Introduction to Microorganisms

A microorganism is an organism that is too small to be seen by the naked eye — in other words, it is "microscopic." Microorganisms include bacteria, viruses, fungi, parasites, and prions, among others. Microorganisms exist virtually everywhere, and most are harmless. In fact, many microorganisms promote good health.

But when a microorganism has the potential to be harmful, it is often referred to as a "germ." There are different types of common germs that can be controlled through basic hygiene and cleaning practices. These include:

• Bacteria
• Viruses
• Fungi (mold and mildew)

About Germs

Germs live in soil, air, water, food, animals, plants, and people. Even most germs with a potential to cause illness can often be helpful. For example, many bacteria that live inside the human body are beneficial, and exposure to other germs can help humans build up their immune systems and stay healthy.

But in some instances, exposure to harmful germs can cause conditions like foodborne illness, diarrhea, and other diseases. Some are easily managed and can go away on their own; others are more serious and can lead to severe illness. It's important to practice healthy habits and prevent the spread of these germs.

Germs can be spread via:

• Direct contact — like touching the hand of someone sick
• Indirect contact — like touching a surface that held raw food, or was contaminated by someone sick
• Through the air — like when someone coughs into the air
• Through contaminated food and water
• Some germs are spread through contact with animals or by a bite or scratch

How and Where Germs Survive

Germs thrive in moist conditions. In some instances, germs can live on surfaces for hours — and even days. For example, according to the Mayo Clinic, flu germs can live on surfaces for up to 48 hours... and CDC has noted that staph and MRSA germs can survive on some surfaces for hours, days or even months, depending on such factors as temperature and humidity.

The important thing to note is that while surfaces may look clean, it can contain many infectious germs. You need to disinfect to reduce germs on surfaces.

Cleaning versus Disinfection

Cleaning and disinfecting are not the same thing. Cleaning removes germs from surfaces, whereas disinfecting actually destroys them.

Cleaning with soap and water to remove dirt and most of the germs is often enough for daily cleaning. However, CDC stresses that it's important to routinely clean and disinfect surfaces, too, to prevent the spread of germs and protect your family.

• Disinfectants are registered with the U.S. Environmental Protection Agency (EPA) and contain ingredients that destroy bacteria and other germs. Check the product label to make sure it says "Disinfectant" and has an EPA registration number.

There are different categories of germ reduction products, as well:

• Disinfectant: Kills pathogenic germs (but not spores)
• Sanitizer: Kills 99.9% of pathogenic germs
• Antiseptic: Kills germs on the skin (such as an alcohol-based hand sanitizer)

Examples of Illness Caused by Germs

• Bacteria: Salmonella and E. coli bacteria can cause food poisoning.
• Viruses: Rhinoviruses can cause colds. Herpes simplex causes cold sores. Influenza can cause the flu.
• Fungi: Trichophyton (a dermatophyte) can cause Athlete's Foot.
• Parasites: Giardia can cause diarrhea.

Viruses are Very Challenging Germs

Viruses are different from bacteria and mold/mildew. They are extremely small — only 1/100th of the size of bacteria or mold/mildew. But unlike bacteria or mold/mildew, which are capable of growing on their own, viruses need a host to infect in order to reproduce. It is through this process that viruses cause disease.

In many cases, it only takes one virus particle to make you sick. That's why frequent handwashing and surface disinfection are important measures to help control the spread of disease — especially those caused by viruses.

Read more about reducing the spread of germs in Cold and Flu.