In a message to the Facebook page posting updates on his condition, the Reyna family said Zachary had changed the world for the better during his short time on earth.
I hope that Zac continues to touch people and his time here is remembered forever. We thank everyone for being so caring and I know it's going to be tough on us at first, but we have an awesome support team back home and we are grateful for that. The battle is over for Zac but he won the war.
"Miami Children's Hospital expresses heartfelt condolences to this devoted family," the hospital said in a statement. "We respect the family's wishes and honor their privacy at this time."
Zachary's doctors believe he contracted the parasite while knee-boarding in a watery ditch near his family home in LaBelle. His family noticed that something was wrong when the normally energetic boy spent all day sleeping.
After he was hospitalized and diagnosed with primary amoebic encephalitis, the infection caused by the parasite, Zachary's doctors gave him an experimental anti-amoeba drug used successfully on a 12-year-old Arkansas girl who had contracted the bug a few weeks before. Over the weekend, however, tests on Zachary's brain showed no activity.
In another Facebook post, the Reyna family said they intended to donate their son's organs.
"Even though Zac has passed, he will still be saving many lives," the family said.
Reyna's infection prompted Florida health officials to warn swimmers against shallow, warm water -- the environment favored by deadly parasites.