HIV and AIDS: For health professionals
What health professionals need to know about HIV and AIDS
The human immunodeficiency virus (HIV) is a sexually transmitted and blood-borne infection (STBBI) that can be transmitted through exposure to the blood, semen, vaginal fluid, rectal fluid and human milk from a person with HIV. Perinatal transmission can also occur during pregnancy or birth.
Acquired immune deficiency syndrome (AIDS) is a long-term sequela of HIV infection.
Consider and discuss HIV testing as part of routine care. Early diagnosis and initiation of antiretroviral therapy (ART) can lead to reduced morbidity and mortality associated with HIV infection, perinatal transmission, and progression to AIDS.
Individuals who are aware of their serostatus are more likely to use effective strategies to prevent HIV transmission. In addition, ART reduces transmission. People who adhere to ART and who achieve and maintain viral suppression have no risk of transmitting HIV sexually. This is known as Undetectable = Untransmittable (U=U), referencing the fact that a suppressed viral load is undetectable by many standard HIV tests.
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 other prevention strategies to lower the risk of HIV acquisition.
Taken before exposure, the ARV medication interrupts HIV's ability to copy itself in the body and prevents it from establishing an infection.
PrEP is highly effective when taken correctly. Using condoms and other prevention methods along with PrEP can also reduce the acquisition or transmission of other STBBI.
Health professionals should consult with an infectious disease specialist or a colleague experienced in HIV care to help:
- guide the clinical assessment
- determine whether PrEP is indicated
Refer to the Health Canada regulatory decision summary for approved indications, benefits and risks related to PrEP.
Post-exposure prophylaxis (PEP)
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 within 72 hours of exposure.
Health professionals should consult an infectious disease specialist or a colleague experienced in HIV care to help:
- guide the clinical assessment
- determine whether PEP is indicated
Treatment as prevention (TasP)
HIV treatment can also prevent transmission. HIV is not passed on through sex when a person living with HIV is on treatment and the amount of HIV in their blood remains very low.
Progression of HIV infection
The amount of time from initial infection to the development of clinical manifestations is highly variable, as is infection 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:
- opportunistic infections
- primary neurologic disease
Due to advances in HIV treatment:
- the progression of the infection has slowed to a great degree; and
- HIV infection is considered a chronic, treatable condition
Depending on the stage of infection, people with HIV may be asymptomatic or may present with:
- non-specific symptoms that may not be recognized as HIV infection
- various signs and symptoms related to immunodeficiency
Primary acute infection
This is the period from initial infection to development of the full serum antibody profile (seroconversion).
Up to 90% of people in the acute infection stage are symptomatic.
Health professionals should remain vigilant, as misdiagnosis of acute infection is common and there is a high risk of transmission at this stage. Health professionals should include HIV infection in the differential diagnosis and test for HIV when someone presents with a:
- non-specific febrile illness and/or
- history of high-risk behaviour
If present, symptoms:
- generally appear 2 to 6 weeks after exposure
- are usually self-limited
- generally last 1 to 2 weeks, although some may last several months
- are similar to those of many other illnesses, including viral syndromes, such as:
The symptoms of acute retroviral syndrome include:
- sore throat
Chronic asymptomatic infection
In this stage of infection:
- viral replication and plasma viremia are more controlled by the immune response represented by the level of CD4+ T cells
- generalized lymphadenopathy is frequently present
- thrombocytopenia may be present
Many individuals living with HIV are within this stage of infection.
Chronic symptomatic infection
In this stage, the infection is characterized by:
- high levels of viral replication and plasma viremia, which increases the risk of transmission
- a depressed CD4+ T cell count
- viral shedding from mucosal sites
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.
Approach to testing
Health professionals should offer screening for sexually transmitted and blood-borne infections (STBBI), including HIV, as part of their clinical prevention and control strategies.
Before offering an HIV screening test, conduct an assessment and ensure the individual understands:
- how HIV is transmitted
- the implications of testing (advantages and disadvantages)
- how to interpret results
Normalizing screening can reduce barriers to screening and testing, and the stigma associated with HIV.
An HIV screening test can be offered without in-depth behaviour-based risk assessment and/or extensive pre- and post-test counselling.
Standard HIV Testing
In Canada, all laboratories performing HIV screening use fourth generation HIV tests, also known as combination tests, which detect both HIV antibodies and the HIV p24 antigen. These screening tests perform better in acute infection than those that only detect antibodies because the p24 antigen is detectable earlier than antibodies. With fourth generation screening tests, some people will have a reactive (positive) result as early as 15 to 20 days after HIV exposure. While most people will have an accurate test result three to six weeks after exposure, for a small number of people the window can be up to 12 weeks. If an HIV screening test indicates a reactive result, the laboratory will conduct specialized confirmatory testing to ensure correct diagnosis of an HIV infection.
In certain circumstances, qualitative nucleic amplification tests (NAAT) and/or quantitative NAAT (viral load testing) can be used to detect the virus itself. Genotyping and phenotyping are used to detect and monitor HIV drug resistance.
Rapid HIV Testing
Rapid HIV test kits licensed in Canada for point-of-care (POC) testing or self-testing require a few drops of blood from a finger prick and provide results within several minutes. Because rapid screening tests are third generation tests that only detect HIV antibodies, they generally have a longer window period than standard fourth generation HIV screening tests. While some people may have a reactive result as early as 20 to 30 days after HIV exposure, the window period can be up to 12 weeks. Reactive results are considered "preliminary" and should be confirmed with standard laboratory testing for the diagnosis of HIV infection.
Where available, rapid HIV test kits 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 window period is the time after acquisition of HIV, when the:
- risk of transmission is high but
- individuals test negative (non reactive) on HIV screening tests, because antibodies and/or antigens aren't immediately produced or detectable
Effective HIV treatments:
- slow the progression of infection to such a degree that HIV is considered a chronic, treatable condition
- enable people living with HIV to have healthy, long and active lives
- have enabled the prevention of HIV transmission through sex
Early diagnosis and treatment reduce the morbidity and mortality associated with HIV and infection progression.
Treatment of HIV infection is a complex area, with changes in recommended regimens occurring as new research and evidence becomes available. If ART is being considered, consult a colleague experienced in HIV care or an infectious diseases specialist. Local public health authorities will have a listing of these health professionals.
Undetectable = Untransmittable (U = U)
U = U is a result of the scientific consensus that HIV is not passed on through sex when a person living with HIV:
- is on treatment
- maintains a viral load of less than 200 copies/ml (measured every 4 to 6 months)
U=U is vital for improving the lives of people living with HIV as well as preventing transmission.
Health professionals in Canada play a critical role in identifying and reporting cases of HIV and AIDS.
People living with HIV in Canada
At the end of 2020, the estimated number of persons living with HIV in Canada was 62,790 (plausible range 55,200 to 70,300). An estimated 90% of people living with HIV in Canada were diagnosed. 87% of those diagnosed were on treatment, and 95% of those on treatment had a suppressed viral load.
In the same year, an estimated 1,520 new HIV infections occurred in Canada (plausible range: 870 to 2,260).
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 nationally notifiable diseases. National notification is voluntary and data are reported by provincial or territorial public health authorities.
Provinces and territories have legislation for the reporting of priority infectious diseases within their jurisdictions. All provinces and territories collect data on diagnosed HIV infections and report to the Public Health Agency of Canada annually. However, not all provinces and territories have mandatory reporting of AIDS.
Provinces and territories report cases to the Public Health Agency of Canada if they meet the national case definition for HIV or AIDS.
The Public Health Agency of Canada, in partnership with provinces and territories, regional and/or local public health partners, coordinates the Tracks enhanced surveillance system at sentinel sites across Canada. The Tracks system monitors trends in the prevalence of HIV and hepatitis C and associated risk factors in key populations.
- National case definition: Human immunodeficiency virus (HIV)
- National case definition: Acquired immune deficiency syndrome (AIDS)
- HIV Factsheets
- Screening and testing
- Approach to HIV Screening
- Biomedical prevention of HIV: PrEP and PEP
- U = U for health professionals
- People living with HIV in Canada (infographic)
- Take an Active Approach to Sexually Transmitted and Blood-Borne Infections (STBBI) Testing (infographic)
- Determinants of HIV and Hepatitis C among people who inject drugs in Canada, 2017–2019 (infographic)
- Access and use of health care and prevention services: Survey report among Indigenous participants who inject drugs in Canada, 2017-2019: Infographic
- HIV and hepatitis C care and treatment services: Survey report among Indigenous participants who inject drugs in Canada, 2017-2019: Infographic
- Use of harm reduction services and experience with overdoses: Survey report among Indigenous participants who inject drugs in Canada, 2017-2019: Infographic
- Human Immunodeficiency Virus (HIV) Screening and Testing Guide
- Sexually transmitted and blood-borne infections: Guides for health professionals
Canada Communicable Disease Report
- HIV in Canada: Surveillance Report, 2019
- A Review of Human Immunodeficiency Virus (HIV) Rapid Testing
- A Synopsis of the Current Evidence on the Risk of HIV Transmission
- An Overview of Recent Evidence on Barriers and Facilitators to HIV testing
- Synopsis of the Human Immunodeficiency Virus (HIV) Screening and Testing Guide
- Canadian Results from the European Men-who-have-sex-with-men Internet Survey (EMIS-2017)
- Canadian and International Recommendations on the Frequency of HIV Screening and Testing: A Systematic Review
- National findings from the Tracks survey of people who inject drugs in Canada, Phase 4, 2017–2019
- Findings among Indigenous participants of the Tracks survey of people who inject drugs in Canada, Phase 4, 2017-2019
- CATIE: Oral pre-exposure prophylaxis (PrEP)
- Association of Medical Microbiology and Infectious Disease (AMMI) Canada Position Statement: Use of Early Antiretroviral Therapy in HIV-infected Persons (PDF)
- WHO Implementation Tool for Pre-Exposure Prophylaxis (PrEP) of HIV infection
- Society of Obstetricians and Gynaecologists: Canadian HIV Pregnancy Planning Guidelines
- Canadian Guideline on HIV Pre-exposure Prophylaxis and Nonoccupational Postexposure Prophylaxis
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