This colorized scanning electron micrograph (SEM) depicts a number of Escherichia coli bacteria of the strain O157:H7. This strain of E. coli is an emerging cause of foodborne illness. An estimated 73,000 cases of infection, and 61 deaths occur in the United States each year. Infection often leads to bloody diarrhea, and occasionally to kidney failure. Most illness has been associated with eating undercooked, contaminated ground beef. Person-to-person contact in families and child care centers is also an important mode of transmission. Infection can also occur after drinking raw milk, and after swimming in, or drinking sewage-contaminated water.