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| Active and Passive Immunity |
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| Active immunity develops as a result of the contact of an individual with pathogenic organisms or their products. They stimulate the body to produce antibodies in response to the antigens. The immunity thus produced is specific for a particular disease. |
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| For e.g., the immunity established against typhoid, chicken-pox or measles is not effective against cholera or tuberculosis. Immunity may be acquired either through the infection of a pathogen or through administration of a vaccine. Active immunity takes a few weeks to a few months to develop but persists for long periods, even for a lifetime. |
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| Passive immunity is produced when antibodies formed in one human being are transferred to another non-immune individual. It may be acquired through: |
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| (1) Transmission of maternal antibodies to the foetus through the placenta. |
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| For e.g., Chicken-pox and measles |
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| (2) Injection of antiserum prepared against a specific disease. For e.g., Tetanus, Diphtheria and rabies. |
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| (3) Administration of immunoglobulins. The transfer of lymphocytes also gives passive cellular immunity. |
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| Passive immunity is rapidly established but lasts for a short while. |
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