Explanation of terms

AZT (also known as Zidovudine (ZDV)) is an antiretroviral drug which inhibits HIV replication. It is used in the prevention of mother-to-child transmission.

Breast-milk substitute means any food being marketed or otherwise represented as a partial or total replacement for breast milk, whether or not suitable for that purpose.

CD4 cells means main target cells for HIV. CD4 lymphocytes (a type of white blood cells) are key in both humoral and cell-mediated immune responses. Their number decreases during HIV infection.

CD8 cells means lymphocytes which play an important role in fighting infections. Their number may be increased during HIV infection.

Cell-associated virus means HIV which lives inside the cell, measured as HIV-DNA.

Cell-free virus means parts of the virus (virions) not associated with a cell, measured as HIV-RNA.

Cervical ectopy means a turning outward of the edges of the endocervix; it may result from chronic inflammation of the cervix.

Cessation of breastfeeding means stopping breastfeeding.

Chorioamnionitis means inflammation of the fetal membranes, associated with a bacterial or parasitic infection (e.g. malaria).

Colostrum is the thick yellow milk secreted by the breasts during the first few days after delivery, that gradually evolves into mature milk at 3-14 days postpartum. It contains more antibodies and white blood cells than mature breast milk.

Commercial infant formula means a breast-milk substitute formulated industrially in accordance with applicable Codex Alimentarius standards to satisfy the nutritional requirements of infants up to four to six months of age.

Complementary food means any food, whether manufactured or locally prepared, suitable as a complement to breast milk or to infant formula, when either becomes insufficient to satisfy the nutritional requirements of the infant.

DNA, an abbreviation for deoxyribonucleic acid, is the carrier of genetic information found in cell nuclei.

Early breastfeeding means breastfeeding in the first 3 weeks of life.

Early postpartum means the first 3-6 weeks after delivery.

Enterocyte is the cell of the lining of the intestinal wall.

Epithelial means the surface layer of cells covering cutaneous, mucosal and serous surfaces.

Exclusive breastfeeding means giving an infant no other food or drink, not even water, apart from breast milk (including expressed breast milk), with the exception of drops or syrups consisting of vitamins, mineral supplements or medicines.

Glycosaminoglycans means linear polysaccharides composed of repeating disaccharides, usually more than 20 per chain, that attach to a protein core forming a proteoglycan. They are macromolecules that may inhibit the binding of HIV to the CD4 receptor.

Human immunodeficiency virus (HIV) refers to HIV-1 in this document, since cases of mother-to-child transmission of HIV-2 are rare.

Immunoglobulins means any of the five distinct antibodies present in the serum and external secretions of the body (IgA, IgD, IgE, IgG and IgM).

Infant means a child from birth to 12 months of age.

Intestinal lumen means the space within the tubular part of the bowel.

Intrapartum means the period during labour or delivery.

Lactoferrin means an iron-binding protein found in human milk.

Late postnatal transmission means a breastfed child who becomes infected with HIV only after 3-6 months of age. Definitions of late postnatal transmission vary between studies.

Lipase means any fat-splitting enzyme.

Lipid means any one of a widely varying group of fats and fat-like organic substances.

Macrophage means a large "wandering" phagocytic cell that ingests foreign matter, and plays an important role in resisting infection.

Mature breast milk means milk produced from about 14 days postpartum to the cessation of breastfeeding.

Meta-analysis means the statistical method of combining the results of similar, but separate, studies.

M-cells means specialised epithelial cells found on the intestinal mucosa.

Mixed feeding means partial breastfeeding and giving some other milk, often bottles of infant formula.

Mother-to-child transmission (MTCT) means transmission of HIV to a child from an HIV-infected woman during pregnancy, delivery or breastfeeding. The term "vertical transmission" is commonly used interchangeably with MTCT.

Mucosa means mucous membranes.

Neonatal describes the period immediately following birth and continuing through the first month of life.

P24 antigen means a protein part of the virus membrane that can stimulate the production of specific antibodies

PCR means polymerase chain reaction, a laboratory method in which the genetic material (DNA or RNA) of the virus is detected and amplified. It can be both qualitative or quantitative.

Partial breastfeeding means some breastfeeding while giving other forms of food.

Replacement feeding means the process of feeding a child, who is not receiving any breast milk, with a diet that provides all the nutrients the child needs. During the first six months this should be with a suitable breast-milk substitute – commercial infant formula, or home-prepared formula with micronutrient supplements. After six months this should preferably be with a suitable breast-milk substitute, and complementary foods made from appropriately prepared and nutrient-enriched family foods that are given three times a day. If breast-milk substitutes are not available, appropriately prepared family foods should be further enriched and given five times a day.

RNA means ribonucleic acid, a substance found in the nucleus of all living cells and in many viruses. It is an intermediate of DNA and the medium by which genetic instructions from the nucleus are transmitted to the rest of the cell.

Supernatant means the upper layer of material, liquid or lighter solid, that remains after the precipitation of a solid part of a mixture.

Synctium-forming virus means a virus that has the ability to form a network, thus involving cells that are not strictly infected.

Tropism means a predilection for a specific tissue.

Viral culture means growth of virus on artificial media under ideal conditions for growth.

Wet-nursing means the breastfeeding of an infant by someone other than the infant's mother.