Sunday, January 15, 2006
How to get worms
Readers of this blog may be already wondering whether they are at risk of the nasty parasitic diseases in which I specialise. Well, that depends on a number of factors. There are a few well known risk factors for contracting parasitic infections. Let me give you an example.
In the United Kingdom we are fortunate to have a temperate climate (though this may change in the next few years). The lack of warm moist soils means that the parasite eggs shed into the environment do not easily survive. At least, not the eggs of parasites normally associated with humans. But the eggs of some animal parasites do survive in british soil, and they can and do infect people (GET READY FOR THE YUCKY BIT).
So how does this happen? Well, imagine yourself as an eight year old child, playing football in the local park. It's summer time, and you don't have a care in the world. You kick the ball all over the field, sometimes at the goal, sometimes into the rough, uncut grass beside the pitch. On one such occasion the ball lands on something a bit soft and greasy. You put your hands down to pick up the ball and SQUELCH, your fingers end up covered in sticky, smelly dog poo. Never mind though, because there is plenty of grass around for you to wipe your mucky fingers clean. A minute later, you are kicking the ball around again, almost having forgotten picking the thing up.
But then along comes Toby McDougall, the school bully. You don't like Toby because last week he pushed you over in the playground and pulled ten hairs out of your head as he held you down. You see him running towards the pitch and you start running in the opposite direction, the joy of kicking a ball around immediately extinguished. He is taller and faster than you, and it only takes a few moments for him to catch up. The first thing you feel is a hand in the middle of your back. Then you are on the ground, and he is straddling your back. First he rubs your face on the grass until it hurts, then he takes your fingers and bites one of them! He keeps your finger in his mouth for several seconds, biting harder and harder. Then you let out a scream so piercing that the school bully releases your finger and stands up with a start. You begin to cry uncontrollably, and this proves too much. The bully kicks the grass in your general direction and runs off with your new football.
You cry all the way home because your finger hurts so much, and you tell your mummy about it as she washes and disinfects your dirty, reddened finger. There are teeth marks, but luckily he didn't break the skin.
You are reluctant to go back to school, and anyway a few days later you get a summer cold with some fever, so your mummy lets you stay at home. When you do go back, you find out that the school bully has also been off school with something like a cold. But when he describes his symptoms to his mates it includes a painful tummy, a cough, and he was very sleepy. Then a couple of weeks later the bully complains to his teacher that he can't see properly. Things have gone a bit cloudy. The teacher tells him to go home.
The bully doesn't return for a few days, and the other children want to know what has happened to him. They ask the teacher. She is unwilling at first, but after a few days of persistent questioning she tells the class that Toby has toxocariasis. The children look bemused. What is this funny sounding thing? They want to know more, and this is what the teacher tells them....
'Toxocariasis is something we get from dog poo (uuugh shout the children). Sometimes dogs have a worm in their tummy (uuuuuuuuugh), which lays eggs that come out when the dog goes to the toilet (uuuuuuuuuuugh). If you pick up the dog poo, some of it might stay on your hands even though you don't know it is there (uuuuuugh). The eggs are so small you can't see them. If you put your fingers in your mouth, the eggs might get into your tummy (uuuuuuuugh). The eggs hatch, and a little worm comes out (uuuuuuuuuuuuuugh). It wriggles into your body and starts wandering around inside. This can make you very sick. Sometimes the worm wiggles all the way up into your eye and starts wiggling around inside your eyeball (uuuuuuuuuuuuugh).
Suddenly you are struck by a panic attack, and you blurt out to the teacher what happened the a while ago in the park. You are scared that you too have a worm in your eyeball. The teacher rings your mummy who takes you home from school and straight to your doctor. He does some tests and later on tells your mummy that you don't have any worms at all. Phew. Fortunately, you didn't put your fingers in your own mouth after picking up the poo-covered football, and it was Toby who got infected. So there, Toby McDougall, bullying me was the worst thing you could have done, 'cos I was immune! Ha!
(Footnote: Toby did make a full recovery, but became the laughing stock of the school. Nicknames like 'poo-eater', 'worm-boy' and 'dog-f**ker' were often heard in the school playground. He left primary school a broken bully, and I never saw him again.)