Immunity and Immunisation

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Immunity and Immunisation

Sindiso Marume holding her brother's health card. Image credit irinnews.org

Sindiso Marume holding her brother’s health card. Image credit irinnews.org

ZIMSEC O Level Combined Science Notes: Disease:Immunity and Immunisation

Immunity-is the ability of the body to resist diseases
There are various types of immunity:

Type of Immunity	How it is acquired
Naturally acquired active immunity	Antigens enter the body naturally resulting in the body being stimulated to produce antibodies against a specific antigen leading to recovery. That information gets stored in the brain for use if the body is exposed to the same infection in future This has a long term effect
Artificially acquired active Immunity	Antigens introduced into the body by means of a vaccine The body, through trial and error, eventually produces the corrent antibodies against the antigen The information is stored for future use by the brain to allow for fast recovery if the body is exposed to a similar infection in the future
Naturally acquired passive immunity	Receiving ready-made antibodies as in the case with infants when they receive antibodies from their mothers: Through the placenta before birth Through breastfeeding after birth
Artificially acquired passive immunity	Obtained by injecting a serum containing antibodies into the body This is a form of immunity that is given when there is risk of infection and there would be no time for the body to produce its own antibodies before the symptons of the infection are felt/death occurs The serum isprpared from the blood of an animal e.g. a horse/mouse that is activiley immunised The plasma of the animal is collected other elements are removed leaving only the antibodies

Antigen-is any substance that causes the body’s immune system to produce antibodies against it
It may be a foreign substance from the environment such as bacteria, chemicals, viruses, pollen etc
Or it may be formed within the body for example toxins produced by bacteria
Antibodies/Immunoglobulin- is a special protein used by the immune system to identify and neutralize foreign objects like bacteria and viruses

Immunisation of infants

Is important to prevent them from contracting diseases such as polio, measles etc
By Zimbabwean law all infants are required to be artificially immunised against certain diseases as shown below

	Age	Immunisation
Primary Courses	Birth 3 Months 4 Months 5 Months 9 Months 18 Months 5 years	BCG (Against Tuberculsis/TB) DPT₁,Polio 1 DPT₂,Polio 2 DPT₃,Polio 3 Measles DPT and Polio BCG, DT, Polio
Boosters	Girls 10-14 years Girls and boys at 13 years 15-19 years	Rubella(German measles) Tuberclosis Tetanus, Polio

NB In the acronym DPT-

D-Diphtheria
P-Pertussis/ Whooping Cough
T- Tetanus
The BCG immunisation will be repeated if there is no scar after 3 months
BCG is used against diseases such as meningitis, TB, miliary disease

To access more topics go to the Combined Science Notes page

By Garikai Dzoma|2017-01-17T11:11:35+02:00August 18th, 2016|Notes, O Level Science Notes, Ordinary Level Notes|Comments Off

About the Author: Garikai Dzoma

He holds an Honours in Accountancy degree from the University of Zimbabwe. He is passionate about technology and its practical application in today's world.