HIV and AIDS

Three weeks ago, Mark had unprotected sex, and today he feels a bit unwell, as if he has the flu. But it’s not flu season, so Mark makes his way to the sexual health clinic to get tested for any sexually transmitted infections. A couple of days later, he receives the results — he is infected with the human immunodeficiency virus, better known as HIV. HIV is transmitted from person to person through bodily fluids, for example when an infected person has unprotected sex. It can also pass from an infected mother to a child during pregnancy, delivery or breastfeeding.

Or if an infected person uses a needle to inject drugs, and then this needle is shared with someone else. When HIV enters the body, it’s detected by the body’s defense — its immune system. The white blood cells, which are part of the immune system, quickly send out molecules attacking the virus. This is why Mark started experiencing flu-like symptoms — it’s the body fighting against the virus! But the HIV virus overwhelms those defences.

How? It infects one type of immune cell, vital for the body’s response to viruses and bacteria, causing diseases — the helper T-cell. HIV first attaches to and then enters T-cells. Once inside the cell, the virus uses the T-cells to make more of itself! It does this by making its own genetic material part of the T-cell’s genetic material, forcing the T-cell to make more copies of the HIV virus.

These new copies of the virus are then able to infect more cells, which produce even more copies of the virus. So the levels of HIV virus in the body rise rapidly. The immune system keeps fighting the infection. Inside infected cells, molecules try to stop the virus from inserting its own genetic material into that of T-cells. Other types of immune cells, the natural killer cells, are also released at this stage, to destroy the infected T-cells.

While this is happening, people infected with HIV don’t experience any symptoms — as if nothing were wrong at all. That’s why people infected with HIV can go years without knowing they carry the virus. But after a while HIV manages to defeat the immune system’s defences. Now, HIV disables the molecules inside T-cells that were trying to stop the virus. HIV is once again able to insert its genetic material into that of the T-cell.

So more and more copies of the virus can be made and released into the bloodstream. The virus also keeps changing inside the body, so that the immune system can no longer detect it. The immune system ends up exhausted. The body can no longer produce new immune cells to replace the destroyed ones. The immune system is shattered and no longer able to fight even the most common infections, such as a simple cold.

It may take months, but more likely years for this breakdown to happen. This is the stage of HIV infection, known as acquired immunodeficiency syndrome — AIDS. People don’t die of AIDS, they die of other infections that the body can’t fight. A couple of decades ago, becoming infected with HIV was very bad news, as there was no known treatment. But for Mark, an HIV diagnosis doesn’t have to mean the end of his life.

We don’t have a way of completely clearing the body of HIV. But we have antiretroviral treatments available that can lower the levels of the virus... ...so the infected person no longer spreads HIV and can live a much longer, healthier life.