized at the Malaysian port of Port Klang. It fears that thousands of animals may have lost their lives for this, as each dried scale weighs only a few grams.