Sexually transmitted infections (STIs) are communicable diseases passed from one person to another during sexual activity. STIs can be transmitted during vaginal, anal, or oral sex, and sometimes by close skin-to-skin contact.
A common fear among people is that STIs can be passed in public places, such as through contact with toilet seats. While it is theoretically possible that some STIs could be passed from person-to-person via a public toilet seat, it is extremely unlikely that you will become infected in this manner.
Evidence for the Health Claim
STIs can be caused by bacteria, viruses, or parasites. Bacterial STIs include chlamydia , gonorrhea , and syphilis . Viral STIs include hepatitis B , herpes simplex , human immunodeficiency virus (HIV) , and human papillomavirus (HPV, the virus that causes genital warts). STIs caused by parasites include pubic lice (crabs) and trichomoniasis , a parasitic infection that can be contracted by both men and women.
Each type of STI is spread differently. Bacterial STIs live in mucous membranes (eg, membranes of the vagina, penis, rectum, and mouth) and are transferred through contact with these infected membranes. Viruses, on the other hand, may exist outside of mucous membranes (eg, in the porous skin surrounding the genitals). But, in the case of hepatitis and HIV, these viruses do not readily pass through intact skin. Finally, parasites are usually spread during sexual contact, but can also be spread through contact with an infected person’s clothing, bed linens, or towels.
The only type of STI that has a reasonable chance of being passed from person-to-person via a public toilet seat is a parasitic STI. The National Women’s Health Information Center states that, in addition to sexual contact, trichomoniasis can be picked up from contact with damp or moist objects, such as toilet seats, if the genital area is in contact with the damp object. But toilet seats do not provide the ideal environment for parasites to live or reproduce. And to become infected, your genital area would have to come in contact with the parasite while it is still on the toilet seat.
Evidence Against the Health Claim
Since bacterial STIs cannot survive outside the environment of mucous membranes in the body, it is essentially impossible to contract one by sitting on public toilet seats. Viral causes of STIs cannot survive for long outside the human body either, so they generally die quickly on surfaces like toilet seats. And in the case of HIV, any surviving virus on a toilet seat would be unable to reach your bloodstream unless you had an open wound that made direct contact with the virus on the seat, a highly unlikely prospect.
To contract an STI from a contaminated toilet seat, a “perfect scenario” would have to occur. The virus from an infected person would have to be deposited onto the toilet seat immediately before you sat on it, live outside the human body for a period of time, and be positioned in the exact place for transmission to take place.
Because this scenario is so unlikely, the US government’s Centers for Disease Control and Prevention states that STIs, including syphilis , HPV, and HIV, cannot be transmitted via toilet seats. They go on to say that contracting pubic lice from a toilet seat is very unlikely because the lice cannot live for long away from a warm body, and they are not able to “walk” or hold onto smooth surfaces such as toilet seats. Furthermore, the National Institute of Allergy and Infectious Diseases states that the genital herpes virus “is spread rarely, if at all, by objects such as a toilet seats or hot tubs.”
It is highly unlikely that you will become infected with an STI through contact with a toilet seat.
The best way of preventing STIs is to abstain from sexual contact. If you do have sex, you can lower your risk of getting an STI by having only monogamous sex (sex with only one person) with someone who does not have an STI. Although condoms do not prevent all STIs, they can prevent some, and you should always use condoms when having vaginal, anal, or oral sex.
Of course, it cannot hurt to take a few extra hygienic precautions when using public toilet seats. If you use a public restroom, it is reasonable to wipe off the toilet seat and cover it with toilet paper or a toilet seat cover before sitting down.