1. HIV

2. Learning Objectives Outline the structure of HIV Discuss the means of transmission and how the spread can be controlled

3. To begin.. Write down everything you already know or understand about HIV

4. What is HIV? HIV (Human Immunodeficiency Virus) causes the disease AIDS (Acquired Immunodeficiency Syndrome). At present there is no cure for the disease. Treatment is available which can prolong the life of the sufferer, but the body remains infected.

5. Structure of the Virus A virus is many times smaller than a bacteria and show no signs of life when outside of a cell. They are described as OBLIGATE INTRACELLULAR PARASITES. HIV is a retrovirus – all of its genetic information is in the form of RNA and a complimentary DNA copy is made using the enzyme REVERSE TRANSCRIPTASE (also present in the virus) The DNA copy is made double stranded and it can then insert itself into the DNA of the T helper lymphocyte.

6. Transmission The HIV virus spreads from one infected person to another in body fluids. Usually spread through sexual intercourse Transfer of infected blood e.g. sharing needles Infected mother to baby (although this can now be prevented through drugs) Blood transfusions (now blood samples are screened for HIV)

7. Transmission HIV enters the body and infects the T helper lymphocytes (particular type of white blood cell) Virus remains dormant for a long time No symptoms but their blood contains antibodies against the virus. At this stage, the person is said to be HIV positive.

8. Transmission After a few years, HIV starts to replicate Infected T helper cells release many new viruses and are then destroyed. During this stage, the body becomes susceptible to other infections (opportunistic infections) such as TB. At this stage, the person has AIDS and are likely to die within 2 years, either from AIDS or and AIDS related infection.

9. Controlling the Spread No cure but drugs are available which can slow down the development of AIDS. The most effective thing to do is ensure you do not catch it! Several ways of doing this…. Screening of blood before transfusions Using barrier protection during intercourse Use of sterile needles Education Offering HIV tests to at risk groups Encouraging people with HIV to contact sexual partners to inform them Encourage more people to take the test as a matter of course.