Health and diseases - microorganisms (bacteria, viruses, fungi, infectious diseases

Theme: Everyday Science

Topic: Microorganisms and Infectious Diseases

Have you ever wondered why your teacher or parents always tell you to wash your hands before eating? It is because of tiny living things called microorganisms or microbes.

These organisms are so incredibly small that we cannot see them with our naked eyes. To see them, we need a special magnifying tool called a microscope. Microorganisms live everywhere: in the air, in water, in the soil, on our skin, and even inside our bodies. While many of them are harmless or even helpful, some cause sickness. These harmful microorganisms are commonly called germs.

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Types of Microorganisms

There are three main types of microorganisms we need to know:

1. Bacteria

Bacteria are single-celled organisms. They come in different shapes, like rods, spheres, or spirals.

• The Bad: Harmful bacteria can cause severe illnesses like typhoid fever, cholera (often spread through dirty water), and tuberculosis (TB).
• The Good: Not all bacteria are bad! Some helpful bacteria live in our stomachs to help us digest food, while others are used to turn milk into delicious yoghurt.

2. Viruses

Viruses are the smallest of all microorganisms. They are so simple that they cannot survive or multiply on their own; they must get inside the cells of a living plant, animal, or human to grow. Viruses cause highly contagious illnesses such as the common cold (flu), measles, chickenpox, and COVID-19.

3. Fungi

Fungi (singular: fungus) can be large like mushrooms, or microscopic like yeast and mould. Microscopic fungi love to grow in warm, damp places.

• The Bad: Harmful fungi cause annoying skin infections such as ringworm (which causes itchy, circular patches on the skin or scalp) and athlete’s foot.
• The Good: We use yeast (a type of fungus) to make bread rise and become fluffy.

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Infectious Diseases and How They Spread

An infectious disease (also called a communicable disease) is an illness that can easily spread from one person to another. Germs travel from person to person in several ways:

• Through the Air: When an infected person coughs or sneezes without covering their mouth, tiny droplets carrying germs fly into the air. Other people breathe these in and get sick (e.g., flu or tuberculosis).
• Through Dirty Water and Food: Eating food left uncovered or drinking untreated water can introduce harmful germs directly into our bodies (e.g., cholera). Flies also carry germs from toilets onto our food.
• Through Direct Contact: Sharing personal items like towels, combs, or clothes can spread skin infections like ringworm.

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How to Stay Safe (Prevention)

We can easily protect ourselves from germs by practicing good hygiene:

1. Wash your hands regularly with soap and clean running water, especially before eating and after using the toilet.
2. Cover your mouth with your elbow or a tissue when sneezing or coughing.
3. Keep food covered to prevent flies from landing on it.
4. Drink safe water by boiling or filtering it.
5. Get vaccinated to help your body build a strong defense system against dangerous viruses.

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Summary

• Microorganisms are tiny living things that can only be seen with a microscope.
• The three main types of microbes are bacteria, viruses, and fungi.
• Harmful microorganisms are called germs, and they cause infectious diseases that can spread from person to person.
• Germs spread through air, contaminated food/water, and direct contact.
• We can prevent diseases through good hygiene, handwashing, and vaccination.

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Classwork

Section A: Multiple Choice

1. Which instrument is used to see microorganisms?
   • A) Telescope
   • B) Microscope
   • C) Magnifying glass
2. Which of these is a disease caused by a virus?
   • A) Cholera
   • B) Ringworm
   • C) Measles
3. What friendly microorganism is used to make bread rise?
   • A) Yeast
   • B) Virus
   • C) Typhoid
4. How does cholera spread?
   • A) Through direct skin contact
   • B) Through dirty water and food
   • C) Through loud shouting
5. Which of the following is a good hygiene habit?
   • A) Sharing towels with someone who has ringworm
   • B) Washing hands with soap and clean water
   • C) Leaving food uncovered for flies

Section B: Short Answer Questions

1. Define the term microorganisms.
2. Mention two ways we can prevent the spread of infectious diseases in our school.