HIV/AIDS Glossary of Terms

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Acquired Immunodeficiency Syndrome (AIDS): A disease of the body’s immune system caused by the human immunodeficiency virus (HIV). AIDS is characterized by the death of CD4 cells (an important part of the body’s immune system), which leaves the body vulnerable to life-threatening conditions such as infections and cancers.

Acute HIV Infection: Also known as primary HIV infection or acute retroviral syndrome (ARS). The period of rapid HIV replication that occurs 2 to 4 weeks after infection by HIV. Acute HIV infection is characterized by a drop in CD4 cell counts and an increase in HIV levels in the blood. Some, but not all, individuals experience flu-like symptoms during this period of infection. These symptoms can include fever, inflamed lymph nodes, sore throat, and rash. These symptoms may last from a few days to 4 weeks and then go away.

AIDS-Defining Condition: Any of a list of illnesses that, when occurring in an HIV-infected person, leads to a diagnosis of AIDS, the most serious stage of HIV infection. AIDS is also diagnosed if an HIV-infected person has a CD4 count below 200 cells/mm3, whether or not that person has an AIDS-defining condition. The Centers for Disease Control and Prevention (CDC) published a list of AIDS-defining conditions in 1993. The 26 conditions include candidiasis, cytomegalovirus disease, Kaposi’s sarcoma, mycobacterium avium complex, pneumocystis carinii pneumonia, recurrent pneumonia, progressive multifocal leukoencephalopathy, pulmonary tuberculosis, invasive cervical cancer, and wasting syndrome.

AIDS Service Organization: A health association, support agency, or other service actively involved in the prevention and treatment of HIV/AIDS.

Antibody: Also known as immunoglobulin. A protein produced by the body’s immune system that recognizes and fights infectious organisms and other foreign substances that enter the body. Each antibody is specific to a particular piece of an infectious organism or other foreign substance.

B Lymphocytes (B Cells): Also known as B cells. Infection-fighting white blood cells that develop in the bone marrow and spleen. B lymphocytes produce antibodies. In people with HIV, the ability of B lymphocytes to do their job may be damaged.

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Community-Based Organization (CBO): A service organization that provides social services to local clients. CBOs include nonprofit organizations and free clinics targeted at helping people with HIV.

CD4 Cell: Also known as helper T cell or CD4 lymphocyte. A type of infection-fighting white blood cell that carries the CD4 receptor on its surface. CD4 cells coordinate the immune response, signaling other cells in the immune system to perform their special functions. The number of CD4 cells in a sample of blood is an indicator of the health of the immune system. HIV infects and kills CD4 cells, leading to a weakened immune system.

CD4 Cell Count: A measurement of the number of CD4 cells in a sample of blood. The CD4 count is one of the most useful indicators of the health of the immune system and the progression of HIV/AIDS. A CD4 cell count is used by health care providers to determine when to begin, interrupt, or halt anti-HIV therapy; when to give preventive treatment for opportunistic infections; and to measure response to treatment. A normal CD4 cell count is between 500 and 1,400 cells/mm3 of blood, but an individual’s CD4 count can vary. In HIV-infected individuals, a CD4 count at or below 200 cells/mm3 is considered an AIDS-defining condition.

Centers For Disease Control and Prevention (CDC): An agency of the U.S. Department of Health and Human Services (DHHS) that is charged with protecting the health and safety of citizens at home and abroad. The CDC serves as the national focus for developing and applying disease prevention and control, environmental health, and health promotion and education activities designed to improve the health of the people of the United States.

CDCINFO: A service sponsored by the Centers for Disease Control and Prevention (CDC) to provide referrals, education, and information about topics including HIV/AIDS, other sexually transmitted diseases (STDs), immunizations, and disease outbreaks. The CDCINFO hotline number is 1-800-CDCINFO (232-4636).

Chlamydia: A sexually transmitted disease (STD) caused by a bacterium called Chlamydia trachomatis. The bacteria infect the genital tract and if left untreated can cause damage to the female and male reproductive systems, resulting in infertility.

Clinical Trial: A research study that uses human volunteers to answer specific health questions. Carefully conducted clinical trials are regarded as the fastest and safest way to find effective treatments for diseases and conditions, as well as other ways to improve health. Interventional trials use controlled conditions to determine whether experimental treatments or new ways of using known treatments are safe and effective. Observational trials gather information about health issues from groups of people in their natural settings.

Co-Infection: Infection with more than one virus, bacterium, or other micro-organism at a given time. For example, an HIV-infected individual may be co-infected with hepatitis C virus (HCV) or tuberculosis (TB).

Combination Therapy: Two or more drugs used together to achieve optimal results in controlling HIV infection. Combination therapy has proven more effective in decreasing viral load than monotherapy (single-drug therapy), which is no longer recommended for the treatment of HIV. An example of combination therapy is the use of two NRTIs plus a PI or an NNRTI.

Department of Health and Human Services (DHHS): The U.S. government’s principal agency for protecting the health of all Americans and for providing essential human services. DHHS includes more than 300 programs covering a wide spectrum of activities. Programs are administered by 11 operating divisions, including the Centers for Disease Control and Prevention (CDC), the Food and Drug Administration (FDA), and the National Institutes of Health (NIH). DHHS works closely with state and local governments, and many DHHS-funded services are provided at the local level by state or county agencies or through private-sector grantees.

Enzyme-Linked Immunosorbent Assay (ELISA): A highly sensitive laboratory test used to determine the presence of antibodies to HIV in the blood or saliva. Positive ELISA test results indicate that a person is HIV infected, but these results should be confirmed with a highly specific laboratory test called a Western blot.

Food and Drug Administration (FDA): The U.S. Department of Health and Human Services (DHHS) agency responsible for ensuring the safety and effectiveness of drugs, biologics, vaccines, and medical devices. The FDA also works with the blood banking industry to safeguard the nation’s blood supply.

Gonorrhea: A sexually transmitted disease (STD) caused by the bacterium Neisseria gonorrhoeae. Many people with gonorrhea have no symptoms. If symptoms do occur, they may be burning on urination, frequent urination, yellow or green discharge from the genitals, redness or swelling of the genitals, and a burning or itching sensation of the genitals. Active gonorrhea infection may increase the risk of becoming infected with HIV through sexual intercourse.

Adapted from AIDSinfo.gov; http://aidsinfo.nih.gov/Glossary/GlossaryDataCenterPage.aspx?fromLetter=All Last Accessed April 2, 2007There is much you can do to stay healthy. Learn all that you can about maintaining good health.

National Prevention Information Network (NPIN): A national reference, referral, and distribution service for information on HIV/AIDS, other sexual transmitted diseases (STDs), and tuberculosis (TB), sponsored by the Centers for Disease Control and Prevention (CDC). http://www.cdcnpin.org

Neonatal: The time period from birth through the first 4 weeks after birth.

Nucleic Acid Test: A laboratory test that can detect very small amounts of specific genetic material in blood, plasma, or other tissue. This test can detect several types of viruses and is used to screen blood from blood donors.

Nucleoside Analogue Reverse Transcriptase Inhibitor: A class of anti-HIV drug. Nucleoside analogues are faulty versions of the building blocks necessary for HIV reproduction. When HIV’s reverse transcriptase enzyme uses a nucleoside analogue instead of a normal nucleoside, reproduction of the virus’s genetic material is halted. Also called nucleoside analogues or “nukes.”

Opportunistic Infections (OIs): Illnesses caused by various organisms that occur in people with weakened immune systems, including people with HIV/AIDS. OIs common in people with AIDS include Pneumocystis carinii pneumonia; cryptosporidiosis; histoplasmosis; toxoplasmosis; other parasitic, viral, and fungal infections; and some types of cancers.

Pap Smear: A method for the early detection of cancer and other abnormalities of the female genital tract. A Pap smear is done by placing a speculum in the vagina, locating the cervix, and then scraping a thin layer of cells from the cervix. The cells are placed on a slide, sent to a laboratory, and analyzed for abnormalities. HIV-infected women often have abnormal results of Pap smear tests, usually as a result of human papillomavirus (HPV) infection.

Passive Immunity: The body’s ability to prevent or fight a specific infection after receiving antibodies from another person. The most common example of passive immunity is when an infant receives the mother’s antibodies by consuming her breast milk.

People Living With AIDS (PLWA): Infants, children, adolescents, and adults infected with HIV/AIDS.

Perinatal Transmission: The passage of HIV from an HIV-infected mother to her infant. The infant may become infected while in the womb, during labor and delivery, or through breastfeeding.

Protease Inhibitors (PIs): A class of anti-HIV drug that prevents replication of HIV by disabling HIV protease. Without HIV protease, the virus cannot make more copies of itself.

Rapid Test: A type of HIV-1 ELISA test that can detect antibodies to HIV in the blood in less than 30 minutes with greater than 99% sensitivity and specificity. A positive rapid test result should be confirmed by an HIV Western blot test.

Retrovirus: A type of virus that stores its genetic information in a single-stranded RNA molecule, then constructs a double-stranded DNA version of its genes using a special enzyme called reverse transcriptase. The DNA copy is then integrated into the host cell’s own genetic material. HIV is an example of a retrovirus.

Ryan White Care Act: The Ryan White Comprehensive AIDS Resources Emergency (CARE) Act is Federal legislation that addresses unmet health needs of people living with HIV/AIDS by funding primary health care and support services that enhance access to and retention in care. The CARE Act is administered by the Health Resources and Services Administration (HRSA).

Sexually Transmitted Disease (STD): Any infection spread by the transmission of organisms from person to person during sexual contact.

Side Effects: The actions or effects of a drug (or vaccine) other than desired therapeutic effects. The term usually refers to undesired or negative effects, such as headache, skin irritation, or liver damage.

Substance Abuse and Mental Health Services Administration (SAMHSA): The lead agency within the U.S. Department of Health and Human Services (DHHS) for improving the quality and availability of substance abuse prevention, addiction treatment, and mental health services in the United States.

Superinfection: A new infection acquired on top of an existing infection. For example, a person infected with one strain of HIV-1 can, if exposed to a different strain, become infected with the new strain in addition to the existing strain. Superinfection can complicate HIV treatment by requiring additional drugs to target the newly introduced HIV strain.

Syphilis: A sexually transmitted disease (STD) caused by the bacterium Treponema pallidum. In the early stage of syphilis, a genital or mouth sore called a chancre develops, but eventually disappears on its own. However, if the disease is not treated, the infection can progress over years to affect the heart and central nervous system. Syphilis can also be transmitted from an infected mother to her fetus during pregnancy, with serious health consequences for the infant.

Undetectable Viral Load (UD VL): The point at which levels of HIV RNA in the blood are too low to be detected with a viral load test. This does NOT mean that the virus has stopped replicating or has been removed from the body entirely, only that the small amount of virus remaining is below the test’s ability to measure it. The viral load below which a test cannot detect the virus depends on the brand of the viral load test.

Vaccination: Administration of a vaccine for either preventive or therapeutic purposes.

Vaccine: A substance that stimulates the body’s immune response in order to prevent or control an infection. A vaccine is typically made up of some part of a bacteria or virus that cannot itself cause an infection. Researchers are testing vaccines both to prevent and treat HIV/AIDS; however, there is currently no vaccine approved for use outside of clinical trials.

Varicella Zoster Virus (VZV): A virus in the herpes family that causes chicken pox (usually during childhood) and may reactivate later in life to cause shingles.

Viral Load (VL): The amount of HIV RNA in a blood sample, reported as number of HIV RNA copies per mL of blood plasma. The VL provides information about the number of cells infected with HIV and is an important indicator of HIV progression and how well treatment is working. The VL can be measured by different techniques, including branched chain DNA (bDNA) and reverse transcriptase-polymerase chain reaction (RT-PCR) assays. VL tests are usually done when an individual is diagnosed with HIV infection and at regular intervals after diagnosis.

Viral Load Test: Test that measures the quantity of HIV RNA in the blood. Results are reported as the number of copies of HIV RNA per mL of blood plasma. The two types of HIV viral load test are reverse transcriptase-polymerase chain reaction (RT-PCR) and branched chain DNA (bDNA).

Wasting Syndrome: The involuntary loss of more than 10 percent of body weight, plus more than 30 days of either diarrhea or weakness and fever. Wasting refers to the loss of muscle mass, although part of the weight loss may also be due to loss of fat. HIV-associated wasting syndrome is considered an AIDS-defining condition.

Western Blot: A laboratory technique used to detect a specific protein. A Western blot test to detect HIV proteins in the blood is used to confirm a positive HIV antibody test (ELISA).

Window Period: The time period between a person’s infection with HIV and the appearance of detectable anti-HIV antibodies. Because antibodies to HIV take some time to form, an HIV antibody test will not be positive immediately after a person is infected. The time delay typically ranges from 14 to 21 days, but varies for different people. Nearly everyone infected with HIV will have detectable antibodies by 3 months after infection.