Our bodies are pretty amazing. Day after day, they work hard - digesting food, pumping blood and oxygen, sending signals from our brains and our nerves, and much more. But there is a group of tiny invaders that can make our bodies sick - they're called germs.

What Are Germs?
Some kids may think that germs are bugs or cooties or other gross stuff. Actually, germs are tiny organisms, or living things, that can cause disease. Germs are so small and sneaky that they creep into our bodies without being noticed. In fact, germs are so tiny that you need to use a microscope to see them. When they get in our bodies, we don't know what hit us until we have symptoms that say we've been attacked!

What Types of Germs Are There?
Germs are found all over the world, in all kinds of places.There are four major types of germs: bacteria, viruses, fungi, and protozoa. They can invade plants, animals, and people, and sometimes they make us sick. 

Bacteria (say: back-teer-ee-uh) are tiny, one-cell creatures that get nutrients from their environments in order to live. In some cases that environment is a human body. Bacteria can reproduce outside of the body or within the body as they cause infections. Some infections bacteria cause include sore throats (called strep throat), ear infections, cavities, and pneumonia (say: new-mo-nyuh).

But not all bacteria are bad. Some bacteria are good for our bodies - they help keep things in balance. Good bacteria live in our intestines and help us use the nutrients in the food we eat and make waste from what's left over. We couldn't make the most of a healthy meal without these important helper germs! Some bacteria are also used by scientists in labs to produce medicines and vaccines (say: vak-seens).

Viruses (say: vy-rus-iz) can't live outside of living cells. They need to be in or on a living thing like a plant, animal, or person in order to grow and reproduce. Whatever a virus lives in is called its host. When viruses get inside people's bodies, they can spread and make people sick. Viruses cause chicken pox, measles, flu, and many other diseases.

Fungi (say: fun-guy) are multi-cell (made of many cells), plant-like organisms. Unlike other plants, fungi cannot make their own food from soil, water, and air. Instead, fungi get their nutrition from plants, people, and animals. They love to live in damp, warm places, and most fungi are not dangerous. An example of something caused by fungi is athlete's foot, that itchy rash that teens and adults sometimes get between their toes.

Protozoa (say: pro-toh-zoh-uh) are one-cell organisms that love moisture and often spread diseases through water. Some protozoa cause intestinal infections that lead to diarrhea (runny poop), nausea, and belly pain.

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