Seven Scary Sci-Fi Diseases That Thankfully Aren’t Real

The science fiction genre is endlessly creative, but that creatively isn’t only limited to cool future technologies and fantastical alien creatures. Science fiction is also rich with inventively horrible diseases, some of which exist light years away in the depths of fictional solar systems, while others have made their way to Earth. Either way, you’ll be glad these dreadful diseases have been plucked from the imagination and exist only on the page and screen. Buckle up—some of these are downright horrifying…


The Pax from Serenity (2005)

In the Firefly universe, Reavers are a nightmarish group who torture and eat anyone they come across. Their existence is denied by the Alliance and brushed off as the stuff of legend by people on the core planets, but those who live on the fringes, like the crew of Serenity, know better. The episodes “Serenity” and “Bushwacked” establish the Reavers as real-life boogeymen of the ‘Verse, but little is known about their origins. The truth about the sadistic space cannibals is finally revealed in the movie Serenity.

After traveling to the planet Miranda, Mal and company find everyone dead and a recording by Dr. Caron explaining what happened. The Alliance released an experimental chemical, G-23 Paxilon Hydrochlorate, known as the Pax, into the atmosphere to calm the population and eliminate aggression. However, it pacified people to such a degree that they stopped doing anything, including eating. But 0.1% of the population had the opposite reaction to the virus, turning into the aggressive Reavers who now stalk the outskirts of the star system. For the victims of the Pax, either outcome is incredibly grim.


The Andromeda Strain from The Andromeda Strain (1969)

Michael Crichton’s techno-thriller The Andromeda Strain taps into the fear that humanity is woefully unprepared for the unknown dangers of space. The novel begins with a military satellite—one designed to capture extra-terrestrial microorganisms for use as bioweapons—falling to earth near the town of Piedmont, Arizona. Soon afterwards almost every resident dies from nearly instantaneous blood clotting, all except for an old man and baby. This triggers Project Wildfire, which sees a group of scientists working together in a top secret research facility in order to figure out what, exactly, has hitched a ride to Earth.

The microbe, named Andromeda, is super effective at killing humans and will make you hope that no weird space bacteria ever makes its way here. The novel’s focus on trying to scientifically analyze the extraterrestrial threat gives the sci-fi tale a feeling of eerie realism. There are no sentient alien creatures to negotiate with or fight against—just a scientific mystery which, if left unsolved, will result in the death of all humanity.


Krytos Virus from the Star Wars Legends novel X-Wing: The Krytos Trap (1996)

Blowing up planets (R.I.P. Alderaan) and unleashing bioweapons is all in a day’s work for the Empire. In Michael A. Stackpole’s X-Wing: The Krytos Trap, the Empire releases the Krytos virus to devastate the population of Coruscant just before the planet is recaptured by the New Republic. Krytos has been engineered to target species which are allies of the New Republic, excluding humans, and is treatable by bacta. You might be asking, “why make a weaponized disease treatable?” Well, paying for the cure will bankrupt the Republic, but not paying will sow resentment towards humans. Either way, the Empire scores points.

Although Krytos is treatable, it is designed to be as painful as possible. The flesh of victims “weakened, sagged, and split open” and they “bled from every pore and orifice.” As well as causing flesh to fall apart, in some species it causes liquefaction from the inside out: “There is a Gamorrean in there who has been turned into a mass of jelly. The disease killed him, but it did so in a way that didn’t let him die until he could experience every fragment of pain possible.” Yeesh. At least everyone on Alderaan died quickly.


Grubb’s Disease from the Judge Dredd comics

In the dystopian world of Judge Dredd, Grubb’s Disease is a slow-acting fungal infection which causes mushrooms to grow all over the body until the sufferer dies, at which point the mushrooms explode into spores. The comic’s artwork is guaranteed to turn mushroom lovers into mushroom haters on sight. The grotesque disease made its first appearance in the story “Fungus,” published in 1982 in 2000 AD, when the ex-mayor of Mega-City One, Jim Grubb, came into contact with it in the wastelands, infecting others before he died. While the growth of the fungus on the body happens slowly, infection is fatal.

Grubb’s Disease has since popped up multiple times in the Judge Dredd comics. In Shirley Temple of Doom, a mob boss uses Grubb’s as a weapon against Judge Stark, who, knowing the infection is terminal, then shoots himself in order to cause the mushrooms to explode and infect the mobster. Grubb’s is also playing a large role in the story “Death Cap,” which is currently being published in Judge Dredd Megazine. “Death Cap” sees ex-Judge Anita Goya face off against a group of marauders who are infected with a mutated variant of the mushroom disease.


The Wild Card Virus from the Wild Cards series


The Wild Cards series, edited by George R. R. Martin and Melinda M. Snodgrass and penned by a variety of SFF authors, is set in an alternate history timeline. At the end of World War II a virus, which was created on the alien planet Takis, is released on Earth as an experiment. 90% of people die upon exposure, the remaining 10% experience individualized mutations. The majority of survivors turn into monsters, known as Jokers, but a lucky few gain superpowers, and are known as Aces. How the mutation will affect each person is unpredictable. I’m sure that we all hope that we’d gain the ability to fly or shape-shift, but we’d most likely end up dead or living out the rest of our years as a vaguely humanoid blob.

To date, there are currently 29 books in the series, plus 21 short stories on Due to the unique effects of the Wild Card virus, authors are able to be incredibly creative within the world of the series, focusing on many different powers and mutations. While the universe overall exists firmly in the superhero genre, each author brings their own spin to the characters, and their stories blend a number of other genres into the mix. There are broad stories that take in the wider political situation and historical events, personal coming-of-age tales, and everything in between—all driven and defined by the lasting repercussions of this world-changing virus.


The Descolada Virus from Speaker for the Dead (1986)

Descolada, which means “unstuck” or “unglued” in Portuguese, is introduced in Orson Scott Card’s Speaker for the Dead, the indirect sequel to Ender’s Game (1985). This virus, true to its name, essentially unglues genetic molecules. Once the strands have been pulled apart, “the DNA tries to recombine, but random proteins insert themselves so that cell after cell goes crazy. Sometimes they go into mitosis, like cancer, and sometimes they die.”

These DNA changes have horrific consequences. At one point, the death of a girl at the hands of the Descolada is described in grim detail. Her body was covered in “cancerous growth and rampant funguses, the flesh swelling or decaying, a new limb, not arm or leg, growing out of her hip, while the flesh sloughed off her feet and head, baring the bone,” and all the while “her bright mind was mercilessly alert, able to feel all that happened to her until she cried out to God to let her die.” The Descolada is truly the stuff of nightmares.


Barclay’s Protomorphosis Syndrome from Star Trek: The Next Generation (1987 – 1994)

There’s an impressive variety of fictional illnesses and diseases depicted in Star Trek, but one of the most horrific examples appears in the TNG episode “Genesis.” Barclay goes to Dr. Crusher with a mild case of the flu and she injects him with a synthetic T-cell to activate a dormant gene so his system can fight the infection. However, Barclay becomes unusually energetic and then the rest of the crew begin to exhibit bizarre symptoms; Worf becomes increasingly irritable, Riker can’t concentrate, and Troi is finding the ship too cold and dry.

Picard and Data, who were away on a mission, return to the Enterprise three days later to utter chaos. Barclay is now terrifyingly part spider, Troi has turned into an amphibian-like creature, and Riker has transformed into a prehistoric primate. An anomaly in Barclay’s genes caused the T-cell injection to mutate and activate all of his dormant genes before becoming airborne and infecting his crewmates. The unaffected Data realizes that the crew are devolving into primitive forms of life from their respective homeworlds and sets about creating a retrovirus. While scientifically inaccurate (to say the least), on the plus side, Protomorphosis Syndrome provides some excellent visual body horror.



These are just a few of numerous nasty diseases science fiction has dreamed up over the years, of course—if you can think of other examples, please share them in the comments!

Lorna Wallace has a PhD in English Literature and is a lover of all things science fiction and horror. She lives in Scotland with her rescue greyhound, Misty.


Back to the top of the page


This post is closed for comments.

Our Privacy Notice has been updated to explain how we use cookies, which you accept by continuing to use this website. To withdraw your consent, see Your Choices.