Investigation underway after E. coli kills 2 children in Northwest

A deadly strain of E. coli has killed two children in the Pacific Northwest and left a third fighting for his life. Health officials and relatives confirmed all three children tested positive for the bacteria.

Four-year-old Serena Profitt of Otis, Oregon, died Monday evening at a Portland hospital. Her friend, 5-year-old Brad Sutton, is currently being treated for complications related to the infection at a hospital in Tacoma, Washington. He remains in critical condition, but is reported to be improving, authorities said Wednesday.

The children fell ill after spending Labor Day together, but Lincoln County, Oregon, health officials said at a news conference on Thursday that they are still not certain where the children picked up the infection.

"We've investigated the places that the people have been in the public and have not found the source that could be dangerous to the public," said Lincoln County Health Officer Dr. David Long, during the press conference. "If we believe a potential danger to the public we would reveal. If someone's culture comes back positive but they're not at risk of spreading the disease to the public then that's personal knowledge and would not reveal that."

Another child, Brooklyn Hoksbergen, 3, of Lynden in northwest Washington, died Sept. 5 in a Seattle hospital. Whatcom County Health Department health officer Dr. Greg Stern said Wednesday she tested positive for a strain of E. coli known as O157. Additional tests on the bacteria sample are pending. However, officials say they do not believe her death is linked to the other two cases.

Her father, Rob Hoksbergen, told KING-TV the family doesn't know how or where she was infected. She was the youngest of four daughters. No one else in her family is ill.

Relatives say the boy and girl in Oregon fell ill after both attended the same Labor Day weekend gathering in Lincoln County on the Oregon coast. Brad and Serena shared a turkey sandwich at an Oregon restaurant, his mother said. The two also reportedly swam in a pond together.

The boy's mother, Elizabeth Sutton, told The Oregonian that her son was infected with E. coli O157:H7. Serena tested positive for E. coli but no strain was immediately identified, a spokeswoman for Oregon Health & Science University in Portland said earlier.

Serena's relatives said she died of a stroke after days of intestinal illness. "She had a room full of people praying, and they did the tests -- there was no activity," Sherri Proffit, the girl's grandmother, told CBS affiliate KVAL. "She couldn't breathe on her own. They had to take her off of life support."

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.