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 or AIDS

Likelihood of transmission per unprotected exposure 

Receptive anal sex:


Receptive vaginal sex:


Insertive vaqinal or anal sex:


Reused injecting equipment:


Needle-stick injury (freshly contaminated):


Contaminated blood transfusion:


Higher with elevated HIV viral load, for example during primary infection and late infection, or if other STIs present or a man is uncircumcised. Significantly reduced by antiretroviral therapy.

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-xposure prophylaxis.

Protective effect of condoms


Transmission by oral sex


Duration of potential infectivity


Important sequelae

Mother-to-child transmission

Direct benefit of detection and treatment of contacts

Usual management of contacts

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

HIV-antibody 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.


AIDS is notifiable by all doctors in all Australian states and territories and in New Zealand. 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.