Athena Aktipis and Joe Alcock suggest that SARS-CoV-2 is a sort of zombie virus, turning people not into the undead but rather into the unsick:
People typically think of zombies as the stuff of science fiction. But in the biological world, zombies are all over the place, from the Ophiocordyceps fungus that perpetuates itself by zombifying ants; to Toxoplasma gondii, a single-celled parasite that completes its life cycle by leading rodents into the jaws of predators. Zombie viruses are also a real thing, influencing their host’s behavior in ways that enhance the viruses’ evolutionary fitness.
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About 40% of those with SARS-CoV-2 are asymptomatic spreaders, never showing symptoms at all. And those who do show symptoms are most contagious in the two days before symptoms appear. Why people don’t feel sick earlier – or sick at all – might be part of the evolutionary strategy of SARS-CoV-2.
A look under the hood of the virus reveals more about that manipulative machinery. SARS-CoV-2 interferes with a person’s immune response; this is why people don’t necessarily feel sick and withdrawn as they would in a typical viral infection. Instead, SARS-CoV-2 silences the body’s alarm signals that otherwise would orchestrate anti-viral defenses. It blocks interferons, a set of molecules that help fight viruses. Interferon activity makes people feel more depressed and socially withdrawn – so when the novel coronanvirus impedes interferon activity, mood is lifted, sociality is increased and you feel less sick.
The virus also decreases pain perception. Normally, pain motivates us to hunker down when we need to heal. But SARS-CoV-2 blocks this response by preventing the transmission of pain signals. This is why people feel fine even when they are teeming with virus before the onset of symptoms.
At the same time, SARS-CoV-2 dampens the body’s response to infection. It hinders pro-inflammatory cytokines, molecules that help spur the immune response. This too makes hosts feel better than they should. Typically, feeling sick helps our bodies prioritize healing by making us reduce our energy expenditure. With SARS-CoV-2, unsick hosts have the energy to do as much as they used to, maybe more.
“…might be part of the evolutionary strategy…”
It did not “evolve” in the traditional sense. It was engineered.
Could there ever be a virus that makes us feel really good? That would be a good evolutionary tactic – to produce euphoria and increased sociability and sexual desire in the host. It could improve our appearance, too, by making our skin and eyes look brighter.
Presumably, when viruses make us feel bad, it’s because our immune systems try to get rid of them. Couldn’t one evolve to live quietly in us, enhancing our happiness in a sort of symbiotic relationship?
Syphilis may fit that description:
The Chyna Coof is so dangerous that not only do you have to take a test to know that you have it, but it makes you feel better than you should.
I am so scared, guys. The end is nigh!