Human immunodeficiency virus (HIV) infection - including symptoms, treatment and prevention

Human immunodeficiency virus is a notifiable condition1

The human immunodeficiency virus (HIV) is a virus that weakens the body’s immune system. It reduces the number of CD4+T cells, a type of white blood cell that has an important role in immunity.

People with HIV who go untreated can develop severe illness. When this happens, the immune system is weakened, making it difficult for the body to fight infections and certain cancers. This is also referred to as acquired immunodeficiency syndrome (AIDS).

Whilst a vaccine or cure for HIV is yet to be discovered, highly effective HIV antiretroviral therapies are available to all people living with HIV in Australia. Sustained, high uptake of these medications has resulted in the virtual elimination of AIDS in Australia.

HIV in Australia is now considered a manageable, chronic condition.

If treatment is taken as prescribed, people living with HIV can achieve an undetectable viral load. Achieving an undetectable viral load not only prevents disease progression, allowing people living with HIV to live long and healthy lives, it also eliminates the risk of transmitting HIV to their sexual partners and to their baby during pregnancy. 

This is known as treatment as prevention or U=U (undetectable equals untransmittable).

How HIV is spread

HIV infection occurs when certain body fluids (blood, semen, vaginal fluid, anal fluid and breast milk) containing the virus come into contact with another person’s tissues beneath the skin’s surface (for example, through needle puncture or broken skin), or mucous membranes (the thin moist lining of many parts of the body such as the nose, mouth, throat, genitals and anus).

In Australia, most HIV infections occur from unprotected sex (anal or vaginal intercourse without a condom) and/or the sharing of injecting equipment (needles and syringes).

If you are pregnant and HIV positive, transmission to your baby may occur if you are not taking effective treatment for HIV. Therefore, HIV testing is routinely offered amongst other tests in early pregnancy.

Routine social or community contact with a person living with HIV carries no risk of infection.

There is no evidence of HIV transmission through:

  • social contact in schools, at home or in the workplace
  • air or water
  • swimming pools or toilets
  • sharing of plates, cups or cutlery
  • kissing
  • coughing or sneezing
  • spitting
  • mosquitos or other biting insects.

In Australia, receiving blood, blood products or an organ transplant is not a risk for HIV infection as screening for HIV occurs.

Signs and symptoms of HIV

Acute infection

A few weeks after infection with HIV, a flu-like illness might develop. This is known as seroconversion illness, which is a sign that the body is reacting to the infection. Symptoms may include:

  • muscle aches
  • low-grade fever
  • headaches
  • sometimes a rash
  • swelling of the lymph glands may also occur.

The symptoms of seroconversion illness can be so mild they go unnoticed, or, in some people, it can be quite severe and last for a few weeks before there is a return to seemingly normal health. Either way, seroconversion illness is so similar to many other viral infections that the diagnosis of HIV infection may not be made at this time.

Longer term, untreated HIV infection

The length of time that a person with untreated HIV infection may live without symptoms varies widely, but usually severe disease develops in adults within 10 years of infection.

When symptoms develop in untreated HIV, they may not be specific and can include:

  • chronic loss of appetite
  • diarrhoea
  • weight loss
  • fever
  • lethargy
  • fatigue.

Untreated HIV destroys certain cells within the immune system (CD4+ also called helper T cells) from the time of infection onwards, causing more and more damage. AIDS occurs when the damage to the immune system is so great the body can no longer stop some infections or cancers it normally fights successfully. Infections not usually seen in healthy people (opportunistic infections) and certain unusual tumours such as Kaposi’s sarcoma, might occur. Untreated HIV can also cause infection and inflammation in the brain, which can lead to nervous system disorders or dementia in some people.

Cervical and anal cancers are more common in people with HIV. Vaccination for human papillomavirus (HPV) can help protect against these cancers.

Diagnosis of HIV

Diagnosis of HIV infection is made using blood tests.

A positive blood test indicates the development of antibodies to HIV and therefore the presence of the virus. Antibodies to HIV usually develop within a few weeks to three months. Even though the blood test for antibodies may not be positive during the early stage of infection (the window period), the virus will be present in certain body fluids (blood, semen, vaginal fluid and breast milk), making the person infectious to other people.

A blood test, where a sample of blood is taken from a vein in your arm, to diagnose HIV infection can be ordered by a general practitioner (GP) or conducted at a sexual health clinic, such as:

While they cannot be used to provide a confirmatory diagnosis, there are other HIV testing options available including rapid and self-testing. For more information see HIV testing.

Incubation period

(time between becoming infected and developing symptoms)

While illness may not occur for months or years after becoming infected with HIV, without treatment, most adults will develop severe disease within 10 years of infection.

Infectious period

(time during which an infected person can infect others)

Once a person has been infected with HIV, without treatment they remain infected for life and may be able to transmit the virus to others.

The risk of transmitting HIV infection to another person is dependent on the level of virus (viral load) in the body fluids (blood, semen, vaginal fluid, anal mucus and breast milk) of the infected person. 

The risk of HIV transmission is greatest when a person’s viral load is high, such as during early infection (when a person may not be aware they have HIV) and late in untreated infection (when the immune system is failing). However, if through taking treatment as prescribed a person living with HIV achieves a low or undetectable viral load, they eliminate the risk of transmitting HIV to their sexual partners and to their baby during pregnancy entirely (U=U). 

For more information see HIV treatment.

Treatment for HIV

It is recommended that HIV treatment starts as soon as possible after diagnosis.

Although there is no cure or vaccine for HIV, major advances in treatment have transformed it into a manageable condition.

Modern therapies can slow or stop disease progression, with many people managing their HIV through a simple daily pill that typically has minimal side effects. In countries like Australia, effective HIV treatment often leads to long-term viral suppression and an undetectable viral load, allowing individuals living with HIV to live long, healthy lives without transmitting the virus to their sexual partners or to their baby during pregnancy (U=U).

For more information see HIV treatment.

Prevention of HIV

HIV infection can be prevented by:

  • Using condoms with water-based lubricant during vaginal, anal and oral sex.
  • Regularly testing for HIV, other blood borne viruses and sexually transmissible infections.
  • Not sharing injecting equipment (e.g. needles, syringes, filters, spoons, swabs and tourniquets), and safely disposing of any found or used needles.
  • Ensuring sterile equipment is always used for any skin penetrating procedures (e.g. acupuncture, tattooing and body piercing).
  • Using HIV pre-exposure prophylaxis (PrEP) or HIV post-exposure prophylaxis (PEP).
  • Using standard precautions (this means treating all blood and body fluids as potentially infectious).
  • Ensuring any open sores, cuts or abrasions are covered with waterproof dressings (especially before handling any blood or other body fluids).
  • Achieving viral suppression with an undetectable viral load (U=U).

Exclusion from childcare, preschool, school and work is not necessary. Children living with HIV may be advised to stay away from school during outbreaks of infectious diseases (for example, chickenpox) to prevent them getting the infection.

Health care workers with HIV must comply with the requirements of their professional boards and in doing so are usually able to continue working. If you are a health care worker, please see the HIV for health professionals page.

1 – In South Australia the law requires doctors and laboratories to report some infections or diseases to SA Health. These infections or diseases are commonly referred to as 'notifiable conditions'.

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