by When Alice Mika was bitten by a mosquito last summer in Melbourne’s west, she thought nothing of it.
Then, more than five months later, a small raised bump appeared on her ankle and she wouldn’t go. She saw her GP who prescribed antibiotics, believing it to be a spider bite.
But over two months, “it was getting worse and worse”, she said. His ankle began to swell and eventually the scabies bite into a gaping hole exposing the layer of fat under the skin.
Mika’s doctors initially did not think she might have the Buruli tick because she told them she had not visited Victoria’s Bellarine Peninsula, one of the coastal areas where the disease was thought to be confined, including the Home Peninsula O’Mornan too.
However in recent years it has spread. As of 2019, cases have been reported in the Geelong suburbs and inner Melbourne areas, including Essendon, Moonee Ponds and Brunswick West.
Related: Skinworms and brainworms: how humanity’s environmental impact has led to new infections
The Victorian government announced last week that 363 cases would be reported in 2023, adding to the exponential increase over the past two decades since 12 cases were reported in 2003.
But how Australians have been ending up with these skin ulcers has been a mystery since Australian scientists discovered this bacterium more than 80 years ago, Professor Tim Stinear, director of the World Health Organization’s Collaborating Center told for Mycobacterium Ulcerans at the Doherty Institute.
But now research led by Stinear, published Wednesday in Nature Microbiology, claims that the “transmission enigma” has been solved with evidence that mosquito bites are spreading the infection between possums and humans.
“The research adds to many years of research that has informed us that mosquitoes are involved in spreading this infection, but we have a lot of skepticism in this area because it is unprecedented for these bacteria to spread . by mosquitoes,” said Stinear.
The researchers captured and tested more than 65,000 mosquitoes between 2016 and 2021 in the Moran Peninsula, known to have one of the world’s highest incidences of Buruli ulcer, and built a “hierarchy of evidence” showing that the insects are responsible for spreading. the infection, Stinear said.
Using forensic-level genomics, the researchers found that the bacteria in the mosquitoes were identical to the bacteria in humans.
They also sequenced the DNA in the blood in the mosquitoes’ abdomens and found that the insects were feeding on native Australian possums and humans.
The researchers also carried out spatial mapping and statistical analysis of the areas where people were getting Buruli ulcer, where possums were carrying the bacteria, shedding it in their faecal pellets, and where mosquitoes were also carrying the bacteria, and found that those areas overlapped. in space.
Professor Rhonda Stuart, director of Public Health and Infection Prevention at Monash Health, said, “It’s a landmark paper. It fills in the gaps in what we have been trying to find out about Buruli ulcer for many years, and the link between human disease, possums and mosquitoes as the likely vectors of transmission.”
Stuart said an increase in the prevalence of mosquitoes as a result of torrential rains could be among the factors contributing to the spread of the Buruli ulcer.
“We’ve seen it with Japanese encephalitis last summer, where normally Japanese encephalitis mosquitoes were only up north, and then we saw them further down as far as southern New South Wales and northern Victoria,” Stuart said.
Related: Floods and hot weather perfect storm for Japanese encephalitis outbreak, researchers warn
Stinear hopes that the results of the research will lead to better control of this infection, including better awareness of how individuals can prevent mosquito bites, stop mosquitoes from breeding around homes and public health measures .
The infection has a very long incubation period, Stinear warned. From the time you get bitten by the mosquito to the time symptoms start to appear, starting with a bite or pimple that won’t heal, is usually about four to five months, he said.
“It can be painless, so people ignore it and eventually, the skin breaks down, and you’re left with an ulcer, but actually underneath the skin there’s a lot of dead and dying tissue that’s not the victim aware of it.”
If a family doctor can diagnose a Buruli ulcer early, a PCR test can quickly confirm the infection and treat it effectively with specific antibiotics.
The infection is not fatal, but if left untreated it leaves people with lesions that can affect quality of life during treatment, and later leave them disabled or disabled for life, Stinear said.
Mika said his ulcer is healing and “going in the right direction”.
“2020 is looking back. Family doctors don’t know everything but it’s a shame they didn’t [the disease] was in Melbourne – he could have been diagnosed earlier.”
