A 13-year-old Grand Rapids, Mich., boy died of gangrene, reports WZZM News 13.

Initial medical reports said Gabe Castro died of bacterial meningitis on April 3, but Kent County Medical Examiner Dr. Stephen Cohle said Tuesday that Castro died of gangrene.

Cohle told the TV station he is unsure how or why the teenager became infected with gangrene, an organism that lives in the intestinal system.

Gangrene develops when the blood supply is cut off to the affected part of the body and can affect any part of the body, according to WZZM.

In an interview with the TV station, Castro’s grandparents, Rey and Barb, said Gabe only complained of a sore throat at first.

Barb Castro said her grandson eventually had severe pain in his legs and had trouble walking, so her husband rushed him to the hospital, where he later died.

Cohle told WZZM that gangrene is not contagious.

Click here to read the full story from WZZM.