Avian Flu, Viruses, Bed Bugs and Murder

27 March 2005
Presented by Chris Smith, Kat Arney


In this show Tim Wreghitt spreads the word on the threat of avian flu, viruses and why we keep catching the common cold, Ian Burgess is itching to talk about bed bugs, lice, fleas, and how to get rid of them, and John Emsley talks about the chemistry of poisoning and his book Elements of Murder. Anna Lacey asks Graham Wynn why conservation is so important, and Philippa Law demystifies the science behind how smoke detectors work.

In this episode

Move Over Alistair Mcgowan

Known more for their ability to uproot trees and spray water out of their trunks, scientists have discovered that elephants may have another hidden talent - doing impressions. Researchers studied sounds made by two African elephants, one living among orphaned elephants on a reserve and the other with two Asian elephants in a zoo. They found that one imitated rumbling trucks, the other imitated other elephants. For example, Mlaika, is a ten-year-old female African elephant living in Kenya among a group of orphans. They found she could imitate the noises she heard from trucks on a road nearly two miles away. Her imitations of the trucks sounded just like recorded truck sounds and nothing like normal calls of African elephants. When the scientists analysed the sounds, they found that Mlaika's truck impressions were near-perfect audio matches. The researchers also studied Calimero, an African elephant who lived for 18 years with two Asian elephants in a Swiss zoo. They found that Calimero could do perfect impersonations of his Asian zoo-mates, who make chirping calls that are completely different from the usual African elephant sounds. The scientists think that the ability to do impressions could help animals to communicate, or develop new ways of communicating. But I doubt we'll be seeing an elephant impression show on TV any time soon - I've heard they do a rubbish Tommy Cooper.

Foiling Criminals With New X-ray Fluorescence Fingerprinting

Scientists from the US are giving a helping hand to forensics with a new technology that detects otherwise invisible fingerprints. Traditional fingerprinting methods involve adding dust or liquid that sticks to greasy prints. The pattern revealed can then be used to catch the criminal. But there are problems with this method, including difficulties with spotting fingerprints on wood, leather, plastic and those belonging to children. The new method uses Micro-X-Ray Fluorescence (MXRF), which can detect fingerprints by the salts found in sweat, such as sodium chloride and potassium chloride. When a person touches something, the pattern of salts they leave behind matches the pattern of ridges on the finger, and so makes the invisible visible. By gathering details about the salts in a fingerprint, scientists can even discover if a person was handling explosives, which would be signalled by high levels of potassium. The technique is designed to be used alongside traditional methods and should be ready for commercial use in two to five years.

- The Importance of Conservation

The Naked Scientists spoke to Anna Lacey interviews the Chief Executive of the RSPB, Graham Wynn

The Importance of Conservation
with Anna Lacey interviews the Chief Executive of the RSPB, Graham Wynn

Anna - In one sentence, why is conservation important?

Graham - We need clean water, we need clean air, we need seas that are well managed for fisheries, and we need to look after wildlife in all its forms, be it birds, or mammals or whatever.

Anna - In the UK and other developed countries, a lot of conservation seems to be setting up parks and setting up reserves that keep people out. In the developing world, people need access to these resources for their livelihood. Do you think we can have conservation in these areas as well as letting people exploit resources for their own economic benefit?

Graham - Yes, I don't think this is either / or. I don't think we need to use every square inch of any country for direct economic exploitation. If we did, then that would damage the economies of those countries. Developing countries need rainforests. They need them for soil protection and to prevent floods. If they look after them, there is the possibility to take timber out of them in what we call a sustainable way so that there's more timber to take out next year. And a lot of these places can be very attractive to tourists and generate money for the local economy in that way.

Anna - Because there isn't a lot of money in the places we want to conserve, it seems that the richer countries are going to have to pay for it.

Graham - Well first of all we have to convince our governments that it's in their economic interest as well to look after the world's environment, not just in the interest of whichever country we're operating in. The ecosystem works at a global level. If we just take the climate change issue, destroying rainforest on the other side of the earth is going to have a big economic and environmental impact back here, for example, in the UK. So we've got to convince politicians that it makes sense to pay more to look after the environment right around the world. I think part of the problem is that conservationists themselves haven't communicated the brilliance and beauty of what is being lost as well as its economic value. So I think that governments have got to pay more. I suspect that if we asked the average person they would contribute as well.

Anna - What type of thing can people do right here in the UK?

Graham - They can join a good conservation organisation like the RSPB - sorry for the cheap plug! But they probably do need to help conservation organisations to save the countryside. This isn't so we can keep people out. If you take some of the reserves in East Anglia like Minsmere on the Suffolk coast or Titchwell on the Norfolk coast, each of them has over 100 000 visitors each year. They're fabulous places to go for a day out. This isn't keeping people out. This is just managing beautiful parts of the coast so that they can support wildlife and lovely landscapes as well as give people enjoyment.

- How Smoke Detectors Work

The Naked Scientists spoke to Philippa Law interviews Dr Lucy Green & Dr Bill O'Neill

How Smoke Detectors Work
with Philippa Law interviews Dr Lucy Green & Dr Bill O'Neill

Philippa - Smoke alarms save loads of people's lives every year, and this week I've been finding out how they work.

Lucy - Hi, I'm Lucy Green from Cardiff University. There are two different kinds of smoke detectors. The first one is called an ionisation detector. This uses a radioactive source within your smoke detector, although it is very very small.

Philippa - Let's speak to Bill O'Neill from the Institute of Manufacturing at Cambridge University.

Bill - The chamber itself is quite simple. It consists of two metal plates with a voltage across them, which we apply with a battery along with a source of ionising radiation. The Americium-241 sits under one of the plates and it emits alpha particles. Alpha particles have the following properties: they essentially ionise the nitrogen and oxygen atoms that are sitting in the chamber. Ionise in this case means that it knocks an electron off an atom so you end up with a free electron and positive ions. What happens is that the negative electron is attracted to the plate with a positive charge, and the positive atoms are attracted to the plate with a negative voltage. Essentially the electronics in the smoke detector sense these small amounts of electrical current that these electrons and ions generate as they move towards their plates.

Philippa - But what happens when smoke gets into your chamber?

Lucy - Well the smoke actually attaches itself to the ions and it stops the current from flowing.

Bill - The smoke detector sees this drop of current between the plates and sets off the alarm.

Philippa - That makes sense, but what's this about radioactive material in them? Surely that's dangerous?

Bill - No. Whenever you hear the words 'nuclear radiation' it sets off alarms in people's minds anyway. But if you think about the amount of radiation in a smoke detector, it's extremely small. It's predominantly alpha radiation, which can't even penetrate a piece of paper, let alone damage anyone sitting beneath it.

Philippa - That doesn't sound so bad. Now, does Einstein have anything to do with all this?

Bill - His work on the wave duality of photons and the equivalence principle of energy and mass allowed people like Ernest Rutherford to develop his work on the alpha particle and Thomson on the electron. So many of the early atomic physicists were really working in the dark and Einstein helped illuminate their environment slightly.

Philippa - Ionising smoke detectors are the cheapest and most reliable smoke detectors you can get. But there's another kind too.

Lucy - The second kind of smoke detector is called the photoelectric detector.

Philippa - Ah, photoelectric, like the photoelectric effect!

Lucy - That's right. This is using the theories Einstein laid down for us. In this kind of detector, you use a light emitter and a light receiver. When you have your light receiver we know from the photoelectric effect that when photons fall onto your receiver you can generate a current. So in your photoelectric detector you have a beam of light and when the light falls onto a surface you have a current generated. But what happens when smoke gets into the chamber? Well it can move in front of the beam of light and stop it form getting to your detector. The current is broken again and the alarm goes off.

Philippa - Since 1992, all new homes have been fitted with interlinked smoke detectors, which means that if one alarms goes off, then that sends a signal to other alarms in the house and they all go off too. Building on that technology, there's now a company in Kent who have invented a new system of smoke alarms that signal to each other via the mains electricity in the home. That means that not only do you not have to fit a whole load of new wires in your house to get one of these safer systems, but also the smoke detectors can actually turn off your electricity. So say if the toaster is puffing out lots of smoke and is about to catch fire, the detectors detect the smoke and switch the toaster off so it can't get any hotter and start a fire. Just like the other things we've heard about in the last few weeks (the CD player, the calculator, the remote control) the technology in smoke detectors may not have been invented so soon, or in the same way, were it not for Einstein and the work he was doing 100 years ago. So as you're listening to your CDs or changing channels on the TV, just remember that Einstein isn't only famous for his silly hair. He's had a tangible influence on all our lives.

- Viruses, Avian Flu, Why We Keep Catching The Common Cold

The Naked Scientists spoke to Dr Tim Wreghitt, Addenbrookes Hospital

Viruses, Avian Flu, Why We Keep Catching The Common Cold
with Dr Tim Wreghitt, Addenbrookes Hospital

Chris - Now tell us a bit about the Chelsea Flower Show, your more light - hearted reason for coming.

Tim - I've been involved with the Chelsea Flower Show for three years, and it's been in connection with the Royal College of Pathologists because we've been trying to tell people what pathologists do. Chris here is a pathologist too! What we want to do is try and tell the public more about science. Last year we did a presentation on allergy, and we had a large stand about what allergies are and how you can diagnose them. On the lines of the Chelsea Flower Show, we also did a section on which flowers are bad for you if you have respiratory allergy, from pollen in particular, and those you can choose that don't have pollen. This year we're doing plants that give rise to drugs that treat diseases.

Chris - Nature's medicine chest is absolutely huge isn't it? Of the top ten drugs that are prescribed on a daily basis, 30 - 40% are derived from plants. Aspirin is a good example, although it has been modified from salicyn, which comes from willow trees. People are now even turning to the seas to see if there are interesting compounds harboured by corals, sponges and sea squirts. When will you be strutting your stuff at Chelsea?

Tim - It's the last week in May, so come along!

Chris - Your actual job isn't being at the Chelsea Flower Show. You are actually a virologist, and tackle people with various infections. Why do colds come back year on year, and why don't we become immune to them?

Tim - One of the problems is that there are so many viruses and other organisms that can cause colds. For example, if you're talking about entroviruses, there are 80 of them. Throughout your life, you may catch one one year and you've got another 79 to go at! When you have young children, you pick up lots of viruses. When they change schools, you pick up a lot more viruses. And equally there are some infections, like mycoplasmas for example, where you only have immunity for six years, so you can have several bouts of the same infection throughout your life. So kids are like virus factories! The other difficulty about children is that they often cough out more viruses than adults. SO often, for example with influenza, you find that influenza epidemics are driven by children in the family, and it is these families that are often drivers of the epidemic.

Chris - Why is it that these viruses come in runs at certain times of year? Why do they have a season, like 'flu always seems to come in winter?

Tim - I'm not sure I know the answer to that Chris, I'm not sure if you do. What's even more interesting is that if you take viruses like parainfluenza viruses, there are three major types, and two of them come in the winter, one of them comes in the summer. It has monotonous regularity. I'm not sure why though.

Chris - The only thing that jumps to mind, although it doesn't fit your rule for the summer is that in winter time everyone shoves themselves indoors, close the windows and congregate in a single warm room. This would probably increase the chance of spreading disease around.

Tim - We've also seen a huge epidemic of mumps recently, especially in students. That's because, especially in males between the ages of 16 and 20, they weren't given boosters of vaccine that many girls were in the catch up campaign. We do have a problem in this country of immunity rates for measles, mumps and rubella, and it's my view that the MMR vaccine is safe and there's a lot of unfortunate information that has been given out. I think that we will be having more outbreaks of these infections if the immunity level falls below a certain percentage.

Chris - We mentioned a study in Japan when Simon Baron-Cohen was here last week to talk about autism, which was one of the things that triggered people to stop having the MMR. 30 000 people were followed up who didn't have the MMR, and the rates of autism in those 30 000 people was higher than those who did have the MMR. So it's interesting to see that the people who don't have the vaccine have a higher rate of autism. It just looks like we're better at finding it.

Tim - I think so, and I also think that there's been a lot of confusing information. I don't blame people for thinking there may be a problem with MMR because of all the publicity it's been given. But there really has been no good evidence associated with this, and I speak as someone with a vested interest. My twin sister died of measles, so I have every reason to try my best to make sure that people are immune to it. It's a very serious disease. I think people have forgotten how severe these diseases are because they are not causing a lot of problems now. I think it's easy to forget that they are still there with the potential to cause problems.

Kat - What are the kind of effects that you can get from measles, mumps and rubella?

Tim - Mumps is the old English word for moping, 'to be mumpy'. It makes you miserable, as does measles. The thing that everyone highlights on is sterility in males, but also in females. It affects the reproductive glands and makes you generally unwell. With measles, the biggest problem is encephalitis, which will kill one person in a thousand. This is a swelling of the brain. If measles gets into the brain, it swells and gets particularly badly affected. You are either left with someone with severe brain damage or it can kill you. People have forgotten this.

Kat - What about rubella? That can affect pregnant women, can't it?

Tim - Rubella is entirely different because rubella is actually quite a mild disease. Rubella vaccine is, I believe, the only vaccine we give to people not to protect the individual but to protect their unborn child. Rubella causes problems in the unborn child such as brain damage, blindness and deafness. It's for that reason that people are vaccinated.

Chris - Tell us about avian flu, as we've had a number of emails from people in the past who are asking what's going on in the Far East, and are we brewing up another pandemic? Indeed, what is a pandemic and what is avian flu as compared with normal flu?

Tim - Over the centuries we know that there have been periodic waves of influenza. Most of the severe outbreaks of influenza which occur every 10, 20 or 30 years are because a new virus has emerged, usually from the Far East. What happens is that the flu virus that is going around in chickens and birds will recombine with a virus in humans. Once that virus that's living among chickens spreads to humans, and more importantly on from humans to other humans, then you have the potential for an outbreak. What we do have is a very sophisticated system throughout the world where people are looking out for these viruses, whether they have changed and whether there is any human to human transmission. Once that happens, all the red buttons are pressed. People are working very hard to produce diagnostic tests and vaccines and so on.

- When The Bed Bugs Bite... & How To Get Rid of Them

The Naked Scientists spoke to Dr Ian Burgess, Insect Research & Development Ltd.

When The Bed Bugs Bite... & How To Get Rid of Them
with Dr Ian Burgess, Insect Research & Development Ltd.

Chris - Let's talk about bed bugs. They're on the rise.

Ian - They've been increasing over the last ten years, and maybe even before that. In the 1950s and 60s we knocked them very hard with DDT, the insecticide everyone loves to hate. We then forgot about them, even though there were little enclaves of them all around the country. Since then, they've been spreading. Because they were treated so much with DDT, a lot of them had some level of resistance. Some of the pesticides we use now have a very similar action to DDT, and so what's happened is that they've used this resistance to repel the pesticides that are in use now, and so we can't kill them so easily.

Chris - How many bugs do you find in the average bed?

Ian - Well in the average bed, probably none! We mustn't confuse bed bugs with house dust mites, which you often find in the popular press. Bed bugs are big things, and for anyone who wants to know what they look like, they are as big as the zero on the old fifty pence piece, up to six millimetres long in some cases. They suck blood while you're sleeping.

Chris - How do you know if you've got bed bugs?

Ian - You find things that you think might be mosquito bites on you. Some people actually show very little reaction, but some people react so badly as to get secondary infections.

Chris - How do you get rid of them?

Ian - You have to call in a professional pest controller because you can't deal with fly sprays and the likes. They live in the walls, the bed frame and the skirting board, so they are not easy to get rid of. It's a structural problem, and in the old days people had to strip off the plaster, take up the floorboards and go around the whole house with a blowtorch.

- Elements of Murder

The Naked Scientists spoke to Dr John Emsley, Bedfordshire

Elements of Murder
with Dr John Emsley, Bedfordshire

Chris - Elements of Murder is the title of your new book. How did you pick on that? It's a bit macabre isn't it?!

John - It is, and it's all about the dark side of the periodic table. I'm a chemist and of course there are elements in the periodic table like arsenic, lead and mercury which are very toxic, and so the book is basically about them. I spice the stories up by including lots of true crime situations. We're now in a position where we can look back 100 years to the Victorian times and the golden ages of poisoning and understand what they were doing. At the time, of course, it was a bit obscure. In fact you couldn't always detect the poison that was being used. For some poisons that was true up to fairly recently.

Chris - Rat poison was popular wasn't it.

John - Yes, that was a phosphorus compound. I remember as a child something called Phosphine that you put down and the rats came and ate it. They would then die.

Chris - In your other book 'The Shocking History of Phosphorus' you said that the best way to tell if someone had phosphor poisoning was to cut them open at the post-mortem and switch off the light.

John - Yes, because elemental phosphorus does in fact glow in the dark, that was the way of doing it. It wasn't a particularly good poison because you could disguise it. It has a particularly strong taste of garlic. The most famous poisoning was a woman in Blackpool. She actually mixed it with rum and murdered her landlady, who was very fond of rum. You could also disguise it by putting it into HP sauce! However, you can't get phosphorus now: it's almost impossible to get it for research as it's too dangerous to transport. There are poisons that are more subtle. Saddam Hussein's favourite poison was thalium. Thalium was the poison of Graham Young, who murdered his work mates about 20 or 30 years ago. Thalium is a good poison because the symptoms are delayed. The most characteristic symptom if you manage to survive is that all your hair falls out. However, if you're given a large enough dose, you die about a week afterwards before any of your hair falls out. We know that some of Saddam's agents came to Britain and poisoned people with thalium. That was in the 1980s, but nowadays it is really difficult to poison people because forensic science is so sophisticated that if poisoning is suspected, then chemists in forensic laboratories will be able to tell what it is. With thalium it is even possible to detect it in cremated remains, and Young's victims were found to be poisoned by that method.

Kat - Was Napoleon killed by the arsenic in his wallpaper?

John - The answer to that is no. He may have been affected by it but I don't think we can claim that he was poisoned to death by it.

Chris - You said that bed bugs weren't as much as a problem in Victorian times because of wallpaper.

John - Once Victorians took to wallpaper, and they were very fond of green flowery wallpaper, which used copper arsenite, that gave off arsine which was a gas that actually killed people. Bed bugs were quickly mopped up by it.

- Why does water go up your nose but not into your ears while swimming?

When I was at school, they taught us that your ears, your nose and your throat were all connected. Why is it that when you jump in the sw...

Why does water go up your nose but not into your ears while swimming?

The ears are indeed connected to the back of your throat by a very narrow tube called the Eustachian tube. It goes from the area just behind your nose, so where the nose joins the back of your mouth, out to your ears. But it goes to the bit of your ear on the inside of your ear drum, not on the outside. The outside of your ear canal, the bit where you can stick your finger in and wiggle it up and down, that ends in your ear drum. This forms a solid layer which separates your external auditory canal, which is the bit you put your finger in, from the inside of your ear. That means that there is no way for water to get in there at all. If you do get water in your ears, it's because some water has got up your nose and trickled down this very fine Eustachian tube and got into your ear. You might then want to know why your ears go pop when you go up in an aeroplane. The reason for that is because the Eustachian tube is quite narrow, the pressure pushing on the outside of your ear compresses the air on the inside of your ear by squashing the ear drum. The idea of the Eustachian tube is to let it equilibrate. If you have a cold or a nasty infection in the sinuses, it can block off the Eustachian tube with some mucus. That mucus can stop the air pressure equilibrating, and that's why you have that funny popping sensation. You can equalise it if you hold your nose and blow hard against it. This forces air into your ear and helps to equalise the pressure. But there is no connection between the outside world across your ear drum.

Entombment of Christ, 1672, in Saint-Martin Church in Arc-en-Barrois (Haute-Marne, France).

- When you yawn, why do your eyes water?

When you yawn, why do your eyes water? Is it normal?

When you yawn, why do your eyes water?

Yes, it is. Part of the reason is that when you yawn, you squeeze your eyes tightly shut. The way that tears flow is that they come out of your lacrimal gland, which is on the upper outer side of the top of your eye; they then flow - in a film - across your eye obliquely downwards and inwards. The tiny black dot on your lower eyelid is called a punctum, and that's where your tear duct starts and where the tears drain away. But if you squeeze your eyelids tightly shut, you close off the punctum, stopping the tears flowing across your eye and into the tear duct, so they build up in the eye. This makes you cry a little bit, which is why tears appear when you yawn.

- Are bugs that bite the way in which most diseases including HIV are spread?

Are bugs that bite the way in which most diseases including HIV are spread?

Are bugs that bite the way in which most diseases including HIV are spread?

Actually very few diseases are transmitted by insects and their relatives. But when it comes to the impact overall, they're perhaps just as good at transmitting diseases as people coughing and sneezing. If you look at the number of cases of malaria each year, and we're talking about tens of millions, we get about two million people die of malaria each year in sub-Saharan Africa. The population at risk is several hundreds of millions, so the chances of getting a disease from an insect are much higher in certain parts of the world, even though the variety is very small. To be a virus transmitted by an insect, you have to be a very special type of creature in that you have to be able to survive going into the insect's gut and pass through into its blood and travel to the salivary glands. It then has to survive transferring back into the human. HIV just can't do that, but malaria can.

- What's the life-cycle of a human head louse?

I found head lice on an elderly lady I was looking after and used a special shampoo that the doctor told me to use. But it didn't kill th...

What's the life-cycle of a human head louse?

The life cycle of the louse is very distinct and discreet in that the eggs take seven days to hatch, and that's almost invariable. Up until that time, you're not going to get rid of all the little ones that are going to hatch out. But it takes them nearly ten days to become adults, and so therefore they can't lay any eggs until they've reached that point. In between those two points, you have a stage where the lice won't move into anybody else. While they're half-grown, they stay put. It's only when they get to about 6 or seven days old that they start getting interested in moving house. From then on, they'll start shifting onto somebody else. Your lady wouldn't have been infectious if she only had baby ones on her.

- Why do you close your eyes when you sneeze?

Why do you close your eyes when you sneeze?

Why do you close your eyes when you sneeze?

The reason is that it's just a reflex. Because your body has to generate a huge rush of air to make you sneeze, everything clenches up tight to make you go atchoo!, and blow air out of all the right holes to clear the mucus. Part of that is to blow air the wrong way up your tear ducts, which is why your eyes water when you sneeze. You do screw up all your muscles to make sure you don't hurt your eyes, so it is sort of protective. Contrary to myth your eyeballs won't pop out if you sneeze with your eyes open.

- Have chickenpox parties gone out of fashion?

When she was younger, she went to chicken pox and mumps parties to spread the illness and build up her immune system. Why don't parents d...

Have chickenpox parties gone out of fashion?

When I was young this was a very common practice, however, chicken pox can actually be a very dangerous disease, in pregnant women in particular. If they haven't had chicken pox and get it early in pregnancy, it can cause problems in the baby, so they need to see a GP very quickly. Equally if adults get chicken pox, again, there's a much higher rate of complications with swelling of the brain and pneumonia. Every year in Cambridge we have one or two people who die from chicken pox. It's more serious than people think. So it's not really that great to get it, even if you're young because you can always pass it onto someone else, who might be pregnant or older. The next thing coming along is a chicken pox vaccine, which may well be in use in a few years time.

Can animal fleas live on humans?

Only cat fleas. Some rodent fleas will bite us but won't actually survive to lay eggs.


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