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

Organism

Human immunodeficiency virus (HIV) infection is caused by HIV type 1 or 2. There are multiple subtypes of HIV-1 (which can also be 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 period from exposure to primary HIV infection syndrome (seroconversion illness) is usually one to four weeks. The period from exposure to development of detectable anti-HIV antibodies is usually less than one month and may be much shorter, but may be up to three months. This will vary with the type of test performed. Given the tests used in WA pathology laboratories, an HIV test should be positive within six weeks of exposure. The presence of the virus itself can be detected earlier. 

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 compromising 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 HIV disease process the body is likely to exhibit symptoms of immune deficiency.

Up to 80 per cent of people who are infected by HIV will experience a glandular fever-like illness within six weeks of infection. This often occurs at the time when HIV antibodies appear, and is called a seroconversion illness or primary HIV infection syndrome. However some patients may be HIV-negative on standard testing for up to three weeks after the onset of symptoms. 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 compromised to the stage whereby 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 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 can result in AIDS and death in the majority of infected people if the infection is not treated with antiretroviral therapy. Combination antiretroviral therapy is highly effective in arresting the progression of HIV infection and suppressing viral replication. 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 two to 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.

Clinical evidence shows that early initiation of antiretroviral therapy is associated with better with better health outcomes for the patient. Referral to a specialist in HIV medicine as soon as possible after diagnosis is essential to provide the patient with an opportunity to commence antiretroviral therapy early.

 (see list of contacts in contacts for specialist advice on STIs and HIV).

Primary HIV infection may be followed by:

  • chronic lethargy
  • depression
  • irritability.

Non-specific viraemic manifestations include:

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

STI Atlas (external site)

Investigations

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

  • tests to diagnose HIV infection and if positive to monitor the amount of virus present (i.e. viral load)
  • tests to assess for immune deficiency (e.g. CD4 + T cell count)
  • 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.

HIV testing may also be performed using rapid point-of-care testing which provides results within 30 minutes. Point-of-care tests have a longer window period than laboratory-based assays. Any positive results must be followed up with definitive diagnostic testing using laboratory-based assays. Point-of-care tests may be useful in high risk populations such as men who have sex with men, populations that are difficult to reach and individuals who might not otherwise access HIV testing or return for results. Point-of-care tests are not recommended for use in populations or settings with very low HIV prevalence.

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 either 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 a nucleic acid or p24 antigen test if acute HIV infection is suspected.
  • If the Western Blot test is positive, then HIV infection is highly likely. It is recommended that the HIV antibody 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. 

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 either with a glandular fever-like illness, or with unusual or persistent infections for which there is no adequate alternative explanation. Presence of any of the following lifestyle clues, epidemiological clues or clinical clues 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, particularly where interaction with local health providers has been reported 
  • Engaging in paid sex
  • History of STI.

Epidemiological clues

  • All antenatal women
  • Migration from high prevalence country 

Clinical clues

  • Presence of another STI
  • Seroconversion illness (e.g. 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 and blood-borne viruses

All patients with HIV infection should have investigations to exclude other STIs and blood-borne viruses.

  • The presence of HIV indicates a risk of other infection.
  • The presence of STIs increases the risk of HIV transmission and acquisition. 
  • Patients with HIV should also be tested for hepatitis B and hepatitis C. 
Treatment

The treatment for HIV can be complex, although with newer antiretroviral therapy available there has been a significant improvement in simpler therapeutic regimens. Specialist advice must be sought, and the person referred to the appropriate service provider. 

  • 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 without antiretroviral therapy. 
  • Early identification of HIV infection can lead to early treatment uptake, which may slow the decline of immune system function. Early diagnosis and treatment initiation can reduce HIV viral load, which reduced the risk of onwards HIV transmission.
  • Clinical evidence has demonstrated that patients who have sustained a HIV viral load of below 40 copies per millilitre (referred to as ‘undetectable’ based on current test sensitivity) for more than six months have a significantly reduced chance of onwards transmission, although this may vary on a case by case basis. Discussions about HIV viral load and risk of onwards transmission should take place between the HIV specialist and patient, with condom use always promoted as a safer sex practice.
  • The use of antiretroviral therapy is a specialised and rapidly changing field of medicine. A patient should initially be referred to HIV specialist services for treatment. General practitioners are encouraged to participate in the shared care of patients with HIV and can be authorised to prescribe HIV medicines. See page on HIV s100 community prescribers
  • 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.
  • 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 for people who are seronegative for these infections. Pneumococcal vaccine and influenza vaccine should also be considered (refer to the NHMRC's Immunisation Handbook (external site).

Pregnancy

Medicines in pregnancy.

Related links

Education, counselling and prevention

Counselling is important step in discussing the need for HIV and any other STI testing as well as discussing the test results and follow-up.  

Pre-test discussion

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

Post-test counselling

A positive HIV antibody test result must be discussed with the patient in person.

A negative diagnosis provides an opportunity to reinforce the pre-test discussion and focus on prevention.

Counselling after a positive diagnosis should address the next steps for the patient which include:

  • The need to inform sexual contacts and contact tracing. There are services available which can assist the patient with this process. See WA AIDS Council website (external site).
  • Legal requirements for notification, with an emphasis on confidentiality
  • Discussion of strategies to prevent onward transmission, and emphasizing the need to practice safer sex and not share injecting equipment  
  • Psychosocial support, and consideration whether there is the need for immediate counselling support given the new HIV positive diagnosis
  • Referral to specialist HIV care (if the diagnosing practitioner is not experienced in HIV medicine, they should avoid technical discussions regarding disease progression or treatment options)   
  • Referral to a support organisation for counselling or other forms of social assistance

Avoid overloading the patient with excessive information and arrange for further counselling at a later time if needed. Provide patient with a fact sheet (Healthy WA).

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 about the prevention of onward transmission. 
  • 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 living with a chronic disease
  • coping with possible stigmatising and discriminating behaviours from others
  • developing strategies for maintaining physical and emotional health
  • initiating changes in behaviours to prevent HIV transmission.

Counselling for these patients should embrace:

  • contact tracing or management of sexual partners
  • patients' rights and responsibilities
  • family and community support resources
  • the need for continued counselling and support. 
Management of partners

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

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

Contact tracing is undertaken by nurses employed by public health units. GPs and primary health care providers can provide invaluable information to public health nurses to facilitate identification and testing of partners.

  • Because HIV can potentially lead to serious health implications and historically has been a highly stigmatised infection, managing sexual partners carries with it a special need for sensitivity and care.
  • Particularly with HIV those responsible for contact tracing should have a clear understanding of local community sensitivities.
  • People with HIV infection should be advised of any risk they pose to uninfected sexual partners, and of the need to practice safe sex.
  • 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 twelve weeks, but the seroconversion illness may pass unnoticed or be difficult to recall.
    • 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. Prior HIV negative serology may be beneficial in establishing the time frame needed for contact tracing. 
    • 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, with the presence of broken skin, ulcers or cuts has been reported as a possible means of transmitting HIV infection but overall it remains a negligible risk activity.
  • 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 and life-long antiretroviral therapy.

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 for the management of non-HIV related health issues. Such and arrangement will most likely include regular monitoring by the specialist, that is communicated to the primary health care provider and visa versa. Ongoing two-way communication between the HIV specialist and primary health care provider is important to ensure that all the patients' health care needs are appropriately men, and that there are no contraindications or concerns in relation to the patient's ongoing antiretroviral therapy.

As discussed previously, patients with HIV should be referred to a HIV specialist or GP specialising in HIV medicine for assessment and for the establishment of a patient management 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, hepatitis B virus (HBV) and hepatitis C virus (HCV). 
  • Discuss with patients their desires or plans for conceiving children. People living with HIV are able to safely conceive and give birth to HIV negative babies. Family planning should be discussed in collaboration with the patient’s HIV specialist.
  • Discuss with patients their general well-being and any mental health indications they may have.
  • While most people living with HIV conscientiously avoid behaviour which exposes others to the risk of HIV infection, a very small number of individuals continue to place others at risk. The Case Management Program (CMP), Department of Health Western Australia, assists individuals to modify their behaviour, through intensive and regular counselling, education and support. This preventive approach is usually successful and only rarely has statutory action, such as isolation of individuals with HIV who put others at risk, been necessary. For more information see the CMP guidelines
Public health issues
  • Contact tracing is important to prevent further transmission and reinfection. 
  • Patients who are not on antiretroviral therapy may be considered infectious, with the most infectious periods being before, during and soon after seroconversion, or when CD4+ T cells are very depleted and the viral load increases.
  • Patients may continue be infectious throughout their illness, depending on factors such as whether they are on or adhering to antiretroviral therapy, and whether they have any concurrent co-infections including other STIs.
  • Always test for other STIs and blood-borne viruses. 
  • 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).

Pre-exposure prophylaxis

Pre-exposure prophylaxis (PrEP) is an important new prevention option and can provide highly effective biomedical prevention of HIV in HIV-negative individuals. See the National PrEP Guidelines and WA’s Interim PrEP Guidelines for more information.

In WA, PrEP can only be prescribed by HIV s100 prescribers, however, it is not funded by the Pharmaceutical Benefits Scheme (PBS). Patients can then either pay for a script of Truvada®  from a pharmacy or import generic versions. See Interim PrEP Guidelines for WA (external site)  WA’s Interim PrEP Guidelines (external site) which provides for more information about how to access PrEP.

A Government-funded PrEP trial will be available soon and updated information will be provided on the Anti-viral therapy to prevent HIV page

Non-occupational post-exposure prophylaxis

NPEP is a course of antiretroviral 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.

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 (external site) to be updated shortly. See the National HIV PEP Guidelines and Policy (external site) for more information.

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). 

Notification

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.

Epidemiological reports and real time notification data