Causative organism

Human immunodeficiency virus (HIV)

Incubation period

1-6 weeks for primary HIV (many are asymptomatic); median of 10-11 years to AIDS without treatment

How far to trace back

Start with recent sexual or needle-sharing partners; outer limit is onset of risk behaviour or last known negative HIV test result

Usual testing method

Serology for HIV
Repeat test if recent infection possible after window period

Common symptoms

Usually asymptomatic unless immune-suppressed.

Glandular fever-like illness possible in HIV seroconversion.

Late presentation may occur which can include AIDS-defining illnesses and other clinical indicator conditions. See Table 1 Indicator Conditions National HIV Testing Policy

Likelihood of transmission in a person with a detectable viral load per act of condomless intercourse 

Higher with elevated HIV viral load, for example during primary infection and late infection, or if other STls are present or a person is uncircumcised. If viral load is undetectable (<200 copies/mL) sexual transmission cannot occur (U=U undetectable equals untransmissible). Use of pre-exposure prophylaxis as prescribed (PrEP) or post-exposure prophylaxis (PEP) significantly reduces risk.  

Type of exposure with known HIV+ source who is not on ART

Estimate of HIV transmission/exposure*

Receptive anal intercourse:



Insertive anal intercourse:



Vaqinal intercourse:




Receptive or insertive oral intercourse

unable to estimate risk - extremely low

Shared needles and other injecting equipment


Needlestick injury or other shapes exposure


Mucous membrane and non-intact skin exposure

* These estimates are based on prospective studies, not cross-sectional data or figures derived from modeling. These estimates do not take into account source viral load, which, if undetectable markedly reduces risk estimates.
†Human bites are extremely low risk. 

From: Post-Exposure Prophylaxis after Non-Occupational and Occupational exposure to HIV

Likelihood of long-term sexual partner being infected

Influenced by whether HIV positive individual is on treatment with undetectable viral load and/or whether partner is taking pre-exposure prophylaxis. 

Protective effect of condoms


Transmission by oral sex

Extremely rare

Duration of potential infectivity


U=U if person is on adequate treatment

Important sequelae

Transmission to others including vertical transmission to a child during pregnancy
HIV-related illnesses - see table 1 Indicator Conditions National HIV Testing Policy

Direct benefit of detection and treatment of contacts

Detection of HIV in contacts, potentially reducing further transmission and allowing early initiation of treatment in newly diagnosed.

Usual management of contacts

HIV-serology testing and counselling. For exposures to HIV within the last 72 hours, contacts may benefit from post-exposure prophylaxis. See STI Guidelines
Referral to support agencies.

Contact tracing priority

Very high. Provider referral is the preferred contact tracing method.
Note: If the index patient has donated or received blood products, semen or body tissue, contact the relevant authority as well.

For those whose HIV has been detected due to a recent TB diagnosis ensure contact tracing for TB contacts is also addressed. All TB contact investigation and follow-up for each TB case is managed by the TB program within each State and Territory. The management of TB contacts is outlined in the CDNA National Guidelines for Public Health Units - Management of TB and your State/Territory TB program guidelines.

See also the section on People Living with HIV in specific populations.



HIV notification is made by laboratories or doctors in most states and territories of Australia. Public health legislation in some jurisdictions requires that people with HIV advise future sexual partners of their condition. All jurisdictions have processes in place for individuals who require support to contact trace and for those who knowingly expose others to the risk of HIV infection.