It can be fatal if forced up the nose as the parasite makes its way to through the nose and up the brain, where it gradually destroys the surrounding tissue.
Symptoms start with a severe headache and can progress to coma.
Gray's family did not want to speak publicly about their loss, but their lawyer provided a statement that said: "Mr Gray's death was tragic and untimely. The family is currently asking for privacy and respect during this difficult time. Otherwise, at this time, the family has no comment."
Following Gray's fatal incident, health officials are working closely with Fantasy Lake Water Park on ways staff and visitors can take precautions to protect themselves against this deadly parasite in the future.
North Carolina's state epidemiologist, Dr Zack Moore, said his sympathies were with Gray's family during this hard time.
"People should be aware that this organism is present in warm freshwater lakes, rivers and hot springs across North Carolina," Dr Moore said.
"So be mindful as you swim or enjoy water sports."
Health officials said the amoeba is known to have infected just 145 people in the US from 1962 to 2018.
- Additional reporting AP