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BRITISH BROADCASTING CORPORATION
RADIO SCIENCE UNIT
CASE NOTES
Programme no. 4. - Insects
RADIO 4
TX DATE: TUESDAY 20TH JANUARY 2009 2100-2130
PRESENTER: MARK PORTER
REPORTER: ANNA LACEY
CONTRIBUTORS: ELIZABETH BRUNTON
STELLA HUYSHE SHIRES
IAN BURGESS
URIEL BOWEN
ANDY HOOD
PRODUCER:听HELEN SHARP听
NOT CHECKED AS BROADCAST
PORTER
Today's programme is all about insects that can injure our health. A subject dear to the hearts of the team at the Medical Entomology Centre in Cambridge, whose brief ranges from testing the effectiveness of pesticides and repellents, to identifying spiders found in bunches of bananas by shoppers. I am afraid it's not an urban myth.
Entomologist Elizabeth Brunton is Deputy Director of the Centre.
Elizabeth, we've got a selection of some of the things that you come across in your day-to-day work, some more easily identifiable than others. I'm looking here at this - is that a tarantula?
BRUNTON
It is a tarantula yes.
PORTER
I mean it's big, it's the size of a saucer nearly isn't it.
BRUNTON
They get much bigger - you can have the size of a dinner plate.
PORTER
I don't really want to know that. Presumably they don't cause you a lot of trouble?
BRUNTON
Not much no. Biting is the last thing they'll do and even then it's like a bee sting, so it's nothing much to worry about.
PORTER
Presumably most of the things here - looking at them - I mean are much, much, much smaller.
BRUNTON
Yes they are, I mean you might think that the big things are quite fearful and dangerous but actually it's the smaller ones that are going to cause you more trouble. You're not going to see them and they carry much more deadly diseases.
PORTER
And some of these are so small you can barely see them, I mean what have we got here?
BRUNTON
Yeah, this is a flea, it's called tunga penetrans and it's about a millimetre big and what the female does is she burrows up into the sole of your feet or what you're sitting - you know we've had people with them on their backsides where they've sat in the sand. And then she burrows in, she takes blood from you and as she grows and swells inside your foot she develops her eggs and then she just spits her out and then she dies. But she can leave with you with an ulcerating wound.
PORTER
Full of eggs.
BRUNTON
Full of eggs.
PORTER
What happens when they hatch then?
BRUNTON
They just come out and they go back into the floor and start their larval stage.
PORTER
And where does this one live?
BRUNTON
It's found in the Tropics.
PORTER
In the Tropics, so that's alright.
BRUNTON
But if you're going out somewhere lovely, you know - Mauritius, Maldives, whatever - where sandals.
PORTER
And here we've got some sort of beetle?
BRUNTON
No it's a cockroach.
PORTER
Oh right, and the difference between a cockroach and a beetle is?
BRUNTON
Do you want me to tell you?
PORTER
Yes.
BRUNTON
Beetles have a hard elytra so the wing cases are hardened on the back or as these are soft so they can fly, both of them come out to fly - they have two sets of wings.
PORTER
So these - if you've got them in your home - they're living where?
BRUNTON
Well the German cockroaches will live in your kitchen area but your Americans and your Australians and Orientals - which are bigger, much bigger - will be found in your drains.
PORTER
But we get them over here?
BRUNTON
We get them over here yes, yes. There's a lot of the problem with cockroaches.
PORTER
So they then carry - can carry disease and if they're walking all over your work surfaces they could spread ...
BRUNTON
They can spread E.Coli, salmonella, food poisoning - yeah - they're thoroughly unpleasant and as soon as you've seen one go and get a pest control expert.
PORTER
And that's why there's such a big fuss made about them in commercial kitchens as well.
BRUNTON
Oh gosh yeah, we find these get sent to us found in food that's been commercially prepared because this is part of what we do and it's one of the things that we often get. It's not pleasant.
PORTER
And they're quite hardy things as well, are they easy to get rid of?
BRUNTON
You can stand on them but ...
PORTER
Not if you've got ten thousands you can't.
BRUNTON
No, no you can't, no. They are quite hard to get rid of yes. There are baits that you can give that they then take back, they'll ingest it, they'll take it back to the nest and then when they die, because of the nature of cockroaches, they will then eat the cockroach that's died, because they're scavengers, and then they get the bait again and then they will die and it will slowly destroy the nest.
PORTER
But once again just treating around your kitchen area is not going to help because you're just killing the ones that are venturing out that day.
BRUNTON
Exactly yes, they've got to go back to the nest.
PORTER
We'll come back to the insects in our homes later on, but first something that lives on moors, parks and woodland in many parts of the UK - the Lyme disease carrying deer tick. Lyme disease is a potentially serious, but normally treatable infection, caused by Borrelia bacteria spread through tick bites. There are around a thousand confirmed cases every year in the UK, but this probably represents the tip of a much larger iceberg as the condition is often missed. Stella Huyshe Shires lives in a part of rural Devon that's full of deer - and their ticks.
HUYSHE SHIRES
Well I had a tick bite in 1999, late in the summer. I didn't notice the rash myself and I don't recall now any other symptoms but my husband happened to notice the rash, which was more or less on the back of my hip.
PORTER
What did it look like?
HUYSHE SHIRES
It was a circle, by the time we noticed it, it was probably about 15 centimetres diameter, clear in the middle and a red ring. It just got gradually bigger and bigger and eventually I went to the doctor who said yes, very interesting, don't know what it is, have some steroid cream and come back if it doesn't go.
PORTER
And had you mentioned the tick bite at that stage or did you not realise the significance of that?
HUYSHE SHIRES
No I didn't realise the significance, there was nothing obvious in the centre, the bite had probably been some weeks before that, I would guess, from the size of the rash. So I didn't relate it to the tick bite and so I didn't mention a tick bite to the doctor.
PORTER
So then what happened?
HUYSHE SHIRES
I went away, it got better, the rash disappeared eventually, I didn't think anymore about it. I gradually got lots of other little symptoms - upper back pain, I lost about a stone in weight, I had distorted hearing, sudden hearing loss, palpitations, sight disturbances, numbness on my face, joint pain, sleep disturbances - lots of little things which tended to come and then go, so by the time I thought of maybe going to the doctor because this was getting a problem it then disappeared and something else happened. So some things I mentioned to the doctor but not very many of them. And then three years later I happened to read a letter in a local agricultural journal saying we should do something about deer in east Devon because of the problems it causes with Lyme disease and I noticed the range of symptoms and my husband said - do you remember that rash you had? So I went back to the doctor and said look, how about this, could this explain my problems, could I have a blood test please? So he gave me a blood test and it came back positive.
BRUNTON
Right what we've got here is a female tick.
PORTER
Large.
BRUNTON
It's very large because it's engorged.
PORTER
Yeah, so this is a scaled up model and it's ....
BRUNTON
Yes it is.
PORTER
... and I think a lot of people will have seen ticks on their animals and things, I mean that's what you might see isn't it - tiny head.
BRUNTON
They look like a broad bean with a little head on the end, so you can see the mouth parts.
PORTER
And what's inside that broad bean? That's engorged because it's been feeding.
BRUNTON
It's engorged - it's got blood in it yes, she's had a good feed on someone. And they take a long time to feed. So they can take a matter of days to get this size because as they're feeding what they're building is chitin which is their outer body, so that's how they grow in size. So she might come in at, I don't know, two or three millimetres big and then as she feeds she could then be four, five millimetres when she's finished and that's her new body, you see.
PORTER
And then what happens when she's finished - when she's had her fill?
BRUNTON
She'll drop off but it can take a long time, you see, so while she's biting you she's producing all these excess water, which she excretes out, but what she also does is they come through her coxal pores when she's got too much water to excrete and this, they say, is where you get Lyme disease from because as her mouth parts are in you the coxal pores are on the tops of her legs, on her body, so the fluid drips into the bites and that then puts in the bacteria - borreliosis.
PORTER
And it's - right, so it's the fluid that's contaminated and that's where it gains entry into you.
BRUNTON
Yes, that's where it gains entry.
PORTER
And once that bacterium gets into you, what happens then, how might you know you've got a problem?
BRUNTON
Well the first thing you should know is that you've been bitten by a tick, but sometimes they're in inaccessible places or you're just not looking - they like nice warm places so it could be your groin or under your armpit. And they will move up your body to find these places. But often you'll end up with flu like symptoms - so you'll have aching joints, you'll have a headache, you'll have a stiff neck. I mean they're all symptoms that could be related to something else. Sometimes you get a reaction called an erythema migrans, which looks like a bulls eye but they're not always at the bite mark, it could be anywhere on your body, it just depends. So with Lyme disease it's an all over body reaction and it can be linked to something else.
PORTER
So it's this combination of tick bite, flu like illness possibly and all this classic sort of bulls eye rash that should make you think of Lyme disease.
BRUNTON
You should think of Lyme disease, you don't always get the rash and it can take between two to 30 days, as an incubation period. And with some people it lies dormant and you just don't get it for years.
PORTER
And is this carried by every tick in the UK?
BRUNTON
It's carried by Ixodes ticks, yes, which are the deer ticks, some people call them the bear ticks if you're out in America and they live in the forests, low lying grassland, you'll find them in - like here we have Thetford Forest, up the road, and that has a lot of ticks. And what happens is when they become the nymphal stages and need a blood meal they'll crawl up to the top of long grass and that's where you'll find them and that's when you're likely to get bitten.
PORTER
So they just hang there waiting for their prey to come past.
BRUNTON
Wait for someone to walk past or deer.
PORTER
Well they might have to wait for ages.
BRUNTON
They can, they can wait for months, years, they don't need to feed all the time, like we would need to feed, they can go for a year without feeding. The life cycle can take up to three years.
PORTER
Now we've got another model here, which is ....
BRUNTON
It's a much smaller one.
PORTER
... a fifth of the size.
BRUNTON
It's always smaller - it's the male.
PORTER
Right.
BRUNTON
So the males are much prettier and they have a very hard scutellum which is like a shield on the back. And you can seem them very clearly, if you're looking for them, hanging on grasses because they tend to be red.
PORTER
But do they - they carry the disease too?
BRUNTON
Yes they do, yes.
PORTER
So it doesn't matter which you get bitten by?
BRUNTON
It's not just down to the females no.
PORTER
Now assuming I've been bitten, I notice the tick on my skin, how do I remove it because presumably you need to remove it as quickly as possible?
BRUNTON
Yes you do. There are two schools of thought on this. One is just to pull them out and the other one is to pull them and twist them out. Because of the way the mouth parts are they are like a saw, so when you pull them out the theory is that you will leave bits of the mouth parts behind. Now that's fine because you can treat it like a splinter - you can squeeze it out - you know you might get a small localised infection if you haven't do it all but it's not doing you any great harm. Whereas if you twist them and take them out the theory is that you release the ....
PORTER
Their grip.
BRUNTON
... the grip, yes, and then they just come out as a whole. So you can buy special tweezers for that.
PORTER
What about the old wives tales then that you should paint them with nail varnish or smear them with Vaseline to suffocate them so they release or even ...
BRUNTON
No it doesn't work.
PORTER
... singe them with a match?
BRUNTON
No it really doesn't work, no, you need to twist and pull them off. They're old wives tales. Nice idea but the theory doesn't work.
PORTER
Just pull them off?
BRUNTON
Just pull them off.
PORTER
And preventing ticks? Presumably if you're going to be walking on moor land all over the country you stand the risk of picking them up.
BRUNTON
Yes you want to tuck your trousers into wellie boots or long boots, you want to check your clothing, make sure you haven't got any arms or anything exposed.
PORTER
But if you're walking in the summer you're likely to have exposed skin because it's warm and you don't want to be wearing trousers and socks tucked in and wellies and things.
BRUNTON
Just keep checking yourself and as soon as you see one pull it off.
PORTER
The simple thing to do is to cover up and/or check yourself after you've been out in areas where ...
BRUNTON
Do the buddy system - have someone do it for you. We always do ...
PORTER
Because it might be round the back where you can't see.
BRUNTON
It might be round the back where you can't see it.
PORTER
Despite living in a known trouble spot, it still took Stella Huyshe Shires three years to realise that her tick bite could have been the root of her problems. Does she think more could be done to raise awareness in people walking in the countryside?
HUYSHE SHIRES
In some places there are signs. The National Trust is very good about putting signs out in the areas that the National Trust owns. So there are signs but they are not all over the place so a lot of people are totally unaware and will go walking in shorts and sandals through long grass and wooded areas. And that's the risk - when you've got bare legs in areas like that.
PORTER
Stella Huyshe Shires who had antibiotic treatment but is still getting some symptoms. And if you would like more information on Lyme disease hotspots throughout the UK, and how the condition is diagnosed and treated then there are some useful links on our website at bbc.co.uk/radio4.
We must head back indoors to meet our next subject - right to the inner sanctum of our homes - the bedroom. Bed bug infestations fell to an all time low in the sixties in the UK thanks to aggressive fumigation with DDT, but the bug has staged a major comeback - both at home, and in guest houses and hotels.
Entomologist Ian Burgess is the Director of Medical Entomology Centre in Cambridge.
BURGESS
This is a blood sucking bug that when fully adult is about five to six millimetres long. So it's ...
PORTER
You won't miss that.
BURGESS
No, you won't miss - well if you see it. And it takes about three to five times its bodyweight in blood at a meal, depending on its age. So - and this is a true bug, i.e. it has a heavyweight proboscis that it tucks under its chest when it's not using it and swings it round. Most people probably don't even know what a bug is but a greenfly is a rather more delicate version of it and attacks plants.
PORTER
This thing it spears - spears you. How do you know you've got them?
BURGESS
Well you know you've got them because the day after you've been bitten probably you will find you start coming out in itchy bumps on those parts of the body that are exposed whilst you're in bed. Now mostly this is face, shoulders, arms, hands, maybe feet.
PORTER
So it's the bits that are outside of the bedding?
BURGESS
Generally speaking yes. I mean it depends on whether you have blankets or a duvet and sometimes they will crawl down underneath loose bed clothing and they will bite you underneath but they don't like physical contact with the fabric.
PORTER
So where are they actually living then - are they actually living in the mattress?
BURGESS
These guys are actually structural pests, they live in the walls - in cracks - they will live behind the skirting boards, the crevices round the edges of the fitted carpet, up behind the architrave if there's a little crack, behind pictures on the wall, they will live in the bed frame - in the wooden cracks - or even in a steel bed where - tubular steel - where it has expansion holes that are drilled into it for when they're welding, they will live inside there, they will live in bedroom furniture, your radio alarm, maybe your telephone, your stereo or anything that happens to be nearby, they will live in the mattress mostly in the seams, those welted seams around the edge, or the daisy buttons in older mattresses.
PORTER
How might I bring an infestation into my house because presumably they have to get to your house somehow for the first time?
BURGESS
Yes, so they don't fly, this is a wingless bug. They're mostly brought in in luggage. You go somewhere ...
PORTER
Hotel.
BURGESS
Hotel.
PORTER
Friend's house.
BURGESS
Maybe a friend's house. You take your overnight bag or whatever and during the night - although these things normally have a little place where they like to go back to every day, so either that some of them get lost or more likely at a certain stage in their life, probably as they're an older nymph or a young adult, they are in the migration stage so they will wander looking for something suitable new to hide in and if your luggage just happens to be there they climb in and you take them back with you.
PORTER
I'll put mine in a bin liner from now on.
Our reporter Anna Lacey joined two pest control officers outside a block of flats in Westminster to find out more about how to get rid off bed bugs.
LACEY
Okay, so I've now got my white coverall suit on, I look like something out of a sci-fi movie at the moment and I've got a full gas mask that I'll be putting on in a moment I think or a bit later and yeah we're just ready to go into the house.
Westminster City Council pest controllers, Uriel Bowen and Andy Hood, are out on their first job of the day where they're trying to rid a house of a bedbug infestation. In 2008 alone they made over 500 visits to homes around the London borough, and have had to use a whole host of methods to keep the pests under control. Bedbugs are round, reddish-brown, biting insects about the size of a small ladybird and can be notoriously hard to wipe out. So before each visit, the officers hope that tenants have followed a series of instructions - tidying up the home, clearing away toys and washing clothes and bed linen at 60 degrees to kill off any bugs, who seem to hide in every warm dark place they can find.
URIEL
There used to be moderately high infestation levels in these buildings but the whole situation is now under control, simply because of the new processes for treatment that we've devised for them. So I suspect [knocking on the door] we're not going to get too much of a problem on this one.
Good morning.
SALEIM
We are expecting you. Please come in.
My name is Saleim, I'm resident of 70 Simpson House and I've been living nearly three years now and this thing happened exact third year. So I don't know what, I've been suffering for the last two months very badly, to be honest. All around or sometimes I found them in the clothes, my clothes, mostly I found them in the bed. In the middle of the night we just wake up and you know they're moving around your body and eating and we suffered a lot of rashes. Then I went to my doctor, GP, they gave us some treatment. Throw most - you can see my lounge is totally empty - I throw my sofa but here we are now.
LACEY
Now what kind of symptoms did you have - you said they were crawling on you and bedbugs bite, so what did you notice on your skin?
SALEIM
It comes very red and you - once you scratch your skin swells as well and the itchiness - unbelievable, like you go mad, you know, so that's the sort of thing that's happened. She has got something symptom today which is I notice in the morning this side ...you can see?
LACEY
Oh so you've been getting little bites too? How old is she?
SALEIM
She is two years and two months.
LACEY
So she's been having bites also?
SALEIM
Yeah of course, three of us suffer very badly to be honest.
LACEY
Uriel and Andy are just about to turn the bed and the mattress up.
ANDY
You've got light spotting on the inside of the framework of the bed where the drawers were and you've actually got an insect right in the corner as well.
LACEY
Okay, I'm just looking inside the bed frame - whereabouts is the insect?
ANDY
Just there, behind that piece of wood.
LACEY
Oh yes I can see it, it's hiding right in the corner near some wood inside the bed frame. It's a divan bed and well it looks about sort of what five, six millimetres across.
ANDY
Exactly yeah. I mean the classic situation for this is that it's in the bed, tenants go to bed at night, instant feeding time, it's like ringing the dinner bell for them. And they'll come out, take a feed and then go back exactly where they've just come from.
LACEY
Dressed from top to toe in our protective clothing - with masks and industrial gloves to match - Uriel and Andy go about spraying the house with insecticide. The eggs - which can be found anywhere in the house - are resistant to most chemicals, which means that the team might have to come back again once the bugs have hatched. When the problem first occurred, Mr Saleim tried to treat the infestation himself with commercially available pesticides - but unfortunately without much luck. This isn't something Uriel recommends.
URIEL
My first advice to anybody will be first of all get professional advice as to exactly what the problem actually is. Have it identified first. Once you've got it identified then you'll know how to actually deal with that. The best place to go is either a professional pest control company or better still go to your local authority, most of them have their own pest control sections within the authority and they will be able to advise you.
PORTER
Pest control officer Uriel Bowen talking to Anna Lacey in Westminster.
Now on to a cause of a lot of parental angst - head lice. At this time of year as many as one in 12 primary school children will have them. Ian Burgess again.
BURGESS
They feed entirely on blood, they are in the group known as sucking lice which only affect mammals. It's impossible to keep them giving them a feed every six hours, they have to feed more frequently than that.
PORTER
And the team nits doesn't actually refer to the lice itself.
BURGESS
No it's a curious word and it refers exclusively to the empty eggshell.
PORTER
And that egg is the little sort of whitey creamy thing that you can see cemented to the hair shaft, that's often a clue that you've got an infestation.
BURGESS
Well it's a clue that you've had one but the thing about the nit, the true nit, is that it is refractile - the shell is constructed in such a way that as light comes on to it, it goes through the surface of the shell but bounces back off the inside surface, so you get something that looks white and it's easy to see and you can almost say that it's a biological decoy - a displacement activity. If you pick those off you think you're doing something. And in fact, I believe it was Aristotle who said something like, lice are curious animals because they're the only things that lay eggs that never hatch because he was only ever looking at the empty eggshells.
PORTER
So a typical 10 year old child who's got lice might have how many on his or her head?
BURGESS
Well there's a lot of misinformation about how many lice you might have. Most of what you find published relates to a series of studies done in the 1920s and early 1930s where they shaved whole heads on adult males because they were in colonial jails and they counted the lice. And the conclusion from that was that the average infestation was about 20 lice. It's really rather different from what we find in reality on children. In line with the increase in numbers of cases we also have an increase in intensity of infestation on most people so that some children are carrying hundreds if not thousands on a regular basis.
PORTER
What is it about head lice that means that they live on the head, what's different from them and lice that affect the body or indeed pubic lice, are they all the same sort of family?
BURGESS
Well they're all in the sucking lice and in fact head lice were the ones that came first because hair provides a suitable cover, I mean it's like a little jungle on top of your head. When people started wearing clothes it gave another opportunity for a biological habitat. And as the numbers on the head increase then they start to run out of space and so they will look for alternatives and of course if you've got some clothing nearby they will migrate from the back of your neck, particularly if you've got longer hair, into that clothing.
PORTER
So the body lice which lives in clothing and goes on to us to feed actually started off as a head louse, it's evolved from the head louse?
BURGESS
Exactly.
PORTER
But as a clinician I get to see quite a few people when I was working in sexual health with pubic lice that seem to only affect the pubic hair or the regions around there, maybe under the armpits and the eyelashes we used to see them in sometimes, which is in a very bizarre collection of places to have them. Is that another further evolvement?
BURGESS
This is a different louse. The head louse and body louse are closely related to the chimpanzee louse. The crab louse is closely related to the gorilla louse. It is physically completely different. The head louse is a long thin thing, the crab louse is a short stubby triangular thing.
PORTER
The butterfly of love, as it's known as sometimes.
BURGESS
Yes that's right. But it gets its name because its two back legs have massive claws for grasping body hairs which are more widely spaced and they are more robust. Now the reason you come across this term the butterfly of love is because it is a sexually transmitted infection, in the main.
PORTER
But back to the troublesome head louse - what is the best way of clearing our offsprings' scalps? Growing resistance amongst lice means that pesticides have become less effective. Manual removal of the lice - the so called wet combing technique using conditioner or essential oils - can work but is time consuming and needs to be repeated regularly to catch the lice as they hatch and grow. Fortunately there is a third way - non pesticide silicon based treatments.
BURGESS
We've been doing some work on the silicon based medicine. We find that it actually seems to stop them getting rid of water. Now you think well how's that going to kill them? But if you think a louse, if it's feeding six or eight times a day, it takes up an awful lot of waste water and they don't pee and they don't produce liquid droppings, like things like mosquitoes, so they've got to get rid of it somehow. And they literally breathe it out. So if you stop them from doing that they just simply ...
PORTER
Explode.
BURGESS
... well not quite but their guts explode sometimes. It sets up a huge osmotic stress within the body because it's trying to pump water out of the gut and then get rid of it and then it flows back in again because - so ...
PORTER
I mean it sounds a nice simple way. Are they effective these ....?
BURGESS
They are and we've done a number of clinical trials on different types of products and they all have a similar type of effectiveness. So it is certainly something that will work.
PORTER
What about stopping your child getting them again? There are some products that are seen as lice repellent products, any science behind that?
BURGESS
We started looking at lice repellents in the early '90s. A client was looking at a chemical and we found that it actually had a repellent effect rather than the killing effect they were looking for. And the - they do work in the lab and they do work on some people. The real problem with a repellent is the fact that you have to use it every day - and we are looking at a chemical substance - you have to apply it correctly and you have to not forget when you're going to a birthday party and things like that. So you've got a cost element, you've got a skill element and an exposure element and overall it's only as good as the person who's using it.
PORTER
And parents are busy people.
BURGESS
And kids are not the easiest things to stick things on their heads.
ENDS
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