Background: The spread of infection through our hands and sneezes
We learned earlier about bacteria, viruses and fungi: three different types of microbes that can cause infection. Someone who has contracted harmful disease-causing microbes is said to be infected. Diseases caused by such microbes are said to be infectious diseases.
- When harmful bacteria reproduce in our bodies, they can produce harmful substances called toxins which can make us feel ill, or in the worst-case scenarios, damage tissues and organs.
- Viruses act like parasites. On entering our bodies, they require a host cell to survive. Once inside a cell, they multiply and burst free when fully grown, and in doing so destroy the host cell.
- Fungi generally do not kill their host. Dermatophytes, a type of pathogenic fungi, prefer to grow or colonise under the skin. It is the secondary products they produce while feeding that cause swelling and itching, such as athlete’s foot.
Many harmful microbes can pass from one person to another by several different routes – air, touch, water, food, aerosols, animals, etc.
It is important to remember that not all microbes are harmful, and some microbes are only harmful when taken out of their normal environment. For instance, Escherichia coli (E. coli) is commonly found in our gut and is harmless, but if it is transmitted to the urinary tract it can cause urinary tract and kidney infections.
Image taken from e-Bug Junior Pack “1.3 Micro-organisms: Harmful Microbes” Student Handout 1.
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