AlDS stands for ‘Acquired Immune Deficiency Syndrome’ a disease in which the body’s immune system breaks down. A virus called the human immunodeficiency virus (HIV) causes AIDS. HIV specifically targets key components of the cellular immune system and depletes the body’s ability to fight infection.

In medical terminology HIV is a retrovirus this means it can copy its genetic material RNA into DNA using a unique enzyme called reverse transcriptase.

Normally, living organisms make RNA out of DNA but in retroviruses such as HIV, the step is in reverse that is it makes DNA out of RNA. HIV inserts its DNA copies into the DNA of the cells of the immune system, turning them into HIV factories and preventing them from protecting the body.

HIV is also a highly variable virus which hides in other parts of the body such as the lymphatic system and establishes strongholds beyond the reach of the immune system or drugs.

When a person is first infected by HIV there is a burst of activity as the virus multiplies. The immune system attempts to battle it by making antibodies. During this period, the viral load (the number of virus particles the body is carrying) is high and the infected person is highly infectious.

But a person’s HIV status can not be detected at this stage by conducting tests because sufficient antibodies have yet to be formed.

This is commonly called the window period and lasts from several weeks to about three months. It may take five years to ten years for an HIV positive to develop AIDS.

An infected person usually experiences an episode of illness at the end of the window period but this often resembles a simple bout of influenza and may pass unnoticed.

The symptoms could include lack of energy, fever and night sweat and diarrhea over a period of a more than a month.

The medicines which are used to fight HIV infection are known as