Human immunodeficiency virus & acquired immunodeficiency syndrome

Infection with the human immunodeficiency virus (HIV) causes damage to your body's immune system and impairs your ability to fight disease-causing organisms. Without treatment, some people with HIV may develop the potentially life-threatening condition known as acquired immunodeficiency syndrome (AIDS). HIV is a sexually transmitted infection.

What's the difference between HIV and AIDS?

HIV is a virus that causes HIV infection which damages the immune system and weakens your ability to fight infections and disease. AIDS is the most advanced stage of HIV infection. 

You can be infected with HIV (a virus) without having AIDS (an illness). Without treatment, people who have HIV eventually become ill and can develop AIDS within 5 to 10 years. But, there is a small percentage of people who do not show any deterioration in their health, even after 10 years and do not develop AIDS.

How is HIV spread?

HIV is found in the body fluids of an infected person which includes semen, vaginal and anal fluids, blood and breast milk. In New Zealand, HIV is most commonly caught by having sex without a condom (called unprotected sex), with a person infected with the virus. 

It can also be passed on by:

  • sharing infected needles and other injecting equipment
  • from an HIV-positive mother to her child during pregnancy, birth and breastfeeding.

What are the symptoms of HIV?

Most people who have HIV do not have symptoms. When symptoms do occur, they are similar to a number of other illnesses. Some of the more common symptoms of HIV-related illnesses are:

  • flu-like symptoms
  • severe and constant tiredness
  • fever, chills and night sweats
  • sudden loss of weight for no known reason
  • white spots or unusual marks in the mouth
  • diarrhoea (runny or watery poos)
  • decreased appetite.

How is HIV diagnosed?

The only way to find out if you have HIV is to have an HIV test. This involves testing a sample of your blood. If HIV infection is found in a person's blood, then this person is said to be HIV positive.

  • If you think you may have been exposed to HIV, your doctor, Family Planning clinic, sexual health clinic or the New Zealand AIDS Foundation can arrange the blood test. The result is confidential.
  • If your first test suggests you have HIV, a further blood test will need to be carried out to confirm the result. If this is positive, you'll be referred to a specialist HIV clinic for some more tests and a discussion about your treatment options.
  • There is a short period just after a person is infected with HIV when the virus cannot be detected. People exposed to HIV may require a follow-up test 3 months later.  

How is HIV treated?

HIV is treated with a combination of medicines, known as antiretroviral therapy, or ART. These work by stopping the virus replicating (spreading) in the body, allowing the immune system to repair itself and preventing further damage. Taking these medicines can reduce the amount of virus in your body and help you stay healthy.

You will also be encouraged to take regular exercise, eat a healthy diet, stop smoking and have the flu vaccine every year to lessen the risk of getting serious illnesses. Without treatment, the immune system will become severely damaged and life-threatening illnesses such as cancer and severe infections can occur. This is known as late-stage HIV infection or AIDS.

Read more about antiretroviral therapy.

How to prevent HIV?

There are a few things you can do to protect yourself from HIV.

  • Safe sex – using condoms and water-based lubricant correctly every time you have vaginal or anal sex reduces the risk of getting HIV by around 95%.
  • Don't share needles – if you inject yourself with drugs, it’s important to use new needles and syringes. Blood is left on syringes and needles every time they’re used. If you share injecting equipment, you can catch HIV from another person’s blood if they are infected.
  • HIV antenatal screening – women with HIV can pass it on to their babies during pregnancy, birth and while breastfeeding. If you’re pregnant, you’ll be offered a screening test for HIV at the same time as you have your other blood tests, as a routine part of your antenatal care. The screening programme is run by the National Screening Unit. If you’re found to have HIV, you’ll be offered treatment that reduces the chance of your baby becoming infected from approximately 25% to less than 2%.
  • Using pre-exposure prophylaxis (PrEP) – an HIV prevention method for people who do not have HIV, but are at risk. By taking a pill every day you can reduce your risk of becoming infected with HIV. Read more about PrEP.

If you are HIV positive, you can take precautions to avoid spreading the infection to others.

  • Tell your sex partner or partners about your behaviour and whether you are HIV-positive.
  • Follow safer sex practices, such as using condoms.
  • Do not donate blood, plasma, semen, body organs, or body tissues.
  • Do not share personal items, such as toothbrushes, razors, or sex toys, that may be contaminated with blood, semen, or vaginal fluids.

Learn more

New Zealand AIDS Foundation 
HIV/AIDS Ministry of Health, NZ
INA (Māori, Indigenous and Pacific Island HIV/AIDS Foundation)


  1. HIV Management in Australasia ASHM,2009
  2. General Practitioners and HIV ASHM, 2015