INTRODUCTION Germs are tiny organisms or living things that make you sick Because they’re far too small to see they sneak into your body without you noticing and then infect you with all kinds of terrible diseases But over time these microscopic monsters were fi nally unmasked Home Wreckers Germs don’t actually try to make us sick It’s just that bodies like ours make very good homes for them and once they get inside they multiply rapidly to make the most of their good luck That’s how they do the damage Catching Germs Germs are found all over the world in all kinds of places Some reach you through the air from sneezes coughs or someone’s breath You can also become infected if you touch something contaminated with germs then touch your nose and breathe in Other germs can be swallowed when you eat bad food 6
Defenders Luckily your body has an amazing defense system for dealing with germs called the immune system It’s a complex army of tiny cells that circulate in your blood and do battle with germs It often takes time to kick in though That’s why you get ill then with luck recover because your immune system has dealt with them Keeping Clean There’s another way we can reduce the danger of germs by cleanliness or hygiene Many germs spread in dirt so by keeping things clean we reduce the chances of infection That’s why it’s good to wash your hands Doctor’s Orders Doctors have two ways of helping your body fight germs One is with vaccination which gets your immune system ready to fight certain germs The other is with antibiotics medicine that is poisonous to germs 7
SETTLING FOR GERMS In the early days of mankind when people roamed around hunting and gathering infectious diseases were probably rare People did not live close enough together for germs to spread or stay long enough near water sources to pollute them Disease on the Farm The development of farming some ten thousand years ago saved mankind from starvation and provided food for the first towns and cities But germs multiplied as people and farm animals began living close together sharing their germs and polluting the water Slow-moving water provided a breeding ground for parasites Cattle gave us tuberculosis and smallpox Dogs gave us measles 8 Chickens may have given us fl u
The First Known Polio Victim On an Egyptian monument from the thirteenth century BCE there is a picture of a man called Roma His leg seems to be withered which could be caused by polio If so he is the first known victim of this terrible disease which may have developed in water dirtied by the dung of farm animals As farming became more intense manure-polluted water encouraged diseases such as polio cholera typhoid and hepatitis Slow-moving irrigation water provided ideal conditions for parasites such as those causing the diseases bilharzia and malaria Horses gave us the common cold Polio may have developed in water dirtied by farm animal dung Pigs may have given us fl u 9
