I wanted to take a different direction with the succubi/incubi mythos and make it more grounded by turning it into a disease for a horror setting. A fungus exists today which can take over the body of ants called the O. unilateralis, and decided to model a parasite in this setting off this creature. Although acting on instinct at first, it eventually grows more intelligent the further It spreads. It feeds on semen, and transmits itself by acting in a similar way to an STD by invading a host body and using it to infect other bodies. This parasite would make the host body infertile, and compel it towards spreading the infection to others.

Hypothetical scenario: This parasite originally infects a female host, taking up residence in the genital area. It slowly subsumes the host's mind, compelling her towards sexual activity with multiple males. The parasite helps this process by heightening her attraction to others, perhaps through hormones or altering features. It uses some chemical to strengthen orgasm, encouraging as much ejaculation as possible for it to feed. During climax, the parasite passes on a piece of itself into the unsuspecting male, turning them into a carrier. Over time, it subsumes their mind and compels them to use any and all methods to have intercourse with as many people as possible as fast as possible, passing on the infection.

Using this method, how can a parasite take over a person biochemically to successfully transmit itself into enough people to create a hivemind? And how can it go unnoticed?

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    $\begingroup$ Related. $\endgroup$
    – Cadence
    Commented Aug 12, 2018 at 19:50
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    $\begingroup$ Have a look at rabies and toxoplasmosis. $\endgroup$
    – Ash
    Commented Aug 12, 2018 at 19:58
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    $\begingroup$ "This parasite would make the host body infertile". That's a sure way for the parasite species to (eventually) kill itself off. $\endgroup$
    – RonJohn
    Commented Aug 13, 2018 at 10:02
  • $\begingroup$ @RonJohn Not necessarily. What if it has a later-stage host species that's not human? Vultures could be the final-stage host, infected by eating human corpses. The parasite needs the vultures to reproduce. But as for the infected humans, as long as it only infects a small proportion of the population, it can safely render them infertile. Infected humans are sexually obsessed and would not concentrate on raising their young, so making them infertile helps the reproductive fitness of the remaining human population, and ensures future generations of humans for the parasite to infect. $\endgroup$ Commented Jan 18, 2020 at 23:23
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    $\begingroup$ @RonJohn Also, if you take a close look at the wording of OP's question, the parasite causes the infected human to become more sexually active, but this is only described as becoming obsessive "Over time". In the early stages of the infection, the acquaintances of the infected victim may not notice anything's odd. By the time the victim's behaviour becomes obsessive/hypersexual, they've already passed on the parasite several times. If the parasite is based on O. unilateralis, it could even have the victim walk out into the desert to die and be eaten by vultures in the final stage of infection. $\endgroup$ Commented Jan 19, 2020 at 0:17

4 Answers 4


I'm going to leave out a lot of detail in the ability to create a hive mind, as in theory lots of individuals performing the same task in order to benefit the the colony is what Hive Minds are all about, and are generally not the typical Modus-Operandi of a parasite. parasites live off their host which negatively effects the host. hive mind animals don't really do this, i'm sure there are some that do, but as a whole they tend not to.

Parasite Targets

Your better option is is to actually not infect males in the same way, the reason i say this is that "any and all methods to have intercourse" means they'll be a lot of rape, and even if the infected victim is then overcome by the parasite and doesn't press charges, there'll still be witnesses, and if suddenly a small town went from 1 or 2 cases of rape a year, to several hundred, then it will be looked at very carefully including the biochemistry of the assailants, also rape victims (assuming the parasite doesn't take control in less than an hour), would get checked over by paramedics and doctors in hospital and cultures taken to see if the victim contracted an infect as part of the process (Standard UK procedure at least) meaning it would likely be discovered in due course of those results.

Seeing as its not often that rape on men is anywhere near as reported, and in theory harder to do as the female assailant will want conventional intercourse, means that there are less "victims" in the conventionally non parasitical sense therefore less people looking into it.

Target Environment

Perhaps the parasite could release chemicals that effect the behavior of the host to encourage it into areas where promiscuity is more likely, perhaps it craves dark areas with bright flashing light, there are many case of illnesses that make people light phobic or dark phobic, so a strange combination of both might encourage the infected into "clubbing" areas, where the free use of alcohol and drugs makes intercourse more likely.

Perhaps the parasite cause the body to burn more calories, this would make the host hotter and therefore more likely to prefer being less dressed/completely undressed even in public, this may assist the virus in other ways, it would not want 2 infected to engage with each other in the bedroom/toilet stall as that would waste efforts and not increase transmission, so perhaps the higher heat could be detected by the parasite and turn the host away from each other

Perhaps the host body has increased muscle tension, seems insignificant at first, but if a woman were to have several partners in an evening, then being... tighter... would make the process quicker once activities began. also she would probably need to produce more lubricant, which in itself could assist in the transmission of the virus.

it also needs to produce a lot of feel good hormones in the host, (unless it can completely control the host) as humans often, when not feeling well, avoid others and call in sick or see a doctor, so to go unnoticed, it must make the host feel really good so they are in a good mood, less likely to call in sick less likely to go see the doctor.

Then of course there is the possibility of the parasite releasing pheromones to attract more mates.

Final thought

You story sounds similar to the Sixth Extinction by Glen Johnson, might be worth reading that series as it covers many similar notes just without the intercourse.

  • $\begingroup$ Toxoplasma gondii may increase testosterone levels in the male rodents it parasitizes (a lot of relevant research was paywalled, but it may be that it induces the same behaviour changes in female rodents by some other means.) Increased testosterone would increase sex drive. So if the parasite is sexually transmitted, it could increase it's host's sex drive (even if only in the case of male hosts), causing increased sexual activity and causing it to be spread. It might be worth a quick edit to your answer to include this? $\endgroup$ Commented Jan 18, 2020 at 23:11

Okay, well, there's a few things here I'm not really sure about.

For one, parasites don't really have a sense of 'instinct' since they aren't sentient or sapient. You can't exactly call them intelligent, although famously dangerous viruses like Ebola or malaria take use of very sophisticated tactics to overrun their host body.

The fact that the parasite feeds on semen is both unnecessary and useless. Not only would it ensure that the parasite can only spread exponentially in the male gender, but real parasites don't really need to 'eat', per se. It could probably remain realistic without that part altogether.

Altering features wouldn't really be easy to do for a parasite. For research on diseases that do exactly that, you can refer to elephantiasis on Wikipedia, which can affect both males and females in the genital areas (it's actually kinda disgusting how large they get). You should probably stick with the parasite altering hormone amounts in the body, since that sounds much more plausible.

Finally, with the way you describe it, the parasite would probably only go unnoticed for but a few days before news stories start covering the unusual amounts of sex in the population. The fact that it makes humans infertile, though, would kill both the parasite and humanity pretty darn quickly.

  • $\begingroup$ You say "parasites don't really have a sense of 'instinct' since they aren't sentient or sapient." That may be true of the fungal parasite OP had in mind, but what about, say, young cuckoos? Driven by instinct, they push the eggs of the host bird's young out of the nest, so that there will be more food for them. Or the larvae of the parasitic wasp Cotesia glomerata? Their instinct drives them on to eat their way out of the caterpillar they parasitize as soon as their teeth develop (instead of just continuing to eat its fat reserves). And to stick around near its wounded body afterwards. $\endgroup$ Commented Jan 19, 2020 at 7:56

I wanna see your Pica-ca-ca 🎶

I am going to talk about a real life disease, but first an important warning: the English name for it is also a very current word for penis in the 6th most commonly spoken language in the world. Depending on where in the world you are, you may get some NSFW results if you google for it. I did.

Pica is...

an eating disorder in which a person eats things not usually considered food. Young kids often put non-food items (like grass or toys) in their mouths because they're curious about the world around them. But kids with pica (PIE-kuh) go beyond that. Sometimes they eat things that can lead to health problems.

People with pica crave and eat non-food items such as:

  • dirt
  • clay
  • rocks
  • paper
  • chalk


And that's the semen-eating part of the disease. The fungus induces a form of Pica on the victim, that leads them to eating sperm.

But why?

A person who is infected will surely try to get as much sperm as they can.

There is a group activity that can help you achieve that. Bukkake (japanese for moist or something) is a fetish consisting of a group of men ejaculating over someone, often simultaneously and usually over the oral and facial regions, for kinks. An infected individual might form or seek bukkake groups so as to maximize their sperm collection.

Since one thing leads to another, the sex acts done before, during and after the mass ejaculation will facilitate the fungus passing from one person to another.

But why sterilize its victims?

Because if you or your partner are pregnant, you have less time for bukkake. Duh.

(Unless you are into prego stuff, which is not very christian. You perv.)


It doesn't need anything special to spread

STD's are a fact of life. Like all diseases, they have found a way to survive and spread. The only difference is that these often nestle and spread from private areas, which is the only reason we treat them differently. They are not. Bonus fact: many STDs can also nestle in the mouth. Practice safe sex on all levels.

Given the current STD statistics any fungi doesn't need to do anything but sit tight and spread.

Diseases taking over

The Cordyceps is a rather large complex fungi that takes over it's host in a very direct way. This is totally unnecessary. In humans we can see that a lot of activities are dictated by the gut flora and fauna. Granted, much is done to keep eating certain foods. That is why it is hard to change eating habits. But we can see other examples as well. Rabies famously makes people avoid water. Toxoplasma gondii is a cat parasite that can infect rodents, causing them to lose fear of cats. That way they spread more easily to their primary host, the cat. The key on these is that they do not 'control' directly. They simply give urges and feelings that make the likelihood of it happening very large. Any person can choose not to go to that fast food restaurant, but they give in.

Now let's put what we've discussed together. Humans are already horny and not careful enough to avoid STDs altogether. It is quite prevalent in the population. If we add a parasite that makes women engage more easily engage in risky sex, you're already there. The men rarely need any further inclination for sex with or without a parasite. This is of course just a generalisation. But that is the point. No parasite needs to be 100% effective, nor would it pan out well. They often need their hosts to have a partially healthy population to still have something to infect tomorrow.


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