Illustration: Sam Woolley (Gizmodo)

The world is filled with disgusting toilets. You might personally prefer toilets that smell okay and aren’t covered in filth, but try telling that to whichever organs are involved in making you really need to use the bathroom. It has happened before, and it will happen again: you’ll be at a public bus station, or a music festival, or the apartment of a man under the age of 26, and you’ll realize, suddenly, that you no longer have any choice.

Of course, horrific viral infection-carriers aren’t always visible to the naked eye (or feelable by the naked ass). All toilets, even the clean ones, are by definition unsanitary. But, clean-seeming or visibly grime-caked, the question remains: is there anything to actually be worried about? That is, can toilets actually transmit disease, or is the worst-case-scenario here just feeling kind of gross? And if they can, then what diseases, specifically?

For this week’s Giz Asks, we reached out to a number of experts in microbiology and immunology for help in answering those questions. The odds of dying/getting sick from the wrong toilet are slim, we learned, but it is definitely possible—and you should probably keep your toilet clean regardless.

William Dampier

Assistant Professor, Microbiology & Immunology, Drexel University

For a healthy individual, the likelihood of actually getting a disease from a toilet seat is pretty small. Your skin has a lot of barriers against things from the outside, and is pretty good at keeping out bacteria. If you had some sort of infection or rash already, you could probably get a staph infection or something like that, but you would have to already have some sort of break in the skin for that to happen. I don’t want to say it’s impossible—it’s possible—but I think the likelihood that any given sit on a toilet seat will result in an infection is probably very small.

I could see if you had a very dirty toilet seat, you could potentially get a staph infection, and there are staph infections nowadays that are resistant to antibiotics. But those tend to be found in hospitals, not in the wild.

The only cases I’ve read [involving someone getting a disease from a toilet seat] were contact-dermatitis type things, and that’s usually in children, where they’re having some sort of allergic reaction or diaper rash that gets irritated by either the plastic or the cleaning fluid that’s used. But that’s also not particularly common, and people grow out of it pretty quickly. At least in the case studies, I haven’t’ seen any instance of somebody contacting [an infection] from a toilet seat, and that is the type of thing that somebody would write up as a case report. I’d take the lack of evidence there as evidence of it not really happening.

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Vincent Racaniello

Higgins Professor, Microbiology and Immunology, Columbia University

I would say that sitting on a toilet can get you a serious E. coli urinary tract infection. E. coli are normal inhabitants of our intestinal tract, but some strains can cause urinary tract infections and some can spread into other tissues beyond the urinary tract. The problem is that fecal contamination of the urinary tract is frequent due to the proximity of these systems. It is far more common in women than men for anatomical reasons: the urethra is shorter in women than in men, making it easier for the bacteria to get to the bladder. In men urine is more likely to flush out the bacteria. This changes as men age when their incidence of urinary tract infection rises.

Here is a story related to me by Dr. James Johnson during an interview I conducted with him: An elderly man was hospitalized with a serious urinary tract infection caused by E. coli that involved his kidneys. His daughter visited him in the hospital, used the toilet in his room, and some time later she developed a urinary tract infection which involved her kidneys, and lead to her hospitalization. Lab analysis revealed that she had been infected with the same strain of E. coli as her father! The likely scenario is that the toilet seat was contaminated with her father’s urine containing the bacteria, which she then picked up from the seat or perhaps even the water.

It’s a good idea to wipe down the toilet seat with a sanitizer but that still leaves the water, which can be contaminated and which might splash up on you. And don’t forget that the toilet generates an aerosol when flushed, and the aerosol can be inhaled. Despite these hazards, the toilet is still one of the greatest inventions of humanity, allowing us to escape countless infections caused by the previous practice of dumping our excrement into the streets.

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Laura Kasman

Associate Professor, Microbiology and Immunology, Medical University of South Carolina

Theoretically, yes, but it would be really unlikely. If you had an open cut or sore on your backside that touched the seat, and someone not too long before you had an infection that touched the seat in the same place as your cut or sore, then yes, you could catch the infection. The most likely culprits would be Staph bacteria, human papillomaviruses that cause warts, or herpes simplex.

One solution: Sit on your hands so they are between your bottom and the seat, and then wash them real well with soap before you leave the bathroom. (You should wash them real well anyway.) Works for cold seats too!

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Do you have a burning question for Giz Asks? Email us at tipbox@gizmodo.com.