A Victorian couple suffering muscle pains, fevers and vomiting discovered their bodies were infested with tiny worms eating through their tissue.

The couple ingested the gnathostomiasis larvae after eating a fish they caught in a river while on a Western Australian holiday.

It is the first time this parasite, which is more common in Thailand and China, has affected a person in Australia.

Dr Andrew Fuller, the head of the infectious diseases at the Alfred Hospital in Melbourne, said it took 10 to 12 days for the couple to fall ill after eating the fish.

The couple suffered abdominal pains and rashes, with the husband even reporting that he could feel something moving under his skin.

The worms are 1-3mm long, have sharp teeth and are able to eat through tissues.

"After you eat the fish the parasite goes through the wall of the stomach and then moves through the body under the skin or it can move into various organs, such as the brain or the spinal cord or any of the organs," Dr Fuller told Nine News.

The couple were treated with antibiotics and recovered before the worms had the chance to make their way into the brain or the spinal cord.

If left untreated, the worms can stay in humans for up to 15 years.