E. coli O157:H7 gets all of the attention, with its name in headlines around the world and a fearsome reputation as a deadly foodborne bacterium. But flying quietly under the radar are O157:H7's six little-known cousins, and they're about to make their debut as a serious threat to human health, according to the New York Times.

"The big six”, as they're known to public health experts, are a range of disease-causing strains of E. coli, and while they're typically overshadowed by O157:H7 — which has killed hundreds and sickened thousands of people — they're just as dangerous.

In April, at least 26 people were sickened by romaine lettuce tainted with one of the strains, including three teenagers who developed kidney failure. The outbreak, caused by E. coli O145, was traced to Ohio company Freshway Foods.

But few food companies test for these strains, and the meat industry is fighting a U.S. Department of Agriculture (USDA) consideration to outlaw selling ground beef tainted with the big six. These strains are difficult and time-consuming to identify.

Organic greens producer Earthbound Farms is one of few companies in the U.S. that screens for the full range of E. coli bacteria, and its tests have been illuminating: about 1 in 1,000 samples show the presence of one of the six strains.

“No one is looking for non-O157 to the level we are,” Will Daniels, Earthbound Farm’s senior vice president for food safety, told the New York Times. “I believe it is really going to emerge as one of the areas of concern.”

E. coli can be killed in meat when it's cooked to at least 160 degrees, but preventing illness from contaminated produce is more complex. Scientists believe the bacteria may be tracked onto foods like lettuce and strawberries by wild animals, or transmitted through irrigation water.

The USDA is currently developing tests that can rapidly detect the big six strains of E. coli, hoping to complete them by the end of 2011.

Six little-known strains of E. coli now a serious threat
After a lesser-known strain of E. coli caused an outbreak of illness in April, other rare strains are seen as a threat to public health.