I was born in Africa, nobody is sure exactly when, but there is proof that states I was around in 1959. I moved to North America sometime in the seventies, though nobody really noticed me until very early in the the eighties. I have since travelled all the world, making myself home in each and every country.My name is HIV, which stands for Human Immunodeficiency Virus.'Human' comes from the fact that I only infect humans. I have cousins, SIV (Simian Immunodeficiency Virus) and FIV (Feline Immunodeficiency Virus), among others, but this indicates that I can only be passed from human to human, I cannot be passed from, say, a monkey to a human.'Immunodeficiency' can be a bit of a mouthful. Basically, your immune system is made up of many kinds of white blood cells. One type in particular, CD4 cells (also called T-cells), make a perfect host for me. I invade these cells, which just happen to be the ones that coordinate the whole battle plan for the rest of your immune system, and for each cell that I invade, I destroy it and make 500 copies of myself, each copy in turn finding, destroying, and replicating in other CD4 cells. Killing off these CD4 cells creates a deficiency in your immune system, which is my middle name!'Virus' alludes to the fact that I am, indeed, a virus. One that just so happens to be a million times smaller than a human cell.All that destroying and replicating I do can be very hard on the immune system, and after your immune system is too weak to continue putting up a fight, I move into my next stage - AIDS.AIDS stands for Acquired Immune Deficiency Syndrome.'Acquired' means that I don't just float around in the air, waiting to be picked up by some poor fool who didn't wash his hands, she can't catch me from sitting on a dirty toilet seat, I'm not genetic, meaning that you're not going to get me just because your aunt, uncle, father, mother, brother, sister or cousin had me... you've got to DO something that brings me into your blood stream.I'll just group 'Immune' and 'Deficiency together, as I believe you've already got a basic understanding:
A healthy immune system has anywhere from 500-1500 CD4 cells per microlitre of blood. In the United States, AIDS is defined as having less than 200 CD4 cells per microlitre of blood.'Syndrome' - A syndrome is, quite simply, a collection of symptoms. There is a number (26) of specific symptoms that are associated with AIDS infection. These are called opportunistic infections (OI's), and are called so because they take advantage of the weakened immune system. OI's include various sorts of cancers, pneumonias and other diseases that rarely affect those with healthy immune systems. In Canada, AIDS is defined as having one or more opportunistic infections along with the presence of HIV.
