Part of the Communicable Disease Control Manual
Chapter last reviewed and updated in December 2018. A description of changes can be found at Updates to the Communicable Disease Control Manual.
- Epidemiology in New Zealand
- Case definition of AIDS
- Spread of infection
- Notification procedure
- Management of case
- Management of contacts
- Other control measures
- References and further information
Acquired immunodeficiency syndrome (AIDS) is the late stage of the spectrum of disease caused by the human immunodeficiency virus (HIV). In New Zealand, both AIDS and HIV are notifiable conditions.
In New Zealand, the number of people developing AIDS declined in the mid-1990s, as it did in many developed countries as a result of improved treatments for people with HIV infection. The majority of people currently found with AIDS tested late for HIV, and therefore were not previously on anti-retroviral treatment that would have prevented AIDS developing.
The survival of those people who do progress to AIDS is also longer than it used to be due to improved treatment, and the annual number of deaths from AIDS is now consistently lower than the number of people notified with AIDS.
For the most up-to-date information on the epidemiology of HIV and AIDS in New Zealand, refer to AIDS – New Zealand, the newsletter produced by the AIDS Epidemiology Group (AEG), which is also posted on the Ministry of Health website.
For surveillance purposes, in New Zealand, a person with HIV infection is said to have developed AIDS when one or more of a list of 25 AIDS-defining illnesses first develop. A CD4 count of less than 200 cells per cubic millimetre of blood, which is used in the United States as a criterion for AIDS, is not used in New Zealand. Medical practitioners will identify patients with a ‘late diagnosis’ of HIV by ascertaining the date of the HIV diagnosis and the date of the AIDS diagnosis.
The 25 AIDS-defining diseases are:
- candidiasis of bronchi, trachea or lungs
- candidiasis of oesophagus
- cervical cancer, invasive
- coccidioidomycosis, disseminated or extrapulmonary
- cryptococcosis, extrapulmonary
- cryptosporidiosis, chronic intestinal (> 1 month’s duration)
- cytomegalovirus disease (other than liver, spleen or nodes)
- cytomegalovirus retinitis (with impairment of vision)
- herpes simplex: chronic ulcer(s) (> 1 month’s duration), bronchitis, pneumonitis or oesophagitis
- histoplasmosis, disseminated or extrapulmonary
- HIV-related encephalopathy
- HIV-related wasting
- isosporiasis, chronic intestinal (> 1 month’s duration)
- Kaposi’s sarcoma
- lymphoma, Burkitt’s (or equivalent term)
- lymphoma, immunoblastic (or equivalent term)
- lymphoma, primary, of brain
- Mycobacterium avium complex or M. kansasii infection, disseminated or extrapulmonary
- Mycobacterium tuberculosis infection, any site (pulmonary or extrapulmonary)
- Mycobacterium, other species or unidentified species, infection, disseminated or extrapulmonary
- Pneumocystis jiroveci pneumonia
- pneumonia, recurrent
- progressive multifocal leukoencephalopathy
- Salmonella septicaemia, recurrent
- toxoplasmosis of brain.
For children, additional conditions in Category C are:
serious multiple or recurrent bacterial infections; that is, at least two culture-confirmed infections (septicaemia, pneumonia, meningitis, bone or joint infection, or abscess of an internal organ or body cavity) within a two-year period.
Laboratory testing for diagnosis
AIDS is a clinical diagnosis. There is laboratory testing available for HIV but not for AIDS.
- Under investigation: A case that has been notified, but information is not yet available to classify it as confirmed or not a case.
- Probable: Not applicable.
- Confirmed: HIV infection with an AIDS-defining disease (as above).
- Not a case: A case that has been investigated and subsequently found not to meet the case definition.
Without treatment, the time from initial infection with HIV to clinical onset of AIDS in an untreated patient is variable, averaging 8–10 years in developed countries.
Mode of transmission
HIV is transmitted from person to person in four main ways:
- through anal and vaginal sex
- through the sharing of contaminated injecting equipment (needles and syringes)
- from an infected mother to her baby during pregnancy or childbirth or through breastfeeding
- through transfusion of infected blood or blood components and the transplantation of infected tissue or organs.
Period of communicability
While transmission of HIV can occur throughout an infected person’s life, the transmissibility varies with the viral load, which is typically high during initial seroconversion and later as the CD4 count falls. Anti-retroviral therapy that successfully suppresses the circulating viral load to low or undetectable levels greatly reduces infectivity.
AIDS is a notifiable condition. Attending medical practitioners must initially notify all cases to the local Medical Officer of Health, using non-identifiable data, in the initial notification form that can be found on the Public Health Surveillance website.
Entry of this information into EpiSurv by the local public health service will automatically result in the AEG receiving access to the information, and in the creation of a web-based detailed notification form. The AEG will send the health provider who notified the case a link to this form, for the health provider to complete online.
Section C of Part 1 of Schedule 1 of the Health Act 1956 covers notification of AIDS, HIV and other sexually transmitted infections. Under this legislation, the notification process must not include identifying information.
The AEG makes confidential quarterly reports to the Ministry of Health and Medical Officers of Health. It produces the AIDS – New Zealand newsletter annually and disseminates it widely, to stakeholders and the public.
Identify the mode of infection in consultation with the attending infectious diseases physician.
No isolation precautions other than standard precautions are needed for HIV-positive cases in health care facilities. Staff who are asked to perform an invasive procedure on the case are commonly informed about the case’s infectious status. In almost all cases, there are no restrictions on attending work, early childhood services or schools or other community activities.
The case should be under the care of a physician or paediatrician who has a special interest in HIV and AIDS.
People found to be infected with HIV should receive counselling on the implications of the diagnosis from a medical practitioner and/or counsellor. The counselling should cover the practical and legal aspects of preventing transmission of HIV. Specific recommendations include:
- not donating blood
- not sharing drug-injecting equipment
- not sharing razors or toothbrushes
- following safe sex practices and informing sexual partners
- informing health care workers (including dentists) of infection.
- sexual or needle-sharing partners of an HIV-infected person
- individuals who have suffered a sharp injury with an object contaminated with HIV-infected blood or body fluid
- newborn babies whose mothers are HIV-positive
- individuals who have received HIV-infected body fluid (eg, blood, semen or cerebrospinal fluid) splashes to a mucosal surface or area of broken skin.
All investigation and treatment, including management of HIV-infected pregnant women, should be undertaken under the supervision of an infectious diseases physician with a special interest in HIV.
Health practitioners must perform all HIV tests with the informed consent (verbal consent is sufficient in most cases) of the person, and with pre-test counselling that covers the reason for the test, the person’s right to decline testing, the date and means by which the results will be made available and an assurance that the practitioner will take steps to maintain confidentiality, including an offer to test under code. More comprehensive pre-test counselling is indicated when the person is at high risk of being HIV-positive.
When considering post-exposure prophylaxis, practitioners should seek immediate advice from the infectious diseases service of the closest tertiary care hospital. An anti-retroviral prescriber must authorise the prophylaxis.
The need for anti-retroviral prophylaxis depends on:
- the period that has elapsed between the exposure and the availability of appropriate treatment (chemoprophylaxis has been shown to have some protective effect up to 36 hours after exposure)
- the type of exposure and source material (eg, a needle-stick injury or sexual contact).
Health practitioners should offer the contact comprehensive counselling, ideally in conjunction with the supervising infectious diseases physician. The New Zealand AIDS Foundation is the lead Ministry of Health non-governmental agency for HIV and AIDS.
Identification of source
If there is a cluster of cases, investigate for a common exposure, including sexual contact, sharing of injecting drug equipment, health care or skin penetration practices (eg, tattooing). If the case could be transfusion-related, contact the New Zealand Blood Service.
Clean equipment and surfaces potentially contaminated with blood or body fluids. For further details, refer to Appendix 1: Disinfection.
Advise injecting drug users on single-use injecting equipment. Needle and syringe exchange programmes exist in pharmacies and community groups throughout New Zealand. A list of outlets is available from the New Zealand Needle Exchange Programme website.
The Ministry of Health offers an HIV screening programme for all pregnant women. Information is available on the National Screening Unit website.
Selik RM, Mokotoff ED, Branson B, et. al. 2014. Revised surveillance case definition for HIV infection. Morbidity and Mortality Weekly Report 63 (RR03): 1–10. (Accessed 1 November 2018.)
WHO. 2007. WHO case definitions of HIV for surveillance and revised clinical staging and immunological classification of HIV-related disease in adults and children. Geneva: World Health Organization. (Accessed 1 November 2018.)
 The CDC classifies HIV-infected children by immunological status and clinical disease stage with clinical categories N, A, B and C, category C being severely symptomatic.