The actor, 32, was filming a new series titled Killing Zac Efron when he apparently became ill with “a form of typhoid or similar bacterial infection”, The Sunday Telegraph reports.
He was flown to Brisbane, Australia with medical professionals on hand, then admitted to St Andrews War Memorial Hospital “in a stable condition”.
According to the newspaper, he was given the all-clear to fly home to the US on Christmas Eve.
Dr Glenn McKay, director of Medical Rescue, the organisation that oversaw Efron’s flight, declined to say whether the actor was the patient in question, but confirmed the organisation “retrieved a US citizen in his 30s from PNG to Brisbane for medical attention in Australia”.
Photos of Efron were posted on social media last week by Wewak tour guide Cyril Tara, who spoke of how he had been touring the country.
Efron’s adventure series, of which he is the star and executive producer, was announced in November.
Killing Zac Efron will show the actor venturing “deep into the jungles of a remote, dangerous island to carve his own name in expedition history”.
Efron was said to be going off-grid for 21 days “with nothing but basic gear, a guide partner and a will to survive”.
“I tend to thrive under extreme circumstances and seek out opportunities that challenge me on every level,” he said of the challenge. “I am excited to explore any uncharted territory and discover what unexpected adventure awaits!”
The Independent has contacted Efron's representative for comment.