The Human Immunodeficiency Virus (HIV). It is a retrovirus which infects cells of human immune system, impairing or destroying their functions. At the early age of this infection, the person has no symptoms. However when the infection progresses, the immune system becomes very week which results in critical condition of the infected person.
The most advanced stage of HIV is Acquired Immunodeficiency Syndrome or AIDS. It can take 10-15 years for an HIV-infected person to develop AIDS; antiretroviral drugs can slow down the process even further.
