Glossary

dyspepsia – a range of symptoms related to digestion problems that can include pain, nausea, heart burn. vomiting and pain in the stomach or upper intestine.

compartment – place in the body that has barriers limiting both HIV and HIV drugs from moving freely. Key sites include the brian, the genital tract and some organs. Also called sanctuary sites.

antibiotic – drug used to treat bacterial infections. Sometimes they work against other kinds of infection.

selective pressure – this is when a factor in the environment causes one type of organism to develop and grow in preference to another. With HIV drug resistance, the presence of a drug exerts selective pressure for resistance to develop. It is based on evolution and the concept of ‘survival of the fittest’ theory developed by Charles Darwin.

CD4 count – number of CD4 cells in a cubic millimetre of blood. CD4 counts results are given as a number that can be anywhere from 0 to over 2000 (rarely).

The range for an HIV-negative person is usually quoted as 430 – 1690. This means 95% of HIV negative people have a CD 4 count between 430 and 1690, but also that a few people have normal levels above or below this. A ‘normal’ CD4 count for an HIV positive person means getting above 500. However, this is an ideal goal and many people remain very well and healthy with CD4 counts that are lower than this.

Test results can also be reported in three main formats. ie a CD4 count of 350 can be written as:

• 350 cells/mm³ (cells per cubic millimetre); or
• 350 cells/μL (cells per microlitre); or
• 350 Χ 10⁶ cells/L (per million cells per litre: i.e.: times 10 to the power of 6, cells per litre)

See: Units of measure.

Since 2015, most treatment guidelines recommend starting treatment at any CD4 count, even when this is above 500.

Once viral load becomes undetectable on HIV treatment (ART), this also stops sexual transmission to HIV negative partners.