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Explore how your body protects you from disease.

Have you ever been sick? Perhaps you felt cruddy from a cold. Or maybe your stomach ached for hours. It wasn't fun, was it? Getting sick is a pain. Sure, you get to stay home from school. That can be nice—for a while. Still, troubled tummies, scratchy throats, and runny noses can make you miserable. Luckily, your body works hard to keep you from getting sick. Read on to find out how.

The germs that make you sick are lurking everywhere. You can't see them. Yet they're here. They are sitting on your desk. They are hiding on your keyboard. They are even in the air that you are breathing.

Diseases are getting around faster than ever. How? For one thing, people take more trips these days. You can go anywhere. You can fly to faraway mountains. You can travel to distant jungles. You can even go to the coldest place on Earth—Antarctica. Sick people bring their germs with them.

People aren't the only things moving around. We ship food, clothes, and other stuff too. Some germs go along for the ride. They may hide out in food or bags. These tiny stowaways can cause big trouble.

There's another reason that diseases are spreading. Earth is heating up. This causes animals that like warmer weather to spread into new places.

Take mosquitoes, for example. They like warm places. So they are moving into areas that are getting warmer. These pests often carry diseases with them.

Some mosquitoes pass those diseases on to people. For instance, they carry the germ that causes West Nile virus. It is a sickness that can bring fever and headaches. It can even make the brain swell.

Flies and ticks can also carry diseases. Ticks can grab onto people's skin and suck their blood. Yuck! When a tick bites, germs can sneak into the person’s blood.

How can you protect yourself from germs? You may not know it, but you have a germ-fighting weapon. It's your own body!

Your first weapon is skin. It acts like armor. It blocks some viruses and bacteria. Viruses are germs that can live only inside animals or plants. Viruses cause the flu and measles.

Bacteria are tiny creatures. Some bacteria are good. They can help your stomach break down food. Other bacteria aren't so good. They can make you sick. Bacteria can cause sore throats and ear infections.

Sometimes germs do get past your skin. They can creep through cuts. They can sneak into scrapes. They can ride on food. They can also enter your body when you touch your nose or mouth with dirty hands.

You and your body can fight off these tiny invaders. Start by washing your hands with soap and water. Soap kills many germs. Water washes them away.

Washing your hands isn't always enough. Tricky germs can still find ways of attacking you. Luckily, you have an immune system to fight them. It hunts down and destroys germs. How does it do that? Let’s take a closer look.

Special cells patrol your body. Some have big appetites. They eat germs! That helps keep you from getting sick.

Other cells make antibodies. An antibody sticks to a germ. There is a different antibody for each kind of germ. Some antibodies keep germs from making you sick. Others help your body find and kill germs.

After a germ is destroyed, the antibodies hang out in your body. They protect you if the same kind of germ comes back. That way you will not get the same illness twice.

The immune system is pretty good at fighting germs. Sometimes it needs help, though. That's where medicines called vaccines come in. They can make your immune system stronger.

A vaccine contains germs that have been killed or weakened. The dead germs can't make you sick. Instead, they trigger your body to make antibodies. If the same germ ever shows up again, then your antibodies attack it.

No two people have the same kind of immune system. Some people get sick all the time. Others never even seem to catch a cold.

Kids usually get sick more often than adults. That's because kids haven't been exposed to as many germs. So kids have fewer antibodies. Your body learns quickly, though. It's probably making antibodies right now.

Don't worry too much. Diseases may be spreading more easily. They may even get sneakier. Good thing your skin and immune system are always working to protect you.

Article by Kirsten Weir. Top-of-page photo by © Visuals Unlimited/Corbis. "Tiny Invaders" appears on pages 16-23 of our Nov.-Dec. 2006 issue.