HIV (HUMAN IMMUNODEFICIENCY VIRUS)

HIV stands for human immunodeficiency virus.

This is the virus that causes AIDS. HIV is different from most other viruses because it attacks the immune system. The immune system gives our bodies the ability to fight infections. HIV finds and destroys a type of white blood cell (T cells or CD4 cells) that the immune system must have to fight disease.

For more information view CDC's questions and answers on "HIV Science".

AIDS stands for acquired immunodeficiency syndrome.


AIDS is the final stage of HIV infection. It can take years for a person infected with HIV, even without treatment, to reach this stage. Having AIDS means that the virus has weakened the immune system to the point at which the body has a difficult time fighting infections. When someone has one or more of these infections and a low number of T cells, he or she has AIDS.


Course of an HIV infection


The course of untreated HIV infection can be divided into three phases: The acute HIV disease, then the latency phase and finally the disease of Aids, ending in death. The acute HIV disease lasts a few weeks. This period is also know as the window of vulnerability, since it is characterised by an explosive replication of the HIV. During this phase, the HIV invade the organs of the defence system and other bodily organs and establish themselves there. The latency phase lasts on average 10 years, during which the virus concentration is relatively low. In the Aids phase the defence system is completely destroyed, as the result of which death occurs after 1-2 years.

 
Weakening and destruction of the immune system



The defence system (immune system) has two main jobs: as well as combating outside invaders such as bacteria, viruses, fungi etc., which give rise to so-called infectious diseases, it also prevents cancer by tracking down and destroying the body's own damaged or degenerate cells.

It takes several years before the human immune system is defeated by the HIV infection. A veritable war goes on between the immune system and the viruses, with many battles. We know now that as early as a few days after infection (during the acute infection stage) several thousand million (!) new viruses are formed and at the same time thousands of millions of helper cells are destroyed. Hence, 2-3 weeks following infection, the acute HIV infection (= primo-infection) can appear, which subsides again after about 6 weeks, when the human immune system has gained the upper hand in the first battle. Even during the symptom-free latency period, the viruses replicate with extraordinary vigour. The human immune system kills as many HIV as are produced, maintaining equilibrium year upon year. When AIDS itself occurs, the immune system becomes exhausted and the quantity of virus steadily increases. The weakening of the immune system through HIV infection makes people increasingly vulnerable, especially to infectious diseases and cancer.

Symptoms of HIV Infection


The only way to know whether you are infected is to be tested for HIV.

You cannot rely on symptoms alone because many people who are infected with HIV do not have symptoms for many years. Someone can look and feel healthy but can still be infected. In fact, one quarter of the HIV-infected persons in the United States do not know that they are infected.


Antiretroviral therapy (ART)



The current therapy for HIV infection is called HAART (Highly Active AntiRetroviral Therapy) and consists of a combination of at least three different active ingredients. There are more than 20 different drugs in use.

A successful HAART suppresses the viral load (concentration of the HIV in the blood) to below the detection threshold and indirectly increases the number of T-helper cells. Due to these drugs, HIV infection can be changed from a fatal illness into a chronic illness. This can not only prevent the appearance of symptoms, but the risk of infection can also be significantly reduced.

The drugs all prevent replication of HIVs via various mechanisms, by interrupting the replication cycle. However, these drugs can only work over the long term, if they are taken daily, 365 days a year.

Due to antiretroviral therapy (ART), people infected with HIV are living significantly longer and have a better quality of life. But ART cannot completely eliminate the HIV in a person and it cannot effect a cure. The drugs must be taken for a lifetime, which is a heavy burden on the patient. As soon as the drugs are stopped, the viruses replicate again explosively. Sometimes the drugs are not tolerated or the HIV are resistant to these drugs, so they no longer work. Despite ART, more than 100 people still die from Aids every year in Switzerland.