Quarantined US actor Tom Hanks has prompted a wave of gentle ribbing from his Australian hosts concerned about his fervid use of their beloved Vegemite spread.

Hanks has been in hospital isolation with his wife Rita Wilson since they tested positive for coronavirus last week. 

On Sunday he posted a photo showing two pieces of toast smothered in Vegemite, a salty and pungent paste made from yeast extract.

"Thanks to the Helpers. Let's take care of ourselves and each other," Hanks wrote in the social media post alongside a photo of a crushed Vegemite tube, a kangaroo doll and the thickly slathered toast, with a large bite missing from one piece.

The response from bemused Aussies was immediate.

"WHERE WERE THESE HELPERS WHEN TOO MUCH VEGEMITE WAS BEING SPREAD ON THAT TOAST??????," tweeted Melbourne comedian Kirsty Webeck.

"Okay you need to scrape around 60% of that vegemite off, otherwise it's gonna be nasty and hurt your mouth friend," warned Amy Thunig.

"Cripes, we've given him coronavirus *and* Vegemite," added Greg Jericho, a Canberra-based journalist.

Hanks and Wilson, both 63, were isolated in hospital on the Gold Coast south of Brisbane last week.

Hanks was in Australia for filming of a biopic about Elvis Presley in which he was due to portray the singer's longtime manager, Colonel Tom Parker. 

Wilson, a singer-songwriter, had given a number of performances and interviews in Sydney and Brisbane, prompting authorities to try to trace spectators and journalists who came into contact with her.

At least one of those contacts, TV entertainment reporter Richard Wilkins, has since revealed he has tested positive for coronavirus.