AIDS

Acquired Immune Deficiency Syndrome, more commonly referred to as AIDS, is the fifth leading cause of death among persons between ages 25 and 44 in the United States. About 47 million people worldwide have been infected with HIV since the start of the epidemic.

What is the cause of AIDS?

AIDS is caused by the Human Immunodeficiency Virus (HIV). AIDS is the final and most serious stage of HIV disease, in which the signs and symptoms of severe immune deficiency have developed.

The HIV virus attacks the immune system and leaves the body vulnerable to a variety of life-threatening illnesses and cancers. Common bacteria, yeast, parasites, and viruses that ordinarily do not cause serious disease in people with fully functional immune systems can cause fatal illnesses in people with AIDS.

HIV has been found in saliva, tears, nervous system tissue, blood, semen (including pre-seminal fluid), vaginal fluid, and breast milk. However, only blood, semen, vaginal secretions, and breast milk have been proven to transmit infection to others.

Transmission of the virus occurs:

• through sexual contact -- including oral, vaginal, and anal sex
  
• through blood -- via blood transfusions or needle sharing
  
• from mother to child -- a pregnant woman can passively transmit the virus to her fetus, or a nursing mother can transmit it to her baby
  
• Other transmission methods are rare and include accidental needle injury, artificial insemination through donated semen, and through a donated organ.

HIV infection is NOT spread by casual contact such as hugging and touching, by touching dishes, doorknobs, or toilet seats, during participation in sports, or by mosquitoes. It is NOT transmitted to a person who donates blood or organs. However, it can be transmitted to the person receiving blood or organs from an infected donor. This is why blood banks and organ donor programs screen donors, blood, and tissues thoroughly.

Who is at Risk?

Those at highest risk include homosexual or bisexual men engaging in unprotected sex, intravenous drug users who share needles, the sexual partners of those who participate in high-risk activities, infants born to mothers with HIV, and persons who received blood transfusions or clotting products between 1977 and 1985 (prior to standard screening for the virus in the blood).

AIDS begins with HIV infection. People who become infected with HIV may have no symptoms for up to ten years, but they can still transmit the infection to others. Meanwhile, their immune system gradually weakens until they are diagnosed with AIDS. Acute HIV infection progresses over time to asymptomatic HIV infection and then to early symptomatic HIV infection and later, to AIDS (very advanced HIV infection):

What are the Symptoms of AIDS?

The symptoms of AIDS are primarily the result of infections that do not normally develop in individuals with healthy immune systems. These infections are termed "opportunistic infections."

Patients with AIDS have had their immune system destroyed by HIV and are susceptible to such opportunistic infections. The general symptoms are fevers, sweats, chills, weakness, and weight loss. See the signs and tests section below for a list of the common AIDS-defining opportunistic infections and the major symptoms associated with them.

Note: Initial infection may produce no symptoms. Some people with HIV infection remain without symptoms for years between the time of exposure and development of AIDS.

How is AIDS Diagnosed?

Not all patients infected with HIV have AIDS. The patients who have tested positive for the HIV antibody test slowly develop AIDS as HIV destroys their immune systems.

In order for a patient who is infected with HIV to have AIDS, their immune system must be severely damaged. The severity of the immune system damage is measured by an absolute CD4 lymphocyte count. The CD4 lymphocyte is an important cell in the blood stream that helps protect from several infections and cancers. If a person infected with HIV has a CD4 count less than 200, they are said to have AIDS.

The following is a list of "AIDS-defining" infections and cancers that people with AIDS acquire as their CD4 count decreases. Many other illnesses and corresponding symptoms may develop in addition to those listed here.

CD4 count below 350/ml

• Herpes Simplex Virus — causes ulcers in your mouth or genitals
  
• Tuberculosis — infection by the tuberculosis bacteria that predominately affects the lungs
  
• Oral or vaginal thrush — yeast infection of the mouth or genitals
  
• Herpes zoster — ulcers over a discrete patch of skin caused by this virus
  
• Non-Hodgkins Lymphoma — cancer of the lymph glands

CD4 count below 200/ml

• Pneumocystis carinii pneumonia
  
• Candida esophagitis — painful yeast infection of the esophagus

CD4 count below 100/ml

• Cryptococcal meningitis — infection of the brain by this fungus
  
• AIDS Dementia — worsening and slowing of mental function caused by HIV
  
• Toxoplasmosis encephalitis — infection of the brain by this parasite
  
• Progressive multifocal leukoencephalopathy — a viral disease of the brain caused by a virus (called the JC virus) that caused quick decline in cognitive and motor functions
  
• Wasting Syndrome — extreme weight loss and anorexia caused by HIV

CD4 count below 50/ml

In addition to the CD4 lymphocyte count, T (thymus derived) lymphocyte count, chest x-rays, pap smears, and other tests are useful in managing HIV disease.

How is AIDS is Treated?

There is no cure for AIDS at this time. However, several treatments are available that can delay the progress of disease for those with HIV and improve the quality of life of those who have developed symptoms.

Antiviral therapy suppresses the replication of the HIV infection in the body. A combination of several antiretroviral agents, termed Highly Active Anti-Retroviral Therapy (HAART), has been highly effective in reducing the number of HIV particles in the blood stream (as measured by a blood test called the viral load) and as a result increase the CD4 positive T lymphocyte count.

Although this is not a cure for HIV, and people on HAART with suppressed levels of HIV can still transmit the virus to others through sex or sharing of needles, the treatment shows great promise. There is good evidence that if the levels of HIV remain suppressed and the CD4 count remains high (>200) that prolongation of life can be achieved. However, HIV tends to become resistant in patients who do not take their medications every day. Also, certain strains of HIV mutate easily and may become resistant to HAART. When HIV becomes resistant to HAART, salvage therapy is required to try to suppress the resistant strain of HIV. This is often not successful, unfortunately, and the patient will usually develop AIDS and its complications.

Treatment with HAART is not without complications. HAART is a collection of different medications, each with its own side effect profile. Some common side effects are nausea, headache, weakness, malaise, and fat accumulation on your back and abdomen. Any doctor prescribing HAART should be carefully following the patient for possible side effects associated with the combination of medications being taken. In addition, routine blood tests measuring CD4 counts and HIV viral load (a blood test that measures how much virus is in the blood) will be taken every three to four months. The goal is to get the CD4 count as close to normal as possible, and to suppress the HIV viral load to an undetectable level.

Other antiviral agents are in investigational stages. Growth factors that stimulate cell growth, such as epogen (erthythropoetin) and G-CSF are sometimes used to treat anemia and low white blood cell counts associated with AIDS.

Medications are also used to prevent opportunistic infections such as Pneumocystis carinii pneumonia and can keep AIDS patients healthier for longer periods of time. Opportunistic infections are treated as they occur.

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