Is swimming a way of HBV transmission?

Can you get HBV while swimming in the same pool where there’s a HBV-positive person?

I’m looking for an answer but I’m left with doubta despite a great bulk of information that it’s not possible.

I’m speaking of a scenario when a HBV+ person has small cuts, nicks (for example after shaving) scratches or abrasion. I don’t necessarily mean deep wounds.

For example, on the website of the department of Public Health in Los Angeles it’s claimed that

although chlorine is effective at killing most harmful organisms in pool water, not all are easily killed

It also mentions that the hepatitis A virus (HAV) is transmittable in water. Another website, related to pool and spa maintenance, goes on to elaborate that indeed only hepatitis A virus can be transmitted in water as it’s contained in fecal matter, which is a way of transmission of the virus, and

it can take up to 16 minutes for chlorine to sanitize hepatitis A after first contact with pool water.

The website Hepatis Central confirms it, stating that the other two viruses (HBV, HCV) involve blood-to-blood contact in order for the transmission to occur.

I found someone asking a doctor a related questions. The person asks:

I was swimming in the sea and someone hit him while swimming he hit his toenail to my finger frist there was no blood just scratch but after squeezing it a lot a blood came out so i freaked is there any possibility of hepatitis b

To which a doctor replies:

Hep B and C can be transmitted by blood products. However this needs mixing of blood from the infected person to other to transmit it. For example if a needle or razor cuts or pierces the person who is infected (and so is contaminated with his blood ) and then pierces other person then there is a chance of tranmittimg the virus. Even with this only 3 to 6 out of hundred people would get it. Regarding nails scratch (as his nail was not stained with his blood) the chance is extremely low. So you don’t need to panic about that. You are very likely safe.

Another health-related website states that

Hepatitis B is not transmitted through swimming pools or water in recreational settings. The virus requires direct contact with infected blood or bodily fluids for transmission.

The Centers for Disease Control and Prevention states that:

Chlorine kills germs found in blood (such as hepatitis B and HIV). CDC is not aware of any instances in which a person has become infected with bloodborne germs after being exposed to blood in a pool

Similarly, according to a post on a website of the Hepatitis B Foundation,

Hepatitis B is 100 times more infectious than HIV. Does that mean you should be worried about contracting or spreading a blood borne pathogen like hepatitis B at the community pool? Personally I don’t believe so, but there are a couple of things to consider. If you’re concerned about a blood spill in the pool water than do not worry. As long as you are frequenting a well-maintained pool that follows guidelines for consistently monitoring chlorine and pH levels in the pool, you’ll be fine (…) Chlorine is a very effective agent against hepatitis B and other pathogens. When made fresh and used in the correct concentrations, (nine parts water to one part chlorine) it kills pathogens like HBV (…) The good news is HBV is not spread via contaminated water, or the oral-fecal route

My doubts arose after reading that there are chlorine-resistant germs, and swimming in a pool can indeed make you catch parasites such as Giardia, Cryptosporidium, shigella, norovirus, and E. coli. This is because they’re alive in faces which, upon unfortunate but unavoidable circumstances, can end up in pool even, I believe, unnoticed and in small invisible quantities.

So what makes chlorine deactivate Hepatitis B, but not Hepatitis A or other pathogens? I assume it must be in the nature and structure of these germs. This beyond the scope of my knowledge and research but leaves me thinking as to why Hepatitis A should be contagious in the water but not Hepatitis B. Another thing that needs to be taken into consideration is how diligently are pools disinfected with chlorine. How can we trust that it’s done properly?

In general the more complex a virus is, the less it can survive outside the body for transmission

That’s why you don’t get a virus that spreads like the common cold but is extremely fatal. It’s a balance of nature, based on physics

Blood borne viruses tend to be complex which is why they are delicate and most commonly spread through things like sharing needles, child birth, and blood transfusions, etc

While it’s theoretically possible for a virus to float through the water from one person to another, or probably even in the air for that matter (standing in the wind etc), practically speaking it’s not going to happen. Even if it did, a single infected copy of the virus is not going to infect someone (again practically not theoretically speaking) because it would have a treacherous journey ahead of it to make it that far even after it got into a body

Otherwise everyone would be dead

This is not directed at you personally, but I think Hollywood contagion movies planted a lot of ideas in the public psyche which is partly why people thought their was a global airborne pandemic that would kill a large percentage of people recently. The more complex a virus is the less transmissible it is in general

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Interesting remark! Pop culture has a strong influence on society. It cannot be dismissed.

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Hi all,

You cannot contract HBV from swimming in a pool with and HBV+ person. Even if the person had an open cut that was bleeding profusely, the virus would be diluted rapidly, and although that concentration of chlorine will not kill the virus immediately, it will steadily degrade it. In short, the only risk would be from direct blood contact that rapidly reached an open sore on the recipient person, not from sharing a pool. You can swim with your mind at peace.

Note that Hepatitis A virus is a very different virus from HBV. It is as stable as a brick and is usually transmitted by an oral-fecal route, so info on HAV transmission is irrelevant to HBV transmission.

The Dr’s reply about transmission from a toenail scratch while swimming is accurate.

There are no chlorine-resistant strains of HBV. That occurs (rarely) in cellular pathogens such as bacteria (viruses are not cells) by upregulating the redox buffering system in a cell and increasing turnover of the bacterial components on the surface of the cell to discard damaged molecules. HBV does not direct these metabolic processes, so this is a zero concern.

Chlorine will inactivate all pathogens by “reducing” critical molecules in them. Reduction is a type of electrochemical reaction that changes the molecules (for example, atomic sodium explodes on contact with water, whereas once it is oxidized (the opposite of reduction) to the resulting sodium ion it is essential for life and forms half of table salt.

The chlorine content of pools is strictly regulated and has to be tested daily in most places. That needs to be recorded and shown to the local health officials, and they’ll shut down a pool that is non-compliant.

As to the movie Contagion: We used it as a capstone event in the medical school immunology/microbiology class I co-directed for nearly 20 years. It is very good and was written in close collaboration with the US Centers for Disease control. They did do a bit of “Hollywood” in it, but basically just by accelerating the timeline for development, approval, and deployment of a vaccine.

I hate to be a fear monger, but the difference in social impact from the recent SARS-CoV2 pandemic and the fictional one in Contagion was just the death rate from an infection (“case fatality rate”). There have been plenty of far more deadly pandemics in history, for example smallpox, measles, and mumps in the Americas after first contact with the Europeans. Those viruses killed an estimated 90% of the pre-contact human population in N and S America (note that this is a crude estimate as it is very hard to tell what the pre-contact population was). Recent outbreaks of Eblola in West Africa have had death rates of up to 90% compared to ~0.5% for SARS-CoV2 before we learned to manage the infection properly. I bring this up as the movie was mentioned, and it makes a good opportunity to point out the importance of public health measures for controlling infections. The measures vary depending on the pathogen, but it is extremely important that people appreciate that the inconveniences the measures entail are essential for the lives of many people.

I hope this helps.




Thank you John! :star_struck: :smiling_face_with_three_hearts: