"Very thankful to everyone who has reached out," teh Baywatch star wrote.
"I did get sick in Papua New Guinea but I bounced back quick and finished an amazing 3 weeks in P.N.G. I’m home for the holidays with my friends and family. Thanks for all the love and concern, see you in 2020!"
He was filming a Man v Wild style adventure series when he contracted a "form of typhoid or similar bacterial infection".
The Daily Telegraph reports that the 32-year-old was treated at St Andrews War Memorial Hospital in Spring Hill for several days before he was given the all clear to head back to the US on Christmas Eve.
Dr Glenn McKay for the Medical Rescue Group told The Daily Telegraph: “I can’t discuss any confidential patient information. I can confirm that Medical Rescue retrieved a US citizen in his 30s from PNG to Brisbane recently for medical attention in Australia.
“He was admitted to St Andrews War Memorial Hospital in a stable condition.”
Efron’s new show sees him go deep into the jungles of a remote, dangerous island to carve his own name in expedition history”.