1.1 Introduction

Section 1 starts with your body and the way that it fights infections using the immune system.

• HIV is a virus, so you need to know how your body reacts to a virus.
• HIV is a virus that attacks the immune system – the parts of your body that fights viral infections – so you need to understand how your immune system is damaged by HIV.

1.2 Aims for this section

After reading section 1, advocates will have a basic understanding of:

• The ways a scientist or doctor understands the immune system
• CD4 cells and CD4 tests and what they mean
• How the CD4 count is used to monitor HIV infection
• Use of CD4 count in treatment decisions and guidelines