HIV

The course of an HIV infection

Follow it from the moment the virus arrives to the point the immune system can no longer cope — and watch for the stage where the path forks.

1. 1HIV passes from one person to anotherHIV is spread by sexual contact, or by the exchange of body fluids such as blood — which is what happens when drug users share needles.+
2. 2An early flu-like illnessHIV initially causes a flu-like illness, so the first sign of infection looks like something ordinary.+
3. 3The fork: is the virus controlled?Antiretroviral drugs can control HIV. Where the virus is successfully controlled, it does not go on to attack the body's immune cells, and the rest of this course is never reached.+
4. 4Uncontrolled, the virus attacks the immune cellsUnless it is successfully controlled with antiretroviral drugs, the virus attacks the body's immune cells.+
5. 5Late stage HIV infection: AIDSLate stage HIV infection, or AIDS, occurs when the body's immune system becomes so badly damaged that it can no longer deal with other infections or cancers.+

Which measure would actually reduce the spread?

Decide before you read on. Ask of each one: does it close a route HIV actually travels by?

A city wants to reduce the number of new HIV infections. Which of these measures works on a route by which HIV is genuinely passed on?

The five words this topic turns on

Cover the definition and say it in your own words before you reveal it.

What you need to know

• HIV is spread by sexual contact, or by the exchange of body fluids such as blood — which occurs when drug users share needles.
• HIV initially causes a flu-like illness.
• Unless it is successfully controlled with antiretroviral drugs, the virus attacks the body's immune cells.
• Late stage HIV infection, or AIDS, occurs when the body's immune system becomes so badly damaged that it can no longer deal with other infections or cancers.
• Viruses live and reproduce inside cells, causing cell damage — and in an uncontrolled HIV infection the cells damaged are the body's own defensive ones.

The big picture

HIV is a virus with a habit that makes it unlike almost any other: the cells it reproduces inside are the very cells the body defends itself with. Follow one infection from the moment it is passed on to the point it can end, and two things stop being confusing — why the course of the infection has a fork in it, and why HIV and AIDS are not two names for the same thing.

⚠ Watch out

Using 'HIV' and 'AIDS' as if they were one word — writing that someone 'caught AIDS', or that infection always ends there. HIV is the virus that is passed on; AIDS is the late stage reached only when the defence has been damaged too far.

Memory hook

One virus, one fork, two futures. CONTROLLED — the immune cells are never reached. UNCONTROLLED — the defence itself is what the virus destroys, and that destruction is what AIDS names.

Check yourself

A friend's flu-like symptoms cleared up weeks ago, so they say the infection has gone. What is wrong with that, and what does the rest of the course depend on?