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Dealing with Harmful Microorganisms

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Dealing with Harmful Microorganisms - Lesson Summary

Harmful microorganisms
Harmful microorganisms can spoil our food, leather, clothing etc. One another harmful effect of microorganisms is that they cause diseases in plants, animals and even human beings.

Harmful microorganisms which cause disease are called as infectious agents.  These are harmful in nature and are also called as pathogens.

1) Pathogens can mostly cause communicable diseases.
       •  Communicable diseases are the diseases which are transmitted from one person to another by different modes of infection. Body fluids of the infectious person carry disease causing organisms. e.g. Discharge from nose, mouth, eyes and the faeces carry these pathogens. Healthy person coming in contact with such infected discharges develops the disease and becomes sick.

2) Pathogens select carriers to reach their particular host. Insects, rodents, sometimes even sheep, pigs and many other animals become carriers for pathogens to reach their final host.

3) Pathogens can be microorganisms which obtain nourishment from the host. e.g. Bacteria, Viruses, Fungi, Protozoa, Helminths.

Harmful effects of microorganisms
Microorganisms show many harmful effects on us. Some of them are elucidated.

Modes of infection
Infection is the transmission of pathogens from diseased individual to healthy individual.

Common diseases in human beings

DISEASE MICROORGANISM MODE OF TRANSMISSION Cholera Bacteria Contaminated food and water Typhoid Bacteria Water Tuberculosis Bacteria Air Polio Virus Contaminated water and air Chickenpox Virus Contaminated air, food, water and direct contact Measles Virus Air Hepatitis-B Virus Contaminated water AIDS Virus Infected needles, blood transfusion and sexual contact. Malaria Protozoa Mosquitoes Amoebic dysentery Protozoa Conatminated food and water

Prevention of infection
       •  We can prevent the spread of infection by using a handkerchief while sneezing or coughing.
       •  Antibiotics are widely used to control the infection. Antibiotics are used to cure a variety of diseases caused by fungi, bacteria and protozoa. Penicillin was discovered by Alexander Fleming in 1929.
       •  Antibiotics, insecticides and pesticides are sprayed in the field to control many plant diseases.
       •  Infection can be prevented by using some bacteria or fungi which produce specific chemicals to prevent the growth of microbes causing disease.
       •  Antibiotics are mixed with the feed of livestock and poultry in order to prevent microbial infection in animals and birds.
       •  Vaccination is the process of administering vaccines.  Diseases can be prevented by vaccination.
       •  During vaccination inactivated or weakened microbescalled as vaccines are introduced into the body. They trigger the production of antibodies. When disease-carrying microbes enter our body, self-protecting proteins called antibodies fight against the invader. e.g. Small pox has been completely eradicated from the world by administering vaccine. Several diseases including cholera, tuberculosis and hepatitis, can be prevented by vaccination.

It is a medicine which triggers the immune system to produce antibodies against a particular disease. A vaccine actually contains organisms resembling disease causing microbes whose property of virulence is suppressed or weakened.

Steps in vaccine production:

Common diseases in plants

DISEASE MICROORGANISM MODE OF TRANSMISSION Rust of wheat Fungi Infected seeds and insects Smut disease Fungi Infected seeds and insects Root rot Fungi Infected seeds and insects Brown spot Fungi Infected seeds and insects Grain rot Bacteria Air Bacterial blight Bacteria Air Citrus canker Bacteria Air Leaf rolls Virus Insect, air Yellow vein Virus Insect, air


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