A Common Myth About Crabs and Toilet Seats Is "Pretty Unusual," Says Expert

 "I think people focus too much on getting them in the environment." 

There are lots of creatures on Earth that can survive in the unique environment of a toilet: microbes that dwell in the toilets aboard the International Space Station, for instance, or the occasional snake that mistakenly finds its way into a septic system. But of all the things that can wander onto toilet seats and beyond, crabs are not among the chosen few for several very good reasons.

Crabs, or pubic lice, are tiny organisms uniquely equipped to infest coarse human hairs, mostly around the genitals. Also called Pthirus Pubis, pubic lice are only of the three types of lice that can infect humans, each of which prefer different types of hair. Pthirus Pubis latch onto human pubic hair using tiny claws and require two main things from their human hosts to ensure their survival. They need hair, to which they anchor their eggs, called nits, and they need human blood, which they use for sustenance. Toilet seats can provide neither of those things.

toilets
There are many gross toilets out there, but pubic lice probably aren't lurking on them. 

As Dr. Peter Leone, an infectious disease expert at the University of North Carolina, explains, getting crabs from a toilet seat really isn’t something people should be worried about.

“It would be pretty unusual,” Leone tells Inverse. “They like to attach to things, like bedding or clothing. I’d be more worried about sleeping in a bed after someone has been in there than getting them from a toilet seat. I think people focus too much on getting them in the environment when usually you have to have intimate contact for these things to be transmitted.”

Even if a pubic louse became dislodged from its happy home in human pubic hair and fell onto a toilet seat, the odds of it surviving long enough to attach to someone new aren’t great. The US Centers for Disease Control and Prevention gives pubic lice only one to two days of survival without a human to feed on. Additionally, they’re not very mobile creatures. As the CDC puts it, lice “do not have feet designed to hold onto or walk on smooth surfaces such as toilet seats.”

Most cases of pubic lice are transmitted sexually, when the pubic hair of an infected person comes into contact with hair from a non-infected individual — though occasionally they are transmitted from clothing or sheets. In either case, the lice and their eggs are actually big enough to be seen. Given their visibility, in the unlikely event that one ended up on a toilet seat, it would be possible to spot scurrying across the rim if you look closely enough.

Speaking of which, actually seeing lice may be a better way to detect an infestation because an infected person may not even feel their presence right away, explains Dr. Maria Trent, a pediatrician with expertise in reproductive health.

pubic lice
Pubic lice prefer to attach to things and do not do well on smooth surfaces, like toilet seats.

“Sexual contact is the primary mechanism of transmission of pubic lice, Trent tells Inverse. “Given the life cycle of the louse, it may be two to three weeks before symptoms such as itching develop. Therefore, an individual who sees adult lice and/or nits on pubic hair — even if they don’t have other symptoms — should take immediate action,” she says.

In short, it’s not worth worrying about getting crabs from a toilet seat — there are much more realistic ways of getting pubic lice that are more in line with their life cycle, like sexual contact. Even in that case, pubic lice are pretty easy to treat. The CDC, the American Sexual Health Association, and Planned Parenthood all provide clear guidelines on how to do this. Specifically, Trent recommends washing any bedding — that’s just good hygiene anyway — using a variety of creams that can kill the adult lice on your body, and “grooming to remove nits, immature lice that attach to body hair.”

Crabs and toilet seats, as gross as they both may be, are not a good match between organism and environment. If you are worried about creatures dwelling in sewer systems and beyond, snakes actually seem to have far better chances of survival in those hostile environments.