Buruli ulcer cases rise in Victoria as flesh-eating disease spreads into Melbourne's inner suburbs

As of December 17, Victoria had recorded 344 cases of Buruli ulcer this year, and health officials say the bacterial infection is no longer confined to the coast. Recent increases have been tied to Ascot Vale, in Melbourne's inner north-west, a long way from the seaside communities where the disease has historically turned up.

Beyond Ascot Vale, the infection has been found in the inner suburbs of Essendon, Moonee Ponds, Brunswick West, Pascoe Vale South and Strathmore. Cases have also been recorded on the Mornington Peninsula and the Bellarine Peninsula, and in East Gippsland, Geelong, Frankston and the Westernport region.

On Friday, Victorian Chief Health Officer Professor Ben Cowie said there was evidence that both mosquitoes and possums may be responsible for the spread. The infection does not pass from person to person. His advice was practical: do not handle possums or their faeces, use insect repellent, and wear long, loose-fitting clothing to guard against mosquito bites. Skin that has been exposed to soil or water, he said, should be washed after outdoor activities.

Anyone can catch the disease, but in Victoria cases are highest among people aged 60 and over. Cowie stressed that the risk of contracting Buruli ulcer is still considered low.

The warnings are not limited to Victoria. Health officials in New South Wales issued similar advice after two cases were confirmed in Batemans Bay earlier this week. Infectious diseases experts described the town as a new endemic focus of human Buruli ulcer transmission, because the cases were genetically linked to an earlier infection in Eden, 150km away.

The disease is caused by the bacterium Mycobacterium ulcerans, which releases a toxin that eats away at skin and the soft tissue beneath it. The average incubation period is five months, so people may go four to five months before realising they are infected. Possums are believed to be the primary target of the bacteria, and as a zoonotic disease it can reach humans through mosquitoes, according to researchers in Melbourne.

It starts as a sore, usually on a leg or arm, that does not heal and lasts for weeks. It slowly enlarges, and once the wound breaks down it leaves a large, open ulcer. Paul Johnson, director of research at Austin Health, told The Age that the infection spreads slowly but progressively in the layer between skin and muscle. "It's quite silent for a while, you might not notice it," he said. Part of the reason is that the infection is not very painful: it interferes with pain signals and with the immune system, making it harder for the body to detect or fight it early.

The advice for anyone concerned is to see a GP. Buruli ulcers can now be effectively treated with antibiotics and dressings. What to watch is whether the Melbourne cluster around Ascot Vale keeps growing, and whether other areas, like Batemans Bay, are identified as new foci.