No form of contaminated food or other cause has been identified in the illnesses, which occurred in April and May, according to the Centers for Disease Control and Prevention.
Three people were hospitalized. One -- a child in the New Orleans area -- died last week.
The reported illnesses were spread across six states. Federal officials have not identified all six states, but officials in Alabama, Georgia, Florida and Louisiana have confirmed outbreak-associated illnesses.
E. coli is a large family of bacteria and most strains are harmless. The most deadly strain is considered E. coli O157:H7, which became well-known in the early 1990s through a deadly outbreak associated with hamburger meat.
Six similar strains are also considered dangerous and one of them is E. coli O145, the strain identified in this new outbreak. Health officials haven't been tracking O145 intensively for very long; it was only in 2009 that the CDC began recommending labs test for it.
The first U.S. foodborne outbreak linked to O145 occurred in 2010, when more than two dozen people in at least five states were sickened by bacteria transmitted through romaine lettuce.
Until the source of the new outbreak is identified, health officials can offer the public only general advice for avoiding the infection: Cook meat thoroughly. Avoid unpasteurized milk and ciders. And -- if you have a diarrhea-like illness -- wash your hands thoroughly and do not prepare meals for others.