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

The Naked Scientists spoke to Dr Tim Wreghitt, Addenbrookes Hospital
27 March 2005

Interview 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.


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