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Among somber stories of rescue and loss, Saturday's flooding had some lighter moments, as social media filled up with pictures and videos of people kayaking, paddle-boating and even floating on a giant pink flamingo through newly high waters.

But health experts warn that floodwater is full of risks — not only obvious dangers like drowning and electrocution, but also nasty organisms and infectious diseases.

CDC warns of chemicals, toxic waste and more

For one thing, flooding can cause sewage disposal systems to overflow, so feces — human and animal — are likely to be in the water. The Centers for Disease Control and Prevention says flooding can also disrupt toxic waste sites and chemicals stored both under and above the ground.

Among the infectious organisms that might be in floodwater: E. coli, shigella, salmonella, hepatitis A, and things that can cause tetanus and typhoid. If you've been in contact with floodwater, watch out for fever, nausea, vomiting, diarrhea, stomach cramps and muscle aches, which can be symptoms of illness.

Tetanus is another risk

Swallowing the water or eating or drinking things that were contaminated by floodwater is usually how people get sick, but tetanus is another story. It can enter your body through broken skin — cuts, scrapes, puncture wounds. Tetanus, also called "lockjaw," affects the nervous system; it causes severe muscle spasms.

It might take weeks to show up, starting as a headache and progressing to difficulty swallowing or opening your jaw. There's a vaccine available for tetanus, and the CDC recommends adults have it every 10 years.

The danger of getting a puncture wound increases in floodwater, which can be full of debris you can't see: glass, lumber, nails and other sharp objects.

If you've been in floodwater and have an open wound, wash it thoroughly with soap and clean water. Watch for redness, swelling or drainage and see a medical professional immediately if that happens. Also, the CDC says to watch for skin rash.

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It's obvious children shouldn't play in floodwater — but don't let them play with toys that were in contact with floodwater either until you have a chance to disinfect them. Wash cloth items in detergent and hot water.

And if you absolutely must enter the water, protect yourself with rubber boots, rubber gloves and goggles, the CDC says.