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• AIDS HIV Terms

AIDS-HIV Related Terms

- H -

• HAART

See Highly Active Antiretroviral Therapy.



• Hairy Leukoplakia

See Oral Hairy Leukoplakia.



• Half-Life

The time required for half the amount of a drug to be eliminated from the body.



• Ham/Tsp

See HTVL-I-associated myelopathy/tropical spastic paraparesis.



• HCSUS

See HIV Cost and Services Utilization Study.



• Health Care Financing Administration (HCFA)

Health Care Financing Administration. Now known as The Centers for Medicare and Medicaid Services (CMS).



• Health Resources And Services Administration (HRSA)

A U.S. Department of Health and Human Services agency that directs national health programs which improve the health of the Nation by assuring quality health care to underserved, vulnerable, and special-need populations and by promoting appropriate health professions workforce capacity and practice, particularly in primary care and public health. Among other functions, HRSA administers the Ryan White CARE Act Titles I, II, III(b), IV, SPNS, and AETCs to provide treatment and services for those affected by HIV/AIDS. HRSA administers programs to demonstrate how communities can organize their health care resources to develop an integrated, comprehensive, culturally competent system to care for those with AIDS and HIV infection. HRSA also administers education and training programs for health care providers and community service workers who care for persons living with HIV or AIDS. Internet address



• Hellp Syndrome

A rare but potentially life-threatening syndrome that includes hemolysis, elevated liver enzymes, and low platelets that can occur during the third trimester of pregnancy. Mitochondrial fatty acid oxidation can occur in pregnant women. Some speculate that the presence of this condition may enhance susceptibility to the syndrome. Receiving nucleoside analog drugs may also increase susceptibility.



• Helper T Cells

Lymphocytes bearing the CD4 marker that are responsible for many immune system functions, including turning antibody production on and off.



• Helper/Supressor Ratio (OF T CELLS)

T cells are lymphocytes (white blood cells) that are formed in the thymus and are part of the immune system. They have been found to be abnormal in persons with AIDS. The normal ratio of helper T cells (also known as CD4+ T cells) to suppressor T cells (also known as CD8+ T cells) is approximately 2:1. This ratio becomes inverted in persons with AIDS but also may be abnormal for a host of other temporary reasons.



• Hematocrit

A laboratory measurement that determines the percentage of packed red blood cells in a given volume of blood. In women, red blood cells are normally 37 to 47 percent of their blood, and in men, red blood cells are normally 40 to 54 percent of their blood.



• Hematotoxic

Poisonous to the blood or bone marrow.



• Hemoglobin

The component of red blood cells that carries oxygen.



• Hemolysis

The rupture of red blood cells.



• Hemophilia

An inherited disease that affects mostly males and prevents normal blood clotting. It is treated by lifelong injections of a synthetic version of the clotting factor lacking in persons with the disease. The new recombinant clotting factor is extracted from normal blood and if not heat treated can carry HIV.



• Hepatic

Pertaining to the liver.



• Hepatic Steatosis

Fatty liver caused by liver toxins such as carbon tetrachloride, and other factors such as alcohol, medications (steroids, minocycline), obesity, diabetes mellitus, cystic fibrosis, total lipodystrophy, and pregnancy.



• Hepatitis

An inflammation of the liver. May be caused by bacterial or viral infection, parasitic infestation, alcohol, drugs, toxins, or transfusion of incompatible blood. Although many cases of hepatitis are not a serious threat to health, the disease can become chronic and can sometimes lead to liver failure and death. There are four major types of viral hepatitis: 1. hepatitis A, caused by infection with the hepatitis A virus, which is spread by fecal-oral contact; 2. hepatitis B, caused by infection with the hepatitis B virus (HBV), which is most commonly passed on to a partner during intercourse, especially during anal sex, as well as through sharing of drug needles; 3. non-A, non-B hepatitis, caused by the hepatitis C virus, which appears to be spread through sexual contact as well as through sharing of drug needles (another type of non-A, non-B hepatitis is caused by the hepatitis E virus, principally spread through contaminated water); 4. delta hepatitis, which occurs only in persons who are already infected with HBV and is caused by the HDV virus; most cases of delta hepatitis occur among people who are frequently exposed to blood and blood products, such as persons with hemophilia.



• Hepatitis C/Co-Infection With HIV

Approximately 40% of patients infected with HIV are also infected with the hepatitis C virus (HCV), mainly because both viruses share the same routes of transmission. HCV is one of most important causes of chronic liver disease in the U.S. It has been demonstrated in clinical studies that HIV infection causes a more rapid progression of chronic hepatitis C to cirrhosis and liver failure in HIV-infected persons.



• Hepatomegaly

Enlargement of the liver.



• Herpes Simplex Virus 1 (HSV-1)

A virus that causes cold sores or fever blisters on the mouth or around the eyes, and can be transmitted to the genital region. Stress, trauma, other infections, or suppression of the immune system can reactivate the latent virus.



• Herpes Simplex Virus 2 (HSV-2)

A virus causing painful sores of the anus or genitals that may lie dormant in nerve tissue. It can be reactivated to produce symptoms. HSV-II may be transmitted to a newborn child during birth from an infected mother, causing retardation and/or other serious complications. HSV-II is a precursor of cervical cancer.



• Herpes Varicella Zoster Virus (VZV)

The varicella virus causes chicken pox in children and may reappear in adults as herpes zoster. Also called shingles, herpes zoster consists of very painful blisters on the skin that follow nerve pathways.



• Herpes Viruses

A group of viruses that includes herpes simplex type 1 (HSV-1), herpes simplex type 2 (HSV-2), cytomegalovirus (CMV), Epstein-Barr virus (EBV), varicella zoster virus (VZV), human herpes virus type 6 (HHV-6), and HHV-8, a herpes virus associated with Kaposi's Sarcoma. See entries under names of some of the individual viruses.



• Highly Active Antiretroviral Therapy (HAART)

The name given to treatment regimens recommended by leading HIV experts to aggressively suppress viral replication and progress of HIV disease. The usual HAART regimen combines three or more different drugs, such as two nucleoside reverse transcriptase inhibitors (NRTIs) and a protease inhibitor, two NRTIs and a non-nucleoside reverse transcriptase inhibitor (NNRTI), or other combinations. These treatment regimens have been shown to reduce the amount of virus so that it becomes undetectable in a patient's blood.



• Histocompatibility Testing

A method of matching the self-antigens on the tissues of a transplant donor with those of a recipient. The closer the match, the better the chance that the transplant will not be rejected. See Human Leukocyte Antigens.



• Histoplasmosis

A fungal infection, commonly of the lungs, caused by the fungus Histoplasma capsulatum. This fungus is commonly found in bird and/or bat droppings in the Ohio and Mississippi Valley region, the Caribbean Islands, and in Central and South America. It is spread by breathing in the spores of the fungus. Persons with severely damaged immune systems, such as those with AIDS, are vulnerable to a very serious disease known as progressive disseminated histoplasmosis. Nationwide, about 5% of persons with AIDS have histoplasmosis, but in geographic areas where the fungus is common, persons with AIDS are at high risk for disseminated histoplasmosis.



• HIV Cost And Services Utilization Study (HCSUS)

A study using a national sample representative of the adult U.S. population infected with HIV and receiving ongoing care that found significant variation in service utilization and receipt of medication. Women were more likely than men to use the emergency department and be hospitalized, and less likely to have received antiretroviral therapy including a protease inhibitor or nonnucleoside reverse transcriptase inhibitor by early 1998.



• HIV Disease

During the initial infection with HIV, when the virus comes in contact with the mucosal surface and finds susceptible T cells, the first site at which there is truly massive production of the virus is lymphoid tissue. This leads to a burst of massive viremia, with wide dissemination of the virus to lymphoid organs. The resulting immune response to suppress the virus is only partially successful and some virus escape. Eventually, this results in high viral turnover that leads to destruction of the immune system. HIV disease is, therefore, characterized by a gradual deterioration of immune functions. During the course of infection, crucial immune cells, called CD4+ T cells, are disabled and killed, and their numbers progressively decline. See Acquired Immunodeficiency Syndrome; Human Immunodeficiency Virus Type 1.



• HIV Prevention Trials Network (HPTN)

A worldwide collaborative clinical trials network established by the National Institutes of Health to evaluate the safety and the efficacy of non-vaccine prevention interventions, alone or in combination, using HIV incidence as the primary endpoint. Internet address



• HIV Set Point

The rate of virus replication that stabilizes and remains at a particular level in each individual after the period of primary infection.



• HIV Vaccine Trials Network (HVTN)

Formed in 1999 by the Division of AIDS (DAIDS) of the National Institute of Allergy and Infectious Diseases. The HVTN mission is to develop and test prevention HIV vaccines through multi-center clinical trials in a global network of domestic and international sites. Internet address



• HIV Viral Load

See Viral Load Test.



• HIV-1

See Human Immunodeficiency Virus Type 1.



• HIV-2

See Human Immunodeficiency Virus Type 2.



• HIV-Associated Dementia

See AIDS Dementia Complex.



• HIV-Related Tuberculosis

See Tuberculosis.



• HLA

See Human Leukocyte Antigens.



• Hodgkin's Disease

A progressive malignant cancer of the lymphatic system. Symptoms include lymphadenopathy, wasting, weakness, fever, itching, night sweats, and anemia. Treatment includes radiation and chemotherapy. See Lymphoma.



• Holistic Medicine

Healing traditions that promote the protection and restoration of health through theories reputedly based on the body's natural ability to heal itself and through manipulation of various ways body components affect each other and are influenced by the external environment.



• Homologous

With regards to immunology, tissue or serum derived from members of a single species.



• Hormone

An active chemical substance formed in one part of the body and carried in the blood to other parts of the body where it stimulates or suppresses cell and tissue activity. See Pituitary Gland.



• HOST

A plant or animal harboring another organism.



• Host Factors

The body's potent mechanisms for containing HIV, including immune system cells called CD8+ T cells which may prove more effective than any antiretroviral drug in controlling HIV infection.



• HPTN

See HIV Prevention Trials Network.



• HPV

See Human Papilloma Virus.



• HRSA

See Health Resources and Services Administration.



• Htlv-I

See Human T Cell Lymphotropic Virus Type I.



• Htlv-I-Associated Myelopathy/Tropical Spastic Paraparesis (HAM/TSP)

A chronic, degenerative neurological disease that causes the demyelination of the spinal cord. It is believed to be due to adult acquired infection with HTLV-1. The disease involves hyperreflexia, spasticity and weakness of the lower limbs, gait abnormality with bladder and sphincter involvement. Patients often present with complaints of incontinence or constipation and difficulty walking.



• Htlv-Ii

See Human T Cell Lymphotropic Virus Type II.



• Human Growth Hormone (HGH)

A peptide hormone secreted by the anterior pituitary gland in the brain. HGH enhances tissue growth by stimulating protein formation. A recombinant (genetically engineered) HGH, called Serostim, has been approved by FDA as a treatment for AIDS wasting syndrome.



• Human Immunodeficiency Virus Type 1 (HIV-1)

1. The retrovirus isolated and recognized as the etiologic (i.e., causing or contributing to the cause of a disease) agent of AIDS. HIV-1 is classified as a lentivirus in a subgroup of retroviruses. 2. The genetic material of a retrovirus such as HIV is the RNA itself. HIV inserts its own RNA into the host cell's DNA, preventing the host cell from carrying out its natural functions and turning it into an HIV factory. See Lentivirus; Retrovirus.



• Human Immunodeficiency Virus Type 2 (HIV-2)

A virus closely related to HIV-1 that has also been found to cause AIDS. It was first isolated in West Africa. Although HIV-1 and HIV-2 are similar in their viral structure, modes of transmission, and resulting opportunistic infections, they have differed in their geographic patterns of infection.



• Human Leukocyte Antigens (HLA)

Marker molecules on cell surfaces that identify cells as 'self' and prevent the immune system from attacking them.



• Human Papilloma Virus (HPV)

HPV is transmitted through sexual contact and is the virus that causes genital warts and plays a causative role in cervical dysplasia and cervical cancer. HPV affects more than 24 million Americans; CDC estimates that there are at least 500,000 new cases each year. In HIV-positive women, the prevalence and persistence of HPV infection increases with decreasing CD4 counts and increasing HIV RNA levels. There is no specific cure for an HPV infection. Interferon is used in the treatment of refractory or recurrent genital warts. Cryotherapy, laser treatment, or conventional surgery can remove the warts.



• Human T Cell Lymphotropic Virus Type I (HTLV-I)

HTLV-I and HTLV-II, like all retroviruses, are single-stranded RNA viruses containing a genome that replicates through a DNA intermediary. This unique life cycle is made possible by the presence of a virally encoded enzyme, reverse transcriptase, which converts a single-stranded viral RNA into a double-stranded DNA provirus that can then be integrated into the host genome. HTLV-I has an affinity for T lymphocytes; it appears to be the causative agent of certain T- cell leukemias, T- cell lymphomas, and HTLV-I-associated myelopathy/tropical spastic paraparesis (HAM/TSP).



• Human T Cell Lymphotropic Virus Type Ii (HTLV-II)

A virus closely related to HTLV-I, it shares 60% genomic homology (structural similarity) with HTLV-I. It is found predominantly in IV drug users and Native Americans, as well as Caribbean and South American Indian groups. HTLV-II has not been clearly been linked to any disease, but has been associated with several cases of myelopathy/tropical spastic paraparesis (HAM/TSP)-like neurological disease.



• Humoral Immunity

The branch of the immune system that relies primarily on antibodies. See Cell-Mediated Immunity.



• HVTN

See HIV Vaccine Trials Network.



• Hydroxyurea

An inexpensive prescription drug used for the treatment of sickle-cell anemia and some forms of leukemia, which has been used investigationally for the treatment of HIV. Its potential safety and effectiveness for treatment of HIV have not been established, and clinicians should be aware of important safety precautions regarding its use. Hydroxyurea does not have direct antiretroviral activity; rather, it inhibits the cellular enzyme ribonucleotide reductase, resulting in reduced intracellular levels of deoxynucleoside triphosphates (dNTPs) that are necessary for DNA synthesis. For the most current information about the use of hydroxyurea in HIV treatment regimens, please see the 'Guidelines for the Use of Antiretroviral Agents in HIV-Infected Adults and Adolescents,' available at



• Hypergammaglobulinemia

Abnormally high levels of immunoglobulins in the blood. Common in persons with HIV.



• Hyperglycemia

An abnormally high concentration of glucose in the circulating blood, seen especially in patients with diabetes mellitus. Hyperglycemia, new onset diabetes mellitus, diabetic ketoacidosis, and exacerbation of existing diabetes mellitus in patients receiving protease inhibitors have been reported.



• Hyperlipidemia

An increase in the blood levels of triglycerides and cholesterol that can lead to cardiovascular disease and pancreatitis. As related to HIV: A side effect of HAART; all protease inhibitors have been shown to cause hyperlipidemia in clinical studies.



• Hyperplasia

Abnormal increase in the elements composing a part (as tissue cells).



• Hyperthermia

An unproven and dangerous experimental procedure that involves temporarily heating a patient's body core to temperatures of up to 108° F on the theory that this temperature kills free HIV and HIV-containing cells. One method for accomplishing this is by passing patients' blood through an external heater. This is called extracorporeal whole body hyperthermia.



• Hypogammaglobulinemia

Abnormally low levels of immunoglobulins. See Antibodies.



• Hypogonadism

Deficiency in the secretory activity of the ovaries or testes. Prior studies have shown that 45% of patients with AIDS and 27% of HIV-infected patients without AIDS have subnormal testosterone levels. Replacement therapy is recommended for men with low or low-normal levels. Testosterone is an anabolic steroid that may restore nitrogen balance and lean body mass in patients with wasting.



• Hypothesis

A supposition or assumption advanced as a basis for reasoning or argument, or as a guide to experimental investigation.



• Hypoxia

Reduction of oxygen supply to tissues.