What are HIV and AIDS?

Human immunodeficiency virus (HIV) is a virus that can lead to acquired immunodeficiency syndrome (AIDS). It attacks specific cells of a person’s immune system, called T-lymphocytes, which then impairs the immune system function. When the person’s immune system is sufficiently weakened, they develop AIDS. People with AIDS become susceptible to opportunistic infections.

There are tens of millions of people living around the world with HIV/AIDS. Without a cure or vaccine, the number of people with HIV/AIDS has increased in recent years. However, with appropriate public awareness, further spread of this condition can be limited.

Signs, symptoms and stages

The early stages of HIV infection trigger flu-like symptoms such as fevers, swollen lymph nodes, a sore throat, rash, fatigue, headache, and muscle and joint pains. Given how common these symptoms are, it can be difficult to initially know if you have HIV. This initial period is referred to as acute retroviral syndrome. If you are sexually active, or experience any of the above symptoms after a sexual encounter and think they might be related, a sexual health check-up is a good idea. This is because the only accurate method with which to diagnose HIV is a blood test. 

After early-stage infection, the disease progresses to a stage with little or no physical symptoms. However, during this stage the HIV infection is still replicating, usually at low levels, which makes the individual still infectious. It typically takes about 10 years for HIV infection to progress to AIDS. Antiretroviral medication helps to reduce replication of the virus and can delay the development of AIDS for up to several decades.

When HIV progresses to AIDS, symptoms include rapid weight loss, recurring fevers, chronic fatigue, prolonged lymph node swelling, diarrhoea that lasts more than a week, pneumonia, sores on the mouth and genitals and neurological disorders such as depression and memory loss. 


HIV is caused by a type of virus known as a retrovirus. It is mainly transmitted through sexual activity, but can also be spread through contact with other body fluids including blood and breastmilk. It cannot be spread by contact with saliva, such as from kissing or sharing cutlery. Once in the body, HIV invades a specific group of T-lymphocytes in the immune system, called CD4+ cells, or T-helper cells. The HIV replicates within these T-helper cells, ultimately destroying them and weakening the immune system. T-helper cells play a major role in protecting the body from infections. They send signals to other cells in the immune system to detect ‘intruders’ such as viruses and bacteria. 

Risk factors

Risk factors for HIV infection include:

  • A sexual partner with HIV;
  • Unprotected vaginal or anal sex;
  • Multiple sexual partners;
  • Engaging the services of a sex worker;
  • Injecting drugs and using shared needles;
  • Tattoos from an unregistered tattooist and;
  • Being accidentally jabbed with a HIV-contaminated needle in a health clinic.


There are two main types of viruses that cause HIV infections – HIV-1 and HIV-2. HIV-1 is the most common globally, while HIV-2 is largely limited to West Africa. There are currently no vaccines for either type of virus; however, there is ongoing research to develop a vaccine. 

Methods for diagnosis and monitoring

HIV diagnosis

Blood tests are performed to check for HIV infection. There are two main ways to be tested – a rapid test or a conventional test. The rapid test uses a fingerprick of blood, which an automated machine can quickly process, producing a result in 10-20 minutes. The conventional test uses a sample of blood taken from a vein, which is sent off to a laboratory for testing and can take up to a week for a result. Both tests commonly assess for:

  • HIV antibody – the body makes antibodies to help fight the HIV infection. Usually, antibodies are produced between 2-8 weeks following a HIV infection, and;
  • p24 antigen – this is a protein that is part of the HIV virus and is produced in high amounts during the early stage of the infection. It can be used to detect the HIV infection at an earlier stage than the HIV antibody test. It can also be used to monitor the response to treatment.

There can be a period of time between becoming infected with HIV and the above tests showing positive results. This is known as the window period. This period can be between six weeks to three months, from the time when you might have been exposed to the virus. Often, if the test result is negative within this period, further testing may be recommended at the six-week or three-month mark (depending on the laboratory) to more confidently rule out the chance of an infection. 

If the first test is positive, a second blood test is often performed to confirm the diagnosis. The following tests can be performed: 

  • Western blot – to test for antibodies to the HIV infection;
  • HIV-1 nucleic acid test – to test for the virus directly, and;
  • Multispot HIV-1/HIV-2 testing – to determine if you have HIV-1 or HIV-2.

HIV monitoring

The following are used to monitor a HIV infection and check how well you are responding to treatment:

  • Viral load test – this test determines the amount of viruses in the body;
  • CD4+ cell test – this test determines the number of CD4+ cells you have. It is used to diagnose AIDS when your CD4+ cell count drops below 200 cell/microL, and;
  • Genotypic resistance testing – this test is performed if your viral load rises while on treatment, to determine if the HIV is resistant to your medication.

Types of treatment

HIV infection

There is no cure for HIV. However, HIV can be effectively managed to ensure a long and healthy life.

If you have HIV, treatment will focus on reducing the number of viruses in the body, which helps maintain a high CD4+ cell count and slow down the disease’s progression to AIDS. Medications used to treat HIV infection are known as antiretroviral medicines. These include:

  • Non-nucleoside reverse transcriptase inhibitors (NNRTIs), which work by blocking the enzyme involved in HIV replication, thereby keeping the viral numbers low;
  • Nucleoside/nucleotide reverse transcriptase inhibitors (NRTIs), which work by blocking the replication of the virus inside the body’s cells;
  • Protease inhibitors, which block an enzyme that is needed for HIV replication;
  • Integrase inhibitors – which block another enzyme involved in HIV replication, and;
  • Fusion inhibitors, which block the virus from entering T-helper cells.

The decision about the type of medications to use and when to use them is often complex. Often you will be referred to a medical specialist in this area to supervise your treatment and provide guidance with making decisions. 

Post-exposure prophylaxis

Post-exposure prophylaxis (PEP) is a course of antiretroviral medication that is taken immediately after a possible exposure to HIV. If you believe you have been exposed to HIV, PEP can help prevent the establishment of an infection. However, it must be taken within 72 hours of exposure. If you suspect that you may be at risk, it is important to see a doctor immediately for testing and possible PEP.

Treatment for AIDS-related infections

AIDS is defined as having a CD4+ cell count that is below 200 cells/microL. AIDS puts you at risk of opportunistic infections, so you will need preventative treatment for the following conditions:

Pneumocystis pneumonia

Pneumocystis pneumonia can occur if you have a CD4+ cell count of less than 200 cells/microL. An infection of the lungs is the most common cause of AIDS-related pneumonia death. The preferred preventative treatment for pneumocystis is an antibiotic known as trimethoprim-sulfamethoxazole. 


Histoplasma is a type of fungus found in soil or bird and bat droppings. Preventative antifungal treatment is recommended when the CD4+ cell count is less than 150 cells/microL.


Toxoplasmosis is an infection found worldwide that is caused by a parasite called Toxoplasma gondii. Healthy people typically do not have any symptoms. In people with AIDS, however, it can be a life-threatening infection.

Reducing the risk of exposure to toxoplasmosis is generally advised. This includes avoiding meat that is undercooked, washing fruit and vegetables properly, avoiding stray cats (and changing cat litter), avoiding gardening and washing your hands before food preparation. 

A blood test is usually performed to assess if individuals have been previously exposed to this common parasite (most people have been). If there has been prior exposure and a person’s CD4+ cell count is less than 100 cells/microL, medications (such as trimethoprim-sulfamethoxazole) can be used to further reduce the risk. If there was no prior exposure, such medications are generally not needed. However, regular retesting for this infection when the CD4+ cell counts are less than 100 cells/microL is recommended, as it is common for the person to easily pick up the infection.


Preventative treatment for mycobacterium avian complex, a type of bacteria, includes antibiotics when your CD4+ cell count is less than 50 cells/microL.


Candidiasis (or thrush) is an infection with a yeast typically found in the mouth and groin areas. Preventative treatment for candidiasis is not recommended unless repeat infections occur, in which case antifungals can be used.


Cryptococcus is a yeast-like fungus found in soil. It can cause infection in the lungs (cryptococcosis) or the brain (cryptococcus meningitis). Preventative treatments are not commonly recommended for this type of infection because they have not been shown to improve survival. When used, treatment includes antifungals.


Coccidioides is a type of fungus that causes coccidioidomycosis, which most commonly manifests as pneumonia, but can spread throughout the entire body. Preventative treatments are not commonly recommended for this type of infection. You can reduce your risk of acquiring this infection by avoiding activities that expose you to dust or soil. If you have a coccidiodes infection, treatment will include antifungals.


Cytomegalovirus is a common virus that in healthy people causes a mild illness, but can cause serious complications in people with AIDS. These include diseases of the digestive system, eyes and spinal cord. 

Preventative treatment for cytomegalovirus is not commonly recommended. When used, preventative treatment includes antiviral medications. 


Cryptosporidium is a type of parasite found in contaminated water. It can also spread through contact with human or animal faeces. The infection causes diarrhoea in healthy individuals, which is generally mild. In people with AIDS, an infection with the parasite can result in severe and prolonged bouts of diarrhoea. Practising good hygiene can limit your risk of acquiring the infection, but there are no proven medications to prevent cryptosporidium infections. 

Alternative treatments

Some people diagnosed with HIV seek out complementary and alternative therapies. None of these alternative therapies cure HIV, but some can help people feel better when used together with conventional medical treatment. However, it is important to discuss any treatments with your doctor before starting them, as they can interact with conventional medications. 

Potential complications

The main complication of HIV infection is the development of AIDS. There are numerous complications associated with AIDS, including opportunistic infections mentioned above. Other complications of HIV/AIDS are:

Bone fracture

HIV is associated with a small increase in the risk of bone fractures.

Neurological complications

AIDS dementia complex

AIDS dementia complex (ADC), also called HIV-associated dementia (HAD), occurs in people with an advanced HIV infection. Symptoms include inflammation of the brain (encephalitis), decreased memory and thinking capacity, behavioural changes and difficulty concentrating, as well as progressive loss of motor function and coordination. ADC can lead to complete dependence and even early death; however, the condition can be effectively treated with antiretroviral medications and also antipsychotic, antidepressant or anticonvulsant medications to relieve specific symptoms. Also, it may be prevented or delayed through the use of antiretroviral medications in people with an HIV infection.

Vacuolar myeopathy

Vacuolar myeopathy is when small holes, called vacuoles, form in the outer layers of nerves. These holes interrupt the electrical messages sent by nerves, disrupting normal bodily functions. This damage is believed to be caused by specific white blood cells, called macrophages. Symptoms of vacuolar myeopathy include stiff and weak legs and instability while walking. In some people it can progress to AIDS dementia.

Progressive multifocal leukoencephalopathy

Progressive multifocal leukoencephalopathy (PML) is caused by a specific virus that destroys the outer layer of nerves. Symptoms include impaired vision and vision loss, speech problems, paralysis, brain lesions and coma. The condition occurs exclusively in individuals who are immunosuppressed and although there is no specific treatment, improving the immune system of HIV patients through use of antiretroviral medications may improve survival.


Neurosyphillis is caused by the syphilis infection. It is recommended to adequately treat syphilis with antibiotics before it causes neurosyphilis.


Kaposi’s sarcoma

Kaposi’s sarcoma is the second-most common HIV-related cancer, occurring in more than half of people with HIV in the late stages of infection. It is caused by Kaposi-sarcoma-associated herpes virus (KSHV). The relationship between HIV and KSHV infection is not fully understood.

Central nervous system lymphomas

Central nervous system lymphomas are a type of cancer that develops in the brain and, rarely, in the spinal cord. This type of cancer is associated with the Epstein-Barr virus. Symptoms include seizures, headache, impaired vision, dizziness, paralysis and speech problems.

Non-Hodgkin lymphoma

HIV increases the risk of developing non-Hodgkin lymphoma. 

Invasive cervical carcinoma

Studies have found an elevated incidence of cervical cancer in HIV-infected women. Although not yet understood, there is believed to be a complex link between HIV and the human papillomavirus that causes cervical cancer.

Pulmonary arterial hypertension

Pulmonary arterial hypertension is when the pressure in the arteries to the lungs is abnormally high. It is not well understood how HIV causes it, but it only occurs in a small number of people with HIV. 

Treatment side effects

The range of side effects of HIV medications is as broad as the range of medications itself. For more information, please discuss with your doctor the potential side effects of the specific medications that you are on. 

HIV and pregnancy

HIV can be spread to your baby during the pregnancy, while in labour, during birth, or through breastfeeding. However, having HIV does not have to prevent you from having children. Seeing your doctor before you become pregnant can allow you to discuss choices about reducing the risk of passing the infection on to your child. 


HIV is no longer the death sentence it once was. The development of antiretroviral therapies means if you are diagnosed with HIV early and comply with your treatment, you can expect a long and healthy life.


It is possible to reduce your risk of getting HIV by:

  • Practising safe sex – using condoms, limiting the number of sexual partners and getting your sexual partners and yourself regularly checked for sexually-transmitted infections;
  • Not sharing needles; 
  • Using a tattooist that is registered with the Department of Health, and;
  • Seeing your doctor immediately after a potential exposure to HIV to obtain post-exposure preventative medication.

Last Reviewed: 03/10/2018

Your Doctor. Dr Michael Jones, Medical Editor.

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