Posted: 1 February 2024
In a major breakthrough, researchers led by University of Melbourne’s Professor Tim Stinear, Director of the WHO Collaborating Centre for Mycobacterium ulcerans at the Peter Doherty Institute for Infection and Immunity (Doherty Institute), have solved the 80-year mystery surrounding the spread of Buruli ulcer, a neglected tropical skin disease which has become an important public health issue in Victoria, Australia.
Published in Nature Microbiology, their findings categorically confirm mosquitoes as the primary vectors transmitting the ulcer-causing bacteria Mycobacterium ulcerans (M. ulcerans) from the environment to people.
How people contract Buruli ulcer has been a central question that has perplexed scientists since the discovery of M. ulcerans in the 1940s in Australia. With an alarming and inexplicable surge in cases in and around Melbourne and Geelong, this discovery represents a pivotal and significant advancement in the efforts to curb the spread of Buruli ulcer and protect communities.
Focusing on the Mornington Peninsula, a seaside region outside of Melbourne with one of the highest incidences of Buruli ulcer in the world, the Beating Buruli in Victoria project team trapped and tested more than 65,000 mosquitoes between 2016 and 2021.
Led by the Doherty Institute at the University of Melbourne, the collaborative research team brings together partners from the Bio21 Institute, Agriculture Victoria, Austin Health, Victorian Department of Health, the Mornington Peninsular Shire, CSIRO, and more.
“How Buruli ulcer is spread to people has baffled scientists and public health experts for decades,” said Professor Stinear.
“So now that mystery is solved with our five-year study revealing that mosquitoes transmit M. ulcerans in southeastern Australia, making mosquito bite prevention and mosquito control obvious forms of prevention.”
Dr Peter Mee, Research Scientist at Agriculture Victoria and one of the lead authors of the paper, emphasised the advanced techniques employed in their research, including the use of forensic-level genomics.
“Thanks to genome sequencing, we discovered that the genetic make-up of the bacteria M. ulcerans in mosquitoes was identical to that found in Buruli ulcer patients in the study area,” Dr Mee said.
“This was a key part of a compelling body of evidence pointing to mosquitoes as the transmission link.”
The Royal Melbourne Hospital’s Dr Katherine Gibney, an infectious diseases and public health physician and one of the study leads at the Doherty Institute, stressed the importance of ongoing wildlife and mosquito population monitoring – a One Health approach.
“Maintaining this type of mosquito surveillance work could offer crucial insights into the epidemiology of Buruli ulcer in the region and inform public health interventions aimed at controlling the disease,” Dr Gibney said.
Professor Paul Johnson, infectious diseases physician at Austin Health highlighted the difficult road the team faced to convince others that mosquitoes were spreading Buruli ulcer.
“We long suspected mosquitoes were involved, but there is no precedence for a bacterial infection like Buruli ulcer being transmitted this way. Our team faced considerable scepticism, so we gathered irrefutable evidence to support our claim,” said Professor Johnson.
“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.”
Minister for Health Mary-Anne Thomas highlighted the importance of the Beating Buruli project.
“We are proud to support the Beating Buruli project, this research will help us better understand how the infection is transmitted and determine ways to prevent infection to protect the health of Victorians,” said Minister Thomas.
Over the last two decades, there has been an exponential increase in reported cases in Victoria, Australia, escalating from 12 in 2003 to 363 in 2023 – the highest count to date.
The Beating Buruli in Victoria team is in the process of rolling out a new trial aimed at reducing mosquito populations in urban areas, specifically around Brunswick West, Pascoe Vale South, Moonee Ponds and Essendon in Victoria, using state-of-the-art, environmentally friendly mosquito traps.
