T-cell – a type of white blood cell (lymphocyte) that are part of the immune system and that mature in the thymus (T). CD4 cells are also called T-cells.

T1/2 (half-life) –  the time taken a drug to clear from the highest concentration to half this level. Drugs have different half-lives in different compartments (ie half-life in blood can be different from the half-life inside a cell). It take 5 x the half-live for a drug to be considered cleared.

What happens when you take a drug?

tachycardia refers to when the heart beats too fast.

bradycardia is when the heart beats too slowly.

See: arrhythmia

TasP (Treatment as Prevention) – a term to emphasise the impact that HIV drugs (ART) has on dramatically reducing the chance of HIV transmission.

ART is firstly for the health of the HIV positive person. But having an undetectable viral load on ART makes it so difficult to transmit HIV that the risk gets so close to zero that it is effectively zero.

For example, in the PARTNER study, nearly 900 couples had sex more than 58,000 times without condoms, without any transmissions. Each couple included one person who was HIV positive with an undetectable viral load on ART and one person who was HIV negative. ZERO transmissions.

TB (tuberculosis) – a bacterial infection that commonly affects the lungs (pulmonary TB) but which can also affect most other organs.

TB section of the training manual.

TD (or tid) – a short hand term for medication dosing that means ‘take three times a day’.

See also q8H.

A feeling that your bowl not completely empty even though it is empty. A medical definition is “a sensation of incomplete bowel evacuation despite an empty rectum”.

The marvels of latin and medicine – words for everything…

thrombocytopenia – a low platelet count (platelets help stop bleeding by clotting blood).

A fungal (yeast) infection that affects the mouth and throat, gullet, sinuses, genital organs and – rarely – the brain. Also called ‘candida’.

Tmax – the time taken for a drug to reach the highest (maximum) concentration.

What happens when you take a drug?

toxicity – medical word for side effect, the potential harm a drug can cause.

toxoplasmosis (toxo) – an opportunistic infection caused by a protozoa. The risk to develop toxo increases after CD4 counts fall below 100 cells/mm3.

Toxo section of the training manual.

transmission of HIV – see HIV transmission

treat as non-pregnant adult – Treat as non-pregnant adult is a very common phrase in HIV and pregnancy. This means that generally your HIV is treated as if you were not pregnant. There are some exceptions, particularly when you do not need treatment for your own HIV and concerning some of the commonly used HIV drugs.

treatment-experienced – someone who has previously used anti-HIV treatments.

treatment-naive – someone who has never taken any anti-HIV treatments before. (Note: people who are treatment naive can still be resistant to anti-HIV drugs if they were infected with a drug resistant strain of HIV}.

triglycerides (TG) – a kind of lipid (blood fat) that is generated by the liver. Untreated HIV infection reduces triglicerides and treatment increases levels again. Some HIV drugs also increase triglycerides.

trimester – a 12 week period of a pregnancy. Different periods during pregnancy are commonly referred to as the first, second and third trimester.

tropism – the type of coreceptor used by HIV in order to attach to and then infect a cell. If HIV uses the CCR5 coreceptor on the surface of the a CD4 cell it is called R5-tropic. If it uses the CXCR4 co receptor it is called R4-tropic). Early HIV infection is usually R5-tropic but over time, especially in late disease (if CD4 counts drop to less than 50 cells/mm3) the virus shifts to being X4-tropic.  Mixed tropic refers to a having some viruses that use R5 and some that use X4.

TST – tuberculosis skin test