# Feasibility of a virus that causes its host to crave sex?

In the near future a man-made virus was released which caused a world wide epidemic in humans and animals , the virus completly shutsdown all cognitive functions in the brain leaving the host in a zombie like state while stimulating certain parts of the hypothalamus causing sexual arousal.

Would this virus actually work and what would be the most efficient way for the virus to spread?

• Not quite the effect you are after but studies show that after the flu vaccine people are more energetic to go out and socialise, as if the virus puts you in a better mood to go out and spread it. how true the results are i'm not sure.
– user69935
Feb 22 '20 at 12:00
• syphilis, which is bacterial, does this.
– John
Feb 22 '20 at 13:10
• From the diseases' perspective, making people fall into a zombie-like state would be suboptimal as people are much more likely to have sex with people who don't appear to act significantly differently. An STD that raises libido to but still keeps people thinking is much more realistic imo Feb 22 '20 at 15:21
• Given that Toxoplasma gondii is known to cause mice and people to like cats, I'd say that it is proven that a pathogen can alter the behavior if the host. Feb 22 '20 at 15:34
• If the virus granted health, youth, and a sense of well being, then human biology would take care of the rest — there is a reason behind the expression ‘young, dumb, and full of cum.’
– EDL
Feb 22 '20 at 21:52

$$$$

the virus completly shutsdown all cognitive functions in the brain leaving the host in a zombie like state while stimulating certain parts of the hypothalamus causing sexual arousal.

I think the scientific term in humans is puberty

$$$$

It would be the perfect way for a sexually transmitted virus to propagate.

The early forms of syphilis were devastating on the body of the host, making it not/less appealing for intercourse, which is a downside for an infective agent basing its propagation on it. It is believed that a mitigation of the physically visible effects of syphilis has been a consequence of the selective pressure given by the above mechanism: the less damaging a certain infecting agent was, the more it could spread.

We also know of agents which affect the behavior of their host to increase their chances of propagation: rabies, some tropical worms, the zombie fungus are just some examples.

All in all it is perfectly feasible that a virus develops this trait, maybe even coupled with some other effect on the host body to make it more sexually appealing.

• Improved pheromones on the sweat. The sweat was proven to be attractive to the opposite sex. Feb 22 '20 at 19:01

Is it possible for a virus (or other parasite) to make its host crave sex? Absolutely and easily. Sex drive is pretty much driven by hormone production and it's trivial for a parasite to tweak the production of a hormone or two. Testosterone would be a likely candidate (it increases libido in both women and men) and maybe something that reduces inhibitions. Easy-peasy, and your infected are horny all the time.

Is it possible for such a virus to succeed this way? Well, that's a lot harder, because it relies on the partner not recognizing the presence of abnormal behavior. Humans tend to be pretty picky about their partners, relatively speaking, and sexual attraction takes time, subtlety, responsiveness, and intelligence. That's brain-stuff, not chemistry-stuff, and parasites aren't very good at brain stuff.

Of course, a particularly physically attractive host might be able to spread the parasite a fair amount anyway just by being readily available - but since particularly attractive hosts tend to be pickier about their partners, the chances of such a host picking up the parasite in the first place is much lower. So it's unlikely for the parasite to ever get off the ground just turning its hosts into sex zombies.

Nevertheless, it's not impossible, if the parasite is subtle in its machinations. There are some studies that suggest that Toxoplasma gondii (like you'd expect any other parasite) might make women more promiscuous, and it might be capable of sexual transmission, although this isn't its primary route of infection (also, humans aren't its main host). But studies are inconclusive, and for good reason - after all, if it was obvious, it wouldn't be as effective, would it?

• "since particularly attractive hosts tend to be pickier about their partners" Attractive women might be, but attractive men tend to spread their seeds far and wide. IIRC 20% of men have 80% of the sex. Feb 23 '20 at 11:00

Consider it as an equivalent to rabies. The virus wants to spread, if it's a sexually transmitted virus then it would encourage sexual behaviour as a means to spread itself through a population.

It wouldn't survive as a zombie virus though as it has to increase, not decrease, attractiveness to other potential partners.

Something more like Fry's worms in Parasites Lost

• This is not an answer. The OP wants to know if such a virus is even possible, not what its effects would be if it already existed. Put another way: Can a virus generate the necessary hormones and/or suppress the cognitive pathways in order to significantly increase sex drive?
– SRM
Feb 22 '20 at 15:19

I think so. Toxoplasmosis is a cat-based parasite which affects other mammals to make them more likely to be eaten by cats, so there is a precedent for illnesses (not a virus in this case) to alter the behaviour of other species.

This is not a deliberate decision no the part of the parasite. Those which affect their hosts in the "right" manner are more likely to procreate, those which affect their hosts in the "wrong" manner are less likely to procreate. After many generations, most parasites are the descendants of the "right" ones.