Laboratory tests today confirmed that two cases of illness in Gulf Coast residents under investigation by the Mississippi State Department of Health were due to E. coli O157:H7.

Both cases were in children with hemolytic uremic syndrome (HUS); one of the children died, and the other is recovering. Department of Health investigators had suspected that E. coli O157:H7 was the cause, but today's blood test results were the first positive identification of Escherichia coli 0157:H7.

This brings to three the total number of confirmed E. coli O157:H7 cases in Coast residents, including an adult man confirmed last week. That individual has recovered. The Department of Health has not released the identities of any of the three individuals.

The source of infection has not yet been identified for any of the three cases. Department of Health disease investigators consider the cases to be a possible outbreak.

"The blood tests cannot 'fingerprint' the disease," said State Health Officer Dr. Ed Thompson. "Even though the tests are exceedingly accurate, we cannot learn from these tests whether the three cases are the same or different strains of E. coli O157:H7. We will continue to investigate as if they were connected."

Additionally, routine surveillance has revealed another youngster from the Hattiesburg area diagnosed with HUS. Health officials have not definitely identified E. coli O157:H7 in that case -- and do not know if tests will show a connection -- but they are continuing the investigation with that in mind.

Public health disease investigators continue to extensively interview the individuals' families and to work with private medical doctors and facilities to look for other possible cases and identify a "common thread."

Escherichia coli 0157:H7 is an emerging cause of foodborne illness in the United States. An estimated 73,000 cases of infection and 61 deaths occur each year. E. coli 0157:H7 infection commonly produces bloody diarrhea and occasionally leads to kidney failure and a blood disorder known as hemolysis.

Like most states, Mississippi began aggressively counting E. coli cases in 1994. Only one case was reported that year, with three reported in 1995, 13 in 1996, seven cases each in 1997 and 1998, and eight in 1999. To date in 2000, case reports total 18.

E. coli O157:H7 was first recognized as a cause of illness in 1982 during an outbreak of severe bloody diarrhea; the outbreak was traced to contaminated hamburgers. Since then, most infections have come from eating undercooked ground beef.

E. coli O157:H7 is one of hundreds of strains of the bacterium Escherichia coli. Although most strains are harmless and live in the intestines of healthy humans and animals, this strain produces a powerful toxin and can cause severe illness. The combination of letters and numbers in the name of the bacterium refers to the specific markers found on its surface and distinguishes it from other types of E. coli.

Most illness has been associated with eating undercooked, contaminated ground beef, but E. coli O157:H7 has also been transmitted by produce, salami, and apple cider. Person-to-person contact in families and child care centers is also an important mode of transmission.

Infection can result from drinking unpasteurized milk and after swimming in or drinking sewage-contaminated water.

Consumers can prevent E. coli O157:H7 infection by thoroughly cooking ground beef, avoiding unpasteurized milk, and washing hands carefully. The Centers for Disease Control and Prevention offers these tips: