Testing for human immunodeficiency virus

SUMMARY

Testing for human immunodeficiency virus (HIV) is recommended for individuals with behavioural or epidemiological risk factors, and those who present with clinical indicator conditions. Routine testing is recommended in pregnancy and as part of symptomatic and asymptomatic sexually transmissible infection check-ups.

In Australia, laboratories primarily use combined HIV antibody and antigen tests for diagnostic testing. A reactive test is followed by a laboratory confirmatory test. Clinicians should consider whether the person is within the testing window period when interpreting results.

On receipt of a confirmed HIV-positive result, healthcare providers must discuss the result and contact tracing with the patient, and ideally refer them to specialised services, including an HIV care provider.

 

Introduction

In 2024, approximately 40 million people worldwide were living with HIV, with around three-quarters receiving antiretroviral therapy.¹ Globally, the majority of people living with HIV are women (53%).² However, the pattern of HIV infection varies widely by region due to sociocultural and behavioural factors, the effectiveness of and access to prevention programs such as education and testing, behavioural interventions and harm minimisation strategies including needle exchange programs, pre-exposure and post-exposure prophylaxis (PrEP and PEP), and treatment as prevention.

In Australia, an estimated 30,000 people were living with HIV at the end of 2023. There were 757 new diagnoses in 2024, up from 553 in 2022.³ Despite this recent increase, overall HIV diagnoses have declined by 27% from 2014 to 2024,³ with significant reductions in new diagnoses among gay, bisexual and other men who have sex with men, though these remain the majority of those living with HIV in Australia.⁴ There has been little change in the number of people acquiring HIV through heterosexual sex within Australia.⁴ It is estimated that, in 2023, 8% of people living with HIV in Australia were unaware of their HIV status, underscoring the importance of testing and diagnosis.⁴

Widespread and normalised HIV testing enables earlier diagnosis and treatment. Earlier initiation of antiretroviral therapy is associated with improved life expectancy of people living with HIV, now approaching that of those without HIV, due to virological suppression leading to improved or maintained immunity and a reduction in HIV-related complications.^5,6 Treatment also prevents HIV transmission by achieving an undetectable viral load (a principle known as 'undetectable equals untransmittable').⁷ Additionally, there is some evidence that early treatment during HIV seroconversion (primary HIV infection and production of antibodies) reduces latent viral reservoirs and viral diversity, potentially making a future cure easier.⁸

This article outlines the indications for HIV testing, types of testing, and how a clinician should manage a positive test result.

 

Who to test

A number of strategies can be applied to testing for HIV at a population and individual level. Internationally, the approach to testing is dependent on the health system and prevalence of HIV within the region. For example, the US Centers for Disease Control and Prevention recommends testing for all individuals between 13 and 64 years of age at least once.⁹ In the UK and Ireland, testing is offered to all patients presenting to emergency departments in regions with higher HIV prevalence.^10,11 In Australia, guidelines recommend HIV testing for people with behavioural or epidemiological risk factors for HIV, and those who present with clinical indicator conditions.^12-15 Universal testing is currently not recommended in Australia.

Testing based on behavioural and epidemiological factors

HIV can be transmitted through sexual contact (via semen and vaginal fluids), blood-to-blood contact, and from mother to child during pregnancy and breastfeeding. As with all testing, informed consent is required, including an understanding of the type of test, reasons for testing, and implications of not being tested.

HIV testing should be routinely performed during antenatal screening as HIV can be vertically transmitted, and interventions to reduce transmission can be implemented.^16,17

Testing for HIV (along with syphilis) should be part of routine sexually transmissible infection (STI) testing; whether someone presents for a sexual health screen, tests positive for another STI, or is being tested as part of contact tracing.¹³

HIV testing is also recommended in those with behavioural or epidemiological risk factors (Box 1). For the full list of indications for HIV testing, refer to the ASHM website.

Testing is recommended approximately every 3 months for gay, bisexual and other men who have sex with men, sex workers, transgender women (if sexually active), people who identify as gender diverse who have sex with men, and people who inject drugs (for nonmedical purposes) or share injecting equipment.¹²

Healthcare workers (including students) who perform exposure-prone procedures should undertake HIV testing at least once every 3 years and be aware of their status.¹⁹ Exposure-prone procedures include those where the healthcare worker's hands may come into contact with sharp instruments, needle tips or sharp tissues inside a patient's open body cavity or wound (e.g. open abdominal or thoracic procedures). Excision of skin lesions is not considered an exposure-prone procedure.¹⁹ Workplace needlestick injuries should be managed as per workplace testing protocols.

For individuals receiving PrEP, HIV testing (along with testing for other STIs) is currently recommended every 3 months.¹⁴ Testing must also be done for individuals receiving PEP.²⁰

Testing based on clinical indicator conditions

HIV testing is recommended in people who present with clinical indicator conditions (Table 1), regardless of the presence or absence of behavioural and epidemiological risk factors.¹⁸ This approach is cost effective,²¹ focuses less on stigmatised behaviours, and encourages testing based on clinical conditions rather than assumptions about risk. It can lead to identification of HIV in individuals who may not have recognised risk factors and in situations where HIV might otherwise be missed, such as unexplained prolonged weight loss or haematological abnormalities (e.g. thrombocytopenia).²² Indicator-based testing enables clinicians to introduce testing in a way that may be more comfortable for both the clinician and the patient by framing it as a routine test.

Indicator-based testing is now embedded in Therapeutic Guidelines, supporting guideline-driven testing as part of standard care, which was not always done in the past.²³

HIV indicator conditions (Table 1) can be divided into 3 categories:¹⁸

• conditions that are acquired immunodeficiency syndrome (AIDS) defining in people living with HIV such as pneumocystis pneumonia or Kaposi sarcoma
• conditions associated with a likely undiagnosed HIV prevalence of 0.1% or higher, such as STIs, recurrent bacterial pneumonia, persistent thrombocytopenia, unexplained weight loss, chronic diarrhoea of unknown cause, and multidermatomal shingles. Many of these are common presentations in primary care settings
• conditions where not identifying HIV may have significant implications for care such as conditions requiring systemic immunosuppressive therapy (e.g. cancer).

Table 1 Indicator conditions for human immunodeficiency virus (HIV) testing¹⁸

	AIDS-defining conditions in people living with HIV	Other conditions where HIV testing should be offered
Sexually transmissible infections	–	Gonorrhoea, chlamydia, hepatitis B, hepatitis C, syphilis, or any other sexually transmissible infection
Respiratory infections	Tuberculosis Pneumocystis Recurrent bacterial pneumonia	Aspergillosis
Neurological conditions	Cerebral toxoplasmosis Primary cerebral lymphoma Cryptococcal meningitis Progressive multifocal leukoencephalopathy	Aseptic meningitis or encephalitis Cerebral abscess Space occupying lesion of unknown cause Guillain–Barré syndrome Transverse myelitis Peripheral neuropathy Dementia Leukoencephalopathy
Dermatological conditions	Kaposi sarcoma	Severe or recalcitrant seborrhoeic dermatitis Severe or recalcitrant psoriasis Multidermatomal or recurrent herpes zoster (shingles)
Gastroenterological conditions	Persistent cryptosporidiosis Oesophageal candidiasis	Chronic oral candidiasis Oral hairy leukoplakia Chronic diarrhoea of unknown cause Weight loss of unknown cause Nontyphoidal salmonella (bacteraemia, osteomyelitis and septic arthritis) Recurrent enteric salmonellosis, shigellosis or Campylobacter Hepatitis B infection Hepatitis C infection
Oncological conditions	Non-Hodgkin lymphoma	Anal cancer or high-grade anal squamous intraepithelial lesion Penile cancer Seminoma Human papillomavirus–related head and neck cancer Hodgkin lymphoma Castleman disease
Gynaecological conditions	Cervical cancer	Vaginal, vulval or cervical or high-grade intraepithelial lesion
Haematological conditions	–	Any unexplained blood dyscrasia including thrombocytopenia, neutropenia and lymphopenia
Ophthalmological conditions	Cytomegalovirus retinitis	Infective retinal diseases including herpesviruses and toxoplasma
Conditions of the ear, nose and throat	–	Lymphadenopathy of unknown cause Chronic parotitis Lymphoepithelial parotid cysts
Other	–	Mononucleosis-like syndrome (primary HIV infection) Pyrexia of unknown origin Any lymphadenopathy of unknown cause
AIDS = acquired immunodeficiency syndrome Adapted from ASHM. Indications for HIV testing. ASHM, 2020. Available at: https://testingportal.ashm.org.au/national-hiv-testing-policy/indications-for-hiv-testing/, with permission from ASHM.

 

Types of HIV testing

Diagnostic testing for HIV infection is performed in the laboratory. Testing may also be conducted outside the laboratory (e.g. clinic, home) using rapid tests.

Laboratory testing

Australian laboratories primarily use fourth- or fifth-generation combined HIV antibody and antigen tests (enzyme immunoassay or enzyme-linked immunosorbent assay [ELISA]).²⁴ Following possible exposure to HIV, it can take several weeks before antibodies or viral antigens are detectable by a test, a period known as the 'window period'. The length of the window period depends on the time to seroconversion and the type of test used.^24,25 Contemporary laboratory-based tests are highly sensitive and specific, with window periods of 3 to 4 weeks. However, laboratories generally set the window period as 6 to 12 weeks,^24,25 after which clinicians can be confident that the test result is accurate, particularly that a negative result indicates the individual does not have HIV. A false negative result can occur during the window period, and retesting should be offered if there have been further exposures within the window period. The usual window periods cannot be applied to people who have taken PEP, PrEP or early antiretroviral therapy. People who acquire HIV while on PrEP may experience a delay in seroconversion and this can impact on traditional testing algorithms.²⁴

A reactive ELISA test (when either HIV antigens, anti-HIV antibodies, or both are detected) performed in a laboratory will automatically undergo confirmatory testing, usually with a Western Blot or, in some cases, a nucleic acid amplification test (e.g. PCR). Nucleic acid amplification tests are primarily used for monitoring response to antiretroviral therapy (by measuring quantitative viral load).^24,26

Rapid HIV tests

Rapid HIV tests are performed outside the laboratory and can be classified as point-of-care tests (performed in clinical settings by a healthcare worker) or self-tests (performed outside clinical settings, such as in the home, by a lay person).²⁴ Rapid tests can provide a result within 30 minutes and require either a finger-prick blood sample or saliva.²⁴ Rapid tests are lateral flow immunoassays and are less sensitive than laboratory-based tests. Therefore, these tests have a longer window period than laboratory-based tests (typically 12 weeks).²⁴

Self-testing may be more convenient, reduces barriers to testing, and avoids stigma; however, individuals should be provided with clear instructions and an explicit route to care in the event of a reactive test. A person receiving a reactive rapid test result should undergo confirmatory diagnostic testing at the laboratory and be tested for other STIs. Self-testing kits can be ordered for free online or purchased from some pharmacies.^27,28

 

How to manage a positive test result

If the initial test is reactive and the confirmatory test is positive, this indicates the person has HIV. Reference laboratories often call healthcare providers when test results are positive or ambiguous, and can give advice on results and information on referral pathways. The clinician is responsible for informing the person with HIV and referring them for specialist care, such as a community s100 prescriber (e.g. general practitioner, nurse practitioner) or a sexual health or infectious diseases clinician, along with baseline testing and advice on starting antiretroviral therapy as soon as possible. HIV test results may be uploaded to an individual's My Health Record unless they have opted out or the healthcare provider has indicated on the test request form that the results should not be uploaded.²⁹

Laboratories are required to automatically notify the local public health unit in the event of a positive result. Healthcare providers must discuss contact tracing with the patient, including informing relevant individuals (e.g. sexual partners). ASHM (an Australian peak body for healthcare professionals working in HIV, bloodborne viruses, and sexual and reproductive health) provides training and resources for healthcare professionals, including guidance on contact tracing and a list of HIV s100 and PrEP prescribers in Australia.

 

Conclusion

HIV testing is recommended as part of routine STI check-ups and antenatal screening, for individuals with behavioural or epidemiological risk factors, and for those presenting with clinical indicator conditions. Clinicians should have a low threshold for ordering HIV testing, particularly in indicator conditions. A reactive test requires confirmatory laboratory testing, and interpretation of test results requires consideration of the window period.

This article was finalised on 21 October 2025.

Conflicts of interest: Louise Owen is the President of the Australasian Chapter of Sexual Health Medicine and previous co-Vice President of the ASHM Board. Louise contributed to the development of the ASHM Post-Exposure Prophylaxis for HIV Guidelines (for which she received one honorarium), as well as the development of ASHM's HIV s100 Prescriber Course. Louise is on several ASHM national steering committees and state advisory committees for LGBTQIA+, HIV and hepatitis working groups.

Ian Woolley was a principal investigator for studies relating to HIV drugs funded by Merck Sharp & Dohme, Gilead and ViiV Healthcare. Ian received support for educational activities from ViiV Healthcare, Gilead and Pfizer, and consultancy fees from ViiV Healthcare, Gilead and Bristol Myers Squibb. Ian was a member of the expert committee for the National HIV Testing Policy and the Australasian Contact Tracing Guidelines. Ian was an expert group member of Therapeutic Guidelines: Antibiotic version 17.

This article is peer reviewed.

 

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