Human vs Virus: The Fight for Survival

Contributor: Jay Gregorio. Lesson ID: 13306

What do H1N1, CoVid-19, and SARS have in common? They are fatal diseases caused by viruses. Is a virus just a germ? Are all germs the same? How do we avoid them? What happens if we don't?


Life Science

learning style
Auditory, Visual
personality style
Grade Level
High School (9-12)
Lesson Type
Dig Deeper

Lesson Plan - Get It!

  • Do you remember when you were taught how to properly wash your hands as a child?

As a teenager, you know the importance of hygiene and how it relates to your overall health. For some reason, however, hand-washing is not taken seriously by many. In fact, some people don't even bother washing their hands after using the bathroom!

  • Is there anything more disgusting than having to shake someone's hand that is full of germs?

shaking hands

Imagine if you could see these microscopic organisms. Maybe you would avoid touching other people and surfaces and definitely wash your hands more often!

In this lesson, you will discover the bacteria and viruses that we call germs, including their characteristics and potential harm to humans. Although we are vulnerable to the infections brought on by these microorganisms, there are simple ways to combat them. Let's explore!

  • Can you think of an item in your home that would have a lot of bacteria? Maybe the toilet in your bathroom?

The answer might surprise you. It is the cutting board in your kitchen!

Researchers from the University of Arizona found that the average cutting board has 200 times more fecal bacteria than a toilet seat.

  • How is that possible?

Cutting boards are used to cut many different food items, including raw meat, which has fecal bacteria from their internal organs. When the boards are cleaned, their grooves and scratches are not usually reached. These are great breeding grounds for bacteria to grow!

What Are Germs?

The term germs refers to microscopic organisms that can cause infectious diseases. They are generally categorized into four types: bacteria, viruses, fungi, and protozoa. Let's take a quick look at each.

Bacteria are tiny, single-celled organisms that get their nutrients from the environment in which they live. They thrive in conditions where they are able to easily reproduce both inside or outside our bodies.

When the number of certain bacteria inside your body is high enough, you start feeling sick. Strep throat, pneumonia, and ear infections are just a few of the many conditions caused by bacteria.

However, not all bacteria are harmful. In fact, your gut is home to trillions of good bacteria that help you digest your food, absorb nutrients, and produce vitamins such as folic acid and niacin.

microscopic bacteria


Viruses are not complete cells but are small particles of genetic material that need a host like plants, animals, or humans in order to survive. Viruses are considered parasites. They invade a host's cells and take them over in order to reproduce themselves.

This means that the environmental conditions outside of a host are not favorable for reproduction, and they will eventually die.

For a short period of time, however, viruses can stay alive floating in the air or on surfaces. This allows them to come in contact with hosts. Once inside a host, viruses spread quickly, causing the host to suffer illnesses such as cold, flu, or even HIV/AIDS.



Fungi are multi-celled, plant-like organisms that cannot make their own food from soil, water, or air. They survive by getting nutrition from plants, animals, and humans where it is dark and damp.

When fungi live on humans, they are not particularly dangerous unless the person suffers from other chronic diseases.

  • Have you ever experienced athlete's foot, which is an itchy rash in between your toes?

This is a fungal infection. Topical creams are used to treat this type of infection.

microscopic look at fungal infection on skin


Protozoa are one-celled microorganisms, bigger than bacteria, that contain a nucleus and other cell organelles.

These organisms thrive in areas that are moist and, therefore, are usually found in water. Protozoa cause illnesses like amoebiasis and giardiasis, which are intestinal infections from contaminated water. These can lead to diarrhea, nausea, and stomach ache.

Protozoa can be very aggressive when they live inside a host's body. They can invade blood cells and destroy them.

Giardia lamblia protozoa


How Do Germs Spread?

  • Have you ever had a terrible flu?

Flu, known as common influenza, can make you feel very sick with high fever, debilitating cough, headache, and exhaustion. It can last from a few days to weeks.

  • But how do you get infected?

Bacteria and viruses can spread through direct contact. Think about all of the things you touch throughout the day. Think about how often you wash your hands. Now, think about when you shake another person's hand.

  • Can you imagine the number of bacteria and viruses that can potentially be transferred to you?

Aside from direct contact, viruses can float in the air inside the tiny droplets released by a person who is sneezing or coughing. If a sneeze is not covered, those droplets can travel up to six feet ahead, landing on any surface, or worse, in your face!

While it is daunting to always be conscious about what you touch or what is in the air, there are things you can do to prevent getting sick from the spread of germs.

  • Wash your hands properly.

Wet your hands with warm or cold, clean, running water and apply soap. Lather your hands by rubbing them together with the soap, including the backs of your hands, between your fingers, and under your nails. Scrub your hands for at least 20 seconds before rinsing.

Check out the CDC video found under Additional Resources in the right-hand sidebar if you want to learn more.

  • Cover your mouth when coughing or sneezing.

The best way to contain the bacteria or virus is to cough or sneeze into a tissue and then discard it into a trash can.

If you do not have a tissue, you can use your elbow. However, it is important to wash or change your shirt later in order to stay safe. Otherwise, the bacteria and virus will remain on your elbow.

  • Stay home when you feel sick.

Going to school if you are ill won't earn you an A in health! It just makes everything worse.

The best thing you can do is rest and minimize your contact with other people. It is also important to seek advice from a medical professional and possibly take appropriate medication. This will not only help you recover but keep others safe as well.

  • Practice a healthier lifestyle.

You are young and are likely engaged in a lot of different physical activities. However, a healthy lifestyle is not just about exercising.

What you eat also impacts your overall health and well-being. Choosing to eat healthy food will boost your immune system and help protect you from getting infected easily by bacteria and viruses.

Check out one or all of the following resources to learn more:

Don't underestimate the power of germs! They can be fatal when they invade your body and reproduce. Help protect yourself from these unwanted attacks.

When you are ready, move on to the Got It? section to dig a little deeper.

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