MadSci Network: General Biology

Re: Which is worse, Public telephone germs, or toilet seats?

Date: Fri Jan 8 21:30:44 1999
Posted By: John Carlson, Medical student, MD/PhD (parasitology) , Tulane University, School of Medicine
Area of science: General Biology
ID: 914027966.Gb


This is an interesting question. In fact, I was hard pressed to find any information at all about transmission of any disease by public toilets or telephone mouth pieces. The simple explanation for the lack of scientific information is that transfer of infective agents by either of these means is actually very rare. Let's look at why that might be.

First there's the telephone mouth piece. A single public telephone can be used by hundreds of people a day at a busy airport. Seeing that some of those must be sick, why aren't illnesses spread?

When a person with a respiratory illness coughs, or even talks, tiny droplets of moisture fly out of their mouths carrying the bacteria or virus into the air. (These droplets are called fomites.) If the sick person is talking into a telephone, those fomites smack into the mouthpiece and sit there. When the next person uses the telephone, the moisture containing the infectious agents sits on the mouth piece, with the lips of a potential host only inches away. The problem for the infectious agents is that they have no good way of becoming airborne again. Since few people actually physically touch the mouth piece with their lips, there is no way for the bacteria or virus to get into the unsuspecting person's body.

In fact, telephones probably do transmit disease. But these illnesses are passed on the handle of the phone, and not the mouth piece. When a sick person coughs into their hands or rubs their nose, the bacteria or virus causing the illness is transferred there. The infectious agents are then passed to the telephone handle when a phone call is made. The new host makes a call afterwards, picking up the tiny bacteria or virus particles on their hands. Later, when eating or touching a susceptible part of the face (eyes, nose, mouth) the parasite enters the new body, and infection can result.

The transfer of disease by hands is very common, often using such intermediate transfer points as door knobs. Simply washing your hands can eliminate most of the colds and other illnesses you ever contract! (During the last Ebola outbreak, the researchers there "shook hands" by touching their elbows together instead of the more traditional palm-to-palm handshake to eliminate this route of possible transfer of illness.)

There aren't many disease-causing organisms in the United States capable of entering directly through the skin. (Our skin is considered the first line of defense of the immune system.) Exceptions include hookworms and possibly some members of the genus of virus that causes common skin warts (Papillomavirus ).

This is also why public toilets are not generally considered a health threat. There are serious diseases that can be spread through ingesting fecal material. (This is yet another reason why washing your hands, particularly before eating and after using a bathroom, is a good idea.) Many diseases are spread from introducing tiny amounts of contaminated feces into your mouth. These diseases include infection by the many organisms that cause diarrhea. But the transmission isn't from using public restrooms, it's from touching objects that other people who failed to wash their hands after going to the bathroom also touched, and then not washing your own hands before eating. Serious diseases in the United Sates that are spread by the fecal-oral route include diarrhea and Hepatitis A. The Centers for Disease Control has a good series of web pages on Hepatitis A, with information on incidence of the disease as well as a description of the vaccine used to prevent its transmission. But again, I could find no documented link between public restrooms and contraction of Hepatitis A or any other disease within the United States.

Because of the number of people who touch them, I would guess that door knobs pose a much greater risk for disease contraction than public phones and public toilets combined. Many studies have now linked hand washing with the prevention of disease. (Searching Medline with the key words: disease; transmission; hand; and washing will bring up a number of studies.) For a detailed description of optimal hand washing technique, go to the bottom of this page for day care providers posted by the Centers for Disease Control.

Thank you for your interesting question!


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