Could we fall victim to an alien virus?

Star Trek: Lower Decks, the latest Star Trek adventure, takes its name and premise from an episode of Star Trek: The Next Generation, which eschewed the bridge crew in favor of a story centering on lower-ranking members of Starfleet. Lower Decks the animated series does the same.

In its premiere episode, we’re introduced to the crew of the U.S.S. Cerritos, an unimportant ship within the fleet. Their mission: second contact. They arrive on newly contacted planets to handle the paperwork and get new civilizations settled within the Federation. All of the work, none of the glory. The central conflict of Episode 1, "Second Contact," arises when a member of the away team is bitten by an alien bug and infected with a virus that quickly spreads back aboard the ship.

Of course, everything is resolved by the end of the half-hour episode, but it raises the question of viral transmission among species, particularly those from other ecosystems entirely.

INTERSPECIES VIRAL TRANSMISSION

More often than not, we concern ourselves with infection from other people. It’s sick friends, family members, or coworkers who pose the biggest threats to our health. We don’t often think of the animals in our lives as vectors for disease. Sure, you’re not meant to touch a wild bird because they carry bacteria. And it’s recommended to wash your hands after handling a friend’s pet turtle. But, by and large, the diseases animals carry don’t impact us.

Viruses, in particular, are specialized. They infect specific hosts and are finely tuned for replicating within and passing between those hosts.

That isn’t to say, however, that viruses don’t jump from one host type to another. The ongoing coronavirus pandemic is evidence enough of that.

Diseases that jump from animals to humans are known as zoonotic diseases or zoonoses. We don’t have good data with which to understand how often this happens in terms of raw numbers, mostly due to the fact that we aren’t aware of all the viruses that exist and infect non-human animals.

It’s often that we don’t become aware of a virus that has been endemic within an animal population until such time as it begins to impact us.

HIV, for example, was unknown to us until it crossed the species barrier to humans. Since that time, we’ve learned immunodeficiency viruses are common in Old World primates and likely made the jump to humans several times since at least 1920. Although those earlier jumps ended before a continued outbreak could be established.

Despite not knowing the likelihood of a given virus to make the jump to humans, we do have a better understanding of how it happens, when it does.

A study published in the journal Science in 2010 suggests the primary factor in cross-species transmission is genetic similarity. They conducted their study using thousands of rabies-infected bats and tracing the transmission of different rabies strains among species.

They looked for a number of factors, including geography, behavior, ecology, and genetic relatedness, and found the majority of cross-species transmissions occurred between bat species that were genetically similar.

Genetic similarity is certainly a shortcut to jumping host species, but viruses are clever and find ways to get around this. Specifically, by using intermediary species. The Nipah virus, in Malaysia, is a prime example of this process; the virus originated in bats before making the jump to humans, but it didn’t take the direct route.

Fruit orchards were planted near pig farms, which attracted infected bats to the area. The virus was then able to jump from bats to pigs, where it is highly contagious during the 14-day incubation period. Once the virus set up shop in pigs, it had an easier vector for jumping further to humans.

Making such a jump can happen in a number of ways within the virus itself.

Usually, initial infection happens as a result of spillover. Direct contact with an infected population results in an isolated infection outside of the usual host population, so long as the virus is able to bind with a cell’s receptors. These infections usually end, as successful person-to-person transmission isn’t possible. Continued contact allows time for the virus to mutate and adapt to the new host species, ultimately resulting in an outbreak.

The evidence suggests it’s unlikely, though not impossible, that a virus that previously existed only in a disparate animal population could make an immediate jump to humans without first going through these intermediary steps.

The real trouble with preventing cross-species transmission is our ability to become aware of these viruses before they impact us, and take appropriate steps to prevent circumstances that would allow for contact and mutation.

First (or second) contact with any new civilization, whether earthbound or extraterrestrial, should include stringent precautions to prevent forward or backward contamination of novel viruses. Needless to say, when it comes to the Galerdonian mission in Lower Decks' premiere episode, Starfleet really bungled things.

PLANETARY PROTECTION

Since at least 1956, the International Astronautical Federation (a real-life group of scientists and advocates, believe it or not) has been aware of and concerned with the need to protect both Earth and other celestial bodies from biological contamination.

The notion of viral contamination from beyond the stars has also been a part of the public discourse for decades. Michael Crichton’s novel The Andromeda Strain was released the year of the first Moon landing and presents a situation wherein an atmospheric satellite is impacted by an interplanetary meteor. It picks up an alien microbe that wreaks havoc on a small Arizona town. The authorities in the novel activate the Wildfire protocol, which utilizes a nuclear weapon to destroy any extraterrestrial contaminants before they can spread.

It’s a good novel, if a little exaggerated. Our real-world protocols aren’t nearly as dramatic and focus almost solely on prevention, not annihilation. NASA’s Planetary Protection Officer — a position that garnered headlines a few years back when an opening was posted — is not concerned so much with protecting Earth from alien invasion, whatever the title might suggest.

Instead, these persons are concerned with protecting Earth and any worlds we might visit from contamination.

This was of particular import during the Apollo program, as astronauts left Earth to walk on the Moon, collect lunar samples, and return with them. Apollo 11 astronauts Neil Armstrong, Edwin "Buzz" Aldrin, and Michael Collins famously spent three weeks in quarantine after returning from the Moon.

Today, there’s little concern about contamination between Earth and the Moon. But, as we set our sights on other worlds, like Mars and Europa, worlds that have the potential to host life, the need for caution increases.

It’s with that in mind that the Planetary Protection Officer works. Right now, the majority of the job is in preventing forward contamination from Earth to other worlds. The Mars 2020 mission, which recently launched the Perseverance rover to the red planet, has a primary mission objective of seeking out signs of life, either current or in Mars' past.

Sending a craft covered in Earth microbes would prevent any ability of Perseverance to objectively accomplish that task. Worse, if microbial life does exist on Mars, it could be irrevocably changed or wiped out by contaminants from Earth. Alternatively, even if there is no life on Mars, it’s possible that some Earth microbes could find a suitable environment there and set up shop.

All of these are scenarios we have a vested interest in preventing.

If the Mars 2020 mission goes as planned, samples collected by Perseverance will be returned to Earth as part of a future mission, currently slated for 2031. If and when that happens, Planetary Protection will also be responsible for ensuring any potential contaminants from Mars are contained.

In short, the protocols we have in place are stringent, even when the risk is incredibly low. The likelihood of returning living microbes from Mars is slim, and the likelihood they could make the jump to humans, a species that enjoys billions of years and hundreds of millions of miles of separations, is even smaller. Still, this is the type of situation where it’s better to be safe than sorry.

It’s curious the Galerdonian virus was able to make it back to the ship at all. Isn’t that precisely what the biofilter is for?