Will sitting on a hot bench that someone else has sat on cause hemorrhoids, boils, or even STDs? Let's clarify once and for all →

During the morning and evening rush hours, when you drag your tired body into the bus or subway to go to work or rush home, what do you want most? Do you hope to have an empty seat for you to sit down and relax your tense nerves, or even take a nap? If you happen to encounter such a surprise, will you sit on it without hesitation? However, recently the topic of "Why can't we sit on other people's hot stools" has become a hot search on Weibo, sparking heated discussions among netizens. Weibo screenshot

In the comments section, some people think that seats that have just been sat on by others are hotbeds for bacteria to grow, and that people may get all kinds of strange diseases at any time, such as sores, boils, or even sexually transmitted diseases, gynecological diseases, or urinary system diseases when sitting on them. So, are these claims scientifically based? Let's clarify it today!

Weibo screenshot

01

Rumor: Sitting on a hot bench that someone else has just sat on will spread STDs

Analysis: No.

First of all, we need to understand what sexually transmitted diseases are. Sexually transmitted diseases refer to infectious diseases that are mainly transmitted through sexual intercourse. Common ones include syphilis, gonorrhea, AIDS, genital warts, etc. In addition to sexual transmission, syphilis and AIDS can also be transmitted through blood and vertical transmission from mother to child. To get a sexually transmitted disease by sitting on a hot bench that someone else has just sat on, the following three conditions must be met at the same time:

① Source of infection: The person sitting in the front seat must be a patient with a sexually transmitted disease and has left secretions containing pathogenic microorganisms on the seat.

② Transmission route: The next person sitting in the heated seat must directly come into contact with secretions containing pathogenic microorganisms, and there must be mucous membranes or wounds at the contact site.

③ Infected person: The last person to sit on the heated seat does not have sufficient immunity to fight pathogenic microorganisms.

When sitting on the hot bench that someone else has just sat on, these three conditions are very demanding and difficult to meet at the same time.

First of all, most people do not put their skin in direct contact with seats in public places. Instead, they wear clothes to avoid direct contact with stains or secretions left by others.

Secondly, even if the previous person was a STD patient and left secretions on the seat, these secretions will soon lose their activity outside the body and cannot infect others. For example, syphilis and gonorrhea are difficult to survive outside the body, and HIV basically loses its activity the moment it leaves the human body.

Again, even if the latter person comes into direct contact with secretions containing pathogenic microorganisms, he will not be infected if there is no mucous membrane or wound at the contact site.

Finally, the skin barrier is an important barrier to prevent the invasion of pathogens. As long as the skin and mucous membranes are not damaged, there will be no risk of infection from contact with the patient's sweat, saliva and other secretions.

Therefore, there is no need to be overly afraid when using bus or subway seats or sitting on hot benches that have been sat on by others.

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02

Rumor: Sitting on a hot bench that someone else has just sat on will cause gynecological and urinary system diseases

Analysis: No.

The basis is basically the same as the previous one, and the three elements of infectious disease transmission are not met: contact with fresh body fluids containing pathogenic microorganisms, skin and mucous membrane damage in the direct contact area and the contact time is long enough, and the infected person has low immunity.

03

Rumor: Sitting on a hot bench that someone else has just sat on will cause hemorrhoids

Analysis: No.

Hemorrhoids refer to the swelling of the veins in the anus and lower rectum, forming one or more soft venous masses. Depending on the location, they can be divided into internal hemorrhoids and external hemorrhoids.

There are many factors that can cause or worsen hemorrhoids:

① Sitting, standing or squatting for a long time can lead to obstruction of rectal venous return, causing local congestion and increased pressure.

② Chronic constipation and dry and hard stools can lead to excessive force during defecation, damaging the anal mucosa and veins.

③Obesity, pregnancy, anal sex, etc. can lead to increased intra-abdominal pressure or local irritation and infection.

④Genetic factors, age factors, dietary factors, etc. can lead to decreased elasticity or fibrosis of the venous wall.

Sitting on a hot bench that someone else has just sat on will not cause or aggravate the above factors, so there is no risk of "sitting on a hot bench and getting hemorrhoids".

04

Rumor: Sitting on a hot bench that someone else has just sat on will cause a boil

Analysis: No.

A carbuncle is a purulent infection of the hair follicles and their deep surrounding tissues, also known as a furuncle. Its clinical features are redness, swelling, severe pain and skin ulcers, and it is more common on the face, neck, back and buttocks.

The main pathogen of furuncle is Staphylococcus aureus, which colonizes the skin surface of about 30% of healthy individuals. The occurrence of furuncle on the skin surface is related to poor skin cleanliness, excessive sebum secretion, trauma and high hormone levels in the body. It is also related to personal immunity and resistance. If a person maintains good hygiene habits, is healthy and has strong immunity, he or she will not be easily infected even if exposed to bacteria.

Although boils are related to bacteria, they are not contagious diseases. And sitting on a hot bench that someone else has just sat on does not count as direct contact.

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What's on the public seating?

Public seats may be stained with dust, stains, hair, dandruff, etc., but you don’t need to worry too much, because most seats are cleaned and disinfected regularly. Of course, there may be some bacteria on public seats, such as Staphylococcus aureus and Propionibacterium on the skin surface. These bacteria are actually our old friends. They can be found in other public facilities, environments, daily necessities, etc., and basically do not pose a threat to the body. If you are really worried about the unsanitary public seats, you can wipe the surface of the seat with wet wipes or disinfectant paper towels, or put a layer of paper towels or cushions on the seat; if you have damaged or sensitive skin, you can wear long pants or long skirts to avoid direct contact with the seat surface; wash your hands frequently, and do not touch your mouth and nose directly with your hands after touching unclean seats.

in conclusion

There may be some bacteria on the hot bench that someone has just sat on, but it is basically not contagious because it is difficult to meet the three conditions for disease transmission at the same time: contact with fresh body fluids containing pathogenic microorganisms, skin and mucous membrane damage at the direct contact site and the contact time is long enough, and the infected person has low immunity. Therefore, you don’t have to worry too much about transmitting sexually transmitted diseases, gynecological diseases, and urinary system diseases by sitting on a hot bench that someone else has just sat on, let alone hemorrhoids and boils. However, if you have damaged skin and low immunity, you should still be careful to avoid direct contact with public seats that may be contaminated.

Author: Meng Yao, doctor of medicine at Zhongshan Hospital, Fudan University

Review | Xu Min, deputy chief physician, Zhu Xianyi Memorial Hospital, Tianjin Medical University

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