- All right, gross story time.
Hepatitis A is passed from one person to the next
via the fecal-oral route.
In other words, to get hepatitis A
you need to eat someone else's poo,
which you don't do, obviously,
except that you do all the time.
Like, if someone with hepatitis A goes to the toilet,
doesn't wash their hands, touches some surfaces,
you touch the same surfaces, then you touch food,
then you eat the food, you've eaten someone else's poo.
And you can get hepatitis A that way.
That's how hepatitis A spreads through a community.
But there's another way to get hepatitis A.
In fact, someone with hepatitis A in Bangor in North Wales
in the U.K. can give hepatitis A to someone
in the Netherlands without leaving Wales.
The process is quite remarkable
and actually the way we figured it out was remarkable too.
So here's the story.
Hepatitis A is not endemic to Wales,
you don't see it often in Wales
but one person from Wales went on holiday
to somewhere in the Caribbean, where it is endemic.
They picked it up because they weren't vaccinated
and they brought it back and they passed it on to everyone
in their household through the fecal-oral route.
Then they all went to hospital.
The hospital had the foresight to sequence the genome
of the virus before sending them home
and saying get well soon.
Now, when you have hepatitis A
you go to the toilet rather a lot.
And every time you do, you release trillions
of viral particles into the toilet.
What we flush down toilets is treated before it's released
into rivers and oceans but as bad luck would have it,
during the time of this household's hepatitis A infection,
there was heavy rainfall.
And in the U.K. we have a system that combines
what comes from toilets and sinks with what flows
through our storm drains.
Normally that's not a problem,
but when you have really heavy rainfall,
it can overwhelm the water treatment system,
and any excess is released untreated.
As bad luck would have it, this household happens
to be situated in an area where waste water
eventually finds its way to major shellfish
harvesting waters in North Wales.
Let's look at mussels in particular.
They're filter feeders which means they draw water
in from their environment, they keep hold of the juicy bits
and they blow everything else back out.
But it turns out they're pretty good
at holding on to hepatitis A virus particles.
They're bio accumulators of hepatitis A.
We then ship those mussels to a major distributor
in the Netherlands who shipped them out all over Europe.
Then all around Europe, you get these new cases
of hepatitis A and then new outbreaks in those communities
through the fecal-oral route.
And this is all thanks to one person in Wales
who went on a holiday to the Caribbean
without a vaccination against hepatitis A.
How do we know that these European cases
of hepatitis A came from Welsh mussels?
Like maybe these Dutch people went to the Caribbean as well.
Well, you can interview patients and say,
have you eaten mussels recently?
The problem is the incubation period
for hepatitis A is really long.
They might not remember what they've eaten
and they've certainly thrown the packaging away
that has the serial number on it that you can use
to track down the ultimate starting point of the mussels.
But it's okay because viruses mutate incredibly quickly.
So if you find a virus here in the Netherlands
and another one here in Bangor in Wales,
and you compare the genomes.
If you discover that those genomes are really similar,
it means that not much time has passed between them,
they must be closely related.
So we're only able to put this picture together
because hospitals sequence the genomes of certain viruses
when patients come in, so that we have this database
of viral genomes.
And it's only because we have this incredible international
cooperation when it comes to infectious diseases.
This isn't just an isolated story.
It happens all the time all over the world
and not just with hepatitis A and not just through mussels.
So it's amazing that we can draw these conclusions
and it's really important that we use that information,
but we still don't have a complete picture.
Like, we still don't fully understand the journey
of the virus through the system.
But I've been speaking to someone
who's been taking a closer look.
- I'm Davey Jones from Environment Center, Wales.
You know you might have a town of 70,000 people
like Clantedno, close to us.
And within that, there might be 500 people who have
norovirus in an outbreak time.
And each one of those are emitting a trillion
viral particles every time they go to the toilet.
Although the sewage treatment plant gets rid of 99% of them,
actually 99% of a trillion, you still got a lot left over.
When the fresh water hits the salt water, the salt actually
causes the chemicals in the water to precipitate out.
To get these little particles formed in the water,
the viruses then stick onto the particles that are then now
big aggregates you know, big things in the water.
Of course, they're the perfect size for filter feeders.
So if you look at a mussel for example,
it's just continually harvesting particles out of the water,
that's what it feeds on.
And those particles only are produced when fresh water hits
salt water.
So that's why you find shellfish largely in estuaries
because the particles drop out of solution
and they're harvesting them.
Our project is called The Viraco Project.
So the idea was that to identify where the major sources
of these viruses were coming from.
How long do they survive in the river system
and in the marine system?
And then how many you get accumulated by shellfish?
So we would go out sample about 20 liters of water which is,
you know, a big volume like this, we then filtered the water
and took it down to about this much 50 milliliters.
And from that we then concentrated even further down
to one milliliter.
The machine that we use is quantitative,
so we can tell you exactly how many norovirus particles
that are there.
How many adenoviruses.
And in 20 liters, they might be 10,000 or more of these
adenovirus in that, yeah.
Most of the viruses that come out in fecal material
are genuinely quite infective.
The longer the viral particles in the environment,
the more likely they are to become damaged.
So they become damaged by UV, radiation, sunlight,
or from other enzymes released from other organisms
in the water that basically break open the coats.
Of the viruses that we're measuring the water,
how many were intact and how many broken.
So you can get STEM cells that grow into little organoids
for example, from the human guts, et cetera,
you know, as an example.
You know you basically can then infect norovirus into them
from contaminated waters and if it's still infective
of course, it then goes into the human tissue
in tissue culture and then the norovirus is--
- [Steve] Exposed. - Exposed, yeah.
And generally speaking, there's actually a lot
of infective particles there so that, the criticism
that's been leveled by particularly some of the industries
who are involved in releasing viruses into the environment,
I think is unfounded.
I think there is a lot of evidence.
- Davey Jones and his team also did some mathematical
modeling of the flow of water through the system.
And they discovered something really surprising.
- The virus comes down to the estuary,
the water comes back in it gets sucked back up the river
then comes down again and then it comes back again.
And then actually it takes a lot of time for it
to eventually go out to the sea.
But during that time what's actually happening
is that batch of contaminated water is actually passing over
the mussel beds and the oyster beds, maybe eight or nine,
possibly 10, maybe 15 times and we never realized that.
We always assume that it would just be,
the water would just flow out into the ocean
and would be gone.
- [Steve] A single pass?
- Yeah.
- [Steve] Over the shell fish, essentially.
- And that's why shellfish is so good at harvesting
because they got multiple gos at getting the virus.
- [Steve] Maybe that's why you have shellfish
in those places because--
- Yeah, well, that's right.
And mussels like sewage,
they grow bigger and fatter when they're fed on sewage.
- So these new technologies are giving us new information
and new knowledge but how should we use it?
How should we change our behavior?
- Firstly, I think we need to change the standards
for water quality.
I think we're testing for the wrong thing.
I think, the moment we're testing for bacteria
and when you look at the survival of bacteria
and viruses in water, they behave completely differently.
You know, really what we wanna be doing is testing
for the things that make us sick and that's viruses.
And the reason we haven't done that before
is because we don't have the methods to do that.
Based on our knowledge now, we know that for example,
when you have storms, you have a lot of virus
coming through the system.
It's flushing the system out basically.
And you can tell shellfish, harvesting areas
or people on beaches.
Instead of being reactive and saying,
we've just measured high concentrations of the virus
in the water, don't harvest shellfish
for another three weeks.
We don't need to go through that step of monitoring viruses.
We know that this high risk events are happening.
We've got sewage discharges, we've got water
at the right time of year, in the winter for example,
when norovirus is in the population because public health
are monitoring viruses all the time.
You can see that.
I mean, there's some really clever ways
which is harvesting information from Twitter.
So I mean, how do you know when people are sick?
Well, it's amazing how many people use Facebook
and Twitter to report that they've got diarrhea
or food poisoning.
- And what about you?
Like, what if you've got norovirus or hepatitis A
and you're totally shedding it everywhere.
Is there something you can do for the greater good?
- I think Actually the advice we should give
is that you should be using a disinfectant
at the same time when you go to the toilet.
So really, if you want--
- [Steve] Obviously, go to the toilet, put some bleach down
and then flush out or something.
- Exactly.
People think that eating oysters might be an aphrodisiac.
I have the opposite view of this.
You only have to eat one oyster that's contaminated with
the smallest amount of sewage and basically you can chop
norovirus and then you become the epicenter
for another outbreak that spreads person to person.
So why don't we cook oysters?
Some people claim that they taste better
if you don't cook them, so.
- I've never tried one and I'm not keen to anymore.
So there you go.
You know, watching the video back I'm concerned
that I've painted quite a negative picture
of the shellfish industry which I genuinely don't wanna do.
Like, it's a well-regulated industry.
For example, all shellfish has to go
through a purification process that takes 48 hours.
It's called depuration.
And it does a great job of getting rid of bacteria.
It doesn't do such a good job of viruses
which is why we still get outbreaks.
But the point is, you're supposed to cook your shellfish
and you're supposed to cook it well.
And it's not like shellfish is the only food based vector
for the spread of viruses.
For example, hepatitis E is often spread through pork
that hasn't been cooked properly.
So you know, cook your pork property as well.
All right, thanks to the Eden Project
for commissioning these videos with funding
from the Natural Environment Research Council.
The Natural Environment Research Council also funded
Davey Jones's Viraco Project so,
thanks to them for that as well.
I hope you enjoyed this video, if you did,
don't forget to hit subscribe and I'll see you next time.
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