An Introduction to CD4 and Viral Load

Whenever you hear discussion of HIV you probably notice a lot of talk about, “CD4 Counts,” and, “Viral Loads.” If these terms make your head start spinning this post should help explain just what they are, and how they relate to one another.

CD4 cells are a type of white blood cell found within all of our bodies. They are also known as, “T-Cells,” and are important because they find bacteria, viruses, and all other kinds of invading germs which they work to try and destroy. In other words, your CD4 cells are an integral part of your immune system. The unique thing about HIV is that it actually targets and attacks CD4 cells. The body will fight against HIV but over time HIV can wear-down these cells, resulting in the number of CD4 cells in your body or, “CD4 count,” being dangerously low. A low CD4 count will result in other viruses and bacteria (also known as opportunistic infections) being able to attack the body with little resistance, resulting in a variety of ailments possibly afflicting someone who has a poor CD4 count.

higher cd4

A normal CD4 range is between 500-1500 per cubic millimeter of blood. When someone has HIV the virus will wear this down to a point where when someone can have a CD4 count of 200 or less–which is when they have developed an AIDS diagnosis. Please note this therefore means that the occasional misconception that HIV and AIDS are in some way different is false–AIDS is simply a status reached by someone when HIV has been in their system attacking the CD4 cells.

What exactly is it within HIV that harms the CD4 count, however? That would be the viral load. Measured by cubic millimeter of blood just as with the CD4 count, the lower a viral load someone has the less HIV virus is in their system attacking their CD4 cells. If someone has a low-enough viral load their CD4 cells will increase instead of decrease as there is less HIV attacking them. Someone infected with HIV can have a viral load that is so low with the use of medications that it is in fact undetectable (which does not mean they are now HIV-negative, just that their viral load is so low tests have difficulty identifying it). Depending on the test a person can be undetectable if their viral load is less than 20 with some of the most sensitive tests, although other tests are unable to detect a viral load anywhere under 75.

viral load image

If a viral load of under 20-75 is undetectable and allows the body to rebuild its immunity that would raise the question of just how high a viral load can go. It is possible for it be in the hundreds of thousands. A viral load that is over 100,000 is therefore extremely severe as the body will find its CD4 cells being constantly attacked and worn-down by the HIV virus whereas someone who is taking medication and undetectable will be able to treat HIV as simply a chronic condition they manage. This gets to the crux of how CD4 cells and the viral load impact one another.

If someone has a high viral load is will harm their CD4 count, but a low viral load achieved through treatment and medication will allow the body’s natural immunity to increase and fight-off other opportunistic infections. This illustrates just how important it is to seek out medical professionals to help if you are HIV-positive. The difference between treating your HIV or not can be that of an undetectable status and high CD4 count or a viral load in the hundreds of thousands and a CD4 count in the single-digits.

cd4 important.png

Hopefully this introduction to all the CD4 and Viral Load talk you may have heard has been helpful. This is just a primer, but you can always come visit us at one of our agency locations if you desire to learn even more or have questions about other health matters. Plus, we of course offer free HIV tests so you can know your status as well!


CD4 Definitions:

Normal CD4 Range Discussion:

Article about the differences between CD4 and Viral Load:

Viral Load test information:

Further CD4 and Viral load information, also the source of the featured post image:


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