Both viruses and bacteria can enter the body different ways. You can eat them if they are in a certain type of food or live in the animal or plant you are eating. You can get them from the water, either swimming in it or drinking it. You can breath them in from the air and they enter your lungs. If you touch a bacteria or virus and then rub your nose or eyes they can enter your body that way as well. Sometimes, when someone sneezes on you the virus or bacteria in their snot will land on you, that is why we say "cover your mouth!".

Once the virus or bacteria is in it can travel in the blood to any cell in your body. Once it reaches the cell of choice it can enter by tricking the cell into thinking it is food or using a entry way that nutrients, molecules and other proteins use to get in to the cell. So, for every different virus or bacteria the method of entry and infection is different. It is a very interesting subject because viruses and bacteria can be very sneaky!!!!!

There are many ways that bacteria can enter your body. All they need is an opening! For example, they can come into your body through your mouth, or your nose, or your ears. Because bacteria are very small, they can even come in through very small openings, such as the pores of your skin! Your body has a lot of defenses to keep the bad bacteria from coming in too far through these openings. However, sometimes the bacteria can come in past the defenses. You might breathe in bacteria that are suspended in the air, or eat bad bacteria that is in your food. This is why it's so important to cook your food well and live in a healthy and clean environment!

Also, bad bacteria can enter very easily through cuts and other injuries, which is why it's important to keep wounds clean.

Viruses may also enter in the same ways as bacteria, but viruses are different than bacteria in many ways. One key difference is that while bacteria just live on and inside your body, viruses actually go inside your cells! They are able to attach themselves to the outside of a cell, and then inject their own RNA (which is a lot like DNA) into the cell, and take it over!

Viruses are very hard for your body to get rid of, which is why doctors get very concerned about some harmful viruses.

Although there are a lot of bacteria and viruses in the world, you should remember that the vast majority of them are not harmful, and in fact a lot of them are very helpful! We tend to notice the ones that make us sick more, though. The best defense against these bad ones is to live in a clean environment, so that there are fewer germs, and most importantly to live a healthy lifestyle, so that your body is in a good condition to fight the invaders.