AIDS – New Zealand

Issue 55 – February 2005
ISSN 1170-2656

HIV infection

In 2004, there were 157 people diagnosed in New Zealand with HIV through antibody testing. This is similar to the 154 diagnosed in 2003. A further 28 people were reported with HIV through viral load testing.¹ Figure 1 shows the total annual number, and reported means of infection, of people diagnosed through HIV antibody testing since it first became available in 1985. It is important to appreciate that infection might have occurred some time before the diagnosis was made.


Figure 1: Number of people diagnosed with HIV in New Zealand through antibody testing by year of diagnosis and means of infection
The high number of new diagnoses among men who have sex with men (MSM) and heterosexual men and women, noted during 2003 (reported in the February 2004 AIDS – New Zealand) has been sustained.

HIV diagnoses among men who have sex with men (MSM)

Overall 73 MSM were diagnosed with HIV by antibody testing in 2004, including 4 who had also injected drugs. This is very similar to the number of MSM diagnosed in 2003.


Figure 2: Place of infection of MSM diagnosed by antibody test by year of diagnosis

Most of these men, 51 (70%), were reported to have been infected in New Zealand, and a further 9 (12%) in Australia. Figure 2 shows the number of MSM diagnosed with HIV and infected in New Zealand since 1996. This figure rose considerably in 2003, and increased slightly in 2004.

Of the 51 MSM diagnosed in 2004 and infected in New Zealand, 27 definitely were infected in the previous 5 years, and 16 of these in the 12 months before diagnosis. This information is based on previous HIV tests. The corresponding figures for 2003 were 14 and 8.

The average age of these 51 men was 38 years; nevertheless there was a wide range. A quarter of them were under 30, and a similar proportion (24%) were aged 50 or over. Most (82 %) were of European ethnicity, with 10% and 2% of Maori and Pacific ethnicity respectively. Just over three quarters (76%) of these men were living in the North Island (mainly in the Auckland region).

HIV diagnoses among people heterosexually infected

Figure 1 (previous page) also shows that there has been a steady rise in the annual number of heterosexually infected people diagnosed in New Zealand over the last 15 years. In 2004, there were 65; 35 men and 30 women. This is higher than the previous largest annual number of 56 in 2003.

As in previous years, the majority (92%) of people with heterosexually acquired HIV diagnosed in 2004 were infected overseas, and only 4 (6%) in New Zealand (Figure 3). This is in contrast to the data for MSM, of whom 70% were infected in New Zealand.


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

In 2004, less than a quarter of those diagnosed in New Zealand with heterosexually acquired HIV were European, Maori or Pacific, compared to 92% of the MSM.

Overall during the past 5 years, of the 241 people diagnosed with heterosexually acquired HIV, 37 (13 men and 24 women) were reported to have been infected in New Zealand. Of these 37, 17 (46%) were infected by a partner who had been heterosexually infected overseas, most of whom were from countries where HIV is relatively common. Of the remaining 20, 6 were women infected by men who had either been infected through homosexual contact or through sharing equipment used for injecting drugs, and for 14 the means of infection of the partner was not reported.

Children infected through mother to child transmission

In 2004, there were 6 children diagnosed with HIV, acquired through mother to child transmission. Of these 6, 2 were born in New Zealand.

Of the 19 children diagnosed in the 5 year period from 2000-2004 infected in this way, 7 had been born in New Zealand to women whose HIV was not recognised when they were pregnant. Over this period there were no infected children born to women whose HIV was diagnosed before they gave birth.

People infected in other ways

While there is no evidence of extensive HIV infection among injecting drug users in New Zealand, over the past 5 years there have been 17 injecting drug users diagnosed. Of these, 7 (41%) were reported to have been infected in New Zealand. This number is still relatively small compared to the number of people infected with hepatitis C in this population.

In the early years of the epidemic there were a significant number of people infected in New Zealand through the receipt of infected blood products. Over the past 5 years, all of the people infected through receipt of blood or blood products had acquired the infection overseas.

The high number of new diagnoses of HIV that occurred in 2003 was sustained in 2004. The number of men who have sex with men (MSM) diagnosed with HIV, infected in New Zealand, increased slightly in 2004. The number of MSM known to be infected in New Zealand in the previous 12 months, also increased. The number of people diagnosed with HIV who were heterosexually infected overseas increased in 2004.

AIDS

AIDS is a late stage of the spectrum of disease caused by HIV. A person with HIV infection is said to have AIDS after he or she first develops one of a number of serious conditions which rarely or never occur in people with normal immunity. The time from being infected with HIV to the development of AIDS varies markedly, and is often quite prolonged. Prior to effective treatments for HIV infection the median time from becoming infected to the onset of AIDS was about ten years. The advent of very effective treatments for HIV may mean that some people with HIV infection will never develop AIDS.

Trends in AIDS notification and deaths

Figure 4 shows the number of notifications of AIDS by year of diagnosis, and the number of deaths of people notified with AIDS by year of death. The levelling of AIDS notifications in the early 1990s was due to a reduction in the incidence of HIV several years earlier. The drop that has been sustained since 1996 resulted from
the effective use of antiretroviral therapy in people with HIV.

Figure 4: Annual number of diagnoses of AIDS and deaths among people notified with AIDS
(The number of notifications and deaths for 2004 might rise due to delayed reports)

In the early years of the epidemic the rise in numbers of AIDS diagnoses was mirrored by a similar rise in deaths a year or so later. This was a reflection of the survival of people with AIDS then being around 18 months. In recent years the number of deaths has remained well below the number of AIDS notifications indicating dramatic
success in treatment of HIV infection which has allowed prolonged survival in many people with AIDS.

As an example, of the 68 people diagnosed with AIDS in 1990 for whom outcome information is available, only 5 (7%) were still alive at the end of 1994. In contrast, of the 22 diagnosed with AIDS in 2000, over three quarters (77%) were still alive at the end of 2004.

Possible to prevent more cases of AIDS

While effective treatment of HIV infection in people with AIDS has dramatically prolonged their survival, early diagnosis of HIV infection could provide even greater benefits by preventing the onset of AIDS.

Of the 127 people notified with AIDS in the five year period 2000-2004, two thirds (similar proportions of MSM and people heterosexually infected) had their HIV infection diagnosed within a month of their AIDS diagnosis. If HIV infection had been diagnosed earlier in these people and they had been offered appropriate treatment most
would not have progressed to AIDS in this time.

This is not the only advantage of earlier diagnosis of HIV. People whose HIV has been diagnosed can be encouraged to adopt, and sustain, HIV risk reduction behaviour, which has the potential to reduce the number of new infections in New Zealand.

Early HIV diagnosis can: result in infected people gaining the major benefits of earlier treatment and care encourage individuals with HIV to adopt and sustain HIV risk reduction behaviour sooner

Table 1. Exposure category by time of diagnosis for those found to be infected with HIV (A small number of transsexuals are included with the males).

			HIV Infection (antibody testing and viral load)*
			<1999		1999-2003		2004		Total
Exposure category		Sex	No.	%	No.	%	No.	%	No.	%
Homosexual contact		Male	728	54.8	385	51.6	84	45.4	1197	53.0
Homosexual & IDU		Male	15	1.1	11	1.5	4	2.2	30	1.3
Heterosexual contact		Male Female	93 102	7.0 7.7	115 129	15.4 17.3	35 33	18.9 17.8	243 264	10.7 11.7
Injecting drug use (IDU)		Male Female	33 8	2.5 0.6	18 3	2.4 0.4	2 0	1.1 0.0	53 11	2.3 0.5
Blood product recipient		Male	30	2.2	4	0.5	0	0.0	34	1.5
Transfusion recipient		Male Female NS	4 5 5	0.3 0.4 0.4	5 3 0	0.7 0.4 0.0	0 1 0	0.0 0.5 0.0	9 9 5	0.4 0.4 0.2
Perinatal		Male Female	5 4	0.4 0.3	8 7	1.1 0.9	3 3	1.6 1.6	16 14	0.7 0.6
Awaiting information/ undetermined		Male Female NS	259 20 13	19.5 1.5 1.0	43 8 0	5.8 1.1 0.0	17 3 0	9.2 1.6 0.0	319 31 13	14.1 1.4 0.6
Other		Male Female	1 3	0.1 0.2	3 4	0.4 0.5	0 0	0.0 0.0	4 7	0.2 0.3
TOTAL			1328	100.0	746	100.0	185	100.0	2259	100.0

NS = Not stated
* Includes people who have developed AIDS. HIV numbers are recorded by time of diagnosis for those reported through antibody testing and by time of first viral load for those reported through viral load testing. The latter include many who have initially been diagnosed overseas and not had an antibody test here. Also, the date of initial diagnosis may have preceded the viral load date by months or years.



Table 2. 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).

			HIV Infection*
			1996-1998		1999-2003		2004		Total
Ethnicity		Sex	No.	%	No.	%	No.	%	No.	%
European/Pakeha		Male Female	130 13	46.3 4.6	383 40	51.3 5.4	80 2	43.2 1.1	593 55	48.9 4.5
Maori †		Male Female	17 2	6.0 0.7	43 5	5.8 0.7	9 2	4.9 1.1	69 9	5.7 0.7
Pacific Island		Male Female	4 3	1.4 1.0	14 10	1.9 1.3	5 1	2.7 0.5	23 14	1.9 1.1
Other		Male Female	66 35	23.5 12.5	138 98	18.5 13.1	40 32	21.6 17.3	244 165	20.1 13.6
Awaiting information/ undetermined		Male Female	10 1	3.6 0.3	14 1	1.9 0.1	11 3	5.9 1.6	35 5	2.9 0.5
TOTAL			281	100.0	746	100.0	185	100.0	1212	100.0

† Includes people who belong to Maori and another ethnic group
* Includes people who have developed AIDS. HIV numbers are recorded by time of diagnosis for those reported through antibody testing and by time of first viral load for those reported through viral load testing. The latter include many who have initially been diagnosed overseas and not had an antibody test here. Also, the date of initial diagnosis may have preceded the viral load date by months or years.

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¹ Viral load testing has been available in New Zealand since 1996. Most of those reported through viral load testing were people previously diagnosed overseas. 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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Related information:

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