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What You Need to Know About Recreational Water Illness

public water parkAs temperatures heat up this summer, people will be looking for ways to cool off. But while pools, lakes and oceans provide relief from the heat, they occasionally cause other forms of discomfort to flare up. Certain germs that are found in swimming water can lead to recreational water illness (RWI), which includes a wide variety of gastrointestinal, skin, ear, respiratory, eye, neurologic and wound infections.

Drexel gastroenterologist, Neilanjan Nandi, MD, answers some common questions about recreational water illness and how swimmers can stay healthy this summer.

What causes RWI?

Common causes of RWI include contact with infectiously contaminated pools of water, such as swimming pools and hot tubs, or by naturally occurring habitats such as in lakes, ponds, oceans, and even mud. It only takes one individual with diarrhea to contaminate an entire body of water. These organisms often enter our body via our mouth, nose, skin and ears.

What are the most common forms of RWI?


The most common RWI symptom is profuse diarrhea from contaminated water supplies containing microscopic parasites such as Cryptosporidium (also known as Crypto) and giardiasis. Diarrheal infections from bacteria like E. coli and norovirus can also occur.


A skin rash (dermatitis) or hair follicle irritation (folliculitis) can develop within a few days of a hot tub dip. This is often caused by a germ known as Pseudomonas aeruginosa. It can be an itchy bump on the skin or hair follicle base that typically resolves within a few days.

Legionnaire's disease

Legionnaire's disease is a significant pneumonia caused by Legionella that is found in drinking water or hot tubs.

Swimmer's ear

Swimmer's ear can result when your ear's production of protective ear wax and other natural defenses are diminished. It can also occur when excess moisture and/or abrasions of the outer ear occur allowing the opportunity for germs to infect and cause sensitivity with any manipulation of the outer ear.

Amoebic infection

A very rare but potentially fatal amoebic infection, Naegleria fowleri (commonly referred to as the “brain-eating amoeba”), has been reported in south and southwestern states of the U.S. (Texas and Florida). Young children under 13 years old and males, in general, are at greater risk. It enters via the nose and utilizes the brain for nutrition. Again, this is very rare but any changes in mental status or headache should be promptly evaluated.

Where are swimmers most at risk?

Where there is water, germs can exist. In addition to swimming pools, hot tubs, water parks and natural bodies of water, it is well established that even soil can be a natural habitat for these organisms. In fact, I have diagnosed several athletes who have competed in 'mud runs' with cryptosporidiosis from oral ingestion of mud while competing.

Shouldn't chlorine kill the germs in swimming pools and hot tubs?

If chlorine levels are not properly regulated, its disinfecting power will be diminished. Some organisms such as Cryptosporidium can remain alive and active for many days before chlorine kills it. Therefore, good hygiene and vigilant pool disinfection quality standards should be regularly met.

Notably, chlorine can combine with our skin, urine and feces to create chloramines. This is the strong odor one senses in poorly ventilated indoor swimming pools. This can lead to respiratory symptoms such as cough, sinusitis or asthma exacerbations.

What should I do if I get sick?

Diarrhea is the most common symptom. However, any headache, neck stiffness, or change in one's mental status such as confusion or memory loss should trigger a prompt visit to the emergency room or at least a visit with your primary care doctor.

What can swimmers do to prevent RWI?

Confirm that your local pool is checking the pH and chlorine at least twice a day. Be mindful of personal diarrheal illness and in your family members. Change children's diapers often during trips to the pool, wash off well after a swim, and consider a nasal clip during swimming or performing nasal irrigation after trips to the pool. If you have an open wound, stay out of the water until it has healed. Remember, our skin is our primary defense against infections.

The information on these pages is provided for general information only and should not be used for diagnosis or treatment, or as a substitute for consultation with a physician or health care professional. If you have specific questions or concerns about your health, you should consult your health care professional.

The images being used are for illustrative purposes only; any person depicted is a model.

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