Glossary of Terms



Acquired immunodeficiency syndrome


AIDS service organization


Canadian AIDS Treatment Information Exchange


Highly Active Anti-Retroviral Therapy


Hepatitis C virus


Human immunodeficiency virus


People who inject drugs


Men who have sex with men


Needle exchange program


Post-exposure prophylaxis, the use of antiretroviral drugs after a single high-risk event to stop HIV from making copies of itself and spreading


People living with HIV and/or AIDS


Public Health Agency of Canada


Pre-exposure prophylaxis, an antiretroviral drug that can be taken by an HIV negative person before potential HIV exposure


Sexually transmitted and blood-borne infections


CD4 Count

A test that indicates the strength of one’s immune system and can be used to predict the risk of complications and debilitating infections. This is often used in combination with the HIV viral load test.


Having two infections at the same time. For example, a person infected with both HIV and hepatitis C or HIV and tuberculosis, has a co-infection. With co-infections, the progression of either disease can potentially be accelerated as a result of infection with the other disease.

Highly Active Anti-Retroviral Therapy

A therapy that involves multiple anti-HIV drugs and is prescribed, before AIDS symptoms are developed, to HIV positive people.

Notifiable Disease

A disease that is considered to be of such importance to public health that its occurrence is required to be reported to public health authorities.

Perinatal Transmission

The transmission of HIV from an HIV-infected mother to her child either in-utero, during childbirth, or through breastfeeding.

Pilot Phase

Activity that has been organized as a trial or test period.

Population at Risk

The population at risk represents those persons at risk of contracting a disease.

Risk Factor

An aspect of someone’s behaviour or lifestyle, a characteristic with which a person is born, or an event that he or she has been exposed to that is known to be associated with a health-related condition. A behavioural risk factor describes a specific behaviour that carries a proven risk of a particular outcome. In research about HIV and/or AIDS, you will often see the term “HIV-related risk behaviour” to describe a behaviour that, when practised, carries a proven risk of HIV infection.


The root “sero” means the serum or the watery portion of blood. In research about HIV and/or AIDS, seroconversion refers to the development of detectable antibodies to HIV in the blood as a result of HIV infection. A person who goes from being HIV negative to HIV positive is said to have seroconverted or is a seroconverter.


Relationships where one partner is infected with HIV and the other is not.


People who are engaged in street activities (such as illicit drug use, sex work, etc) that may increase their risk for HIV and STI transmission.

Viral Load

The viral load test is a quantitative measurement of HIV nucleic acid (RNA) that provides important information that is used (in conjunction with the CD4 cell count) to monitor the status of HIV disease, guide recommendations for therapy and predict the future course of the HIV infection/disease.