I have an interstellar war in which us humans fight an alien nomad fleet. The aliens begin to lose the war and need something to fall back on. Humanity over many millennia has built star gates(kinda like Star Gate) and has ten colonies. The aliens took one and are using the gate in that system to attack other human colonies. They designed a flu virus that, like the natural flu, spreads through the air, but causes the infected human's brain to lose the ability to absorb serotonin and hypes adrenalin levels, giving it the ability to cause a planet-wide riot on a selected human world.

Since humanity has all but won the war, human ships patrol the star gates for any incoming attacks. Since the gates are so well defended and the alien fleet is so depleted, they don't want to risk trying to break through the blockades. They send a spy with the virus through. At this point, the spy has to figure out how to release it.

The obvious options are infecting swine or earth birds, or directly infecting people. Which has the ability to reach and infect the most people assuming the population densities on this colony are equal to that on modern earth and the locations of the population, like earth, is generally near coasts, rivers, and strategic positions?

It should also be noted that this flu, other than its serotonin-destroying properties, can infect all vectors that H1N1 can infect, as well as being transmitted via contact with infected blood.

What is the best way to introduce this virus into one of the colonies?

  • $\begingroup$ Do you want this to be 100% delivered on-location by a spy, or are other delivery methods possible? And is the intent to control the timing of this specifically, or do they just want to introduce the virus to humanity at large to delay and cause issues? $\endgroup$ Commented Mar 11, 2015 at 15:52
  • $\begingroup$ @DanSmolinske I want the spy to deliver this virus to one of the colonies. That colony will be monitored and when 75% of the populace is infected and rioting and the military is trying to maintain order! they will attack. The spy has to go to the surface of the planet in order to infect any of the vectors. $\endgroup$
    – Jax
    Commented Mar 11, 2015 at 15:54
  • $\begingroup$ Ok. My thoughts were engineered spawners (ex: genetically modified cockroaches that release the virus), or slow delivery by asteroids, but it doesn't sound like those would work for you. $\endgroup$ Commented Mar 11, 2015 at 16:05
  • $\begingroup$ @DanSmolinske Cockroaches....sheesh, even after thousands of years of trying while building a small interplanetary republic we still haven't gotten rid of them! Hardy little suckers! $\endgroup$
    – Jax
    Commented Mar 11, 2015 at 16:07
  • $\begingroup$ Humanity wouldn't have survived to have ten off-world colonies if they didn't have very good quarantine protocols or broad spectrum antiviral drugs. Is there some kind of handwavigen-protein induced delay before symptoms appear? Should answers assume humanity has stopped progressing with medicine and it's at modern levels? $\endgroup$
    – Samuel
    Commented Mar 11, 2015 at 17:19

5 Answers 5


The answer is probably much more complicated than you'd think it would be.

First, influenza would be a terrible vector for the kind of symptoms you want to create. Influenza generally impacts the sinuses, lungs, throat, and other parts of the respiratory tract. Very, very rarely will the influenza virus enter the brain, and even when it does, its symptoms are limited to inflammation and swelling (which can obviously be fatal, but does little to mess with brain chemistry). This is largely because of the mechanism that influenza uses to reproduce in the human body.

Working backwards, we can identify a better disease vector. First, serotonin in the brain comes from the raphe nuclei. To prevent our hosts from using serotonin, we would have to either disrupt the raphe nuclei or prevent serotonin from being absorbed in the neocortex. Serotonin triggers the 5-HT receptors, so we would need to identify receptor antagonists that would block those receptors, and then develop a vector that can deliver those antagonists.

Also, we would have to increase epinephrine production in the adrenal glands (which are located on the top of the kidneys, not in the brain). There are some diseases, such as pheochromocytoma, that lead to increased epinephrine and norepinephrine production. Our vector would also have to perform these functions.

In other words, what we are looking for is a vector that can produce and distribute throughout the body hormones and neurotransmitters. And that would most likely be a bacteria; not a virus. This is because a virus must reconfigure its host cell to create the desired environment; it doesn't have the ability to produce these on its own.

A bacteria is its own protected factory, which would allow it to be engineered to produce our needed chemicals. Starting with a base like whooping cough would give you the desired airborne transmission. If you wanted to go with the multi-animal transmission route, the plague may be a good starting point.

The best way to introduce our bacteria would probably be through the water supply. If the spy can get access to the post-filtered clean water, your disease will easily spread. That will hopefully let it reach critical mass, and get the rest of the colony infected by airborne spread.

  • $\begingroup$ Apparently H1N1 can come with a host of neurological complications...all studies mention more study is needed though. ncbi.nlm.nih.gov/pmc/articles/PMC3559119 quote: Mild neurological complaints may be reported in up to 42% of patients infected by H1N1 virus. Severe neurological complications occurred in 9% of the patients. The most common neurological manifestations were headache, numbness and paresthesia, drowsiness and coma. One patient had a Guillain-Barre syndrome-like illness, and died in a few days. Another patient had focal status epilepticus and encephalopathy. $\endgroup$
    – Twelfth
    Commented Mar 11, 2015 at 18:18
  • $\begingroup$ @Twelfth There's a big difference between H1N1 causing neurological symptoms by interacting with the peripheral nervous system and it penetrating the brain. In a survey of eight children with severe neurological symptoms, only one had H1N1 detected in the cerebrospinal fluid: ncbi.nlm.nih.gov/pubmed/15520093 $\endgroup$
    – Nick2253
    Commented Mar 11, 2015 at 18:23
  • $\begingroup$ The problem with bacteria is that most if not all are easily treatable with some sort of antibiotic. If I go down the bacteria road it'll end up being back to the drawing board for the aliens. $\endgroup$
    – Jax
    Commented Mar 11, 2015 at 18:36
  • $\begingroup$ And if humanity survives for thousands of more years, it is likely that we have perfected the art of treating bacterial illnesses if not most viral illnesses. $\endgroup$
    – Jax
    Commented Mar 11, 2015 at 18:38
  • 1
    $\begingroup$ @DustinJackson The fact that all bacteria are treatable with antibiotics is a common misconception. Only certain types of bacteria are treatable with certain types of antibiotics. And every day, more and more antibiotic-resistant strains of bacteria are naturally developing. There's a serious threat that, in a few decades, far from having bacterial infections under control, we will once again be besieged. $\endgroup$
    – Nick2253
    Commented Mar 11, 2015 at 19:30

It can spread like H1N1, which spreads like the seasonal flu? That makes life easy!

You want to place it somewhere where it can easily spread, but heath officials will not bother to clean as much. So, for example, contaminating a blood bank would be great, but it would be quickly discovered. That makes the blood bank a poor choice. Since this spreads like the flu, I would expect the best places for it are where flu viruses spread today.

Put it a rag which is wiped on things in the subways, buses, and other high-traffic meeting places transport, and you can ensure a wide spread of people contracting the disease, who then travel to spread the disease elsewhere. You could even go to Disney-world (or your colonies' equivalent) and cover surfaces there with it. Schools, especially elementary schools, would be ideal since children do not have as many concerns about germs as adults do.

To be more specific, door handles, rails, and buttons are your pathogen's friends. Any surface people regularly touch, especially if those people are moving on to various reaches of the colonies, are your main targets. I doubt we'll get beyond touching buttons or using in the far future, unless you bio-engineer people to not resemble homo sapiens anymore.


Since the virus is airborne, you could spread it using a chemical fog.
The Tom Clancy book Executive Orders has terrorists using a modified spray can at convention centers to spread a virus.

That would get it out into the general population. Depending on how the symptoms presented, it could be self limiting. You have the initial infection, the victims don't know they are infected, and continue about their lives, touching surfaces, spreading the virus to others. At some point the symptoms become obvious and you have a point where people will quarantine themselves. "I'm not feeling well, so I'm not going to work today". If the symptoms are bad enough population wide, then outside quarantines will be imposed.

For the maximum spread, you'd want a virus with a really really long incubation period, where the symptoms are minimal or non-existant, but the host is still infectious. That way the biggest number of people will be exposed before the first victims begin to show symptoms.

Likewise, other than the serotonin blocking, you'd want the symptoms to be really mild even after the incubation period. The best course would be a virus that doesn't do anything to make people suspect it's there. "Yesterday she was fine, today she's acting really weird and violent."


If all you need is a vector which will be handily passed around the population very quickly, the obvious thing to use is cash.

Presumably a government funded spy trying to save their entire race should have access to a lot of money. All they have to do is:

  • withdraw a lot of paper money from a band
  • douse it in the pathogen
  • go and buy a lot of things in different cities with the now toxic but legal money.

The money itself will spread rapidly around the cities it is spent in, infecting people as it goes.

The big advantage of money is that if it's handed out to people, they'll spread it of their own volition. Giving it out as charity to the homeless would be a pretty effective vector for example.

This way, the agent doesn't have to spread the agent themselves, they can easily turn anyone they meet into a willing contamination vector.


Influenza is terrible at infecting neurons. You need to use something like rabies instead. Unfortunately, influenza and rabies, while both RNA viruses, have rather small genomes (12-14 kb), which makes your task daunting.

But, fine, you have aliens with interstellar transport capability. They can probably do daunting molecular biology: take a highly infectious airborne virus like influenza or rhinovirus as a backbone, re-engineer the viral capsid proteins to admit a larger payload, add genes that will produce a rabies-like virus (or at least the protein that binds NCAM to give it entry to the nervous system), and then add a reverse transcriptase and such to be able to modify the DNA (good if you want long-lasting effects), using a serotonin-neuron-specific promoter (or a glial cell promoter that drives production of antibodies to serotonin receptors with export sequences on them).

And then go through yet another layer of optimization to get it to work passably well in birds or something for the cross-species infection.

But good grief that's a lot of work. It's very inefficient. Why infect birds when you can just visit a bunch of cities leaving around virus-saturated items where children can pick them up? Why, when you have such powerful control over a person's molecular biology, would you just mess with their serotonin and adrenaline systems? Better to have a virus that has a quick initial infection and then goes latent (Herpesviruses are good at that) with special triggers to activate it in times of high stress. Infect a bunch of people, then cause a scare, and BOOM! You cripple a huge portion of the population. No need to be subtle, is there? Just cause loads of neurological damage.

The biggest plot hole is that people, given that they are competitive with the aliens, will doubtless have extremely advanced molecular biology also. So it will take a matter of days to have sequenced and inferred the function of the entire elaborate construct, and another couple weeks to have ways to generate high affinity binding proteins that provide essentially complete immunity. Any long-lasting futzing with neuromodulators is doomed to failure; you need something that takes out vast numbers of people really fast, or humans will reactively solve the problem before it causes any appreciable harm.


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