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HIV is a global pandemic. In fact, this is the largest pandemic in human history. In modern time, this disease is rather unusual. This is an infection for which we have no cure, no vaccine, and against which our immune system is helpless. The virus exploits the cells of our own immune system (called CD4+ T lymphocytes) as virus-producing factories.
HIV can now be successfully controlled by drugs
Lots of drugs against HIV were developed since the emergence of infection. None of the existing drugs provide cure but they allow to control infection and prevent development of AIDS (Acquired Immunodeficiency Syndrome). HIV infected patients are considered as having AIDS if their level of CD4+ cells falls below 200 cells per microliter of blood. Healthy individuals have CD4+ count between 500 and 1200 cells per microliter.
The number of drugs against HIV is constantly growing and now we can manage the disease quite effectively. Introduction of HIV protease inhibitors in the 1990s was the turning point in the efficient HIV control. The use of modern drug combinations largely prevents the development of drug resistance. Now most people with HIV in the industrialized countries can expect to live almost as long as any uninfected person.
Best time for starting HIV therapy is still not known
HIV can take up to 10 years to get developed into AIDS. For many years after initial infection people with HIV have no health problems. Because of this long delay in the disease development, doctors were always unsure what is the best time point to start the therapeutic intervention. Anti-HIV drugs do have side effects that can lead to other health problems after many years of use. Besides, longer drug usage means higher chances of developing drug resistance. On the other hand, allowing the immune system to deteriorate too much before starting the therapy may lead to the development of HIV associated sicknesses and slower recovery once drugs have started.
As a consensus solution, medical practitioners monitoring HIV-infected patients wait for CD4+ count to drop to an intermediate level which is lower than the cell number in healthy people but still above 200 cells per microliter, the level of AIDS. In the UK, this consensus level at which drugs are started is 350 cells per microliter, in the USA – 500 cells per microliter.
Large international trial (called START - Strategic Timing of Antiretroviral Treatment) is currently on the way to find out which patients have better treatment outcomes – those who start the therapy immediately upon diagnosis, or those who wait till CD4+ level drops well below healthy norm.