E. coli: What high levels in water mean

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E. coli: What high levels in water mean

E. coli thrives in flooded areas, but it's not the killer strain.

Are people exposed to Hurricane Katrina's floodwaters at risk of deadly Eschericia coli (E. coli) infection? The short answer is no. These questions and answers will tell you why.

What is E. coli?

E. coli refers to a group of bacteria normally found in the intestines of healthy humans and animals. Of the hundreds of types of E. coli, most are harmless. Certain strains of E. coli cause bladder infections or diarrhea among travelers and children in the developing world, but in healthy people, these illnesses are rarely life-threatening. When found in high numbers in water, however, E. coli is a general marker for fecal or sewage contamination. Such water is unsafe for consumption or, in some cases, contact with skin.

It's important not to confuse this "generic" E. coli with the specific, more feared and virulent strain — E. coli O157:H7 — spread mainly through undercooked ground beef and responsible for a number of deaths each year. The O157:H7 strain produces powerful toxins that can cause severe, bloody diarrhea and life-threatening kidney failure.

How does E. coli get into floodwater?

Creeks, rivers, streams, lakes and groundwater normally contain harmless, or generic, E. coli. Rain and melting snow wash the microorganisms from the ground into these bodies of water. In floods, overflowing sewage systems and agricultural and industrial waste mingle with spillover from swollen lakes and streams, raising levels of E. coli. Other organisms, more likely to cause disease, also are invariably present in such contaminated water. In the aftermath of Hurricane Katrina, these have included norovirus, which causes diarrhea, and Vibrio vulnificus bacteria, which cause fatal wound infections.

What do official reports about E. coli and other contaminants mean?

Tests of the water that still covers much of New Orleans and other parts of the Gulf Coast have found E. coli levels too high to measure using standard water-testing equipment. That level of contamination suggests that many other disease-causing microorganisms are present as well, so people in the region are at risk of many infections if they wade through flooded streets — particularly if the water comes into contact with any open wounds. It's also unsafe to get floodwater on the hands or face, where germs are easily transferred to the mouth, nose and eyes.

If you swallowed this floodwater, you'd likely get ill, not necessarily from E. coli, but from other disease-causing contaminants, including viruses and bacteria that keep company with E. coli.

Last Updated: 09/14/2005
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