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Mystery of the Flesh Eaters -

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Mystery of the Flesh Eaters

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It lives outdoors and attacks during hot summer months, usually after a heavy rainfall. These few,
meagre clues began a decade long hunt for the cause of an shocking infectious disease. Tanya Ha
reports how Dr John Gerrard tracked down the culprit responsible for vectoring a virulent flesh
eating bacteria into humans.

NARRATION

Max Byles never saw what bit him. But a week later, he lay fighting for his life in a Gold Coast
hospital.

Dr John Gerrard

It was unlike any infection which I had ever previously encountered, or which I had ever read about
in any textbook.

NARRATION

Something was eating away at his tissues inside and out.

Dr John Gerrard

He had lumps on his lower limbs, his upper limbs and his trunk, in association with high fevers.
And we detected an abscess that was growing in the left lobe of his liver.

NARRATION

The strange parasite in Max had been causing similar wounds in patients across Australia and the
US. But what was it, and where did it come from?

Tanya Ha

It lives outdoors. It attacks during hot summer months, and usually after heavy rainfall. These few
meagre clues started an infectious disease hunt that lasted nearly a decade.

Max Byles

I went to go home, but couldn't move me right leg properly. It was all limp on me. And by next
morning, I had a lump coming out on the side of my stomach. Went a bit silly in the mind. And the
first person I knew at hospital was Dr Gerrard.

Dr John Gerrard

High fever ... Are you, are you feeling any better at all?

Max Byles

I don't know, I think I feel a little bit better.

NARRATION

To find out what was infecting Max, blood and tissue samples were taken to the hospital laboratory
for culture. A few days later, a distinctive, but unknown bacterium covered the agar plates.

Dr John Gerrard

That looks ah, quite unusual. Some swarming around the edges.

NARRATION

DNA sequencing revealed a genetic match to a genus of bacterium known as Photorhabdus.

Dr John Gerrard

Which means 'light rod' in Greek. What that means is it glows in the dark.

NARRATION

John took a swab of the bacterium, drew the letter 'B' and headed into a dark room.

Dr John Gerrard

It seemed a little unlikely, and we felt a bit silly about it at first. Within a few minutes, lo
and behold, this letter, the letter 'B' appeared before our eyes. It was really quite magical.

NARRATION

Known as an insect pathogen, Photorhabdus normally lives inside a small worm. The worm attacks by
penetrating the skin, or cuticle, of the insect. Once inside, the worm vomits up the Photorhabdus
bacterium. Toxins released by the bacterium kill the insect and preserve its body. The worm them
multiplies, and uses the insect cadaver for food.

Attacking a human is vastly different to attacking an insect. So it seemed that perhaps this
bacterium was carried by a different vector.

Tanya Ha

And one that might live in a common garden environment - perhaps a spider.

Dr John Gerrard

Almost all of the patients had been involved in some form of outdoor activity prior to infection. I
collected water samples, I collected soil samples. Samples of the manure of animals. I collected
insects, spiders. It really just led nowhere. It was really quite naïve that you could go to a, to
a farm and think that you would just find this organism in any simple way.

NARRATION

It was at this house in Kingscliff where John finally got his break. Never before had a patient
been able to pinpoint exactly where they were when the infection occurred.

Tanya Ha

So what were you doing when you originally got the infection?

Greg Burton

Oh, I was digging a hole here, for this post.

Tanya Ha

So whatever it was, it was in the ground here?

Greg Burton

Yeah.

Tanya Ha

It probably still is.

Greg Burton

Yeah, well all I did was dig the hole for this.

Dr John Gerrard

He had been building a fence on the boundary of his house, using just his right hand as a scoop.

NARRATION

And just a few days later, the flesh on Greg Burton's right hand had been eaten away.

Dr John Gerrard

This was an extraordinary infection that had completely eroded the skin and soft tissue on the back
of his right hand, exposing all the tendons. So I, I knew exactly where to look. I had a hole in
the ground where I could look for this organism.

NARRATION

Nothing was visible in the sand, so John added insect larvae to the samples to tempt out the
pathogen.

Dr John Gerrard

One week later, all the insects had died, and they were glowing in the dark. And about a week
later, first a small number and then hundreds, then thousands, then hundreds of thousands of tiny
worms began to erupt from these insects.

NARRATION

Dr John Gerrard had his vector.

Dr John Gerrard

It is unheard of for worms to vector infection into humans.

NARRATION

But that's exactly what this microscopic nematode does.

Dr John Gerrard

Looking back, we discovered that most or all of the patients had been exposed to sand or sandy soil
at or near the beach. Well, we don't know what the, the natural prey of this worm is. We don't
believe it's humans, but as yet, that remains undiscovered.

NARRATION

It seems that what we are seeing is an insect pathogen caught in the act of jumping to a human
target.

Dr John Gerrard

Thirty years ago, it was said that the era of infectious diseases was over. And then thirty years
ago, along came HIV. We have avian influenza from birds. SARS originated from civets. We have
become increasingly interested in not just mammals and vertebrates as a source of, you know, of
emerging infectious diseases in humans; but other animals, invertebrates, as a source of emerging
infectious diseases in humans.

NARRATION

Two other well-known insect pathogens have jumped to humans in the past. The results? Anthrax and
the Bubonic Plague.

Dr John Gerrard

I certainly do not believe that this organism is likely to cause a widespread plague. I think we
would have seen that by now, and I'm very happy to allow my children to play in the sand.

NARRATION

All patients have recovered with aggressive antibiotic treatment.

Tanya Ha

Oh, so it ate away that much?

Max Byles

It took years before we actually found out what it was. And then when they said it was a little
worm the size of a pinhead, I couldn't believe it.

NARRATION

Even more extraordinary, it may one day save your life. The molecules used by Photorhabdus to kill
insects and preserve their bodies are yielding hundreds of potential new drug structures - from
anti-fungals to anti-cancer drugs. It's a small invader with a lot to offer science.