AMA VICDOC Summer 2024 - Magazine - Page 47
P RO F PAU L J OH N SO N
THE DAWN OF THE MOLECULAR DIAGNOSTICS
ERA, POSSUMS AND MOSQUITOES
done this before; direct culture had always
been unsuccessful. And so began a 30-year
program of PCRing everything we could
Buruli ulcer first came to Paul’s attention in
to work out what was going on.”
the early 1990s when he was a newly minted
By the mid-2000s, after some false starts,
physician at the Fairfield Infectious Diseases
Paul and his colleagues had figured it out.
Hospital in Melbourne.
They were able to show that Buruli in
“It was the dawn of the molecular
Australia is linked to outbreaks in nearby
diagnostics era. Back then, diagnosis of
possum populations.
Buruli ulcer was by histology, and only very
“We discovered possums also get Buruli
slowly confirmable by culture. It took weeks
ulcer and excrete M. ulcerans in large
and weeks to grow,” says Paul.
quantities in their faeces, and we’ve shown
“At the time, I was also working on a
that disease in possums comes first. We have
PhD at the Royal Children's Hospital.
With support from my then boss, Professor also detected M. ulcerans in mosquitoes in
Roy Robins-Browne, I diverted some of the Victoria, and recently in the Beating Buruli
project shown that M. ulcerans strains in
research team to the problem of making a
humans, possums and mosquitoes are the
PCR for Buruli ulcer.”
same. Mosquitoes link possums to humans
After a few weeks, the team’s lead
– we now have two strong lines of evidence
scientist, Dr Bruce Ross, developed the
world’s first diagnostic PCR for M. ulcerans. that mosquitoes are the predominant mode
of transmission, at least in this part of
"This meant that we could now also
look in the environment. No one had ever
the world.”
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