A young woman died this week in Ohio after being infected by Naegleria fowleri, commonly called a brain-eating amoeba.Officials from the Franklin County Public Health Department confirmed that the 18-year-old died from amoebic meningoencephalitis , in which the membrane around the brain and spinal cord swells because of infection by the amoeba.The Franklin County resident was on a whitewater rafting trip in North Carolina when, officials believe, she was infected. She dies on Sunday. Naegleria fowleri is a naturally occurring organism that lives in freshwater throughout the United States. While harmless if ingested, the amoebas can be fatal if they travel through the nasal cavity to the brain."The deceased's only known underwater exposure was believed to be when riding in a raft with several others that overturned at the U.S. National Whitewater Center in Charlotte," according to a statement from the North Carolina Department of Health and Human Services.There are zero to eight infections in this country from parasitic amoebas each year, and nearly all are fatal, according to the U.S. Centers for Disease Control and Prevention, which advises people to take steps to avoid getting water up their nose in freshwater lakes and streams. Swimmers can keep their head above water, use a nose clip or hold their nose shut when underwater.In rare cases, people can become infected if they use contaminated tap water in a sinus-rinsing device. The CDC advises people to filter or boil water before using it in such devices. The CDC says that symptoms start one to nine days (with a median of five days) after swimming or other nasal exposure to Naegleria-containing water and die one to 18 days (also with a median of five) after symptoms begin. There is no known cure.Dr. William Schaffner, an infectious-disease expert at Vanderbilt University Medical Center in Nashville, Tennessee, said in an interview last summer that officials can't screen all bodies of water for the organism."The amoebas are in small numbers everywhere," he said. "They go hibernate in the wintertime. They're part of the natural environment."Schaffner also pointed out that cases are extremely rare and that people shouldn't fear going to freshwater lakes or feel they should swim only into the ocean or chlorinated pools.