Micro-organisms and Infection
You have probably had an infectious illness. All of us have caught a cold at one time or another, and many of us have had one of the common children’s illnesses such as chicken pox.
Infectious diseases are caused by different types of micro-organisms: bacteria, viruses, fungi, parasites. The most common illnesses are caused by the first two. We are all subject to infection by these micro-organisms, and it is the strength of our immune system which determines whether or not we become ill.
Transfer of Infection
When a person is infected by one of these micro-organisms, the infection can then be transferred from one person to another, either by direct contact, for example by kissing or shaking hands, or it can be transferred through some intermediate contact. Remember when the swine flu scare was at its height, you were advised to turn off the tap with your elbow after washing your hands, in case there were micro-organisms on the tap. Always wash your hands or use a disinfectant before touching food to prevent infection being transferred to yourself or others.
Infection can be conveyed by food or water, or it can be introduced directly into the blood through a small cut or sore. It can also be conveyed by air. Think of all the tiny droplets of infected liquid which fly through the air when you sneeze.
Bacteria are living, single cell organisms. Since they are living organisms, antibiotics are effective against them, but bacteria can also become resistant to antibiotics.
Examples of diseases caused by bacteria are:
Tetanus, Whooping cough, Typhoid, Cholera, Tuberculosis, Meningitis, Diphtheria, Gonorrhoea, Scarlet Fever, Food poisoning
A virus is not a living organism, and antibiotics can therefore not be used to fight a virus infection. However, there are other medicines which can be used. A virus is a small piece of the genetic material, DNA, which is packed in proteins. It makes us ill by entering the cells in the body and using the material in the cell to reproduce itself.
Examples of diseases caused by virus are:
Influenza (including swine flu), HIV/AIDS, Measles, Mumps, Rubella/German measles, Rabies, Hepatitis, Poliomyelitis, Common cold, Chicken pox, Glandular fever (Mononucleosis)
There are about 200 different fungi which can cause illness, some of which attack skin and nails, while others are found in the mucous membranes in the mouth and vagina. These illnesses are often uncomfortable, but seldom dangerous.
Examples of fungal infections are:
Athlete’s foot and Ringworm
Parasites are small one-celled organisms or insects, which are less common in Norway, but cause illnesses like malaria and scabies.
Today, many of these diseases are less common, especially in the western world, because of the scientific development of effective medicines and as a result of widespread vaccination programmes.
Tasks and Activities
- What is the cause of infectious diseases?
- Why do some people become ill more easily than others?
- How is infection transferred from one person to another?
- What is one good way to prevent the transfer of infection?
- What can be used to fight bacterial infections?
- Why do antibiotics have no effect on virus infections?
1. What is the English term for the following illnesses? (They are all in the text.)
- Røde hunder
Tetanus/stivkrampe, Meningitis/hjernehinnebetennelse, chicken pox/vannkopper, rubella/røde hunder, whooping cough/kikhoste, mumps/kusma, athlete’s foot/fotsopp, glandular fever/kyssesyken, measles/meslingerHide
2. Match the illness to its cause in the task, Diseases and Micro-organisms.