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Make a splash without getting sick this summer.

First Jaws kept millions of Americans out of the water, and now some experts fear that the rapid increase of recreational water illnesses (RWI) may do the same thing. And they caution that with the soaring rates of childhood obesity, anything that prevents kids from getting regular exercise -- including swimming -- may do more harm than good.

RWI refers to any illness or infection caused by organisms that contaminate water in pools, lakes, hot tubs, and oceans, resulting in diarrhea, skin rashes, swimmer's ear, and other conditions. And they are on the rise. The rate has more than doubled in the past 10 years, according to data from the CDC.

"No one who swims is safe from RWIs," says Alan Greene, MD, an assistant clinical professor of pediatrics at Stanford University in Stanford, Calif., and author of several books including From First Kicks to First Steps.

In the summer of 1975, Jaws had beachgoers heeding the advice of the movie's tagline, "Don't go in the water." But unlike great white sharks that may lurk below the ocean's surface, simple prevention methods as well as quick treatment can help keep RWIs at bay -- where they belong, Greene says. "Not swallowing water and drying your ears can reduce the great majority of RWIs," he says.

As with most things, the best defense is a good offense.

Know Thy Enemy

Infection-producing germs that can lurk in water include Pseudomonas aeruginosa, which causes swimmer's ear (an infection of the outer ear canal, known medically as otitis externa) and skin rash (dermatitis). Others include cryptosporidium, Giardia lamblia, shigella, and E. coli, which can cause diarrhea. Each year, 10,000 RWI cases of diarrhea and 6.2 million cases of swimmer's ear occur, according to the CDC. "You can catch respiratory illnesses and colds but by far, skin rashes, swimmer's ear, and gastrointestinal bugs are the most common," he says.

Diarrhea may occur when contaminated water is swallowed and driven into the mouth or nose, Greene explains. It may not begin immediately after a swim; sometimes it comes on one to two weeks later.

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