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Post  Admin on Sat Aug 07, 2010 10:14 pm

Human immunodeficiency virus (HIV) is a virus called lentivirus which is a member of the retrovirus family (the virus that causes acquired immunodeficiency syndrome (AIDS)).

Basically, what HIV does is to infect primarily vital cells in the human immune system such as helper T cells (to be more specific they are called CD4+ T cells), macrophages and dendritic cells. There are three main mechanisms in which HIV infection leads to low levels of CD4+ T cells.

1. Direct viral killing of infected cells
2. Increased rates of apoptosis in infected cells
3. Killing of infected CD4+ T cells by CD8 cytotoxic lymphocytes that recognize infected cells.

When CD4+ T cells numbers decline below a critical level, cell-mediated immunity is lost and the human body becomes progressively more susceptible to opportunistic infections.

So far, there are two species of HIV known to exist: HIV-1 (global virus) AND HIV -2 (mainly in the West Africa due to its poor capacity for transmission). HIV-1 is the virus that was initially discovered and termed both LAV and HTLV-III. It is more virulent, more infective and is the cause of the majority of HIV infections globally. The lower infectivity of HIV-2 compared to HIV-1 implies that fewer of those exposed to HIV-2 will be infected per exposure.

The routes of transmission are unsafe sex, contaminated needles, breast milk and transmission from an infected mother to her baby at birth (vertical transmission).

Infection with HIV-1 is associated with a progressive decrease of the CD4+ T cell count and increase in viral load. The stage of infection can be determined by measuring the patient’s CD+ T cell count and the level of HIV in the blood.
Basically, HIV infection has four stages: incubation period, acute infection, latency stage and AIDS. The initial incubation period upon infection is asymptomatic and usually lasts between two and four weeks, whereas the second stage, the acute infection , lasts an average of 28 days and can include symptoms such as fever, lymphadenophathy (swollen lymph nodes), pharyngitis (sore throat), rash, myalgia (muscle pain), malaise and mouth and esophageal sores.

The third stage, latency stage shows few or no symptoms and can last anywhere from two weeks to twenty years and beyond. AIDS, the fourth and final stage of HIV infection shows as symptoms of various opportunistic infections.

If you need to know more or have any question or comments, please do feel free to post your question or comments.

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