Recreational Water Illnesses (RWIs)

Minnesota Department of Health
Revised 3/2018

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What are recreational water illnesses?

Recreational water illnesses (RWIs) are caused by germs and chemicals found in the water we swim or play in, including swimming pools, water parks, hot tubs, splash pads, lakes, rivers, or oceans. They are spread by swallowing, breathing in mists or aerosols of, or having contact with contaminated water.

What are possible causes of RWIs?

The most common type of RWI is diarrhea. Diarrheal illnesses can be caused by germs such as Cryptosporidium, E. coli O157, norovirus, and Shigella. Germs that cause other types of RWIs include Pseudomonas and Naegleria fowleri. RWIs can also be caused by chemicals in the water or chemicals that turn into gas and cause air quality problems at indoor aquatic facilities.

What are the symptoms?

The most common symptoms of RWIs include diarrhea (sometimes bloody), vomiting, stomach cramps, loss of appetite, weight loss, and fever. Other RWIs can cause skin, ear, eye, respiratory, or neurologic symptoms.

How are RWIs spread?

When people are ill with diarrhea, even a speck of their stool can contain millions of germs. Swimming while ill can easily contaminate the water – even if you don’t have an accident. Also, lakes and rivers can be contaminated by animal waste, sewage spills, and water runoff following rainfall. If you swallow water that has been contaminated, you may become sick.

Other non-diarrheal RWIs are caused by germs that live naturally in the environment (water, soil). If disinfectant is not maintained at the appropriate levels in a pool or hot tub, these germs can increase to the point where they cause illness when swimmers breathe or have contact with the water.

A very rare but often fatal brain infection can be caused by Naegleria fowleri. This ameba infects people by entering the body through the nose.

How do I report a suspected RWI?

To report a suspected waterborne illness, call the Minnesota Department of Health at 1-877-366-3455 (or 651-201-5655 from the Twin Cities).

How can I prevent RWIs?

Each of us needs to do our part to keep the water healthy for everyone. To help protect yourself and other swimmers:

• Stay out of the water if you have diarrhea.
• Shower before and after swimming.
• Don't swallow the water.
• Take children on frequent bathroom breaks.
• Change diapers frequently and away from the water. Wash your hands and the child's hands after changing diapers.

The only sure way to prevent Naegleria fowleri infection is to avoid participation in freshwater-related activities. You can reduce the risk of infection by limiting the amount of water going up the nose. When taking part in water-related activities in bodies of warm freshwater:

• Avoid warm freshwater when the water temperature is high and the water level is low.
• Avoid putting your head under the water.
• Hold your nose shut or use nose clips.
• Avoid digging in, or stirring up, the sediment.