The unusual vaccination plan to halt ‘out of control’ flesh-eating disease

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Possums would be vaccinated against the Buruli ulcer under a plan by infectious disease experts to control what they say is an astounding surge of flesh-eating disease across Melbourne and regional Victoria.

As the state heads into the riskiest months for transmission, public-health officials are urging those living or travelling to affected areas – including Melbourne’s inner-north – to take steps to avoid mosquito bites.

Alice Mika is still battling a Buruli ulcer infection from last summer.Credit: Jason South

Scientists believe the insects are fuelling the spread by biting infected possums and then humans. The skin infection is caused by the bacterium Mycobacterium ulcerans. If it gets under the skin, it can grow and produce a toxin that melts skin cells and fat.

A record 378 cases of the Buruli ulcer have been reported in Victoria in the past 12 months. More than 40 cases have been detected in Merri-bek – formerly known as Moreland – where annual infections are on track to double in a year. In the Moonee Valley area, 23 cases have been recorded over the year.

Barwon Health director of infectious diseases Associate Professor Daniel O’Brien said a new approach was needed to slow the spread of the infection, which could lead to skin and tissue loss.

“It’s a serious disease that’s out of control,” he said. “We need to prevent people from catching it in the first place.”

Oral bait tuberculosis vaccines would be put out for possums to consume under a proposal by O’Brien and his co-authors published in the Medical Journal of Australia.

This vaccine has been found to offer protection against the Buruli ulcer because tuberculosis is from the same bacterial family.

Oral bait vaccines have been used to stop the spread of rabies in wildlife in Europe and North America. In New Zealand, possums have been vaccinated against bovine tuberculosis by eating chocolate-flavoured pellets.

“Possums carry the disease and their faecal droppings are infectious,” said O’Brien, who is trying to secure philanthropic funding for a trial.

“If you could prevent them getting sick, then you might be able to interrupt the chain of transmissions and perhaps eradicate it completely.”

Because of the long incubation period, it typically takes six months between being infected with the bacterium and a diagnosis. This means people get infected in summer and autumn when mosquitoes are active, prompting a spike of detections in winter and spring.

However, many patients and local doctors are still unaware that the Buruli ulcer has spread beyond historical hotspots near the coast.

Point Lonsdale on the Bellarine Peninsula was an epicentre 20 years ago. The Buruli ulcer has since jumped across Port Phillip Bay to the Mornington Peninsula, and established itself in suburbs across Melbourne and Geelong.

“Now it seems to be able to actually get away from the coast and get into the inner city, there’s not really a limit to it,” said Professor Paul Johnson, an infectious diseases physician with Austin Health.

Alice Mika didn’t think much of the small bump that appeared on her right ankle in June.

“I thought it might’ve been an infected spider bite,” the 26-year-old Airport West resident said.

Over the next two months, Mika saw three different GPs who suspected she had a staph or insect bite infection and prescribed antibiotics – but they didn’t seem to help.

How to prevent the Buruli ulcer

  • Reduce the number of mosquitoes in and around your property by removing or covering with mosquito wire any source where mosquitoes breed, such as gutters, pot plant containers, buckets, open tins, or cans.
  • Make sure your water tank is screened off to prevent mosquitoes from breeding there. 
  • Mosquito proof your home by installing insect screens. 
  • Avoid mosquito bites by using personal insect repellents containing diethyltoluamide (DEET) or picaridin.
  • Cover up by wearing long, loose-fitting, light-coloured clothing.
  • Avoid mosquito-prone areas especially at dusk and dawn when they are most likely to be out. 

Source: Western Public Health Unit

The bump grew into a dollar-sized ulcer, her ankle doubled in size, reddened and she struggled to walk.

It wasn’t until Mika mentioned her plight to a colleague at Sunshine Hospital that she got some answers.

“My colleague said, ‘I’ve heard of this Buruli thing and what you are describing sounds like it might be that’,” she said.

A test confirmed it and she began an eight-week course of new antibiotics and had surgery to drain her wound.

Mika suspects she contracted the ulcer after being bitten by a mosquito over summer.

“It will probably take six to 12 months before it’s healed,” she said.

New data shows Brunswick West, Pascoe Vale South, Essendon, Moonee Ponds, Strathmore and Coburg have emerged as suburbs of concern in Melbourne.

“It’s quite astounding, or substantial, the degree of increases that we are seeing,” said Western Public Health Unit director Dr Finn Romanes.

He said those living near affected areas should also be vigilant, noting there could be quite significant local transmission within a suburb before Buruli ulcer was declared endemic in the area.

“It’s very clearly affecting all age groups, all genders, and people of absolutely every background.”

A Department of Health spokeswoman said officials looked forward to seeing further research into the vaccination of possums.

She said this would “identify whether this program could inform public health actions in the future”.

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