A six-year-old boy who died last week in Millbury, Mass. was poisoned with E. coli, according to public health officials.

The case was confirmed by a state laboratory Thursday, but the source of the infection is not yet known. The county's director of public health, Derek S. Brindisi, told the Worcester Telegram & Gazette that the case is being treated as an isolated food-borne illness, but that has yet to be confirmed.

Owen Carrignan died died Saturday from complications of hemolytic-uremic syndrome, or kidney failure. The disease is associated with E. coli infections.

The boy's father, Shawn Carrignan, told the Boston Herald that Owen had eaten a hotdog at a friend's cookout the previous weekend, but others who consumed the same food were not sickened.

“He went from playing a soccer game one Saturday and in less than a week he’s gone, the healthiest kid in the world,” he told the paper. “I am still batting my brains how he got it.”

E. coli infections have been associated with raw ground beef, raw seed sprouts or spinach and unpasteurized products like milk, juice and unpasteurized cheese. The pathogens can be largely eliminated, however, by proper cooking.

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