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What are recreational water illnesses (RWIs)?

RWIs are illnesses that are spread by swallowing, breathing, or having contact with contaminated water from swimming pools, spas, lakes, rivers, or oceans. Recreational water illnesses can cause a wide variety of symptoms, including gastrointestinal, skin, ear, respiratory, eye, neurologic and wound infections. The most commonly reported RWI is diarrhea. Diarrheal illnesses can be caused by germs such as Crypto, short for Cryptosporidium, Giardia, Shigella, norovirus and E. coli O157:H7.

See also: Fact Sheets on Healthy Swimming

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Where are RWIs found?

RWIs can be spread through use of swimming pools, hot tubs, decorative water fountains, oceans, lakes, and rivers.

Swimming Pools, Waterparks, Spray Features

The most common illness spread through use of swimming pools is diarrhea. If swimmers are ill with diarrhea, the germs that they carry can contaminate the water if they have an "accident" in the pool. On average, people have about 0.14 grams of feces on their bottoms which, when rinsed off, can contaminate recreational water. When people are ill with diarrhea, their stool can contain millions of germs. Therefore, swimming when ill with diarrhea can easily contaminate large pools or waterparks. As a result, if someone swallows water that has been contaminated with feces, he/she may become sick. Many of these diarrhea-causing germs do not have to be swallowed in large amounts to cause illness. Remember that standing water is not necessary for RWIs to spread so even spray decks can become contaminated (the water is just in a collection tank underground) and spread illness. To ensure that most germs are killed, chlorine or other disinfectant levels and pH should be checked regularly as part of good pool operation.

Hot Tubs

Skin infections like "hot tub rash" are the most common RWIs spread through hot tubs and spas. Chlorine and other disinfectant levels evaporate more quickly because of the higher temperature of the water in the tubs. Respiratory illnesses are also associated with hot tub use if the hot tub is not well maintained. Because of this it is important to check disinfectant levels even more regularly than in swimming pools. "Hot tub rash" can also be spread in pools and at the lake or beach.

Decorative Water Fountains

Not all decorative or interactive fountains are chlorinated or filtered. Therefore, when people, especially diaper-aged children, play in the water, they can contaminate the water with fecal matter. Swallowing this contaminated water can then cause diarrheal illness.

Lakes, Rivers, and Oceans

Lakes, rivers, and oceans can become contaminated with germs from sewage, animal waste, water runoff following rainfall, fecal accidents, and germs rinsed off the bottoms of swimmers. It is important to avoid swallowing the water because natural recreational water is not disinfected. Avoid swimming after rainfalls or in areas identified as unsafe by health departments. Contact your state or local health department for results of water testing in your area or go to EPA's beach site or their National Health Protection Survey of Beaches.

See also: Fact Sheets on Healthy Swimming

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How are RWIs spread?

Keep in mind that you share the water with everyone else in the pool, lake, or ocean.

Diarrheal Illnesses

If swimmers are ill with diarrhea, the germs that they carry can contaminate the water if they have an "accident" in the pool. On average, people have about 0.14 grams of feces on their bottoms which, when rinsed off, can contaminate recreational water. When people are ill with diarrhea, their stool can contain millions of germs. Therefore, swimming when ill with diarrhea can easily contaminate large pools or waterparks. In addition, lakes, rivers, and the ocean can be contaminated by sewage spills, animal waste, and water runoff following rainfall. Some common germs can also live for long periods of time in salt water.

So, if someone swallows water that has been contaminated with feces, he/she may become sick. Many of these diarrhea-causing germs do not have to be swallowed in large amounts to cause illness.

Other RWIs

Many other RWIs (skin, ear, eye, respiratory, neurologic, wound, and other infections) are caused by germs that live naturally in the environment (water, soil). In the pool or hot tub, if disinfectant is not maintained at the appropriate levels, these germs can increase to the point where they can cause illness when swimmers breathe or have contact with water containing these germs.

See also: Fact Sheets on Healthy Swimming

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Why doesn't chlorine kill these RWI germs?

Chlorine in swimming pools does kill the germs that may make people sick, but it takes time. Chlorine in properly disinfected pools kills most germs that can cause RWIs in less than an hour. Chlorine takes longer to kill some germs such as Crypto, which can survive for days in even a properly disinfected pool. This means that without your help, illness can spread even in well-maintained pools.

Healthy swimming behaviors are needed to protect you and your family from RWIs and will help stop germs from getting in the pool.

See also: Fact Sheets on Healthy Swimming

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Who is most likely to get ill from an RWI?

Children, pregnant women, and people with compromised immune systems (such as those living with AIDS, those who have received an organ transplant, or those receiving certain types of chemotherapy) can suffer from more severe illness if infected. People with compromised immune systems should be aware that recreational water might be contaminated with human or animal waste that contains Cryptosporidium (or Crypto), which can be life threatening in persons with weakened immune systems. People with a compromised immune system should consult their health care provider before participating in behaviors that place them at risk for illness.

See also:

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How can we prevent RWIs?

Prevention for Swimmers and Parents

Prevention for Aquatics Staff

Properly maintaining pools and educating staff and swimmers helps keep RWIs out of aquatic facilities.

Prevention for Public Health Professionals

Health professionals are a resource for training pool operators, disseminating information on RWIs to pool operators and the public, and responding to public health emergencies.

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Content Source: Division of Parasitic Diseases, National Center for Zoonotic, Vector-borne, and Enteric Diseases
Page last modified: May 2, 2007