Sunday, March 14, 2021

Animals self-isolate and socially distance to protect from infectious disease, scientists find


Jacob DubĂ© 
PSOTMEDIA
3/12/2021

For the past year, Canadians have been asked to follow unprecedented safety measures to slow the spread of the COVID-19 virus. Health experts asked people with symptoms to self-isolate in their own homes, and the rest of the public began to socially distance themselves from friends, family and strangers on the street.

© Provided by National Post Some species of ants actually practice social-distancing measures when an infection breaks out.
These actions might seem jarring to some accustomed to unrestricted social contact, but according to a new review published in Science , other animals have been self-isolating and social-distancing for years to fight against infectious diseases.

Species such as bats, ants, lobsters, fish, mice and primates have been observed to react to infectious diseases in their communities — some entire populations distance themselves even when they’re not sick to prevent a spread.

“Nonhuman animal systems, particularly those with social structures similar to those of humans, present unique opportunities to inform relevant public health questions such as the effectiveness, variability, and required duration of social distancing measures,” the authors said in the review.

Lead author Sebastian Stockmaier, a PhD candidate at the University of Texas’ Integrative Biology Department, told the National Post that he had been planning on writing a review on this subject for five years, but it was shelved when he began his field research on how vampire bats react to pathogens.

© AP Photo/Gerald Herbert A Vampire Bat drinks bovine blood in New Orleans.

When the coronavirus began to spread around the world in early 2020, Stockmaier revived the review. He brought on a collection of researchers with different specialities — including ants, birds, fish, and humans — and finished a first draft by last May.

“I think that collaboration was really fruitful because we had so many different perspectives about this topic,” Stockmaier said.

Stockmaier and his team identified five common methods that certain wildlife often use to protect themselves against infectious diseases. The first, he says, is avoidance. Simply put, if an individual is identified as being sick, others actively go out of their way to avoid them, a phenomenon that has been identified in birds, mice and lobsters.

“If you were going to the grocery store right now, and someone sneezes right next to you, you’ll probably take a step back,” he said.

The next two methods are both passive and active self-isolation. Passive self-isolation, Stockmaier says, is when an animal develops symptoms for an infection and the symptoms cause them to stray away from the pack, similarly to when we stay home when we’re sick. Some animals become more lethargic or less interested in social interactions, which incidentally separates them from the group. Sick vampire bats will avoid grooming others in their group, and infected bees share less food. Notably, this form of self-isolation is more accidental, but still works to prevent future infections.

Active self-isolation, when an animal identifies that it is sick, and willingly separates itself from its group to prevent an outbreak, happens most often in animals with strong social bonds. Certain ants will willingly leave their colonies and die if they become infected, in a form of “altruistic suicide”.

© Courtesy Stockmaier et al Stockmaier and his team identified five methods that animals use to prevent the spread of infectious diseases.

The fourth method, proactive social distancing, is what Stockmaier says we’re mainly doing right now. Health experts have advised that, infected or not, we all maintain a social distance from others to prevent a potential spread of the coronavirus. This was typically not seen in animals other than humans, but co-author Nathalie Stroeymeyt discovered that some species of ants begin to keep their distance from one another when a few in a colony become infected with a fungal pathogen. The review noted that social distancing was extremely effective in preventing the spread of these pathogens.

One mystery, Stockmaier said, is how the ants were able to collectively identify an infection and decide to do something about it.

“How do other individuals sense that there’s an exposed individual around?” he said. “We have the media and so on, but how do these ants know that there’s a threat going on?”

The final method to prevent infectious diseases that the review noted is exclusion, which would mean that the infected individual is forcibly prevented or exiled from the rest of the group. It’s been shown in insects, Stockmaier said, and has anecdotally been seen in some primates, who have been caught acting more aggressively to sick group members.

According to Stockmaier, more research is needed to look at how an animal’s behaviours evolve to react to certain infections — and how the pathogens also evolve to adapt to the animals.

“It’s not surprising to see animals doing these things,” he said. “Animals are encountering pathogens every day too, so we’re not the only ones being affected by infectious diseases. It’s just fascinating to see that there are certain behaviours that have evolved in certain animals that serve that purpose.”

But while it’s easier to pinpoint why an animal might take some of these behaviours to fight against infectious diseases, Stockmaier said it’s tougher to figure out why humans act the way they do. Caretaking, for example, goes against most of our natural instincts when it comes to preventing viruses, because it actively increases your chances of being infected.

“For some people it’s hard to pinpoint the benefits, like why do they do it, why does it evolutionarily make sense to do this,” he said. “There might be delayed benefits, and there’s all these things that you can’t get a grasp on that play a role in there that you might not have going on in animal societies.”

We won’t know until more studies are done into our behaviour, but at least in the meantime we have our animal relatives to look to for help.


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