Northern Territory Sexual Health and Blood Borne Viruses Unit
Surveillance Update
Vol. 10 No. 2,
Jul-Sep 2009 & Oct-Dec 2009
A. Introduction
In this surveillance update we present the quarterly statistics for notifiable sexually transmissible infections (STIs) and blood borne viruses (BBVs) in the Northern Territory (NT) for July-December 2009. Where appropriate, the annual statistics for 2009 are also presented. Continuous monitoring of the epidemiology of STIs and BBVs is essential to the control of these infections, and it is hoped that relevant service providers may utilise the information provided in this report in the planning of targeted prevention and intervention programs to address the STI/BBV issues in the NT.
The data used for this report includes surveillance data extracted from the NT Notifiable Diseases System (NTNDS) of the Centre for Disease Control (CDC), and HIV and AIDS data from the HIV/AIDS Database maintained by the Sexual Health and Blood Borne Virus Unit (SHBBVU). The statistics of Australia and other States/Territories used for comparison were extracted from the National Notifiable Disease System and the ‘HIV/AIDS, Viral Hepatitis and Sexually Transmissible Infections in Australia Annual Surveillance Report 2009’ published by National Centre in HIV Epidemiology and Clinical Research. An updated population data set for the NT provided by the Health Gains Planning is used for rate calculation. As this data set does not contain estimated population data for 2009, the data for 2008 is used to calculate all 2009 rates.
Data for chlamydia and gonorrhoea infection Surveillance data between May and December in 2009 are incomplete due to notification problems arising during the H1N1 influenza pandemic. Although measures have been taken to retrieve missed cases, the data checking and cleaning process is still on-going. Therefore, the data contained in this report are preliminary and should only be used as a guide to understand the general trends of these STIs in 2009.
All notification rates for quarters and six-month periods presented in this report are crude annualised rates. Due to some notifications being categorised as ‘interstate’, the sum of district-specific notifications presented in tables with district breakdown may be lower than the total number of notifications shown in other tables. In the calculation of Aboriginal and non-Aboriginal notification rates, adjustments were made so that the notifications for which ethnicity was not known were allocated to the two categories proportional to their known distribution in the two populations.
As STI rates are known to be influenced by the amount of testing, caution should be taken when interpreting the statistics reported in this publication. This is particularly true for the NT where the STI rates have been high and an increase in notifications can often be due to an increase in testing or a large-scale community screening activity, and therefore does not necessarily represent an increase in transmission.
B. Quarterly Statistics
Table B.1.1 Number and rate of gonorrhoea, chlamydia, syphilis and trichomoniasis notifications, NT, Jul-Dec 2009
Gonorrhoea Chlamydia Syphilis Trichomoniasis Quarter
Cases Rate Cases Rate Case Rate Case Rate 2009
Jan-Mar 399 726.1 594 1080.9 39 71.0 430 782.5 Apr-Jun 509 926.2 745 1355.7 46 83.7 469 853.4 Sub-total 908 826.1 1339 1218.3 85 77.3 899 817.9 Jul-Sep 298 542.3 517 940.8 29 52.8 455 828.0 Oct-Dec 354 644.2 567 1031.8 24 43.7 414 753.4 Sub-total 652 593.2 1084 986.3 53 48.2 869 790.7 2009 Total 1560 709.7 2423 1102.3 138 62.8 1768 804.3 2008
Jan-Jun 893 812.5 1256 1142.8 138 125.6 1200 1091.8 Jul-Dec 657 597.8 1032 939.0 116 105.5 995 905.3 2008 Total 1550 705.1 2288 1040.9 254 115.6 2195 998.6
Figure B.1.1 Notification rates of gonorrhoea, chlamydia, syphilis and trichomoniasis, NT, 2005-2009
0 200 400 600 800 1000 1200
Gonorrhoea Chlamydia Syphilis Trichomoniasis Disease
Notification rate (per 100,000 population)
2005 2006 2007 2008 2009
Table B.1.2 Number and rate of gonorrhoea, chlamydia, syphilis and trichomoniasis by sex, NT, Jul-Dec 2009
Gonorrhoea Chlamydia Syphilis Trichomoniasis Gender
Cases Rate Cases Rate Cases Rate Cases Rate Jul-Dec, 2009
Males
Jul-Sep 144 505.3 200 701.8 15 52.6 40 140.4
Oct-Dec 162 568.4 219 768.4 15 52.6 31 108.8
Total 306 536.9 419 735.1 30 52.6 71 124.6
Females
Jul-Sep 154 582.1 315 1190.7 14 52.9 415 1568.7
Oct-Dec 192 725.8 348 1315.4 9 34.0 383 1447.7
Total 346 653.9 663 1253.1 23 43.5 798 1508.2
Unknown
Jul-Sep 0 2 0 1
Oct-Dec 0 0 0 0
Total 0 2 0 1
2009 total
Males 757 664.1 888 779.0 73 64.0 133 116.7
Females 803 758.8 1,532 1447.7 65 61.4 1634 1544.1
Unknown 0 3 0 1
Total 1560 709.7 2423 1102.3 138 62.8 1768 804.3
Figure B.1.2 Notification rates of gonorrhoea, chlamydia, syphilis and trichomoniasis by sex, NT, 2005-2009
0 400 800 1200 1600 2000
2005 2006
2007 2008
2009 Female
2005 2006
2007 2008
2009
Male Famale
Notification Rate (per 100,000 population)
Gonorrhoea Chlamydia Syphilis Trichomoniasis
Table B.1.3 Number and rate of gonorrhoea, chlamydia, syphilis and trichomoniasis notifications by ethnicity, NT, Jul-Dec 2009
Ethnicity Gonorrhoea Chlamydia Syphilis Trichomoniasis Quarter Cases Rate Cases Rate Cases Rate Cases Rate Aboriginal
Jul-Sep 274 1648.6 269 1618.5 22 132.4 429 2581.1 Oct-Dec 317 1907.3 275 1654.6 19 114.3 398 2394.6 Total 591 1777.9 544 1636.5 41 123.3 827 2487.9 Non-
Aboriginal
Jul-Sep 18 47.0 198 516.5 6 15.7 16 41.7
Oct-Dec 29 75.7 239 623.5 4 10.4 11 28.7
Total 47 61.3 437 570.0 10 13.0 27 35.2
Unknown 29.0 2.9
Jul-Sep 6 50 1 10
Oct-Dec 8 53 1 5
Total 14 103 2 15
2009 Total (Adjusted)
Aboriginal 1449 2179.4 1452 2184.5 114 171.9 1704 2562.9 Non-Aboriginal 111 72.4 971 633.1 24 10.8 64 41.8
Figure B.1.3 Notification rates of gonorrhoea, chlamydia, syphilis and trichomoniasis by ethnicity, NT, 2009
0 500 1000 1500 2000 2500 3000 3500
Gonorrhoea Chlamydia Syphilis Trichomoniasis Notification rate (per 100000 population) Aboriginal Non-Aboriginal
Table B.1.4 Number and rate of gonorrhoea, chlamydia, syphilis and trichomoniasis notifications by district, NT, Jul-Dec 2009
Gonorrhoea Chlamydia Syphilis Trichomoniasis
District Cases Rate Cases Rate Cases Rate Cases Rate Darwin
Jul-Sep 63 183.9 296 864.0 13 37.9 141 411.5
Oct-Dec 62 181.0 314 916.5 3 8.8 126 367.8
Total 125 182.4 610 890.2 16 23.4 267 389.7
Katherine
Jul-Sep 64 1335.0 66 1376.7 4 83.4 112 2336.3
Oct-Dec 57 1189.0 40 834.4 5 104.3 86 1793.9
Total 121 1262.0 106 1105.5 9 93.9 198 2065.1 East Arnhem
Jul-Sep 15 369.5 27 665.1 3 73.9 54 1330.1
Oct-Dec 22 541.9 42 1034.5 2 49.3 52 1280.9
Total 37 455.7 69 849.8 5 61.6 106 1305.5
Barkly
Jul-Sep 10 630.8 8 504.7 2 126.2 17 1072.4
Oct-Dec 7 441.6 14 883.1 3 189.2 20 1261.6
Total 17 536.2 22 693.9 5 157.7 37 1167.0
Alice Springs
Jul-Sep 145 1414.0 116 1131.2 6 58.5 126 1228.7
Oct-Dec 202 1969.9 146 1423.8 11 107.3 127 1238.5 Total 347 1691.9 262 1277.5 17 82.9 253 1233.6
Figure B.1.4 Notification rates of gonorrhoea, chlamydia, syphilis and trichomoniasis by district, NT, 2009
0 500 1000 1500 2000 2500
Gonorrhoea Chlamydia Syphilis Trichomoniasis
Notification rate (per 100,000 population)
Darwin Katherine East Arnhem Barkly Alice Springs
Table B.1.5 Number and rate of gonorrhoea, chlamydia, syphilis and trichomoniasis notifications by 5-year age group, Jul-Dec 2009
Gonorrhoea Chlamydia Syphilis Trichomoniasis
Age
group Cases Rate Cases Rate Cases Rate Cases Rate Jul-Dec 2009
<10 0 0.0 5 28.1 0 0.0 4 22.5
10-14 27 323.2 29 347.1 1 12.0 16 191.5
15-19 185 2249.5 289 3514.1 1 12.2 149 1811.8 20-24 178 1995.4 378 4237.4 6 67.3 158 1771.2 25-29 104 1075.8 191 1975.7 6 62.1 140 1448.2
30-34 72 786.8 85 928.8 5 54.6 86 939.7
35-39 48 526.1 43 471.3 9 98.6 99 1085.1
40-44 16 196.7 28 344.3 8 98.4 91 1118.9
45-49 12 151.3 15 189.1 5 63.0 56 705.9
50-54 3 42.8 11 157.0 3 42.8 35 499.6
55-59 5 85.0 6 102.0 3 51.0 14 238.0
60-64 0 0.0 3 72.6 2 48.4 7 169.5
65+ 2 35.8 1 17.9 4 71.6 14 250.6
Total 652 593.2 1084 986.3 53 48.2 869 790.7
Figure B.1.5 Notification rate of gonorrhoea, chlamydia, syphilis and trichomoniasis notifications by 5-year age group, Jul-Dec 2009
0 500 1000 1500 2000 2500 3000 3500 4000 4500
<10 10- 14
15- 19
20- 24
25- 29
30- 34
35- 39
40- 44
45- 49
50- 54
55- 59
60- 64
65+
Age group
Notification rate (per 100,000 population) Gonorrhoea Chlamydia Syphilis Trichomoniasis
B.1 Gonorrhoea
A total of 652 notifications were recorded in this 6-month period, giving a notification rate of 593.2 per 100000 about 28.2% lower than that for the first six months of 2009 (Table B.1.1). This is usually the case in the NT because large-scale annual sexual health screens are normally conducted in the first half of the year.
The annual notification rate for 2009 is 709.7 per 100,000, about the same as that for 2008. It appears the decreasing trend in the rate of gonorrhoea noted in 2005-2008 had slowed down in 2009 (Figure B.1.1). However, compared with the national rate of 35.7 per 100,000 (2008 rate), the NT rate remains substantially higher (about 20 times higher).
The rate for females continued to be higher than the male rate in this reporting period.
The 2009 rates for both sexes remained at about the same level as those for 2008.
The rate for the Aboriginal population for this reporting period was about 29 times the non-Aboriginal rate (Table B.1.3). In 2009, after adjusting for the number of
notifications with unknown ethnicity, about 93% of all notifications were Aboriginal, and the Aboriginal-to-non-Aboriginal rate ratio was 30:1. However, the non-Aboriginal rate for the NT in 2009 (72.4 per 100,000) was more than three times the non-
Indigenous rate for Australia (22 per 100,000 in 2008). At the district level, Alice Springs continued to record the highest number and rate of notifications. (see Table B.1.4).
As was the case in previous years, the highest notification rates were recorded in the 15-19 and 20-24 year age groups, which accounted for 56% of all notifications.
(Table B.1.5 and Figure B.1.5). There were no notifications recorded in the age group of under 10 years, but a total of 27 cases were recorded in the 10-14 year age group.
B.2 Genital Chlamydia
There were 1,084 chlamydia notifications recorded in this reporting period, giving a rate of 986.3 per 100,000. The increasing trend in the notification rate noted in the last five years persisted in 2009 with no sign of slowing down (Figure B.1.1 and Table B.1.1). The NT rate for 2009, 1,102.3 per 100,000, was about 4 times that for
Australia (270.6 per 100,000 in 2008). The number of chlamydia notifications was about 1.6 times that of gonorrhoea notifications in 2009 (1.5 in 2008).
There were considerably more female notifications than male ones: the female to male rate ratio was 1.7:1 in this reporting period and 1.9:1 for the whole year 2009 (Table B.1.2). Notably, the annual rate for females continued to rise considerably in 2009 while that for males remained at about the same level as previous three years.
The testing data collected from two major pathology laboratories showed no
significant difference in the number of chlamydia tests performed in 2008 and 2009, but the positivity rate did increase considerably (data not shown here). Therefore, it is likely that the increase in female rates was caused by increased incidence.
In this reporting period, about 50% of all notifications were Aboriginal, and the notification rate for Aboriginals was about 2.9 times the non-Aboriginal rate (see Table B.1.3). The Aboriginal status was not reported in 9.5% of all notifications; in comparison, it was not reported in only about 2.1% of gonorrhoea notifications. The NT Aboriginal rate for 2009 almost double the Indigenous rate for Australia (1,131 per 100,000 in 2008) while the NT non-Aboriginal rate was 2.3 times the non- Indigenous rate for Australia (273 per 100,000 in 2008).
The highest number of notifications was recorded in Darwin (610 cases), followed by Alice Springs (Table B.1.4). In terms of notification rates, the highest was recorded Alice Springs (1277.5 per 100,000).
The highest age-specific rates continued to occur in the 15-19 and 20-24 year age groups (Table B.1.5), in which 62% of all notifications were recorded. A total of 5 cases notified were in the age group of under 10 years and 29 in the 10-14 year age groups.
B.3 Syphilis
A total of 53 cases were notified in this reporting period, giving a notification rate of 48.2 per 100,000. There appears to be a decreasing trend in the annual notification rate in 2007-2009 and the 2009 rate represented a decrease of 46% compared with the 2008 rate (Table B.1.1 and Figure B.1.1). The decrease was greater in the
infectious syphilis category (or, syphilis of less than two years duration, 54% vs. 42%, see Table B.3.1). However, the 2009 rate of infectious syphilis (17.3 per 100,000) was about 3 times the corresponding rate for Australia (6.1 per 100,000 in 2008).
Unlike other bacterial STIs, there were more cases notified in males than in females (Table B.1.2). The rate decrease from 2008 to 2009 was approximately the same in both sexes at about 45% (Figure B.1.2).
About 77% of all notifications in July-December and 83% in 2009 were recorded in the Aboriginal population. The adjusted Aboriginal rate for 2009 was about 16 times the non-Aboriginal rate (Table B.1.3). The number of syphilis notifications had decreased significantly from 2008 to 2009 in both Aboriginal and non-Aboriginal population (Table B.3.2).
Darwin and Alice Springs districts recorded the highest number of notifications, but the highest notification rate was recorded in the Barkly region (Table B.1.4).
Table B.3.1 Rate of syphilis notifications by category (per 100,000), Darwin District, 2005-2009
Category 2005 2006 2007 2008 2009
Greater than 2 years
duration/unspecified 55.7 58.4 81.9 77.8 45.5 Less than 2 years duration 42.2 71.2 55.4 37.8 17.3
All 97.9 129.6 137.3 115.6 62.8
Table B.3.2 Number of syphilis notifications by ethnicity, Darwin District, 2005-2009 Ethnicity 2005 2006 2007 2008 2009
Aboriginal 179 259 269 214 111
Non-Aboriginal 17 11 21 37 23
Unknown 6 3 5 3 4
Total 202 273 295 254 138
The highest rates were recorded in the relatively older age groups of 35-39 and 40- 44 years in this reporting period (Table B.1.5). However, the highest number of
notifications of infectious syphilis was recorded in the 25-29 year age group (6 cases), followed by the 40-44 year age group (5 cases).
There were two congenital syphilis cases notified in this reporting period. A total of three cases were notified in 2009, compared with one in 2008 and two in 2007.
B.4 Trichomoniasis
A total of 869 cases were notified in this reporting period, giving a notification rate of 790.7. The increasing trend in the annual notification rate of trichomoniasis noted in 2005-2008 was reversed in 2009 with a nearly 20% decrease from 2008 to 2009 (Table B.1.1 and Figure B.1.1).
The vast majority of notifications (92%) were recorded in females (Table B.1.2).
However, the decrease occurred in both sexes, thought it decreased more in males (37% versus 18% in females).
About 95% of notifications were recorded in the Aboriginal population in this reporting period (Table B.1.3). The adjusted Aboriginal rate for 2009 was about 61 times the non-Aboriginal rate. Darwin recorded the highest number of notifications although the highest notification rate was recorded in Katherine (Table B.1.4).
As was the case with gonorrhoea and chlamydia, the highest rates were recorded in the 15-19 and 20-24 year age groups, in which about 35% of all notifications were recorded (Table B.1.5). Notably, there were 4 cases recorded in the age group of under 10 years and 16 in the 10-14 year age group.
B.5 Donovanosis
There were no donovanosis notifications recorded in 2009.
B.6 Other Sexually Transmitted Infections
There were no notifications of chancroid or lymphogranuloma venereum recorded in 2009.
B.7 Hepatitis C
In this 6-month period, a total of 76 cases were notified, 44 (58%) in males and 32 (42%) in females (Table B.7.2). The vast majority (96%) were categorised as
‘unspecified’, and only 3 (4%) were categorised as ‘newly acquired’ (all were female, see Table B.7.3). The majority of notified cases (76%) were non-Aboriginal, and the ethnicity was unknown in about 9% of notifications. The notification rate for males was about 1.3 times the female rate, while the non-Aboriginal rate was about 1.9 times the Aboriginal rate.
Over 60% of the notifications were recorded in Darwin District (Table B.7.4).
However, the highest rate among all districts was recorded in Katherine. The highest age-specific rates were recorded in the relatively older age groups in males (50-54 and 45-49 year age groups, see Figure B.7.1). In females, the highest rate in females was recorded in the 50-59 year age group, but the 25-29 and 30-34 year age groups recorded the highest numbers of notifications.
In 2009, there were 170 unspecified (97%) and 6 newly acquired cases of hepatitis C.
Among them, 133 (68.9%) were new to the NTNDSS and were therefore investigated by the enhanced surveillance system, and data were successfully collected for 77 (response rate=58%) of these cases. Information was obtained for 28 cases which indicated that the case was notified previously in the NT or outside of NT, which leaves 142 cases being truly unspecified. Among the 77 cases, 38 reported previous or current injecting drug use (49%), 25 (32%) never used injection drugs, and
information was unknown for 14 cases (18%).
Table B.7.1 Number of hepatitis C notifications by sex, NT, 2005-2009
Sex 2005 2006 2007 2008 2009
Female 99 88 84 83 64
Male 171 177 141 132 112
Total 270 265 225 215 176
Table B.7.2 Number and rate of hepatitis C by sex and ethnicity, NT, Jul-Dec 2009
Quarter Sex Aboriginal
Non-
Aboriginal Unknown Total
Case Rate Case Rate Case Case Rate
Jul-Sep Female 2 23.7 9 50.0 2 13 49.1
Male 0 0.0 18 88.6 1 19 66.7
Total 2 12.0 27 70.4 3 32 58.2
Oct-Dec Female 6 71.0 13 72.2 0 19 71.8
Male 3 36.7 18 88.6 4 25 87.7
Total 9 54.1 31 80.9 4 44 80.1
Jul-Dec Female 8 47.3 22 61.1 2 32 60.5
Male 3 18.4 36 88.6 5 44 77.2
Total 11 33.1 58 75.7 7 76 69.1
2009
Total Female 18 53.3 42 58.3 4 64 60.5
Male 12 36.7 90 110.7 10 112 98.2
Total 30 45.1 132 86.1 14 176 80.1
Table B.7.3 Number of hepatitis C notifications by sex, ethnicity and disease categories, NT, Jul-Dec 2009
Type Gender Indigenous status
Aboriginal
Non-
Aboriginal Unknown
Total %
Female 1 2 0 3
Newly
acquired Male 0 0 0 0 4%
Unspecified Female 7 20 2 29
Male 3 36 5 44 96%
Total 11 58 7 76
% 14% 76% 9%
Table B.7.4 Number and annualised rate of hepatitis C notifications by gender and district, NT, Jul-Dec 2009
Case Rate Case Rate Case Rate Case Rate Case Rate
Jul-Sep Female 7 43.3 4 169.7 1 50.9 0 0 1 19.3
Male 12 66.4 3 123.1 0 0.0 1 122.2 2 39.4
Oct-Dec Female 13 80.3 0 0.0 1 50.9 0 0.0 5 96.5
Male 16 88.5 4 164.2 1 47.7 0 0.0 3 59.2
Jul-Dec 2009 48 70.1 11 114.7 3 36.9 1 31.5 11 53.6
63.2% 14.5% 3.9% 1.3% 14.5%
Quarter Sex
District
Darwin Katherine East Arnhem Barkly Alice Springs
Figure B.7.1 Annualised notification rate of hepatitis C by age groups, NT, Jul-Dec 2009
0 50 100 150 200 250 300 350 400
15-19 20-24 25-29 30-34 35-39 40-44 45-49 50-54 55-59 60+
Age group Annualised notification rate (per 100,000 population)
Female Male All
B.8 Human Immunodeficiency Virus (HIV)
Between July and December 2009, there were 9 new notifications recorded, 1 female and 8 males. Two were classified as ‘newly acquired HIV’ cases, and both of them were male. There were no new diagnoses in Aboriginal people. Other demographic details of these notifications and those from January to June are summarised in Table B.8.1. Heterosexual contact continues to be the most common exposure category, followed by male homosexual contact. Notably in 2009, three cases were Australian residents acquiring the infection while travelling to high prevalence countries in South East Asia (Table B.8.2)
Table B.8.1 Demographics and exposure categories for HIV cases who were residents of Australia, NT, 2009
Category Jan-Jun Jul-Dec Total %
Sex
Male 5 8 13 68%
Female 5 1 6 32%
Total 19
Ethnicity
Aboriginal 0 0 0 0%
Non-Aboriginal 10 9 19 100%
Exposure category
Male homosexual contact 2 3 5 26%
Male homosexual / bisexual
contact 0 1 1 5%
Heterosexual contact 8 5 13 68%
Injecting drug user 0 0 0 0%
Table B.8.2 Place of infection by sex for HIV cases notified in 2009, NT Place of infection Female Male Total
Interstate 0 3 3
NT 3 4 7
Immigrants/travellers with HIV 2 3 5
Overseas travel 1 2 3
Unknown 0 1 1
Total 6 13 19
Although the annual number of HIV notifications remained low in the last five years, it appeared to be increasing in the last three years (Figure B.8.1).
Figure B.8.1 HIV notifications in the NT, 2005-2009
0 2 4 6 8 10 12 14 16 18 20
2005 2006 2007 2008 2009
Number of notifications
Female Male
D. Readers’ responses
The SHBBVU is very interested in readers’ responses to this report. Please forward any comments or suggestions to:
Surveillance Project Officer Head of Sexual Health and BBV Unit
Jiunn-yih Su James Broadfoot
Sexual Health and BBV Unit, Centre for Disease Control
Department of Health and Families PO Box 40596, Casuarina
Northern Territory, 0811 Phone: (08) 89228874 Fax: (08) 8922 8809
Email: [email protected], [email protected]
All data in this report are provisional and subject to future revision.
This report is downloadable in PDF format from the website of the Department of Health and Families:
http://www.health.nt.gov.au/Centre_for_Disease_Control/Publications/Sexual_Health _Surveillance_Updates/index.aspx
Suggested citation:
Northern Territory Department of Health and Families. Sexual Health and Blood Borne Viruses Unit Surveillance Update. 2009; Vol. 10, No. 2.
