Notes On Transmission of Diseases - CBSE Class 9 Science

Transmission
Transmission is the process of passing something from one individual to another individual. Infectious diseases are spread through microbial organisms from an infected person to a healthy person.

Microorganisms are transmitted through physical contact, air, water and carriers. 
    •  Air borne diseases:These are the diseases transmitted through air. Microorganisms are transmitted in the form of droplet nuclei in the air. e.g. common cold, pneumonia and tuberculosis.
    •  Waterborne diseases: These are the diseases transmitted through water. Excreta of infected animals and humans contaminate drinking water. e.g. cholera 
    •  Physical contact: These are the diseases transmitted through direct contact. e.g. AIDS is transmitted from an infected mother to her child during pregnancy. AIDS is also transmitted through intimate contact between partners.
    •  Carriers: The most common carriers or vectors that transfer micro-organisms from one human being to another are female mosquitoes, dogs, hens, etc. e.g.  Rabies virus transmitted by dogs and cats bite.

Effects of infectious diseases
Immune system in our body is activated. It functions to attack the foreign invaders and protect the body.
Inflammation is the response exhibited by the active immune system to kill the infectious agents. Inflammation includes swelling, pain, fever etc.

Treatment of infectious diseases
The two ways to treat infectious diseases are by reducing the effect of the disease and by eliminating the cause of the disease.
Antibiotics are the medicines used to treat the diseases caused by bacteria, fungi and protozoans. e.g. penicillin
Anti-viral drugs are the medicines used to treat diseases caused by viruses. These drugs are difficult to be prepared when compared to anti-bacterial drugs.

Prevention of infectious diseases
    •  Airborne micro-organisms can be prevented by providing living conditions which are not over crowded.
    •  Water-borne micro-organisms can be prevented by providing safe drinking water.
    •  Vector-borne diseases can be prevented by providing clean environment.
    •  Public hygiene is a basic step in the prevention of infectious diseases.
    •  Proper and sufficient food is necessary for the immune system to work properly.
    •  Immunisation through vaccine.

Immunisation and vaccine
Immunisation is the protection of individuals from communicable diseases by administration of a suspension of dead micro-organisms.

Vaccine is a biological preparation that improves immunity to a particular disease after inoculation. e.g. smallpox vaccine was the first vaccine developed against small pox by Edward Jenner, hence called "Father of Immunology".

Summary

Transmission
Transmission is the process of passing something from one individual to another individual. Infectious diseases are spread through microbial organisms from an infected person to a healthy person.

Microorganisms are transmitted through physical contact, air, water and carriers. 
    •  Air borne diseases:These are the diseases transmitted through air. Microorganisms are transmitted in the form of droplet nuclei in the air. e.g. common cold, pneumonia and tuberculosis.
    •  Waterborne diseases: These are the diseases transmitted through water. Excreta of infected animals and humans contaminate drinking water. e.g. cholera 
    •  Physical contact: These are the diseases transmitted through direct contact. e.g. AIDS is transmitted from an infected mother to her child during pregnancy. AIDS is also transmitted through intimate contact between partners.
    •  Carriers: The most common carriers or vectors that transfer micro-organisms from one human being to another are female mosquitoes, dogs, hens, etc. e.g.  Rabies virus transmitted by dogs and cats bite.

Effects of infectious diseases
Immune system in our body is activated. It functions to attack the foreign invaders and protect the body.
Inflammation is the response exhibited by the active immune system to kill the infectious agents. Inflammation includes swelling, pain, fever etc.

Treatment of infectious diseases
The two ways to treat infectious diseases are by reducing the effect of the disease and by eliminating the cause of the disease.
Antibiotics are the medicines used to treat the diseases caused by bacteria, fungi and protozoans. e.g. penicillin
Anti-viral drugs are the medicines used to treat diseases caused by viruses. These drugs are difficult to be prepared when compared to anti-bacterial drugs.

Prevention of infectious diseases
    •  Airborne micro-organisms can be prevented by providing living conditions which are not over crowded.
    •  Water-borne micro-organisms can be prevented by providing safe drinking water.
    •  Vector-borne diseases can be prevented by providing clean environment.
    •  Public hygiene is a basic step in the prevention of infectious diseases.
    •  Proper and sufficient food is necessary for the immune system to work properly.
    •  Immunisation through vaccine.

Immunisation and vaccine
Immunisation is the protection of individuals from communicable diseases by administration of a suspension of dead micro-organisms.

Vaccine is a biological preparation that improves immunity to a particular disease after inoculation. e.g. smallpox vaccine was the first vaccine developed against small pox by Edward Jenner, hence called "Father of Immunology".

Videos

Activities

Activity 1
Centreofthecell.org unravelled the difference between good bacteria and bad bacteria. User needs to click on the 'Kill the bad bacteria' button. Using the mouse button click on the target which is displayed as a small circle. Just by clicking on the bacteria, user will be scored displayed under two categories as 'Good killed' and 'Bad killed'. The damage will not be shown in a bar which id highlighted with red colour.
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Activity 2
Centreofthecell.org has designed a template to explain about 'Flu Epidemic'. Student has to enter the game by clicking on the 'Start' button. An imaginary case study is explained and user has to follow the instructions and act accordingly to stop the spread of the disease named as 'Flu'. This is a viral disease which spreads very fast as it does not respond to antibiotics. It does not even has any vaccine for prevention.This has to be stopped from spreading all over the country. User has to act smart and stop it. Just click on 'Continue' button and follow the instructions.
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References

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