With the spread of monkeypox around the world on the heels of Covid-19, there are fears that escalating outbreaks of animal-to-human disease could trigger another pandemic.
While such diseases — called zoonoses — have been known for millennia, experts say they’ve become increasingly common in recent decades due to deforestation, factory farming, climate change and other man-made upheavals in wildlife.
Other diseases that jump from animals to humans include HIV, Ebola, Zika, SARS, MERS, bird flu and bubonic plague.
The World Health Organization said Thursday it is still investigating the origins of Covid, but the “strongest evidence is still in the area of zoonotic transmission”.
And with more than 1,000 cases of monkeypox recorded worldwide in the last month, the UN agency has warned there is a “real” risk the disease could take hold in dozens of countries.
WHO emergency director Michael Ryan said last week that “it’s not just happening with monkeypox” – the way humans and animals interact has become “unstable”.
“The rate at which these diseases spread to humans increases, and then our ability to amplify this disease and spread it in our communities increases,” he said.
Monkeypox hasn’t spread to humans recently – the first human case was identified in DR Congo in 1970 and has since been confined to areas of central and western Africa.
Despite its name, “the recent monkeypox outbreak has nothing to do with monkeys,” said Olivier Restif, an epidemiologist at the University of Cambridge.
While it was first spotted in macaques, “most often zoonotic transmission is carried by rodents, and outbreaks are spread through personal contact,” he told AFP.
– Worse to come? –
According to the UN Environment Program, around 60 percent of all known human infections are zoonotic, as are 75 percent of all new and emerging infectious diseases.
Restif said zoonotic pathogens and outbreaks have increased in recent decades due to “population growth, livestock numbers and encroachment on wildlife habitats.”
“Wild animals have drastically changed their behavior in response to human activities and migrated from their depleted habitats,” he said.
“Immune-compromised animals that are around humans and pets are a surefire way to transmit more pathogens.”
Benjamin Roche, a zoonoses specialist at the French Research Institute for Development, said deforestation had a major impact.
“Deforestation reduces biodiversity: we lose animals that regulate viruses naturally, which makes them easier to spread,” he told AFP.
And it could get worse, as a major study released earlier this year warns that climate change is increasing the risk of another pandemic.
As animals flee their warming natural habitats, they will encounter other species for the first time – potentially infecting them with some of the 10,000 zoonotic viruses thought to circulate “silently” among wild mammals, mainly in tropical forests, according to the study.
Greg Albery, a disease ecologist at Georgetown University who co-authored the study, told AFP that “the host-pathogen network is about to change fundamentally.”
– “We must be ready” –
“We need improved surveillance in both urban and wild animals so we can identify when a pathogen has jumped from one species to another – and if the receiving host is in the city or in close proximity to humans, we should.” particularly worry us,” he said.
Eric Fevre, an infectious disease specialist at Britain’s University of Liverpool and the International Livestock Research Institute in Kenya, said that “a whole host of new, potentially dangerous diseases could emerge – we have to be ready”.
This includes “focusing on the public health of populations” in remote settings and “better studying the ecology of these natural areas to understand how different species interact”.
Restif said that “there is no silver bullet – our best bet is to act at all levels to reduce risk”.
“We need huge investment in frontline health care and testing capacity for disadvantaged communities around the world so that outbreaks can be detected, identified and controlled without delay,” he said.
On Thursday, a WHO Scientific Advisory Group released a preliminary report outlining what to do if a new zoonotic agent emerges.
It lists a number of early investigations into how and where the pathogen spread to humans in order to determine the potential risk and longer-term environmental impact.
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