Sunday, August 17, 2008


What is HIV/AIDS?


HIV- (human immunodeficiency virus) belongs to the retrovirus family (HIV-1 and HIV-2). Retroviruses are unique because they possess the enzyme reverse transcriptase. Reverse transcriptase allows the viral RNA genome to be replicated into DNA, rather than the usual RNA copies. The HIV attacks the immune system, the body’s natural defense system. Without a strong immune system, the body is unable to fight any disease that it encounters.

Both the virus and the infection it causes are all together referred to as HIV infection. The virus takes over certain immune system cells to make many copies of its own (replication). While many viruses can be controlled by the immune system, HIV targets and infects that same immune system i.e. cells that are supposed to protect the body from illnesses. These are a type of white blood cell called CD4 cells. HIV takes over CD4 cells and turns them into virus factories that produce thousands of viral copies. As the virus grows, it damages or kills CD4 cells, weakening the immune system, thus causing slow but constant damage to the body’s natural defense system of which at this stage is commonly called AIDS.

The virus may be passed from one person to another when infected blood, semen, or vaginal secretions come in contact with an uninfected person’s broken skin or mucous membranes. In addition, infected pregnant women can pass HIV to their baby during pregnancy or delivery, as well as through breast-feeding. People with HIV have what is called HIV infection. Some of these people will develop AIDS as a result of their HIV infection.

AIDS – (Acquired Immunodeficiency Syndrome):

Acquired – means that the disease is not hereditary but develops after birth from contact with a disease causing agent (in this case, HIV).
Immunodeficiency – means that the disease is characterized by a weakening of the immune system.
Syndrome – refers to a group of symptoms that collectively indicate or characterize a disease.

In the case of AIDS this can include the development of certain infections and/or cancers, as well as a decrease in the number of certain cells in a person’s immune system.

Acquired Immune Deficiency Syndrome is a set of symptoms and infections resulting from the damage to the human immune systems caused by the (HIV). This condition progressively reduces the effectiveness of the immune system and leaves individuals susceptible to opportunistic infections and tumors. It is the condition diagnosed when there are a group of related symptoms that are caused by severe human immunodeficiency virus infection. AIDS makes the body vulnerable to life-threatening illnesses called opportunistic infections. But having HIV does not mean you have AIDS. Even without treatment, it takes a long time for HIV to progress to AIDS—usually 10 to 12 years. If HIV is diagnosed before it becomes AIDS, medicines can slow or stop the damage to the immune system. With treatment, many people with HIV are able to live long and active lives.

Immune system: (as pertains to the HIV/AIDS)

Your immune system is your body's natural defense against infection and illness. Specialized cells and organs all work in concert to protect your body and keeping your body away from diseases and thus healthy. Understanding these different parts of your immune system and how your immune system works will help to better understand HIV and AIDS. There will be more discussions dedicated to immune system in another entry.

Organs and Cells of the Immune System:

•Bone Marrow.
All the specialized cells of the immune system are formed in the bone marrow. Their formation is begun in bone marrow and then they move into the blood stream where they mature.
This small but important organ produces T-cells. In addition, the thymus actually chooses which T-cells are best suited for the immune system. The remaining ones are eliminated by the body, assuring a healthy, effective immunity.
You can think of the spleen as a filter for the blood. It catches foreign material in the blood and activates different types of immune system cells.
•Lymph Nodes.
The lymph nodes filter foreign material from the lymph fluid. Fluid that drains from various tissues in the body collects in the lymph system and passes through the nodes, being filtered as it passes.

•Cells-Leukocytes or WBCs.
The leukocytes are further subdivided into granulocytes (containing large granules in the cytoplasm) and agranulocytes (without granules). The granulocytes consist of neutrophils (55–70%), eosinophils (1–3%), and basophils (0.5–1.0%). The agranulocytes are lymphocytes (consisting of B cells and T cells) and monocytes. Lymphocytes circulate in the blood and lymph systems, and make their home in the lymphoid organs. For the sake of the topic we'll consider T-cells here.

T-Cells also called CD4 Cells:

T-Cells- There are two subsets of T-cells: CD4 cells and CD8 cells. CD4 cells secrete factors that activate other white blood cells that participate in the immune response. HIV attacks CD4 cells, damaging the body's ability to initiate the immune response.

CD8 cells are important in directly killing tumor cells, viral infected cells and some parasites. T/CD4 cells are also called “helper” cells. And in other words lead the attack against infections. While the T-8 cells (CD8) are called “suppressor” cells that end the immune response. CD8 cells can also be “killer” cells that kill cancer cells and cells infected with a virus.

It is important for people who are HIV+ to know their CD4 cells count as this can give a picture of the effectiveness or the status of their immune system.

Knowing how many functioning CD4 cells are circulating in the blood gives an idea of how strong the HIV+ person's immune system really is. A CD4 cells count measures the number of functioning CD4 cells in the body and therefore measures the health of the immune system.
The CD4 test ranges vary but Normal Values - In a healthy adult is typically 600 to 1200 cells per cubic millimeter of blood. And Between 600 and 350 - In an HIV+ person is considered "very good". And Between 350 and 200 - The immune system is weakened and therefore the HIV+ person may be at increased risk for infection and illness.

Signs and Symptoms:

Symptoms of infection with HIV can vary. Often a flu-like syndrome occurs in 50 to 80% of those who contract HIV within the first 2 - 6 weeks, including a combination of the following symptoms:
•Sore throat
•Swollen lymph nodes
•Joint pain
•Muscle aches
•Mouth ulcers
After you are infected with HIV, you may remain relatively symptom-free for years or the disease may progress more rapidly. In this stage, the CD4 count may be below 500 per cubic millimeter. You may develop infections or chronic symptoms including:
•Swollen lymph nodes
•Weight loss
•Cough and shortness of breath
•Low platelet count, which may manifest as easy bruising, bleeding gums, or nose bleeds
During the last stage of the disease, HIV infection may meet the official criteria for AIDS, which is the presence of an opportunistic infection (such as Pneumocystis carinii pneumonia, or PCP) or a CD4 count below 350-200 per cubic millimeter. At this stage, symptoms may include
•Pneumonia, including PCP
•Night sweats
•Persistent fatigue
•Extreme weight loss and wasting, exacerbated by diarrhea. Up to 90% of HIV patients worldwide experience diarrhea
•Meningitis and other brain infections
•Fungal infections
•Malignancies such as lymphoma, cervical cancer, and Kaposi's sarcoma (KS) (affects the skin and oral mucosa and may spread to the lungs. KS can actually occur in earlier stages of HIV as well).


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