How strong is your immune system?
HIV can attack many cells in the body, but its effect on the immune system can be measured by seeing how HIV reduces certain white blood cells. The T4 white blood cell (also known as the CD4 or T-helper cell) can be counted and this tells the strength of the immune system. When the T4 cell count goes down, it's harder for the immune system to fight disease.
A person's T4 cell count can go up and down for many reasons. A normal immune system usually has between 700 and 1200 T4 cells. There are different normal levels for different laboratories. The one I use, has a normal level down as far as 500. So I've been told to try to use the same lab, that way my results are accurate to their counts. A person with fewer than 500 T4 cells is more likely to develop an illness. People who have HIV and a T4 cell count of 200 or below have an even greater chance to develop a serious illness. Try not to panic if you have a low number of T4 cells. Many people with a low T4 cell count are doing fine and have no symptoms.
One of the new tests that is being done is called the Viral Load. This one was a little harder for me to understand how it works, but basically, it measures the virus present in the blood. It is a more accurate and direct way to measure the virus and can predict the progression to AIDS. Some of the new medications that are available now, are used to reduce the viral load.
Please remember this information is from my own personal research, as someone trying to learn about my disease.