Glossary

Selected words and phrases

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.

elite controller (EC) – if your viral load stays undetectable for more than five years without ART you are an elite controller.

Elite controllers also have a very good CD4 count (always above 500 cells/mm³) that stays at a similar level over many years.

Even with this good immune response, ART is still generally recommended in the long-term.

This is because over decades – some ECs have been undetectable for more than 20 years – there is a concern that low level HIV in different body compartments like the brain, might lead to accumulative serious damage that isn’t easy to detect until it is too late.

This is a real concern, though evidence is limited because of the rarity of ECs.

See: long-term slow progressor (LTSP)/long-term non-progessor (LTNP).

percentage (%) – a number as a proportion of 100.

grade/grading – the grade of hepatitis infection refers to the amount of inflammation in liver tissue, found by a biopsy. It is usually measured on the Ishak scale from 1-18) where 0 is none and 18 is the maximum. See staging.

symptomatic – showing signs of illness.