HIV/AIDS：ARE YOU AT RISK?
HIV is a virus．A virus is a very small living thing that causes disease．There are many different viruses，for example，the flu virus or the SARS virus．HIV weakens a person's immune system；that is，① the part of the body that fights disease．You can have HIV in your blood for a long time，but eventually HIV will damage your immune system so much that your body can no longer fight disease．This stage of the illness is called AIDS．If you develop AIDS，your chances② of survival are very small．
