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AIDS New Zealand - Issue 58

Issue 58 – September 2006
ISSN 1170-2656

HIV INFECTION AND AIDS IN NEW ZEALAND – JANUARY TO JUNE 2006

HIV Infection

79 people were newly diagnosed with HIV through antibody testing.
26 were men infected through sex with other men, 44 were people infected through heterosexual contact, 1 was a child infected through perinatal transmission overseas, for 2 people information is yet to be received, and for 6 the means of infection was unknown.
A further 15 people with HIV infection, who had not had an antibody test here, had their first viral load test in New Zealand in this period. These were mostly people who had been previously diagnosed overseas.¹
Information on the means of infection and ethnicity of all those diagnosed in the period, and previously, is shown in Tables 3 and 4

AIDS

16 people were notified with AIDS.
7 were men infected through sex with other men, and 9 were people infected through heterosexual contact.
7 were European, 1 Maori, and the remaining 8 were of other ethnicities.

SPECIAL FOCUS ON HETEROSEXUAL TRANSMISSION

While overall the majority of people diagnosed with HIV have been men who have sex with men (MSM), the number of people with HIV infected through heterosexual contact has steadily increased over the past few years (Figure 1). In this issue of AIDS - New Zealand we focus on people who have been heterosexually infected.

Since antibody testing first became available in 1985, a total of 584 people (280 men and 304 women) have been diagnosed through antibody testing with heterosexually acquired HIV. This was 8% of those with a recorded means of infection up to 1996, and 24% since then.

Figure 1 Number of people diagnosed with HIV in New Zealand through antibody testing by year of diagnosis and means of infection. (Infection might have occurred some time before the diagnosis was made).

In parallel with the increase in the number of heterosexual infections, Figure 2 shows an increase in the number of females affected and an overall increase in the proportion of all HIV infections that are female.

Figure 2 Annual number of females diagnosed with HIV by antibody test and proportion of HIV diagnoses that are female

PLACE OF INFECTION, ETHNICITY, PARTNER’S RISK AND COMPARISON WITH OTHER COUNTRIES

Information on likely place of infection, ethnicity, and partner’s risk for people diagnosed with HIV has been sought since the start of 1996. It is important to appreciate that this provides information only from those with diagnosed HIV, which will not include all infected, but also that different rates of testing for different groups could impact on the findings. In addition, infection could have occurred many years before it was diagnosed.

Place of infection

Of the 497 people diagnosed with heterosexually acquired HIV since the beginning of 1996, 414 (83%) were reported to have been infected overseas, 69 (14%) in New Zealand and for the remaining 14 (3%) the place of infection was unknown. Those infected overseas include people from other countries as well as visitors to them.

During this period, two thirds (66%) of those infected overseas were reported to have been infected in Africa, 23% in Asia and 11% in a variety of other overseas countries.

The trend since 1996 is shown in Figure 3. This shows that the main driver of the rise is an increase in the number of people infected in Africa. The annual number of people diagnosed with HIV that was acquired heterosexually in New Zealand has not risen markedly in this period.

Figure 3 Place of infection of those infected through heterosexual contact, diagnosed by antibody test, by year of diagnosis

Ethnicity

The ethnicity of all the 497 people diagnosed with heterosexually acquired HIV since 1996 (Table 1) shows that care and support is needed for a wide range of people.

Table 1 Ethnicity of all women and men, diagnosed by antibody test, with heterosexually acquired HIV (1.1.96-30.6.06)

Examining the ethnicity of the 44 women and 25 men whose infection was acquired in New Zealand in this period (Table 2) suggests that – while the numbers are small – Maori women might disproportionately be being infected in New Zealand compared to European and Pacific women.

Table 2 Ethnicity of women and men infected in New Zealand, diagnosed by antibody test, with heterosexually acquired HIV (1.1.96- 30.6.06)

Partner’s risk

Of the 69 people heterosexually infected in New Zealand, 30 (11 men and 19 women) were infected by a partner from a high prevalence area; 9 were women infected by a bisexual man; 2 had a partner infected through injecting drugs. Of the remaining 28, no specific risk in the partner had been identified for 2, and how the partner was infected was not reported for 26.

Comparison with the UK and Australia

The rates of heterosexually acquired HIV – per million population – for New Zealand, the United Kingdom and Australia are shown in Figure 4.

Figure 4 HIV heterosexual diagnosis rate per 1,000,000 population. The rate for recent years in the UK & Australia will rise as further reports are received.

In all three countries the majority of people with HIV are from countries where there is a high prevalence of HIV. In the UK, as in New Zealand, an increase in people from such parts of the world has been the major driver for the increase in heterosexually acquired HIV diagnoses in the past few years.

IMPLICATIONS OF THE RISE IN HETEROSEXUALLY ACQUIRED HIV IN NEW ZEALAND

Most heterosexuals diagnosed with HIV were infected overseas, and the recent rise is predominantly of people infected outside New Zealand. International comparisons show this is not a situation unique to this country.

The increasing proportion of new HIV diagnoses among heterosexuals, and the range of ethnicities of these people, mean that health care and support services need to be provided to an increasingly diverse group of people.

The greater concentration of infections among people from high prevalence parts of the world means that there is increased risk of HIV spreading within these communities, and also from them into the wider New Zealand population. Such immigrant groups must be involved in HIV prevention planning and delivery, as has been done for others at risk in New Zealand. It is important, to ensure that these people are not subjected to stigma and discrimination. As well as this being a human
rights issue, discrimination would have an adverse effect on the implementation of health promotion in these communities.

Among those of European ethnicity with heterosexually acquired infection, over half, and more of the men, were infected overseas.Although we do not know how many of these were New Zealanders travelling or living abroad,these figures suggest that some people, especially men, are acquiring HIV when travelling overseas.

While a relatively small proportion of all those heterosexually infected were infected in New Zealand, among the women Maori appear to be over represented. Although the numbers are small, indicating that this might be a chance finding, they provide a warning that Maori women might be at greater risk of HIV and therefore need to be actively involved in prevention planning and delivery.

Information on the partner’s risk among people infected in New Zealand reveals that most were either from a high prevalence area, were bisexual men or had injected drugs. Spread through the wider community would be heralded by more infections caused by people who were themselves heterosexually infected in New Zealand. This is referred to as second generation heterosexual spread. While scarcely any second generation spread has been found, the lack of information on the partner’s means of infection in some cases means the true extent of this - even among diagnosed cases - is uncertain.

With the increase in HIV among women comes the risk of children being infected through mother to child transmission. Since 1996, there have been 11 children infected in this way, born in New Zealand. Encouragingly, over this time there has been no infant infected born to a woman whose infection was recognised while she was pregnant. The introduction of HIV screening among pregnant women, as is currently occurring will reduce this serious problem.

Table 3. Exposure category by time of diagnosis for those found to be infected with HIV. (A small number of transsexuals are included with the males).

Table 4. Ethnicity‡ by time of diagnosis in New Zealand for those found to be infected with HIV. (A small number of transsexuals are included with the males).

Footnote:
1 Viral load testing has been available in New Zealand since 1996. Only the trends in those diagnosed through antibody testing have been analysed as
this has been available for the whole period.

For further information about the occurrence of HIV/AIDS in New Zealand contact:

Sue McAllister
AIDS Epidemiology Group
Department of Preventive and Social Medicine, University of Otago Medical School
PO Box 913
Dunedin
New Zealand
Phone: (03) 479 7220
Fax: (03) 479 7298
Email sue.mcallister@stonebow.otago.ac.nz

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