For health professionals: HIV and AIDS

Get detailed information on the human immunodeficiency virus (HIV) and acquired immune deficiency syndrome (AIDS) for health professionals.

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What health professionals need to know about HIV and AIDS

HIV is a sexually transmitted and blood-borne infection. AIDS is a long-term sequelae of infection.

It is recommended that the consideration and discussion of HIV testing be made a component of periodic routine medical care. Early diagnosis and initiation of highly active antiretroviral therapy can lead to reduced morbidity and mortality associated with:

  • HIV infection
  • disease progression

Health care providers are strongly encouraged to:

  • follow the guiding principles of the HIV screening and testing guide
  • tailor testing approaches to:
    • meet the needs of their patients
    • reduce barriers to HIV testing

Natural history and disease progression

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

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

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

  • opportunistic infections
  • primary neurologic disease
  • malignancy

Due to advances in HIV treatment:

  • the progression of the disease has slowed to a great degree
  • HIV infection is now considered a chronic, manageable condition

Clinical manifestations

Depending on the stage of infection, an individual infected with HIV may present with non-specific symptoms that may:

  • not be recognized as an HIV infection
  • be asymptomatic
  • present with various signs and symptoms related to immunodeficiency (refer to the following stages for more information)

Symptomatic 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 maintain a high index of suspicion in individuals with a:

  • non-specific febrile illness
  • history of high-risk behaviour

The symptoms:

  • generally appear 2 to 6 weeks after exposure
  • are usually self-limited
  • generally last 1 to 2 weeks, but some symptoms may last several months
  • are similar to those of many other illnesses, including viral syndromes, such as:
    • influenza
    • mononucleosis

The symptoms of acute retroviral syndrome include:

  • fever
  • myalgia
  • arthralgia
  • sore throat
  • headache
  • rash
  • nausea
  • diarrhea
  • vomiting

Chronic asymptomatic infection

In this stage:

  • viral replication and plasma viremia are more controlled by the immune response
  • generalized lymphadenopathy is frequently present

Many HIV-infected individuals fall into this category.

Chronic symptomatic infection

In this stage, the disease is characterized by:

  • high levels of:
    • viral replication
    • plasma viremia
  • a depressed CD4+ T cell count

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


Many different types of HIV screening tests are licensed for use in Canada. Type and availability can vary by jurisdiction.

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 infection when the individual:

  • is highly infectious but
  • tests negative on HIV antibody screening because antibodies are not immediately produced or detectable

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


Advances in HIV treatment:

  • have slowed disease progression to such a degree that HIV infection is now understood to be a chronic, manageable condition
  • are enabling more people with HIV to live healthy, long and active lives

This is an increasingly complex area, with rapid changes in optimal therapy as new research becomes available.

Recommendations, including on specific therapy for a specific patient, should be made in collaboration with a colleague experienced in:

  • infectious diseases

Your local public health authority will have a listing of these health professionals.


Health professionals in Canada play a critical role in identifying and reporting cases of HIV/AIDS. Refer to the surveillance section for more information on surveillance in Canada.

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