E. coli O104:H21 was discovered in 1982, when it caused an outbreak of severe bloody diarrhea. It had infected hamburgers, and those affected had eaten these hamburgers not fully-cooked.
An outbreak of E. coli responsible for at least 22 deaths in Northern Europe in May of 2011 was reported to be caused by another O104 strain, H4.
E. coli O104:H21 can cause outbreak of infection similar to that caused by H7, the most common shiga-like toxin-producing E. coli (SLTEC). SLTECs are the most well-known causes of gastrointestinal illness and diarrhea.http://www.cdc.gov/mmwr/preview/mmwrhtml/00038146.htmOutbreak of Acute Gastroenteritis Attributable to Escherichia coli... Read More