redrikki:

futureevilscientist:

biologyweeps:

katistrophe:

mcubed35:

taylor-tut:

So listen up y’all, nothing drives me crazier as both a writer and a scientist than seeing alien diseases that make no fuckin’ sense in a human body. 

If you’re talking about alien diseases in a non-human character, you can ignore all this.

But as far as alien diseases in humans go, please remember:

DISEASE SYMPTOMS ARE AN IMMUNE RESPONSE.

Fever? A response to help your immune cells function faster and more efficiently to destroy invaders.

Sore/scratchy throat? An immune response. Diseases that latch onto the epithelium of the throat (the common cold, the flu) replicate there, and your body is like “uh no fuckin’ thanks” and starts to slough off those cells in order to stop the replication of new virus in its tracks. So when it feels like your throat is dying? guess what it literally is. And the white spots you see with more severe bacterial infections are pus accumulation, which is basically dead white blood cells, and the pus is a nice and disgusting way of getting that shit outta here.

(No one really knows why soreness and malaise happens, but some scientists guess that it’s a byproduct of immune response, and others suspect that it’s your body’s way of telling you to take it easy)

headache? usually sinus pressure (or dehydration, which isn’t an immune response but causes headaches by reducing blood volume and causing a general ruckus in your body, can be an unfortunate side effect of a fever) caused by mucous which is an immune response to flush that nasty viral shit outta your face.

Rashes? an inflammatory response. Your lymphocytes see a thing they don’t like and they’re like “hEY NOW” and release a bunch of chemicals that tell the cells that are supposed to kill it to come do that. Those chemicals cause inflammation, which causes redness, heat, and swelling. They itch because histamine is a bitch.

fatigue? your body is doing a lot–give it a break!

here is a fact:

during the Spanish 1918 Plague, a very strange age group succumbed to the illness. The very young and very old were fine, but people who were seemingly healthy and in the prime of life (young adults) did not survive. This is because that virus triggered an immune response called a cytokine storm, which basically killed everything in sight and caused horrific symptoms like tissue death, vasodilation and bleeding–basically a MASSIVE inflammatory response that lead to organ damage and death. Those with the strongest immune systems took the worst beating by their own immune responses, while those with weaker immune systems were fine.

So when you’re thinking of an alien disease, think through the immune response.

Where does this virus attack? Look up viruses that also attack there and understand what the immune system would do about it. 

Understand symptoms that usually travel together–joint pain and fever, for example.

So please, please: no purple and green spotted diseases. No diseases that cause glamorous fainting spells and nothing else. No mystical eye-color/hair-color changing diseases. If you want these things to happen, use magic or some shit or alien physiology, but when it’s humans, it doesn’t make any fuckin’ sense. 

This has been a rant and I apologize for that. 

As a microbiologist, I think the main advice here is to take into account real diseases and conditions before you make up a fictional disease or condition.

Some bacteria have physical effects on the body that cause symptoms (EHEC varitype of E. coli ruptures cells at the site of infection, which is usually the large intestine, hence, you have bloody stools from it). If your alien or “made-up” bacteria or virus causes a certain symptom, find a real bacteria or virus that causes the same symptom. They need to behave in a similar fashion and have similar physical traits. Bacteria and viruses do not evolve functions because they’re cool. They evolve them because they’re useful.

There are also dietary issues, medications and chronic diseases that cause physical changes–copper toxicity can cause an orange ring around the iris, an eyelash lengthening “medicine” causes darkening and/or color change of the iris, hemochromatosis (sometimes known as “Bronze Diabetes”) causes darkening of the skin etc. If you want to use this sort of thing, again, find something real that causes it and work through things logically. 

Play your cards right, do your research and you will have hordes of readers in the scientific and/or biological community cheering, screaming and crying because they love your work.

@biologyweeps, this feels up your speculative alley – anything to add?

Ohhh.

I’d like to add that the same goes for parasitic infections, more or less. If you want a certain trait for a diseases, cross reference with existing parasites to see what’s happening, and also make sure you check what happens if you put a parasite in a host it’s not meant for. We can sensibly assume that alien parasites that encounter a human would be ‘wtf’ and potentially cause complications that would never happen in the native species. Maybe in the native species it causes a cold like reaction at worst, but in a human the parasites may attempt to nest in a totally different tissue. Maybe that causes widespread tissue damage by the parasite itself as it tries to borrow in? Again, check existing cases to see what horrific things could happen.

While we’re on it, also check how your disease is communicated. One of the things that annoy me so much with zombie movies is that ‘biting’ is supposed to be a very effective way to spread it. It’s not. Anything that requires such intimate contact is actually kind of hard to communicate. Airborne things? Now there we are at potential ‘oh shit’ territory. So if you want your disease to sweep the country/planet/ship, pick something that’s easily communicable. 

Also consider the incubation period. How long until someone shows symptoms? Are they already infectious to other people before showing symptoms or still after they stopped? As mentioned above, illness symptoms are in most part immune responses and the immune system needs time to get up and run. Give it that time.

And while we’re at it… there are symptoms that aren’t immune responses. For example the cramps that accompany tetanus are caused by a toxin the bacterium produces that damages/destroys nerve cells. Viruses can cause tissue damage when they insert in cells, replicate in there and destroy the cell on exit. Think of how HIV can wreak havoc on the human immune system by killing of a specific kind of cell. Depending on where your viruses likes to replicate it can massively impact the look of it. Something that destroys liver cells will look different (and if survived may come with different long term damage) than something that prefers skin or muscle cells. If it’s alien also consider how it might behave differently in its original host. 

Fantastic post, I can relate to OP 100%. More points:

Nothing makes me groan harder than a made-up plague which gives anyone X diseases within seconds to MINUTES. I’m looking at you, most zombie movies. And if your alien/synthetic/sci-fi pathogen is at all like a virus (read: no metabolism of its own, just genetic material of some kind which it uses to reprogram host cells), then the rate at which it mupltiplies is limited to what normal human cells can do. Now, viruses can multiply pretty damn fast. But give you symptoms within MINUTES? Nope.

So long as we’re on the subject of epidemiology, and speed:

 "Oh no, patient died less than a day after being infected! We’re all doomed!“ Wrong. While that SOUNDS scary, a plague that kills that quickly would not actually be that dangerous, and would be unlikely to have evolved to begin with. A disease needs to pass itself on to at least one other person, on average, before it kills its host, or it’s doomed to extinction. Any virus that kills its host before it has a decent chance of being passed on will basically quarantine itself. (Of course, you CAN do this if you handwave its origins as being made in a lab or whatever, just know it won’t realistically pose a truly terrifying threat on a population level.)

Mmore ideas for a realistically scary made-up plague:

– Long incubation period (say, a couple of weeks), making quarantine much more difficult, disruptive to everyday life, and unlikely to succeed.

– Infectious period != symptomatic period, i.e. someone can spread the disease before they appear sick. (Note: if this condition is met, then dying very rapidly after *manifesting symptoms* becomes plausible again, more plausible than dying quickly after being infected.)

– The possibility or relative prevalence of healthy carriers – think Typhoid Mary. I.e. rare people who skip the symptoms part entirely but are still infectious.

– The disease is transmitted through an animal that is hard to keep out, the definition of “hard to keep out” would depend on the setting here. Poor water sanitation means waterborne bacteria and microscopic parasites would be a huge danger. Insect or arachnid (e.g. tick) bites could be a danger in almost any setting..

– As an alternative to above point: the bacterial/viral/parasite/whatever can form spores that are fucking EVERYWHERE. (Read: the reason for both tetanus and botulinum poisoning.)

– The pathogen is both dangerous and impossible to fully exterminate through vaccination because it has a huge population of reservoir hosts. (Reservoir hosts are entire SPECIES that can carry and propagate the disease without being affected much by it.) Same way the Black Plague is still out there because a shitton of rodent species passively carry it.

And many more things if you do some research for inspiration! Pathogens are scary, fascinating things, and I really wish we had more realistic fictional representation of them than “virus which causes zombie behaviour in 3 seconds flat” (looking at you, 28 Days Later) and “virus which can MIND-CONTROL people who view the main carrier through a COMPUTER SCREEN” (wtf???) (looking at you, Jessica Jones).

@scriptmedic might this interest you as well?