Glossary of AIDS and HIV-related Terms III. (T..Z)
Explanation of the most common AIDS and HIV-related Terms:
- Safer sex
- Sexual activities that are not likely to transmit HIV. Safer sex involves sexual
expressions in which partners make sure that blood, semen, vaginal mucus
and menstrual blood from one person do not come into contact with the other
person’s bloodstream or mucous membranes (vulva, vagina, rectum, mouth
and/or nose). This can be prevented by the use of male or female condoms.
- The development of antibodies in response to an antigen. With HIV,
seroconversion usually occurs 4 to 12 weeks after infection is acquired, but in
very few cases it has been delayed for 6 months or more.
- Testing negative for HIV antibodies.
- Testing positive for HIV antibodies.
- The rate of seropositivity in a deﬁned population. Suggests the rate of HIV
infection for that population.
- A contraceptive that works by killing sperm in semen. Some spermicides, such
as nonoxynol-9 have also been demonstrated to kill HIV in laboratory tests.
- The ongoing and systematic collection, analysis, and interpretation of data
about a disease or health condition. Collecting blood samples for the purpose
of surveillance is called serosurveillance.
- A group of symptoms as reported by the patient and signs as detected in an
examination that together are characteristic of a speciﬁc condition.
- T Cell
- One type of white blood cell. One type of T cell, the T-4 Lymphocytes
is especially apt to be infected by HIV. These cells normally
participate on the immune response, signalling other cells in the immune system
to perform their special functions. By injuring and destroying these cells HIV
damages the overall ability of the immune system to ﬁght diseases.
- Vertical HIV transmission
- Transmission of HIV from mother to foetus or baby during
pregnancy or birth.
- The presence of virus in the blood, which implies active viral replication.
- Viral load
- The quantity of the virus in the bloodstream.
The ability to
measure viral load is a key component in effective combination therapy.
- Infectious agent responsible for numerous diseases in all living beings. They
are extremely small particles, and in contrast with bacteria, can only survive
and multiply within a living cell at the expense of that cell.
- Wasting syndrome
- The HIV wasting syndrome involves involuntary weight loss of 10% of baseline
body weight plus either chronic diarrhoea (two loose stools per day for more
than 30 days) or chronic weakness and documented fever (for 30 days or more,
intermittent or constant) in the absence of a concurrent illness or condition
other than HIV infection that would explain the ﬁndings.
- Western blot
- A blood test used to detect antibodies to HIV. This test is often used to conﬁrm
the results of all positive ELISA tests. Their combined accuracy is 99%.
- White blood cells
- Blood cells responsible for the defence of the body against foreign disease
agents and microbes. HIV targets two groups of white blood cells called CD4+,
lymphocytes and monocytes/macrophages.
- Window period
- The period between transmission of HIV and the production of antibodies by
the immune system. It takes the immune system up to 3 months to produce
antibodies to HIV that can be measured in the HIV antibody test. During this
window period, an individual tests negative for the virus but is nevertheless
capable of transmitting it to others.