What is AIDS? : Swiss AIDS Federation

The difference between HIV and AIDS

HIV is an incurable infection, but it does respond well to treatment so that it does not develop into AIDS. If you have been unsafe, it is important to recognise any symptoms and to get advice. Starting therapy in good time strengthens your immune system and improves your health.

AIDS (Acquired Immunodeficiency Syndrome) is the long-term result of infection with HIV (Human Immunodeficiency Virus). "Immunodeficiency" describes a weakness in the body's ability to defend itself against the pathogens (disease-causing agents) which cause illness. Advanced immune deficiency can lead to a number of serious illnesses, and later even death. An HIV infection cannot be cured. Once a person has been infected, regular medical check-ups are important so that they do not miss the best time to start treatment. HIV is treated with antiretroviral drugs. These must be taken every day without fail, and most likely for life.

What is HIV?

HIV is probably the best known sexually transmitted virus. An HIV infection that is left untreated will develop into AIDS. The body’s own immune defence no longer works, which makes AIDS fatal.

An HIV infection should be treated promptly. That way, your life expectancy remains comparable to that of a person without HIV. And an HIV-positive person undergoing successful treatment is no longer contagious.

NOTE: An HIV infection should be detected with a test and treated quickly. It’s important to keep the virus from further damaging your immune system. Shortly after the beginning of treatment, the viral load in your blood becomes undetectable, which means that you can no longer infect anyone.

Flu-like symptoms (fever, swollen lymph nodes, fatigue, etc.) after a high-risk situation could be signs of an HIV infection. If that happens, you should go to a counselling centre or see your doctor immediately to discuss a possible HIV infection.

How does an untreated HIV infection proceed?

Untreated, the HIV infection passes through three stages starting from the transmission of the HIV infection until the onset of AIDS.
The duration of these stages is different from person to person. That is why there is a huge variation in the amount of time someone is able to live HIV positive and symptom free: from a few months to over fifteen years. How intensely the HIV viruses replicate and thus damage the immune system is measurable at any time in a laboratory by means of a blood test.

Stage 1: Primary infection and latency phase

In the first weeks after infection the viral load increases quickly. This is why in this phase the HIV virus is especially easy to pass on to sexual partners, both male and female. During this time, symptoms often appear similar to those of a cold or mild flu: fever, rash, tiredness, headache. Many affected people and even doctors do not notice these symptoms or do not connect them with an HIV infection. Therefore, it is important to discuss them when you visit your doctor. More about Primary infection

Stage 2: latency phase


The symptoms of the first phase disappear spontaneously after a few weeks, as the immune system reacts to the attack of the HI virus with antibodies. For the time being the HIV infection proceeds unobtrusively. As a rule, it’s possible to remain HIV positive and symptom-free for years and lead a normal life. The virus nevertheless spreads stealthily and constantly puts strain on the immune system.

Stage 3: Phase with general symptoms

Due to the continuous exposure to the HI virus, the immune system becomes weaker, it can no longer defend itself sufficiently against all pathogens. The body now increasingly shows signs of an immune deficiency. This can manifest as skin diseases, continuous swelling of the lymph nodes, extreme night sweats and further symptoms.

Stage 4: AIDS

In this stage, the immune system is so severely affected that it can no longer prevent severe, life-threatening diseases. When certain combinations of diseases emerge, one talks about AIDS.
The scope of the so-called “AIDS defining” diseases is large. They range from cancer to certain forms of pneumonia to a fungus of the oesophagus. After the onset of AIDS, life expectancy without treatment ranges from a few months to three years.


If you have any questions about HIV or noticeable symptoms, get advice from your regional AIDS centre or your GP.

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