HIV and AIDS: For health professionals

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What health professionals need to know about HIV and AIDS

The human immunodeficiency virus (HIV) is a blood-borne infection that can be transmitted:

Acquired immune deficiency syndrome (AIDS) is a long-term sequela of infection.

Consider and discuss HIV testing as part of routine medical care. Early diagnosis and initiation of antiretroviral therapy (ART) can lead to reduced morbidity and mortality associated with:

Timely awareness of serostatus can reduce HIV transmission due to reduction in risk behaviour. In addition, ART reduces transmission. People who adhere to treatment and who achieve and maintain an undetectable viral load have effectively no risk of transmitting the infection sexually.


Pre-exposure prophylaxis (PrEP)

Pre-exposure prophylaxis (PrEP) is the use of prescription antiretroviral (ARV) medication by people who are HIV-negative, but at high risk for HIV infection. PrEP is used in combination with safer sex practices to lower the risk of HIV acquisition.

Taken before exposure, the medication interrupts HIV's ability to copy itself in the body and prevents it from establishing an infection.

Taking PrEP reduces the risk of getting sexually transmitted HIV by more than 90%. Participants in iPrEx and PrEP trials were:

PrEP is highly effective when taken correctly. Using condoms and other prevention methods along with PrEP can further reduce the risk of sexually acquired HIV.

In 2016, Health Canada granted market authorization of ARV (Emtricitabine, 200 mg, and Tenofovir Disoproxil Fumarate, 300 mg) for PrEP.

Health care providers should consult with an infectious disease specialist or a colleague experienced in HIV care to help:

Refer to the Health Canada regulatory decision summary for approved indications, benefits and risks related to PrEP.

Post-exposure prophylaxis (PEP) following recent exposure

Post-exposure prophylaxis (PEP) is the use of prescription ARV medication by people who are HIV-negative to lower the risk of HIV acquisition following a high-risk exposure. PEP should be started as soon as possible and is most effective when started within 72 hours of exposure. The decision to start PEP should be made jointly with the patient.

Health care providers should consult an infectious disease specialist or a colleague experienced in HIV care to help:

Treatment as prevention (TasP)

Medications used to treat HIV can also prevent HIV transmission. People living with HIV who adhere to ART and who achieve and maintain an undetectable viral load have effectively no risk of transmitting HIV sexually.

Treatment as prevention (TasP) is an important prevention strategy. Discuss the benefits of ART as part of routine HIV care.

Disease progression

The amount of time from initial infection to the development of clinical manifestations is highly variable, as is disease progression.

HIV infection results in the progressive destruction of CD4+ T lymphocytes. These white blood cells are crucial to the normal function of the immune system.

Consequently, people with HIV and subsequent immune suppression are at risk of developing a variety of AIDS-defining conditions, including:

Due to advances in HIV treatment:

Clinical manifestations

Depending on the stage of infection, people with HIV may be asymptomatic, or may present with:

Primary acute infection

This is the period from initial infection to development of the full serum antibody profile (seroconversion).

Up to 90% of patients in the acute infection stage are symptomatic.

Clinicians should remain vigilant, as misdiagnosis of acute infection is common and there is a high risk of transmission at this stage. Clinicians should include HIV infection in the differential diagnosis and test for HIV when someone presents with a:

If present, symptoms:

The symptoms of acute retroviral syndrome include:

Chronic asymptomatic infection

In this stage:

Many individuals with HIV infection fall into this category.

Chronic symptomatic infection

In this stage, the disease is characterized by:

Viral replication depletes the CD4+ T cells to the level of profound immunosuppression, leading to opportunistic infections.


Different types of HIV screening tests are licensed for use in Canada. Type and availability can vary by jurisdiction. Information on HIV screening and testing can be found in the HIV screening and testing guide and HIV factsheet: types of tests.

Approach to testing

Healthcare providers should offer screening for sexually transmitted and blood-borne infections (STBBIs), including HIV, as part of their clinical prevention and control strategies.

Before offering an HIV test, conduct an assessment and ensure the individual understands:

Normalizing screening can reduce barriers to screening and testing, and the stigma associated with HIV.

An HIV test can be offered without in-depth behaviour-based risk assessment and/or extensive pre- and post-test counselling.

The use of rapid HIV test kits (where available) for point-of-care (POC) or self-testing can facilitate uptake of screening. In addition, rapid HIV testing provides an option for people who face barriers accessing testing in healthcare settings.

The detection of the HIV antibody is the most widely used means of diagnosing HIV.

The window period is the time after acquisition of HIV, when the:

The length of the window period varies with the test used. Of the 2 main types of tests:

  1. third-generation HIV enzyme immunoassay (EIA) antibody tests:
    • are able to detect the antibody in 99% of people 3 months after exposure
    • may detect the antibody as early as 20 to 30 days after exposure in some individuals

    Note: Rapid HIV testing kits licensed in Canada for point of care or self-testing are third-generation tests. Reactive (positive) results should be confirmed by serology.

  2. fourth-generation combination tests:
    • also permit the detection of p24 antigen during the acute phase of infection
    • reduce the window period to between 15 and 20 days

HIV infection can also be diagnosed by detecting the presence of the virus itself through the following tests.


Advances in HIV treatment:

Early diagnosis and treatment can lead to reduced morbidity and mortality associated with HIV infection and disease progression.

Treatment of HIV is a rapidly evolving and complex area, with changes in optimal therapy occurring as new research and evidence becomes available. If ART is being considered, consult a colleague experienced in HIV/AIDS care or an infectious diseases specialist. Your local public health authority will have a listing of these health professionals.

Effective ART can be an important prevention strategy. People who adhere to ART and who achieve and maintain an undetectable viral load have effectively no risk of transmitting HIV sexually. Effective ART can also help prevent the vertical transmission of HIV.

Undetectable = Untransmittable (U = U)

U = U reflects the scientific evidence that someone who is being treated for HIV and who achieves and maintains an undetectable viral load has effectively no risk of transmitting HIV sexually. Refer to the HIV U = U factsheet.

Health care providers should encourage the consistent and correct use of condoms to prevent the acquisition or transmission of other STIs.

Health care providers should:


Health professionals in Canada play a critical role in identifying and reporting cases of HIV/AIDS.

People living with HIV in Canada

At the end of 2018, the estimated number of persons living with HIV in Canada was 62,050 (plausible range 54,600 – 70,500).

An estimated 1 in 8 Canadians who has HIV hasn't been diagnosed and is unaware of the infection.

In the same year, an estimated 2,242 new HIV infections occurred in Canada (plausible range between 1,080 – 3,850).

People living with HIV around the world

The World Health Organization's Global Health Observatory provides data on HIV and AIDS around the world. It estimates that about 38 million people were living with HIV at the end of 2019.

Surveillance of HIV and AIDS

HIV and AIDS are both notifiable diseases. The national notification system is voluntary and receives cases reported through provincial or territorial departments of health.

Provinces and territories have provincial or territorial legislation for the reporting of priority infectious diseases within their jurisdictions. All provinces and territories report newly diagnosed cases of HIV to the federal department. However, not all provinces and territories have mandatory reporting of AIDS.

The provinces and territories report cases to the federal government if they meet the national case definition for HIV or AIDS.

Related links

Awareness resources


Canada Communicable Disease Report


External resources

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