A long-running medical mystery has finally been solved, with Melbourne researchers confirming mosquitoes carry the bacteria that causes flesh-eating Buruli ulcers.

The insects have long been suspected as carriers but scientist working on the study say they faced significant scepticism as they set out to prove the link.

It's now officially confirmed, with the Doherty Institute study published in respected peer-reviewed journal Nature Microbiology.

Victoria recorded a record 363 cases of flesh-eating ulcer in 2023, which can lead to severe skin damage including painful lumps, limb swelling and severe pain.

Clusters centre around the Mornington Peninsula and Geelong areas, with cases also reported in inner Melbourne.

Lead researcher Professor Tim Stinear said the findings show prevention efforts need to focus on controlling mosquito populations and stopping bites.

"How Buruli ulcer is spread to people has baffled scientists and public health experts for decades," Prof Stinear said.

"So now that mystery is solved."

Over the course of five years scientists trapped and forensically tested more than 65,000 mosquitoes on the Mornington Peninsula, finding the bacteria in the insects was identical to that found in ulcer patients.

Infectious diseases physician Professor Paul Johnson said there was no precedent for bacteria to be transmitted this way.

"Our team faced considerable scepticism, so we gathered irrefutable evidence to support our claim," he said.

"This research is significant because we can all take simple actions, like applying insect repellent and removing stagnant water around the house, to protect the community and reduce the risk of Buruli ulcer."

The scientists are now focused on a trial aiming to reduce the number of mosquitoes in inner Melbourne.