A southwest Virginia 2-year-old died from an E. coli bacterial infection that also sickened another person in close contact with her, and East Tennessee hospitals have reported at least eight other E. coli infections since June 1.

Dr. David Kirschke, medical director of the Northeast Regional Health Office in Johnson City, says seven of the cases are from the same strain of bacteria, but a common cause has not been found, according to The Knoxville News Sentinel.

Kirschke says some of the patients ate improperly cooked meat, but others were infected while swimming in untreated water. He says the department is treating the cases as an outbreak and interviewing people who became ill from E. coli to learn the likely causes of infection.

The department urges people to thoroughly cook meat and carefully wash all fruits and vegetables.

Virginia Department of Health spokesman Robert Parker told the Bristol Herald-Courier that lab results confirmed the presence of E. coli in the 2-year-old child who died over the weekend.

The Dryden, Va., girl died at Johnson City Medical Center on Sunday. Officials said at the time she might have been exposed to E. coli.

According to a coroner’s report, the source of exposure was believed to be a contaminated pool.

Parker advised that children who develop diarrhea should be treated promptly because it is a symptom of E. coli.