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Harvard Commentaries
Harvard Commentaries
Reviewed by the Faculty of Harvard Medical School

What Your Doctor Is Saying What Your Doctor Is Saying

Pool Rules: What Your (Public Health) Doctor Is Saying

January 06, 2015

By Robert H. Shmerling M.D.

Beth Israel Deaconess Medical Center

The other day, the “pool monitor” of a public pool in our neighborhood wandered around reminding people to shower before getting into the water. For anyone asking why, she simply pointed to the conspicuous sign, posted, as required by public health regulations, that read:

"All persons are required to take a cleansing shower bath before entering the pool."

The next rule caught my eye, as well:

"No person with a communicable disease is allowed to use the pool."

When I first read these rules, they seemed reasonable enough. But as I thought about it, the logic was difficult to understand. What diseases or conditions are being prevented by these health codes? Many communicable diseases are not spread through water (for example, the common cold or most sexually transmitted diseases). How do these rules promote health?

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Swimming by the Rules

It’s probably reassuring to most people to know that everyone is required to shower before getting in the pool and that a person who might pass a disease to you or your kids is not allowed in the water. Yet, it struck me that, as written, these rules were unlikely to be effective and would prohibit many from swimming who pose no threat to the health of others.

For example, a number of important communicable diseases such as hepatitis B, hepatitis C and HIV are not known to be spread by simply swimming in a pool with others. It would be unfair and would accomplish nothing to exclude people with these diseases from swimming pools. Never mind that these rules are probably impossible to enforce; my own observation is that they are often ignored.

I looked into what these rules were intended to accomplish, and here's what I found. First, the "communicable diseases" are only those known to be spread from person to person via contaminated water. More specifically, the regulations are aimed at preventing diseases caused by organisms that are shed in the feces of an infected person and can spread to another person who ingests contaminated water.

The particular concerns are bacterial infections, (Shigella, Campylobacter, Salmonella, certain types of E. coli), hepatitis A and parasitic infections (Cryptosporidium and Giardia). A person who has been diagnosed with one of these infections should not swim in a pool in which others swim until the infection has resolved and they're completely recovered.

The time required to eliminate an infection and not be considered infectious varies, depending on the organism. But waiting at least two weeks after complete recovery before swimming in a public pool is recommended. In the world of infectious diseases, there are relatively few that are relevant to your swimming decisions.

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About That Required Pre-Swim Shower…

The reason a shower is required before entering the pool is that an infectious organism could be living on your skin and the shower is intended to reduce or eliminate the risk that you will expose others in the pool to that organism.

However, for those people who do take a shower before entering a pool, it is not likely that the quick rinse or even use of soap and water will do much to change what must be a very low risk in the first place. The acid level and chlorine in swimming pools already kills most infectious organisms (though cryptosporidia is a notable exception); and other than infections such as those listed above (that are spread by water contaminated with feces), most organisms living on your skin are of no risk to others anyway.

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Why Do Health Codes Continue To Require This?

It is possible that health codes and regulations were created in response to diseases that used to be more common than they are today. In addition, the understanding of disease may be better now than when these rules were established. For example, before different types of hepatitis were identified and their means of spread understood, it may have been more difficult to prevent their spread, so restricting pool access may have seemed reasonable at the time. There may have been fear of people who were ill, and sickness may be associated with poor hygiene, so requiring showers of everyone may have been appealing to those charged with overseeing public health. Finally, it may also be a matter of "inertia" — once rules are set up, it's harder to change them over time than to simply leave them in place, especially if they don’t seem to be causing much harm. It’s hard to say that requiring showers of everyone entering a pool — even if it's unnecessary — is particularly harmful. On the other hand, if a person with HIV is kept out of the pool because of his or her "communicable disease," that's a discriminatory misunderstanding of the regulations' purpose.

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It can be difficult to understand what your own doctor is saying — but at least you have the opportunity to ask questions to clarify the message. But when the message is coming from your "public health doctor," it's not so easy to ask questions or to apply a one-size-fits-all rule to your own particular situation. Of course, that’s the challenge of establishing public health codes and regulations — to effectively protect health with rules that are not too constrictive and are applied fairly to all.

Perhaps the most important thing to know about preventing the spread of illness while swimming is to avoid the pool if you have a diarrheal infection or have been diagnosed with one of the waterborne communicable diseases mentioned above. If you don't have any of those illnesses and are otherwise healthy, you may still have no choice — rules are rules — but speaking from a strictly medical point of view, there's little reason to shower before swimming unless that's what you like to do.

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Robert H. Shmerling, M.D. is associate physician at Beth Israel Deaconess Medical Center and associate professor at Harvard Medical School. He has been a practicing rheumatologist for over 20 years at Beth Israel Deaconess Medical Center. He is an active teacher in the Internal Medicine Residency Program, serving as the Robinson Firm Chief. He is also a teacher in the Rheumatology Fellowship Program.

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