Introduction to HIV

Written by Brian Boyle, MD, JD

What are HIV and AIDS?
How AIDS Works in the Body
HIV Treatment
Who Should be Tested for HIV?
HIV Contraction
Common Misconceptions About Contraction
The Importance of HIV Testing and Diagnosis
How Does HIV Testing Work?
Test Counseling
Conclusion

What are HIV and AIDS?

The Human Immunodeficiency Virus, which is commonly called HIV, is a virus that directly attacks certain human organs, such as the brain, heart, and kidneys, as well as the human immune system. The immune system is made up of special cells, which are involved in protecting the body from infections and some cancers.

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The primary cells attacked by HIV are the CD4+ lymphocytes, which help direct immune function in the body. Since CD4+ cells are required for proper immune system function, when enough CD4+ lymphocytes have been destroyed by HIV, the immune system barely works. Many of the problems experienced by people infected with HIV result from a failure of the immune system to protect them from certain opportunistic infections (OIs) and cancers.

Defining the terms

People infected with HIV are broadly classified into those with HIV disease and those with Acquired Immunodeficiency Syndrome, or AIDS. A person with HIV disease has HIV but does not yet have any symptoms or related problems, and still has a relatively intact immune system (that is, a CD4+ lymphocyte count greater than 200 cells/mm3). A person with AIDS, on the other hand, has very advanced HIV disease and his or her immune system has incurred significant damage. As a result, people with AIDS are at very high risk for a number of OIs, cancers, and other AIDS-related complications. The Centers for Disease Control have defined the conditions that mark a progression from HIV disease to AIDS. They are: certain infections, such as repetitive pneumonias, Pneumocystis carinii pneumonia (PCP), and cryptococcal meningitis certain cancers, such as cervical cancer, Kaposi's sarcoma, and central nervous system lymphoma CD4+ count less than 200 cells/mm3 or 14 percent of lymphocytes

How AIDS Works in the Body

Before highly active antiretroviral therapy (HAART) became available, most people who contracted HIV eventually progressed to AIDS and had some AIDS-related complication, such as:

• a deterioration of immune system function and an increased risk of infections and cancers
• brain damage that may cause dementia or memory loss
• heart problems that can cause heart failure and symptoms such as shortness of breath, fatigue, and swelling of the abdomen and legs
• severe kidney damage requiring dialysis
• an inability to perform activities of daily living such as balancing a checkbook or driving a car
• metabolic changes that may cause significant weight loss or diarrhea

Due to these potential problems, a person with AIDS is at very high risk of becoming very ill, and, if some action is not taken to protect the person from these infections or reverse the damage done by HIV, he or she is at risk of dying.

The speed of progression to AIDS
The damage caused by HIV occurs more quickly in some people than in others, but generally an untreated HIV-infected person can expect that they will progress to AIDS within 10 years of their infection. During the time the person is infected with HIV, a war rages between the person's immune system and HIV, with HIV slowly wearing the immune system out.

A slow progress: A number of factors can affect how rapidly HIV progresses, some that can be controlled, and some that can't. Some people have certain genes that slow HIV progression, or they are infected with a weak strain of HIV that their immune system is more able to control. In general, taking better care of yourself and following your doctor's advice also slows the progression of HIV disease to AIDS.

A more rapid progress: Factors that may cause a more rapid progression to AIDS are: infection by a virulent strain of HIV, having a high viral load setpoint (a certain level of HIV replication that varies from person to person), older age, and the abuse of drugs or alcohol.