Sometimes, it’s hard to remember mosquitos are a necessary link in the food chain. Their talents, such as pollinating and providing a food source for much larger insects and birds, are so often overshadowed by the irritation and devastation they cause.
While the idea of a world without mosquitos might sound great to most, these small but mighty insects are an integral part of our ecosystem. Still, the list of fevers, viruses and plagues they effortlessly spread to global populations is more than extensive.
From Dengue fever to Malaria, mosquitos are responsible for countless global infections and deaths each year. Now, yet another devastating illness has been tied to their wicked little bite.
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The latest mosquito-borne outbreak
If last year’s sheer volume of stress-inducing headlines turned you off scrolling the news entirely, you may have missed the rising number of Buruli ulcer cases here in Australia. By the end of 2023, Victoria recorded 363 confirmed cases of the flesh-eating bacteria, the largest number in nearly 20 years.
If you need a refresher, Buruli ulcer is the name given to a skin infection caused by the bacterium Mycobacterium ulcerans. Over several months, what initially presents as a small mosquito bite begins to develop into an ulcer masking extensive destruction of the underlying tissue.
Left untreated, a Buruli ulcer will continue to enlarge and infect the surrounding skin, hence the commonly used ‘flesh-eating’ moniker in mainstream media.
Treatment for the skin infection usually requires a six to eight-week course of antibiotics, with surgical intervention needed in severe cases to remove compromised tissue.
How does Buruli ulcer spread?
Until now, researchers have been unable to understand the origins of each recorded outbreak in Victoria, unsure of how infected individuals initially became exposed to the bacteria, or how it managed to spread undetected throughout communities.
Analysing a sample of common mosquito species across a 350 km² area of Victoria, scientists from Nature Microbiology were able to trace the presence of the infection’s pathogen, understanding the insects’ integral role in its spread.
Researchers have long suspected Australian native possums harboured the pathogen responsible, but are only now finally able to explain the bacteria’s interspecies jump from possum to person.
According to molecular testing (contract tracing, but for insects) two of our country’s most common mosquito species presented as positive for the bacteria, matching the pathogens found in both possum poo and confirmed human cases of Buruli ulcer.
The study has led scientists to conclude that the devastating skin infection in humans occurs when mosquitoes feed from a possum that harbours the bacteria and then spread the pathogens to people through their bite.
How to protect yourself against the bacteria
Understanding the key role mosquitoes play in spreading the bacteria to humans is crucial in our efforts to minimise the risk of infection in Australia. Controlling the number of mosquitos at risk of carrying the bacteria close to our homes and workplaces is the most effective way to combat the spread of the Buruli ulcer.
Given these pesky insects lay their eggs in the presence of water, small containers of collected water in your backyard (such as a bucket, pot plant or watering can) should be emptied at least once a week.
Of course, protecting your skin from bites will always be your first line of defence against contracting a mosquito-borne disease. Experts recommend wearing loose-fitting long clothing and regularly applying topical insect repellent to exposed areas of the skin.
As always, if you are concerned about the appearance or feel of any mosquito bite or skin lesion, consult your GP or dermatologist.
