The Human Immunodeficiency Virus (HIV) is an infection which can sometimes develop into Acquired Immunodeficiency Syndrome (AIDS). It is most commonly passed on by sexual contact. The virus attacks the infection fighting cells of the immune system which, over time, weakens and becomes unable to defend the body against bacteria, viruses and germs.

For more information visit the NHS Direct website :- http://www.nhsdirect.nhs.uk/articles/article.aspx?articleID=196