Notes

Germs are tiny organisms that can cause disease — and they're so small that they can creep into your system without you noticing. 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-guy) 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 do cultures to figure out which germs (if any) are making you sick.