Age of panzootic: Scientists warn of more devastating diseases jumping between species

bThe first flu poses a threat that is “unique and new in our lifetimes” because it has become a “panzootic” that can kill huge numbers of multiple species, experts warn. Highly pathogenic bird flu, or H5N1, has been circulating on dairy farms for months, with dozens of human infections reported among farm workers. It has now jumped to more than 48 species of mammals, from bears to dairy cows, causing mass deaths of sea lions and elephant seal cubs. Last week, the first person in the US died from the infection.

This ability to infect, spread among, and kill such a wide range of creatures has prompted some scientists to call H5N1 a “panzootic”: an epidemic that crosses species barriers and can devastate diverse animal populations, which is also a poses a threat to humans. As shrinking habitats, biodiversity loss and more intensive agriculture create perfect breeding grounds for infectious diseases that can jump from one species to another, some scientists say panzootics could become one of the era’s most significant threats to human health and safety.

Panzootic means ‘all’ and ‘animals’. “Panzootic is almost a new thing, and we don’t know what kind of threat it is,” says Prof. Janet Daly of the University of Nottingham. “We have some viruses that can infect multiple species, and we have some viruses that can cause massive outbreaks, but we don’t tend to have the combination – that’s something of a new phenomenon … That’s where H5N1 is headed, and it makes it so unpredictable. (It is) unique and new in our lives and our memories.”

Ed Hutchinson from the MRC-University of Glasgow Center for Virus Research said: “It is very difficult for infectious diseases to effectively stop being specialists and move on to a new strain. So when that happens, it is striking and worrying.”

The consequences for biodiversity can be enormous. Bird flu has led to a ‘catastrophic’ decline in seabird populations, killing millions of wild birds. More than 20,000 South American sea lions have died in Chile and Peru and an estimated 17,000 southern elephant seal cubs have died in Argentina – equivalent to 96% of all puppies born in the country in 2023.

The risk of bird flu spreading among humans is a ‘huge concern’, UN health authorities have warned. Recently, a man in Louisiana died after being exposed to a combination of a non-commercial backyard flock and wild birds. Since March last year, 66 confirmed bird flu infections in humans have been reported in the US, but previous cases have been mild. So far, there is no evidence that the disease is spreading among people, and experts are keeping a close eye on that.

Three quarters of emerging diseases can be transmitted between animals and humans. This is important when it comes to mapping them and protecting people, researchers say.

Some researchers argue that Covid-19 could be an example of a panzootic because it has infected more than 58 non-human species, included deer, mink, and even snow leopards (although unlike bird flu, the flu does not effectively spread between them and kill them, and thus does not meet the traditional definition).

“We are overwhelmed by the number of species susceptible to (Covid-19) infection,” researchers say.

Identifying the virus that causes Covid-19 as a potential panzootic could have resulted in active surveillance of animals. say researchersand the earlier development of vaccines.

Scientists also warn that interspecies pandemics are on the rise. “There is a fair amount of work now showing that most human viruses are zoonotic (that is, of animal origin),” says Michelle Wille, senior research fellow at the University of Melbourne’s Center for Pathogen Genomics.

Mark Honigsbaum, medical historian and author of Pandemic Century, says: “Why are they becoming more common? The simple answer is: it is because of the way we humans are settling and colonizing larger and larger parts of the planet.”

Loss of biodiversity is the leading cause of infectious disease outbreaks, as habitat degradation and industrialized agriculture bring humans into close proximity with other species. People are already transformed or occupied more than 70% of the world country. Since the 20th century, the ‘livestock revolution’ has been the main driver of this transformation of the way we use land. The number of food animals and the amount they produce has increased rapidly to feed the growing population.

Deforestation and climate change are also forcing people and animals into close contact, as wildlife is pushed into smaller spaces. In addition, as the climate warms, mosquitoes, midges and ticks are expanding their geographic range.

The more pathogens there are in animal populations, the greater the risk that humans will be exposed to them. Honigsbaum says, “We will see more of these outbreaks, and it is only a matter of time before one of them causes another pandemic.”

“I don’t see those risks going away,” Hutchinson says, but adds that the risks can be reduced. “We’re getting a better understanding – if not a fantastic, practical setup – of what we could do to reduce some of those risks. That is my attempt at a moment of hope.”

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