Human immunodeficiency infection (HIV) and acquired immunodeficiency syndrome (AIDS)

Human immunodeficiency virus (HIV) infection is caused by HIV type 1 or 2. There are multiple subtypes of HIV-1 (sometimes referred to as clades). Viruses that are a combination of these subtypes may also be encountered and are referred to as circulating recombinant forms (CRFs).

The incubation period for HIV infection can be 1-3 months and the period of communicability can be lifelong. This table shows the risk of transmission associated with a variety of HIV exposure.
Clinical presentation

HIV disease is characterised by depletion and/or dysfunction of the cells of the immune system. HIV infection targets macrophages (which ingest and process infectious agents) and CD4+ T lymphocytes. These cells are central to all functions of the immune system, so that when they are affected by the disease process there is a very extensive immune deficiency.

Up to 80 per cent of people who are infected by HIV will experience a glandular fever-like illness within 6 weeks of infection. This occurs at the time of HIV antibody appearance, and is called a seroconversion illness or primary HIV infection syndrome. Subsequently, there is a period of months to years during which the person is well, even though there is a progressive depletion of CD4+ T lymphocytes and a progressive increase in HIV viral load. Eventually, immune function becomes so poor that opportunistic infections and/or cancers develop. This stage is known as acquired immunodeficiency syndrome (AIDS). The most common cancers are Kaposi's sarcoma and lymphoma. A wide range of pathogens may cause disease in AIDS. Most are viruses such as cytomegalovirus and other herpes viruses, fungi such as Pneumocystis jiroveci, Cryptococcus neoformans and Candida sp. or mycobacteria.

HIV infection may also affect immune system cells in the nervous system and cause neurological diseases. The most common neurological disease is a chronic encephalitis, which may result in a sub-cortical dementia associated with other neurological abnormalities, usually referred to as HIV-associated neurocognitive disorder (HAND).

HIV infection is a progressive condition, which will result in AIDS and death in the majority of infected people if the infection is not treated with antiretroviral therapy. Combination antiretroviral therapy is very effective in arresting the progression of HIV infection. Patients on antiretroviral therapy can enjoy a normal life expectancy but must remain on treatment.

HIV infection should be considered in patients with risk factors, and/or a consistent clinical illness.

Primary HIV infection syndrome

Primary HIV infection syndrome (seroconversion illness) presents a rare opportunity to identify HIV infection, which otherwise may remain unidentified for years. Primary HIV infection syndrome usually occurs within six weeks of infection and may include:

  • fever
  • malaise
  • anorexia
  • myalgia
  • headache
  • sore throat
  • lymphadenopathy
  • generalised maculoerythematous rash
  • night sweats
  • severe lethargy
  • nausea
  • arthralgia
  • photophobia
  • diarrhoea
  • thrombocytopenia
  • mouth ulceration
  • rash.

Neurological manifestations including meningoencephalitis and peripheral neuritis may also be observed.

The acute illness may be accompanied by neutropenia, lymphadenopathy, thrombocytopenia, and mildly elevated erythrocyte sedimentation rate (ESR) or serum transaminase levels.

The role of antiretroviral therapy, in the treatment of primary HIV infection is currently unclear but its use should be considered. This should be discussed with a specialist in HIV medicine as a matter of urgency (see list of contacts in contacts for specialist advice on STIs and HIV).

Sequelae to the acute illness include:

  • chronic lethargy
  • depression
  • irritability.

Non-specific viraemic manifestations include:

  • mucosal ulceration
  • desquamation of skin
  • exacerbation of seborrhoea
  • recurrence of herpes simplex virus (HSV).

Laboratory investigations of HIV infection include tests for three different purposes:

  • tests to diagnose and monitor evidence of HIV infection
  • tests for immune deficiency
  • tests for opportunistic infections and malignancies arising from HIV-induced immunodeficiency.

Only tests of HIV infection and immune deficiency are considered here.

Tests for diagnosing HIV infection

HIV diagnosis in Australia is based on detecting antibodies to HIV in a blood sample. Initial testing is undertaken using an enzyme immunoassay (EIA). Positive results are confirmed by a Western Blot assay. Current tests detect antibodies to both HIV-1 and HIV-2.

Window period

The screening test detects antibody to and antigen of the virus. There is a period after infection, when the screening test will not detect antibody or antigen because they are yet to be produced or are present at a level that cannot be detected. This is called the window period. The time after infection at which antibody is identified is a function of the individual's response to HIV and the type of test used, but it is usually in the order of two to six weeks. Although HIV testing may be negative, the person is usually highly infectious.

  • A negative screening test for HIV excludes HIV infection provided that the last potential exposure was at least 12 weeks before the test. If not, the test must be repeated at an appropriate time.
  • Some reactive EIA results are not due to HIV infection. Therefore, all repeatedly reactive results must have confirmatory tests performed such as an HIV Western Blot test and/or nucleic acid or p24 antigen test if acute HIV infection is suspected.
  • If the Western Blot is positive, then HIV infection is highly likely. It is recommended the tests be repeated on a second blood specimen from the patient to confirm the diagnosis of HIV infection.
  • Tests for detection of HIV proviral DNA are available but are only used in special circumstances, for example when there is uncertainty about the diagnosis of primary HIV infection or for the assessment of the babies of HIV-infected women. This should be discussed with a specialist in HIV medicine or infectious diseases (see list of contacts in contacts for specialist advice on STIs and HIV). Viral load (RNA) testing is used to monitor the infection after a diagnosis is made.

Tests for monitoring HIV infection

The degree of HIV replication can be assessed by assaying the amount of HIV RNA in plasma. This is often referred to as the viral load. The viral load and CD4+ T cell count are used as indicators of when to start antiretroviral therapy.

Tests of immune function

HIV infection causes a decline in the number of several types of lymphocyte, particularly CD4+ T lymphocytes. These are essential cells in the body's immune system. As they decline, the opportunistic infections and malignancies that are characteristic of HIV-induced immunodeficiency become more frequent.

The CD4+ T cell count is the main laboratory test indicator of the degree of immune deficiency produced by HIV infection:

  • Normal: Over 500 CD4+ T cells/µL of blood.
  • Early immune deficiency: 350-500 CD4+ T cells/µL of blood. Clinical signs and symptoms are few.
  • Intermediate immune deficiency: 200-350 CD4+ T cells/µL of blood. Increasing signs and symptoms, especially infections of skin and mucosa.
  • Advanced immune deficiency: <200 CD4+ T cells/µL of blood. Frequent clinical manifestations of immune deficiency.

Assessing HIV risk factors

Assess risk factors for HIV, and consider testing in patients with a glandular fever-like illness, or in those patients with unusual or persistent infections for which there is no adequate alternative explanation.

If the initial HIV antibody test is negative, repeat it during the convalescence of the illness, and again at least three months after exposure.

  • In its early stages, and if the practitioner has not had the benefit of extensive experience with the condition, HIV infection is difficult to diagnose. Early diagnosis of HIV infection is essential to allow counselling, to offer treatment that will slow the progress of the disease, and to reduce the spread of infection.
  • Patients are infectious throughout their illness, although the most infectious periods are before, during and soon after seroconversion or when CD4+ T cells are very depleted and the viral load increases.

Is HIV testing appropriate?

Presence of any lifestyle clue, epidemiological clue or clinical clue indicates that HIV testing should be offered.

Lifestyle clues

  • Unprotected sex.
  • Male-to-male sex.
  • Sharing of injecting drug use equipment.
  • Use of unsterile tattooing and body piercing equipment.
  • Unprotected sex with a person who has migrated from or recently travelled to a country with a high prevalence of HIV.
  • Overseas travel to or work in a country with a high prevalence of HIV.
  • Engaging in paid sex.
  • History of STI.

Epidemiological clue

  • All antenates in regions with high STI rates.

Clinical clues

  • Presence of another STI.
  • Seroconversion illness (fever, myalgia, rash).
  • Atypical or severe prolonged infections without other apparent cause (e.g. oral candidiasis, oral hairy leukoplakia, severe persistent genital herpes).
  • Tuberculosis in a person from sub-Saharan Africa or South East Asia.

Investigating other STIs

All patients with HIV infection should have investigations to exclude other STIs including Herpes simplex virus (HSV).

  • The presence of HIV indicates a risk of other infection.
  • The presence of STIs increases the risk of HIV transmission and acquisition. 

The treatment for HIV/AIDS is often complex and varied, and specialist advice should be sought.

  • In the absence of antiretroviral therapy, HIV infection usually progresses from no apparent illness to AIDS and death over a median of ten years. However, the pace of disease progression is variable. Almost all people who are infected with HIV will eventually have symptoms related to the infection.
  • Early identification of HIV infection can lead to treatment that may slow the decline of immune system function. Early diagnosis also helps to prevent transmission of HIV to other people.
  • The use of antiretroviral therapy is a complex and rapidly changing field of medicine, which should be supervised by a specialist in HIV medicine. Only specialists and general practitioners who have undertaken HIV training and accreditation can prescribe HIV antiretorviral therapy.
  • People with HIV may have special needs, and need access to a support network that will assist in maintaining good health and delaying the onset of symptoms.
  • People with HIV may need access to out-of-hours care and special services.
  • Planning HIV care requires the identification of patients who need:
    • immediate medical care
    • antiretroviral therapy
    • management of coinfections.
  • Hepatitis A and B vaccination should be considered in those who are seronegative for these infections. Pneumococcal vaccine and influenza vaccine should also be considered (refer to the NHMRC's Immunisation Handbook (external site).


Medicines in pregnancy.

Related links

Education counselling and prevention

Counselling is important in managing HIV and should be considered at every contact with the patient.

As a minimum, consider counselling at the first presentation and subsequently during treatment and follow-up.

  • Counselling is an opportunity to educate and support the patient in prevention strategies. This should be done in a confidential setting.
  • The key points are:
    • building mutual trust and respect
    • communicating the confidentiality of the diagnosis
    • communicating the reasons for testing and contact tracing
    • formulating expectations from treatment
    • promoting awareness of risk behaviours.
  • Counselling should also include discussion of the implications of STI/HIV testing (i.e. that testing does not prevent transmission). Emotional reactions can accompany a positive STI/HIV diagnosis, with delayed reactions sometimes occurring several days after the consultation.

The purpose of pre-test discussion is to obtain informed consent and should address:

  • confidentiality
  • the reason for the tests
  • identifying risk activities
  • understanding of the requirement for statutory notification and contact tracing
  • awareness of the disease process
  • awareness of modes of transmission and prevention
  • the patient's past coping strategies/community or family or friend support systems.

Post-test counselling

Positive HIV antibody results must be discussed with the patient in person.

A negative diagnosis provides an opportunity to reinforce pre-test discussions and re-emphasise prevention.

Counselling after a positive diagnosis should address:

  • patient lifestyle and support systems, including those in whom the patient might confide
  • potential for a crisis (e.g. suicide).

If the test is positive, avoid overloading the patient with excessive information and arrange for further counselling at a later time.

At follow-up:

  • stress confidentiality
  • confirm the patient's understanding of the infection
  • if the patient is ready to deal with more information, provide further details of the infection and how to prevent its transmission
  • continue to educate concerning risk behaviour
  • provide continued support
  • provide information about other sources of information and support, such as the WA AIDS Council (see contacts for specialist advice on STIs and HIV).

People with HIV should be counselled by a person able to discuss the medical, psychological and social implications of HIV infection. Appropriate social support and psychological resources should be available, either on site or through referral, to assist the patient in coping with emotional distress.

Emotional distress is a normal response when first being informed of a positive HIV test result. Patients face several major adaptive challenges:

  • accepting the possibility of a shortened life span
  • coping with the reactions of others to a stigmatising illness
  • developing strategies for maintaining physical and emotional health
  • initiating changes in behaviours to prevent HIV transmission.

Counselling for these patients should embrace:

  • implications for management
  • contact tracing (managing sexual partners)
  • legal requirements of notification
  • patients' rights and responsibilities
  • family and community support resources
  • the need for continued counselling. 
Management of partners

Every possible effort for thorough contact tracing should be undertaken in all cases of HIV/AIDS.

Contacts include not only sex partners but also anyone who has shared needles or other injecting equipment with the index case.

Contact tracing for HIV/AIDS enables early diagnosis and treatment of possible HIV infection and associated illness, and offers the opportunity to encourage risk-reducing behaviours. Contact tracing is a means of concentrating risk-reduction efforts on people at high risk of contracting or transmitting HIV infection.

  • Because HIV is a potentially fatal infection, managing sexual partners carries with it special needs for sensitivity and care.
  • Particularly with HIV/AIDS, those responsible for contact tracing should have a clear understanding of local community sensitivities.
  • People with HIV infection should be advised of the risk they pose to uninfected sexual partners, and of the need to practice safe sex and to inform their partners of their infection.
  • Contacts of HIV-infected patients should be traced, and offered testing and counselling.
  • A person who has HIV infection or is at risk of HIV infection must not make any blood, semen or organ/tissue donations.

Special considerations

Several publications have been produced by the Australian, State and Territory governments, other agencies and community groups, to assist health care providers and patients in preventive education and in managing HIV infection. These are available from the Department of Health and various other agencies (see contacts for specialist advice on STIs and HIV and contacts for patients – where to go).

  • Determining how far back to trace contacts can be difficult.
    • The incubation period for primary HIV infection is one to 12 weeks, but the seroconversion illness may pass unnoticed or be inaccurately recalled.
    • Trace back at least 12 weeks before a confirmed primary HIV illness. If an infected contact cannot be found, then a source for the infection has not been located. Therefore, extend the trace-back period.
    • If the date of primary infection cannot be confirmed, the trace-back period may be years, depending on the patient's history of risk behaviour and clinical presentation.
    • As HIV-2 infection is not endemic in Australia, expert support for contact tracing should be sought if there is a possibility of a patient with HIV-2 having been infected locally.
    • A patient who presents with AIDS will usually have been infected for several years (median – 8 to 10 years).
  • Oral sex has been reported as a means of transmitting HIV infection but overall it remains an uncommon method of transmission.
  • If the index case has donated or received blood products, contact the relevant Blood Transfusion Service.

Find out more information about contact tracing.

Follow up

Advise patients of the need for indefinite specialist follow-up. Especially those patients on antiretroviral therapy that are being routinely cared for by a general practitioner.

Effective HIV management requires access to antiretroviral therapy and monitoring associated with the long term use of these drugs. Shared care arrangements with a general practitioner should be established for all HIV positive patients. This will facilitate regular monitoring by the specialist and effective communication between the specialist centre and the primary care provider.

Patients with HIV should be referred to a physician specialising in HIV medicine for assessment and the establishment of a care plan.

Special considerations

  • Specialist advice should always be sought for treatment and follow-up of HIV-infected patients.
  • Review patients three months after exposure to repeat blood tests for syphilis, HBV and hepatitis C virus (HCV). 
Public health issues

Contact tracing is important to prevent further transmission and reinfection. Always test for other STIs.

If a child is diagnosed with HIV, the virus may have been transmitted vertically during pregnancy or delivery. If the mother is HIV-negative, issues of sexual abuse and/or sexual assault should be considered.

The Department of Health has an operational directive in place that address management of occupational exposure to HIV. These are Management of Occupational Exposure to Blood and Body Fluids in the Healthcare Setting (OD 0641/15) (external site).

Non-occupational post-exposure prophylaxis

Following a risk assessment, if a patient is considered to have had a high risk exposure to HIV within the previous 72 hours then they should be referred for non-occupational post-exposure prophylaxis (NPEP) as soon as possible.

For example, the patient:

  • is a gay man who has had unsafe sex or the condom broke while having sex with a known or suspected HIV-positive man
  • is the HIV-negative partner in a sero-discordant couple (i.e. their sex and/or injecting partner is HIV-positive) and the condom broke or they have shared needles and other injecting equipment
  • has had unsafe sex with a person from a country with high HIV prevalence.

NPEP is a course of anti-retroviral drugs (e.g. Truvada® [300 mg Tenofovir and 200 mg Emtricitabine] once daily for four weeks) that should be commenced as soon as possible (and definitely within 72 hours), following exposure to HIV. NPEP may help reduce the risk of HIV transmission after unsafe sex, sharing of injecting equipment or a needle-stick injury when it is known or likely that there has been a high risk of exposure.

NPEP is available from:

  • Royal Perth Hospital Sexual Health Clinic – 9224 2178 (or page the Immunology Registrar after hours)
  • Fremantle Hospital South Terrace Clinic – 9431 2149 (or contact the Infectious Diseases physician after hours via Fiona Stanley Hospital switchboard – 6152 2222).

If these services are not convenient for the patient, the appropriate clinicians in the above hospitals may also authorise the use of NPEP starter packs (seven days of medication) which should be available from Emergency Departments in larger metropolitan hospitals and regional hospitals.

Patients who identify themselves as having had a high risk exposure to HIV may also call the NPEP telephone line or 'PEP line' (1300 767 161). A nurse assesses all callers and then will refer high-risk callers requiring NPEP to one of the above services. Callers assessed as low risk and not requiring NPEP, or who seek advice too late, may still need a sexual health check and/or blood tests and therefore are directed to go to their GP or to a sexual health clinic. The Department of Health and the WA AIDS Council actively promote this telephone line to at-risk groups.

Copies of NPEP resources for at-risk patients are available from the WA AIDS Council on 9482 0000.

For more information about NPEP, including how to assess risk, find out about availability, refer patients and provide follow-up care, see the Department of Health’s operational directive Protocol for non-occupational post-exposure prophylaxis (NPEP) to prevent HIV in Western Australia to be updated shortly.


This is a notifiable infection. Medical practitioners must complete the appropriate notification forms for all patients diagnosed with a notifiable STI/HIV, as soon as possible after confirmed diagnosis.