Zoonoses, diseases capable of jumping from animals to humans, have been around for millennia. However, they have grown more common in recent decades thanks to climate change and deforestation causing habitat destruction, driving humans and wildlife into closer contact. Diseases known to have leapt from animals to humans include avian influenza, bubonic plague, Ebola, HIV, MERS, SARS and Zika. And while the World Health Organization (WHO) said on Thursday it is still investigating the origins of SARS-CoV-2, the virus that causes COVID-19, it is believed the “the strongest evidence is still around zoonotic transmission”.
The latest zoonotic infection of widespread concern is monkeypox — with more than 1,000 cases of the viral disease having been recorded around the world in the last month.
In fact, according to the WHO, there is a “real” risk the disease could now be established in dozens of countries beyond its usual range in Central and Western Africa.
The first human case of monkeypox was detected in the Democratic Republic of the Congo in 1970.
Despite the name — given because the virus was first discovered in macaques back in Copenhagen in 1958 — the present monkeypox outbreak has nothing to do with monkeys, epidemiologist Dr Olivier Restif of the University of Cambridge told AFP.
“Zoonotic transmission is most often from rodents, and outbreaks spread by person-to-person contact.”
Last week, the WHO’s emergencies director Michael Ryan said that the problem, however, was not just with monkeypox — but that the whole way humans and animals interact has become “unstable”.
He added: “The number of times that these diseases cross into humans is increasing, and then our ability to amplify that disease and move it on within our communities is increasing.”
According to the United Nations’ Environment Program, some 60 percent of all known human infections are zoonotic in origin, as are 75 percent of all new and emerging infectious diseases.
Dr Restif has explained the number of zoonotic pathogens has increased in the last few decades as a result of “population growth, livestock growth and encroachment into wildlife habitats.
“Wild animals have drastically changed their behaviours in response to human activities, migrating from their depleted habitats.
“Animals with weakened immune systems hanging around near people and domestic animals is a sure way of getting more pathogen transmission.”
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Paper author and disease ecologist Greg Albery told AFP “the host-pathogen network is about to change substantially”.
“We need improved surveillance both in urban and wild animals so that we can identify when a pathogen has jumped from one species to another.
“If the receiving host is urban or in close proximity to humans, we should get particularly concerned.”
Veterinary infectious disease expert Professor Eric Fevre of the University of Liverpool said: “A whole range of new, potentially dangerous diseases could emerge — we have to be ready.”
Dr Restif agreed, adding: “We need huge investment in frontline healthcare provision and testing capacity for deprived communities around the world, so that outbreaks can be detected, identified and controlled without delays.”