Avian Flu, How Flu Spreads, Anti-Flu Drugs, and how to avoid Influenza

16 October 2005


As the flu season and the threat of avian flu comes closer, Professor John Oxford from the Royal London Hospital discusses what the flu is, where flu comes from and whether drugs and vaccines can prevent human and avian influenza. Professor Pat Troop, Chief Executive of the Health Protection Agency, describes the systems in place to stop an avian flu outbreak from spreading, and Dr Paul Digard, from the Division of Virology at the University of Cambridge, tells us how the flu virus escapes through layers of mucus in the nose. Meanwhile, in the Naked Scientists laboratory this week, Dave and Derek give us the run down on why snot is useful to the body.

In this episode

How Break-ups Cause Break-outs

Could a lost love stress your skin? Researchers have found that the emotional stress of a break-up compromises the skin's ability to repair itself making it more vulnerable to damage from free radicals and causing it to age more rapidly. The study examined women aged between 21 and 45 half of whom described themselves as happy and half of whom were going through a relationship break-up. The skin of the happy women repaired itself to an average of 90% of its capacity compared to just 50% of those going through a split.

Solar Powered Handbag

Anyone who has spent ages rummaging around in their bag for their keys on a dark evening, usually in the rain, will appreciate a new self-illuminating solar-powered handbag designed by Brunel University's Rosanna Kilfedder. Powered by an internal battery, the bag's electroluminescent lining glows whenever the zip is opened, showing you what's inside, and switches off again after 15 seconds to prevent the battery going flat if the bag is left open by accident. On sunny days the external solar panels help to recharge the battery, which can also be used to run a mobile phone, or even a portable music player. Dubbed Sun Trap, the design has won backing from the Brunel Enterprise Centre and, if all goes according to plan, could be helping people locate their keys, lipsticks, and other things lurking in the bottoms of their bags, within a year.

- The Influenza Survival Kit

The Naked Scientists spoke to Chris Smith interviews Dr Paul Digard from the Division of Virology at the University of Cambridge

The Influenza Survival Kit
with Chris Smith interviews Dr Paul Digard from the Division of Virology at the University of Cambridge

Paul - 'Flu's a virus, so it grows by taking over cells in your body and turning them into factories that replicate more virus. The cells 'flu infects are found in your airway and upper respiratory tract. It infects you by you breathing it in, it gets into your lungs, replicates in them and then to get out and infect another person, you have to cough or sneeze the new viruses out, so they can be passed on.

Chris - So I breathe it in, it locks onto my cells, turns them into virus factories and I go down with it. But how does it actually get out of me, in terms of getting out of the cells that it's infected? How does it do that?

Paul - The virus factories are releasing new particles from their surface all the time. One infected cell will produce 10 000 new virus particles. The peculiar thing about flu is that it makes two sorts of virus particles. There's one sort that's very small, about one ten thousandth of a millimetre across, like a standard sized virus particle. But there's a second sort, which is a hair like structure, and we call it a filament. It's an interesting question as to why the viruses make these filaments, because the filaments are very large for a virus. These things are easily 20 to 50 times the length of a normal virus.

Chris - So what do you think they do?

Paul - it's a very good question, because if you think about the virus factory, it can produce about 10000 particles of the small size, but the amount of material needed to make one of these hair like structures is 20 to 50 times more. So that's 20 to 50 times less particles that can be made in that one infected cell.

Chris - So they must be pretty important to the cell and have quite an important job to do then.

Paul - Yes, exactly. The virus wouldn't do it without a compelling reason. And I have to say that we don't know what the reason is, but the best hypothesis we have at the moment is that it's involved in getting past the mucus layer. Your respiratory tract is lined with a mucus layer as a protective barrier against all sorts of nastiness in the outside world. This forms a coating over the cells, and it's possible that these filaments are a way of reaching past that barrier.

Chris - It's almost as though flu has it's own snot escape kit then.

Paul - Yes, the filaments can poke past this layer of snot and release virus much closer to the open air than when it's in the layer of gunk covering your nasal passage.

- Avian Flu: What Is it & Where Does it Come From?

The Naked Scientists spoke to Professor John Oxford, The Royal London Hospital

Avian Flu: What Is it & Where Does it Come From?
with Professor John Oxford, The Royal London Hospital

Chris - We've heard a little bit from Paul Digard about how flu is a virus. But could you just crystallise for us, what actually is the flu and where does it come from?

John - Well we can start with what it looks like, which is a football with lots of spikes sticking out around the outside. I like your idea of an escape kit, because the virus does have an escape kit and it needs it too. One of those spikes on the outside of the football is a mushroom shaped thing and that's called a neuraminidase, and that helps the virus chop its way through the layer of snot, as it were, and this is a very very very important layer. In fact, we put a lot of hope in this layer if the virus actually comes on the scene. The new drugs against flu, the ones we will be depending on, they're also targeted against this mushroom as well, so it's a pretty important part of the virus.

Chris - Where did it come from in the first place?

John - We think the virus came from birds and that flu actually is a bird virus. Ten or eleven thousand years ago when Cambridge still had metres of ice on it, there weren't many humans around but there were plenty of birds. A thousand years later, there were maybe 20, 30 or 40 humans here, and then from then on, viruses like influenza which need a person to person transmission, they could spread. It's at that stage that we think the virus did a leap out of birds and into humans. Ever since, the birds such as ducks and geese have been the reservoir and we have also had the virus evolving with us. That's the position we're in at the moment. The question is whether a new virus is going to jump out of the reservoir and catch us all unawares.

Chris - What stops it doing that anyway? Presumably it's because there are now two types of virus: bird types and human types that it doesn't just chop and change all the time. Why should it have a barrier?

John - Well when were you last in contact with a migrating goose or a swan?

Chris - Well I saw some fly over my house the other day.

John - Yes but did you go up and rub your nose into its beak? Probably not.

Chris - Actually no. I have to admit that I didn't.

John - Well that underlies the main problem. How does it get from one to the other? What we think happens is that the ten of thousands of geese that are currently moving around Europe get tired, they fly down onto a lake, pond or canal and they excrete virus. They are silent carriers. They don't know they're infected and they don't feel unwell. They let their waste out into the lake. Then along comes a domesticated goose or duck, it picks up the virus, doesn't get any symptoms either, passes it on to a chicken, and then the problems start.

Chris - And why is a chicken a problem?

John - We don't know that really. It could be because chickens are pressurised with the modern farming techniques.

Chris - What with having lots of them in a small space. I suppose that makes transmission very effective. But then how does it get into a person?

John - Well the hapless farmer comes along to admire his wonderful flock and notices that one or two of them are ill. A few days later, they're all dead. It's called wall to wall carpeting of feathers. He then realises what's happening. He calls in the vet who examines the beak and pokes a swab up their bottom. The vet is usually the first person to get in close, catch the virus and die.

Catherine - So we hear that flu is a problem in birds and in humans. What about other animals?

John - It's mainly this bird reservoir and humans. All other animals on this planet get flu. We know horses get it, whales get it. You name it and they have it, although obviously at the moment we are more interested in the human aspect than whales.

Chris - So why should this particular strain of bird flu be an issue? Why is it more problematic than the normal strains of flu that reach our shores?

John - Because this is an entirely new one. This has emerged from this reservoir and no-one has ever seen it before. No-one on this planet has any immunity to it. We're all relying on our snot basically, as that's all we've got, and of course these new drugs and maybe some new vaccines.

Chris - So when you say we've never seen this before you're saying that most of us, because we've come across flu in the past have a degree of underlying immunity to the virus. But because this one is so different, we have no protection. Our pre-existing exposure gives no protection.

John - Yes, we're very very vulnerable, and that's what the worry is.

Catherine - But can't they just make a vaccine for it?

John - You can stock up on antiviral drugs. The class of drugs that blocks the mushroom on the virus is a very powerful class of drugs, and I think we will be relying on those. But as for the vaccine, which will also be very important indeed, one has to make a choice. I think the choice to make is to go for the virus we've got at the moment and assume that it's not going to mutate too much. We can then make some vaccines and all relax in our beds.

Chris - Because there's some evidence that this particular strain has been in circulation for a little while before and there is a backdated or stored version of that that has been shown to be protective if it's turned into a vaccine.

John - Yes, and the most recent experiments in volunteers shows that you can get some protective immunity. You might need a lot of inactivated virus to do it, but in practice you can get something. So I think there's every reason now to press the button, make some more of this vaccine and relax a little bit.

- How To Stop The Flu Spreading

The Naked Scientists spoke to Professor Pat Troop, Chief executive of the Health Protection Agency

How To Stop The Flu Spreading
with Professor Pat Troop, Chief executive of the Health Protection Agency

Chris - So what actually is the Health Protection Agency?

Pat - We're a specialist public health organisation and our job is to help protect people against infections like flu, meningitis or food poisoning. We try to find out when it happens and mount a response with doctors and nurses, who try to stop it spreading and hopefully put and end to it. We do other things with chemical spills and other things too, but for tonight I think the infections part is most important.

Catherine - So how have you responded to this potential problem with avian flu?

Pat - The first thing we need to know is where is it and where's it got to? We work with people all over the world to find out where it is at anyone time and work out whether it is likely to affect us. We also look to see whether it's changing. Then we've got all sorts of systems I place to try and pick it up the moment it arrives. You may know something called NHS Direct where people can phone up and ask for help from nurses who are on the other end of the phone. We analyse the information that goes there every day and pick up how many people are phoning in with coughs or colds every day.

Chris - But what about actually getting samples of the virus?

Pat - We can do that as well. We have samples of the virus at the moment and what we've done is work out how to test for it. In our laboratories, we've being doing tests on it so that if we have any samples, we can check to see if it's the same one and know if it's going to spread badly. So we know how many people are getting ill, and which viruses are there, so we can all swing into action.

Chris - You also just look for general flu anyway don't you?

Pat - Yes, we keep that going all the time. We keep all sorts of systems through the GPs, through the labs, through the people, so we know all the time what's going on and then tell doctors and nurses how to cope with it.

Catherine - How can you control for migratory birds and integrate that in to find out what's going on?

Pat - That's much more difficult. The vets do look for things, and monitor what's happening with large chicken flocks. But there's also a big survey on wild geese coming over at the moment and checking how many are infected and how many are getting ill with it. They're getting birdwatchers out there to keep an eye out too. There are lots of migrating birds on the east coast, and we're asking people to keep an eye out for any that might have the flu.

Chris - So if we detected a case tomorrow in the UK, what would get put into action?

Pat - We'd first of all check that it is the flu and that it's the right one. We would then find out who they'd also been in contact with to see who else might have the flu and we can try and contain it in a very small area. Once you've got an infection like this, the most important thing is to stop it spreading. You encourage people to stay at home if they have flu, put your hand over your mouth when you cough, wash your hands, and all the basic kinds of things you're told to do. We also have some antiviral drugs for people who are likely to be very ill with the disease. As you've already heard, we haven't yet got a vaccine for this, So all that hygiene stuff, keeping away from other people and taking some drugs is all we have at the moment.

Chris - Will you do things like closing large sporting events and stop lots of people congregating together?

Pat - It might happen. In the early stages we wouldn't do that, because we'd hope that we'd be picking up the early spread. But if it started to spread very widely, we might have to say don't congregate in large groups, as all you'll do is spread it further.

Catherine - At what point are people most infectious?

Pat - Well John is more of an expert on this than me, but I think you can be infectious as soon as you've been in contact can't you?

John - Yes, well within 24 hours anyway.

Pat - So you don't always feel ill before you start passing it on. This is part of the problem with flu, and one of the reasons it spreads so quickly.

- What causes your feet to stink?

I've always wondered what causes your feet to stink. Is it from your feet sweating, or do other things come into play?

What causes your feet to stink?

It may shock some people, but your feet actually squirt about half a litre of sweat into your socks and shoes every single day. You also shed in the order of about 40 000 skin cells every minute or so from your body. Over a lifetime that adds up to a few stones in weight of dead skin. Now this is perfect bacterial food, so you have a combination of a warm, damp place with lots of food. This makes your feet a thriving emporium of bacteria and fungi. When these eat the skin in your shoes, they produce volatile substances that smell. It's these substances that come whiffing up to your nose. People who wear trainers a lot end up locking their feet in and let them stew. The way around it is either to use odour eaters or wear sandals, as this lets your feet ventilate. Alternatively, you can wear leather shoes, as this helps your feet breathe more naturally.

- Does holding your breath affect susceptibility to electric shocks?

I'm in contention with someone at work, who is saying something that I don't believe is true. He maintains that if you hold your breath, ...

Does holding your breath affect susceptibility to electric shocks?

The reality is that if you take a deep breath, the only things it's going to do is affect the volume of your lungs, and affect your blood pressure and heart rate. When you take a deep breath in, it triggers a reflex that makes your heart rate go up a little bit, but that's about all. It won't affect anything to do with your bones and it certainly won't affect whether you can tolerate being electrocuted. If you put your fingers anywhere near mains electricity, you have a very real chance of being killed. You must tell this person to stop spreading silly rumours, because he's going to get someone killed at some point.

- When you let the water out of the bath, why does the water spiral down the plug hole?

When you let the water out of the bath, why does the water spiral down the plug hole?

When you let the water out of the bath, why does the water spiral down the plug hole?

The shape of the plug has something to do with it, because you get a kind of whirlpool effect. The size of the whirlpool is affected by the size of the the plug hole. Some people believe that the direction of the whirlpool is down to the Coriolis Effect, the conservation of angular momentum which applies to moving things - like air and fluids - as the Earth turns in space. But simple calculations show that actually the Coriolis force is too small to account for the direction that water goes down the plughole, so the whirlpool produced when the plug comes out must be a product of the shape of the sink and the drain hole.

- What's the difference between an epidemic and a pandemic?

What's the difference between an epidemic and a pandemic?

What's the difference between an epidemic and a pandemic?

We really shouldn't be using the word pandemic. It basically means a global outbreak. Really, flu is the only one that is pandemic. It can start anywhere and can sweep around the world. An epidemic can mean an outbreak in Norfolk and then maybe spreading to London but not going too far into Europe. So an epidemic is usually restricted, but a pandemic sweeps the whole world.

Why do we cough up phlegm?

Actually, not a lot of people do. Most of the phlegm that you produce ends up in your stomach. On the way to your lungs, all of your airways are lined with a sticky substance called mucus. It's there to mop up things like bacteria, viruses and particles of dust and dirt from the air. The linings of your lungs have tiny thread-like projections on their that beat. They all beat in the same direction which creates a current which pushes the mucus out of your lungs and up to your throat. Now if you get a lot of mucus, sometimes you cough and it can come flying out of your mouth. But most of it goes down into your stomach. That's very important, because as it has all the nasty things you've breathed in locked up in it. These are carried down into your stomach where stomach acid kills all the bugs. What's left then goes into your intestines. In the walls of your intestines the dead bugs and dirt meet special patches called Peyer's patches, and that's where your immune system learns what's doing the rounds in the air around you, what sorts of things it has to mount an attack against, and what sorts of things it has to ignore. So normally you swallow most of your phlegm, but if you have excess production, coughing it up helps to get rid of it.

- What's the longest period someone has had the flu for?

What's the longest period someone has had the flu for?

What's the longest period someone has had the flu for?

It's something like three or four days. In someone your age Lydia, it would probably be four or five days. But we've known people who've had it much longer, maybe even eight, nine or ten days. That's really bad luck though!

- Why do you sneeze when you look at the Sun?

Why do you sneeze when you look at the Sun?

Why do you sneeze when you look at the Sun?

This is a reflex called the photic sneeze reflex and no-one's exactly sure what underlies it. We know that it's genetic and is passed on in families. About one person in four or one person in five is affected. People used to think that when you looked at the Sun, the bright light made your eyes water, the water ran down into your nose, tickled your nose and made you sneeze. This is not true because it happens too fast. What scientists think is that there's some sort of crossed wiring in the back of the brain where the size of your pupil is controlled, and that's what causes that to happen.

- During infection, does the amount of virus in you determine how ill you feel?

Does the number of virus particles you have in your body affect the severity or duration of an illness?

During infection, does the amount of virus in you determine how ill you feel?

I think that answer is that the fewer virus particles you have in your nose at one time, the longer the incubation period is likely to be. So it will be the same severity, but it will take longer to get to that point.

- Could your skeleton cope with the gravity on Jupiter?

You said earlier that you would weigh 13 tonnes if you lived on Jupiter. Would your bones be able to withstand that, or would you end up ...

Could your skeleton cope with the gravity on Jupiter?

Standing on Jupiter would be like having a bus standing on your head, as you'd weigh so much. So the bones in your feet which are set up to withstand 50 kg of weight pushing through them, would now have to withstand 13 tonnes. I don't think even the nest hip replacement would be able to withstand that kind of load. So you would be as flat as a pancake.

- Are flu vaccines contraindicated if you have egg allergy?

My wife has had a letter from the doctor about a flu jab. But it also - that if she has an egg allergy, she's not to attend. Why?

Are flu vaccines contraindicated if you have egg allergy?

This is because the flu vaccine is grown in eggs, so there will be a smidgen of contaminating egg in the final vaccine. If she's allergic, she might get a reaction so it's best not to go along.


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