Activities of the AIDS Epidemiology Group


Current activities

The AEG has a primary role in HIV and AIDS case reporting and the measurement of HIV in sub-populations at risk, and is also actively involved in surveys of behaviour. It also takes an interest in the surveillance of other sexually transmitted infections (STIs) and blood borne viruses as this provides information that will be relevant to the spread of HIV.

HIV and AIDS reporting


People with AIDS

AIDS is notifiable under the Health Act.  A person with HIV infection is considered to have AIDS when they first develop one of a number of conditions generally uncommon in people with normal immunity, as outlined in the Ministry of Health Management Guidelines.  A CD4 count of less than 200 cells per cubic millimeter of blood, that is used in the US as a criterion for AIDS is not used in New Zealand, nor most other countries.

A Case Report Form for AIDS is completed on any patient who meets criteria for AIDS.  The form, once completed, is sent to the local Medical Officer of Health who then forwards it to the AEG.

These notifications are made using a code and not the patient’s name.

The AEG provides quarterly reports of people notified with AIDS to the Ministry of Health and publishes these data twice a year in AIDS – New Zealand.


People diagnosed with HIV infection

Since antibody testing for HIV first became available in New Zealand in 1985, information on the number of people newly diagnosed with HIV – and when available their age, sex and likely means of infection – has been collected by the two laboratories, Auckland Hospital Virus Laboratory and The Institute of Environmental Science and Research Limited, Porirua (ESR), that perform the confirmatory Western Blot HIV antibody test

Since 1996, the AEG has carried out enhanced surveillance of HIV whereby further information is sought from the clinicians who requested the test.  The additional information requested includes the reason for the test, the infected person’s ethnic group, district of usual residence, likely country of infection, and whether – and if so when – they had previously had a negative HIV test.  For people heterosexually infected information on the partner’s risk is sought.

Such information is again collected using a code not the patient’s name.

From the beginning of 2002, information has also been received from the four New Zealand laboratories (Auckland, Hamilton, Wellington and Christchurch) performing viral load tests on the codes of people who are having a viral load test for the first time.  If – from the coded information – it appears that a person having a viral load test has not been recorded by the AEG as having a positive HIV antibody test, information is sought from the clinicians who requested the test.  This is to gain information on people who are being cared for HIV infection but have not had an HIV test in this country.

Information is held in conditions of strict confidence.  No information on identifiable individuals is ever released.  Before any information is published care is taken to ensure that identity of individuals cannot be deduced.

As with AIDS notifications, the AEG provides quarterly reports of people diagnosed with HIV to the Ministry of Health and publishes these data twice a year in AIDS – New Zealand.  It is important to appreciate that these data relate to people diagnosed with HIV which will not provide a total measure of people living with HIV as some infected people will remain undiagnosed.

HIV Surveillance in sub-populations at risk


Men who have sex with men


Antenatal HIV surveillance and evaluation

The Universal Routine Offer HIV Antenatal Screening Programme commenced in the Waikato District Health Board in 2006 and has been progressively rolled-out to other District Health Boards (DHB) throughout the country.

The AIDS Epidemiology Group has been contracted by the National Screening Unit (NSU) to evaluate the impact of non-negative results in women who require repeat sampling for evaluation of their HIV status. This aspect of the evaluation of the Programme is based on a report written by the AEG, in which the potential for false positive tests causing harm to the affected women was recognised.


International Collaborative Indigenous Health Research Partnership

Dr Nigel Dickson, is a member of an international team that was successful in gaining funding for a five year research into the role of resiliency in responding to blood borne viral and sexually transmitted infections in indigenous communities. This is a joint project between Australia, Canada and New Zealand. The New Zealand arm is being led by Dr Clive Aspin, of Nga Pae o te Maramatanga, of the University of Auckland.

Past activities

Unlinked anonymous prevalence studies among sexual health clinic attenders

In countries like New Zealand where the prevalence of HIV infection in the general population is very low it is necessary to study sentinel populations – groups into which HIV is, or might be spreading.  Sexual health clinics were chosen as a sentinel population as patients are likely to have been practising sexual behaviours which put them at risk of HIV infection.

The AEG has carried out three unlinked anonymous prevalence studies in sexual health clinics in New Zealand. The first was in 1991/92 in Auckland and Christchurch; the second in 1996/97 in Auckland, Hamilton, Wellington and Christchurch; and the third was in 2005/06 in Auckland, Hamilton, Wellington, Christchurch, Palmerston North and Tauranga.

Unlinked anonymous prevalence studies among injecting drug users

Prevalence studies have also been undertaken among injecting drug users utilising the needle and syringe exchange programme.

Review of Behavioural Donor Deferral Criteria Review

In 2007, Professor Charlotte Paul, Preventive & Social Medicine, Dunedin School of Medicine, chaired a working party established by the New Zealand Blood Service (NZBS) to review the criteria used by NZBS to accept or reject offers of blood donation as it particularly relates to behaviour and the risk of HIV infection.



Dunedin School of Medicine University of Otago AIDS Epidemiology Group