Sandra Gompf, who is also an infectious disease specialist, has posted billboards around Tampa for her group AmoebaSeason.com
Gompf lost her 10-year-old son to meningitis he got from an amoeba while swimming at a lake.
The amoeba can go up the nose and into the brain.
Dr. Gompf says hot summer weather is the prime time.
"As water heats up, chlorine evaporates and, if it's exposed to soil, it can become contaminated, so hose-fed toys like Slip-n-Slides and baby pools, those are the kinds of things people need to think about," Gompf said.
Earlier this month, an Ohio teen died after being infected at a whitewater rafting park in North Carolina.
Dr. Gompf says anyone going into non-chlorinated water should use a nose clip to keep water out.