While not necessarily a threat to human health, E. coli has been used as an indicator of other pathogens in excrement, such as viruses, the Duluth (Minn.) News Tribune reported.

But Central Michigan University Microbiologist Elizabeth Alm says E. coli has been found in Lake Huron sand with no fecal matter from people, birds or animals.

Alm says her finding means scientists need to create a new indicator for harmful pathogens in water and might also indicate dangerous organisms are thriving in beach sand.

"Geese and gulls and diapers may still be sources of some fecal matter and some E. coli, but we clearly can have E. coli without any of them," She said. "We need to do a lot more research to see what else may be naturalized in the sand."

The findings appear in the Journal of Great Lakes Research.

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