Does a handshake, a shared plate or a mosquito bite give you AIDS? No. So how does the virus really spread, and what does it do once it is inside the body?
1. What AIDS is
AIDS is one of the deadliest diseases in the world, and it is a contagious one. It was first found in America in 1981, and since then it has been recognised as a killer disease. It is found mostly in Africa.
The human body has a natural system of immunity: the lymphocytes of the blood make antibodies to fight disease. A person who gets this disease loses that immunity, which is why it is called AIDS, short for Acquired Immune Deficiency Syndrome.
2. What the virus does inside
AIDS is caused by HIV, the Human Immuno Deficiency Virus (Figure 1.08). It enters the blood stream, attacks the T-lymphocytes of the white blood cells and destroys the body's natural immune system. Tap the virus in the picture.
Figure 1.08tap the virus
HIV among the blood cells
HIV. It attacks the T-lymphocytes of white blood cells.
The virus aims at the T-lymphocytes, and when they go, the immune system goes with them.
Drawn by hand after the book's figure, not to scale.
Once the immune system is destroyed, the body is attacked by rare diseases, such as respiratory diseases, brain diseases, gastro-intestinal diseases and tumours. Walk through the whole path one step at a time.
step by steppress next
From HIV to AIDS
Step 1. HIV enters the blood. The virus reaches the blood stream.
Step 2. T-lymphocytes are attacked. The virus attacks these white blood cells.
Step 3. Immunity is destroyed. The body's natural immune system no longer works.
Step 4. Rare diseases attack. Diseases of the respiratory tract, brain and gut, and tumours, attack the body.
For the first 5-10 years after HIV infection, no symptoms usually show in the body. Such persons act as carriers and can infect others. So looking healthy does not mean being free of the virus.
See those quiet years. Drag the years: the T-lymphocytes fall without a sound, and the symptoms come much later.
drag and seeDrag to the end
The years after infection
The line is a model, not measured. The 5-10 symptom-free years and the rare diseases are the book's.
3. How it spreads, and how it does not
HIV travels in body fluids such as blood and sperm. The main routes: unprotected sexual relations; from a pregnant woman who has it to her child; by breast-feeding of newborns; by blood transfusion from an affected person; and by one syringe used by several drug addicts.
AIDS is not transmitted by food, water, insects or external touch of the body of an AIDS patient. So there is no reason to avoid an affected person; what they need is kindness and treatment. Tap the eight chips and check.
classifytap a chip
Spreads or not
Spreads. Blood from an affected person carries the virus straight into the blood stream.
Does not spread. AIDS is not transmitted by food.
Spreads. When several drug addicts use one syringe, the virus passes through blood from one body to another.
Does not spread. AIDS is not transmitted by water.
Spreads. It passes from an affected pregnant woman to her child, and through breast-feeding of a newborn.
Does not spread. AIDS is not transmitted by insects.
Spreads. The virus spreads through sperm and other body fluids.
Does not spread. Touching the outside of an affected person's body does not spread AIDS.
Four spread it and four do not. The virus travels in blood and body fluids, not by outside contact.
4. Prevention and control
The most important thing in prevention is telling people how AIDS is transmitted. Knowledge about unprotected sexual relations, awareness of the danger of drug users' syringes and care in giving and receiving blood reduce the risk. The government and social organisations can build public awareness.
Recently, bone marrow transplants have experimentally cured some AIDS patients completely. The disease can also be kept under control with oral medication, although it is not completely cured.
5. Check yourself
Three questions, the first on the name.
check yourselfpick one answer
Question 1
HIV attacks which of the following?
Not red blood cells. The right answer is: White blood cells.
Right. HIV attacks the T-lymphocytes of white blood cells.
Not platelets. The right answer is: White blood cells.
Not plasma. The right answer is: White blood cells.
In the second, find the virus's target.
check yourselfpick one answer
Question 2
Through which of these can HIV spread?
Right. HIV can spread by the same syringe used by several drug users.
It does not spread through water. The right answer is: Use of the same syringe by several drug users.
It does not spread through insects. The right answer is: Use of the same syringe by several drug users.
It does not spread through food. The right answer is: Use of the same syringe by several drug users.
In the last, think about which route the virus takes.
check yourselfpick one answer
Question 3
Which cells does HIV attack after entering the body?
Right. HIV attacks the T-lymphocytes of white blood cells.
B-lymphocyte is not in the book. The right answer is: T-lymphocyte.
Hepatocyte is a liver cell. The right answer is: T-lymphocyte.
Erythrocyte is a red blood cell. The right answer is: T-lymphocyte.
The whole note on seven cards.
cut from the notetap to turn over
Seven cards
QuestionWhat is the full form of AIDS?
AnswerAcquired Immune Deficiency Syndrome
QuestionWhich virus causes AIDS, and what is its full form?
AnswerHIV: Human Immuno Deficiency Virus
QuestionWhich cells does HIV attack?
AnswerThe T-lymphocytes of white blood cells.
QuestionName some ways HIV spreads.
AnswerUnprotected sexual relations, mother to child, blood transfusion, shared syringes.
QuestionBy what does AIDS not spread?
AnswerFood, water, insects or external touch of the body of patients.
QuestionWhat is the most important thing in preventing AIDS?
AnswerInforming people how AIDS is transmitted.
QuestionIs AIDS completely cured by medicine?
AnswerNo; oral medication keeps it under control; bone marrow transplants experimentally cured some patients.