You may think germs are something you don't have to worry about — only the people selling toilet cleaners on TV are concerned with germs.

But germs are tiny organisms that can cause disease — and they're so small that they can creep into your system without you noticing. You even need a microscope to see them. To stay healthy, it helps to give some thought to germs.

Germs Basics

The term germs is really just a generic word for four different types of organisms: bacteria, viruses, fungi, and protozoa.

Bacteria are tiny, single-celled organisms that are found throughout nature, including in the bodies of human beings. A certain number of bacteria are good for our bodies — they help keep the digestive system in working order and keep harmful bacteria from moving in. Some bacteria are even used to produce medicines and vaccines.

But bacteria can cause trouble, too — ever had a urinary tract infection or strep throat? These infections are caused by bacteria.

Viruses are even smaller than bacteria and can't live on their own. In order to survive, grow, and reproduce, they need to be inside other living organisms. Most viruses can only live for a very short time outside other living cells. For example, they can stay on surfaces like a countertop or toilet seat in infected bodily fluids for a short period of time, but they quickly die there unless a live host comes along. But some viruses, such as the kind that cause hepatitis (an infection of the liver), can survive on surfaces for a week or longer and still be able to cause infections.

Once they've moved into your body, viruses spread easily and can make you quite sick. Viruses are responsible for not-so-serious diseases like colds as well as extremely serious diseases like smallpox.

Fungi (pronounced: fun-jye) are multi-celled, plant-like organisms that usually aren't dangerous in a healthy person. Fungi can't produce their own food from soil, water, and air, so instead, they get nutrition from plants, food, and animals in damp, warm environments.

Two common fungal infections are athlete's foot and ringworm. People who have weakened immune systems (from diseases like AIDS or cancer) may develop more serious fungal infections.

Protozoa (pronounced: pro-toe-zo-uh) are one-celled organisms like bacteria. Protozoa love moisture, so intestinal infections and other diseases they cause are often spread through contaminated water.

Once organisms like bacteria, viruses, fungi, and protozoa invade your body, they get ready to stay for a while. These germs draw all their energy from you! They may damage or destroy some of your own healthy cells. As they use up your nutrients and energy, most will produce waste products, known as toxins.

Some toxins cause the annoying symptoms of common colds or flu-like infections, such as sniffles, sneezing, coughing, and diarrhea. But other toxins can cause high fever, increased heart rate, and even life-threatening illness.

If you're not feeling well and visit your doctor, he or she may order testing to examine your blood and other fluids under a microscope or perform cultures to determine which germs (if any) are making you sick.

How Can I Protect Myself From Germs?

The best way to prevent the infections that germs cause is by protecting yourself. Because most germs are spread through the air in sneezes or coughs or through bodily fluids like saliva, semen, vaginal fluid, or blood. If you or someone else is sick, your best bet is to limit contact with those substances.

Washing your hands often is absolutely the best way to stop germs from getting into your body. When should you wash? After using the bathroom, after blowing your nose or coughing, after touching any pets or animals, after gardening, or before and after visiting a sick relative or friend. And of course you should wash your hands before eating or cooking.

There's a right way to wash hands, too — you need to soap up well using warm water and plenty of soap, then rub your hands vigorously together for 15 seconds (away from the water). Rinse your hands and finish by drying them thoroughly on a clean towel. It's a good idea to carry hand sanitizer with you for times when you are eating out or not near a sink.

If you spend any time in the kitchen, you'll have many opportunities to get rid of germs. Be sure to use proper food-handling techniques, like using separate cutting boards, utensils, and towels for preparing uncooked meat and poultry.

Another way to fight infections from germs is to make sure you have the right immunizations, especially if you'll be traveling to other countries. Other yearly immunizations, such as the flu vaccine, are strongly recommended unless your doctor tells you otherwise.

With a little prevention, you can keep harmful germs out of your way!

Reviewed by: Kate M. Cronan, MD
Date reviewed: September 2010