Zoonosis: animal-to-human diseases could kill 12 times more people by 2050 - with climate change making it worse

Scientists are calling for "urgent action" as environmental issues like climate change and deforestation threaten to make animal-to-human disease outbreaks more common.

A new study by US biotech company Ginkgo Bioworks, published in science journal BMJ Global Health this week, has warned diseases transmitted from animals to humans - or zoonotic diseases - could kill 12 times as many people in 2050 as they did in 2020. While the research did not include Covid-19, which is thought to have originated in bats, PA reports the team's analysis looked at historic trends for four others: filoviruses (including Ebola and Marburg virus), SARS Coronavirus 1, Nipah virus, and machupo virus - which causes Bolivian haemorrhagic fever.

Scientists looked at more than 3,150 outbreaks between 1963 and 2019, identifying 75 "spillovers" from animals to people in 24 countries. These events caused 17,232 deaths, with the lion's share of them - 15,771 -caused by filoviruses, largely in Africa.

The researchers said epidemics had increased by almost 5% every year between 1963 and 2019, with deaths up by 9%. “If these annual rates of increase continue, we would expect the analysed pathogens to cause four times the number of spillover events and 12 times the number of deaths in 2050 than in 2020,” they added.

Researchers also suggested the true figures were likely to be even higher, given they excluded the 2020 Covid-19 pandemic. The World Health Organisation (WHO) reports this has caused nearly 7 million deaths worldwide to date.

Zoonotic disease spillovers were no longer "an aberration or random cluster”, the authors wrote, but followed “a multi-decade trend in which spillover-driven epidemics have become both larger and more frequent”. The team added that “urgent action is needed to address the large and growing risk to global health” based on the historical trends.

A separate article on Research Outreach explained that human impact on climate change and wildlife habitats - through activities like deforestation - could play a significant part in the increase of zoonotic disease outbreaks. As the planet heats up, infectious diseases that were once confined to warmer parts of the world - and the animals that can carry them - were able to slowly expand their range, it said.

At the same time, deforestation and biodiversity loss can also contribute, with a Yale University article saying removing or thinning trees can help create better conditions for vector species like mosquitoes to breed - such as sunlight pouring onto once-shady forest floors increasing water temperatures, and replacing forest with farmland both helping create more suitable habitat for them.