Northern Territory Sexual Health and Blood Borne Viruses Unit
Surveillance Update
Vol. 11 No. 2,
Jul-Sep 2010 & Oct-Dec 2010
A. Introduction
This surveillance update presents the quarterly statistics for notifiable sexually transmissible infections (STIs) and blood borne viruses (BBVs) in the Northern Territory (NT) for July-December 2010. The annual statistics for 2010 are also
presented where appropriate. Continuous monitoring of the epidemiology of STIs and BBVs is essential to the control of these infections, and it is hoped that health 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 notification data were extracted from the NT Notifiable Diseases System (NTNDS) of the Centre for Disease Control (CDC) on 7 Feb 2011. HIV and AIDS data were retrieved from the HIV/AIDS database maintained by the Sexual Health and Blood Borne Virus Unit (SHBBVU) on the same day. 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 2010’ published by the National Centre in HIV Epidemiology and Clinical Research. The population data for the NT were provided by the Health Gains Planning. As this population data set did not contain estimated population data for 2010, the data for 2009 were used to calculate all 2010 rates.
All notification rates for quarters and six-month periods presented in this report are crude annualised rates without standardisation. Due to a proportion of notifications being categorised as ‘interstate’, the sum of district-specific notifications presented in tables with district breakdown might be lower than the total number of notifications shown in other tables. When calculating Aboriginal and non-Aboriginal notification rates, adjustments were made so that the notifications for which ethnicity is not known were allocated to the two categories proportional to their known distribution in the two populations.
STI rates have been known to be influenced by the amount of testing. This is particularly true for the NT where the STI rates have been high, opportunistic
screening tests have been recommended for and frequently performed in the at-risk age groups, and large-scale community-wide STI screens are not uncommon, all of which can lead to an increase in notifications. Readers are advised to take this factor into consideration when interpreting the notification statistics in this surveillance update.
B. Quarterly Statistics
Table B.1.1 Quarterly numbers and rates (per 100,000) of gonorrhoea, chlamydia, syphilis and trichomoniasis notifications, NT, 2010
Gonorrhoea Chlamydia
Infectious
Syphilis Trichomoniasis Quarter
Cases Rate Cases Rate Case Rate Case Rate 2010
Jan-Mar 420 747.2 651 1158.1 10 17.8 534 950.0 Apr-Jun 498 885.9 632 1124.3 16 28.5 531 944.6 Sub-total 918 816.6 1283 1141.2 26 23.1 1065 947.3 Jul-Sep 571 1015.8 789 1403.6 8 14.2 727 1293.3 Oct-Dec 499 887.7 630 1120.8 8 14.2 621 1104.7 Sub-total 1070 951.8 1419 1262.2 16 14.2 1348 1199.0 2010 Total 1988 884.2 2702 1201.7 42 18.7 2413 1073.2 2009
Jan-Jun 908 807.7 1339 1191.0 22 19.6 899 799.7 Jul-Dec 652 579.9 1084 964.2 16 14.2 869 773.0 2009 Total 1560 693.8 2423 1077.6 38 16.9 1768 786.3
Figure B.1.1 Notification rates of gonorrhoea, chlamydia, syphilis and trichomoniasis, NT, 2006-2010
200 400 600 800 1000 1200 1400
otification rate (per 100,000 population)
2006 2007 2008 2009 2010
Table B.1.2 Quarterly numbers and rates (per 100,000) of gonorrhoea, chlamydia, syphilis and trichomoniasis by gender, NT, 2010
Gonorrhoea Chlamydia Syphilis Trichomoniasis Gender
Cases Rate Cases Rate Cases Rate Cases Rate Jul-Dec, 2010
Males
Jul-Sep 267 915.3 317 1086.7 5 17.1 78 267.4 Oct-Dec 243 833.0 271 929.0 6 20.6 54 185.1 Total 510 874.2 588 1007.9 11 18.9 132 226.3 Females
Jul-Sep 304 1124.2 472 1745.5 3 11.1 649 2400.1 Oct-Dec 256 946.7 359 1327.6 2 7.4 567 2096.8 Total 560 1035.5 831 1536.6 5 9.2 1216 2248.4 2010 total
Males 976 836.4 1,113 953.9 27 23.1 229 196.3 Females 1012 935.6 1,589 1469.1 15 13.9 2184 2019.2 Total 1988 884.2 2702 1201.7 42 18.7 2413 1073.2
Figure B.1.2 Notification rates of gonorrhoea, chlamydia, syphilis and trichomoniasis by gender, NT, 2006-2010
0 400 800 1200 1600 2000 2400
2006 2007
2008 2009
201 0
Fema le
200 6
2007 2008
2009 2010 Male Famale
Notification Rate (per 100,000 population)
Gonorrhoea Chlamydia Syphilis Trichomoniasis
Table B.1.3 Quarterly numbers and rates (per 100,000) of gonorrhoea, chlamydia, syphilis and trichomoniasis notifications by ethnicity, NT, Jul-Dec 2010
Ethnicity Gonorrhoea Chlamydia Syphilis Trichomoniasis Quarter Cases Rate Cases Rate Cases Rate Cases Rate Aboriginal
Jul-Sep 528 3114.1 421 2483.0 7 41.3 695 4099.1 Oct-Dec 459 2707.2 372 2194.0 7 41.3 586 3456.2 Total 987 2910.6 793 2338.5 14 41.3 1281 3777.6 Non-Aboriginal
Jul-Sep 35 89.2 314 799.9 1 2.5 20 50.9 Oct-Dec 31 79.0 220 560.4 1 2.5 18 45.9 Total 66 84.1 534 680.1 2 2.5 38 48.4 Unknown
Jul-Sep 8 54 0 12
Oct-Dec 9 38 0 17
Total 17 92 0 29
2010 Total (Adjusted)
Aboriginal 1854 2733.1 1627 2399.4 39 57.5 2338 3446.8 Non-Aboriginal 134 85.6 1075 684.4 3 1.3 75 48.0
Figure B.1.3 Notification rates of gonorrhoea, chlamydia, syphilis and trichomoniasis by ethnicity, NT, 2010
0 500 1000 1500 2000 2500 3000 3500
Gonorrhoea Chlamydia Syphilis Trichomoniasis
Notification rate (per 100000 population)
Aboriginal Non-Aboriginal
Table B.1.4 Quarterly numbers and rates (per 100,000) of gonorrhoea, chlamydia, syphilis and trichomoniasis notifications by district, NT, Jul-Dec 2010
Gonorrhoea Chlamydia
Infectious
Syphilis Trichomoniasis District Cases Rate Cases Rate Cases Rate Cases Rate Darwin
Jul-Sep 105 299.5 376 1072.4 2 5.7 191 544.8 Oct-Dec 89 253.8 259 738.7 1 2.9 134 382.2 Total 194 276.7 635 905.6 3 4.3 325 463.5 Katherine
Jul-Sep 86 1754.9 83 1693.7 3 61.2 181 3693.5 Oct-Dec 85 1734.5 78 1591.7 2 40.8 158 3224.2 Total 171 1744.7 161 1642.7 5 51.0 339 3458.8 East Arnhem
Jul-Sep 33 796.9 55 1328.2 0 0.0 104 2511.5 Oct-Dec 40 966.0 46 1110.8 0 0.0 97 2342.4 Total 73 881.4 101 1219.5 0 0.0 201 2427.0 Barkly
Jul-Sep 24 1478.7 16 985.8 0 0.0 46 2834.3 Oct-Dec 22 1355.5 18 1109.1 3 184.8 37 2279.7 Total 46 1417.1 34 1047.4 3 92.4 83 2557.0 Alice Springs
Jul-Sep 309 2946.6 253 2412.6 2 19.1 188 1792.7 Oct-Dec 251 2393.5 221 2107.4 2 19.1 188 1792.7 Total 560 2670.0 474 2260.0 4 19.1 376 1792.7
Figure B.1.4 Notification rates of gonorrhoea, chlamydia, syphilis and trichomoniasis by district, NT, 2010
0 500 1000 1500 2000 2500 3000 3500
Gonorrhoea Chlamydia Infectious Syphilis Trichomoniasis
Notification rate (per 100,000 population)
Darwin Katherine East Arnhem Barkly Alice Springs
Table B.1.5 Number and rate (per 100,000) of gonorrhoea, chlamydia, syphilis and trichomoniasis notifications by 5-year age group, Jul-Dec 2010
Gonorrhoea Chlamydia Syphilis Trichomoniasis Age
group Cases Rate Cases Rate Cases Rate Cases Rate
<10 0 0.0 8 44.3 0 0.0 1 5.5
10-14 36 429.6 28 334.1 0 0.0 39 465.4 15-19 318 3801.6 392 4686.2 0 0.0 256 3060.4 20-24 286 3145.1 450 4948.6 5 55.0 231 2540.3 25-29 178 1763.2 267 2644.9 2 19.8 197 1951.5 30-34 110 1186.5 124 1337.5 3 32.4 163 1758.2 35-39 65 697.9 54 579.8 2 21.5 157 1685.8 40-44 48 583.3 49 595.5 2 24.3 121 1470.5 45-49 12 149.0 20 248.4 0 0.0 85 1055.6 50-54 8 112.1 12 168.1 1 14.0 59 826.5 55-59 5 81.9 8 131.1 1 16.4 20 327.6
60-64 1 22.9 3 68.8 0 0.0 10 229.5
65+ 3 50.2 4 66.9 0 0.0 9 150.6
Total 1070 951.8 1419 1262.2 16 14.2 1348 1199.0
Figure B.1.5 Notification rate of gonorrhoea, chlamydia, syphilis and trichomoniasis notifications by 5-year age group, Jul-Dec 2010
0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000
<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 1070 notifications were recorded in this 6-month period, giving a notification rate of 951.8 per 100,000 (Table B.1.1). This represented a 64.1% increase over the rate for the same period in 2009. The annual rate for 2010 also increased
considerably over the rate for 2009 (by 27.4%).
The rate for females continued to be higher than the male rate in this reporting period and in 2010. (Table B.1.2) The annual rate increased over 2009 rates in both sexes (Fig. B.1.2). The rate for the Aboriginal population for this reporting period was about 35 times the non-Aboriginal rate (Table B.1.3). After adjusting for the number of notifications with unknown ethnicity, about 93.2% of all notifications in 2010 were Aboriginal. At the district level, Alice Springs continued to record the highest rate of notification, followed by Katherine. (Table B.1.4).
In this reporting period, the highest notification rates were recorded in the 15-19 and 20-24 year age groups, which accounted for 56.4% 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 the 10-14 year age group recorded 36 notifications.
The large increase in notifications in this reporting period was believed to be due to a considerable increase in testing caused by the prevalence studies conducted in many remote communities in preparation for the multi-jurisdictional randomised control trial study, the STRIVE Project. For more details about this study, please visit the following website:
http://www.nchecr.unsw.edu.au/NCHECRweb.nsf/page/ATSIHP-STRIVE
No notifications were recorded in the under 10 age group, but there were 36 cases notified in the 10-14 year age group during this reporting period.
B.2 Genital Chlamydia
The number of chlamydia notifications rose to 1,419 in this reporting period, compared with 1084 cases in the same period in 2009 (Figure B.1.1 and Table B.1.1). The notification rate for this period, 1,262.2 per 100,000, represented an annualised notification rate of 986.3 per 100,000. The annual rate for 2010 represented an increase of 11.5% over the rate for 2009.
In this reporting period, there were considerably more female notifications than male ones. The notification rate for females was about 50% higher than the male rate (Table B.1.2). The annual rate for 2010 was higher in both sexes when compared with the rates for 2009 (Figure B.1.2).
About 55.9% of notifications in this reporting period were Aboriginal cases, and the Aboriginal rate was 3.4 times the non-Aboriginal rate (Table B.1.3). Aboriginal status was unknown in 6.5% of notifications. In comparison, it was unknown in only 1.6% of gonorrhoea notifications. This difference is believed to be due to the facts that a high proportion of chlamydia cases were diagnosed by urban general practitioners and that Aboriginal status is often not available for such cases. In contrast, cases of gonorrhoea were more likely to be diagnosed in remote regions where their Aboriginal status is more likely to be recorded in clinical databases.
Darwin continued to record the highest number of notifications among all districts (635 cases), followed by Alice Springs (Table B.1.4). In terms of notification rates, the highest was recorded Alice Springs (2260.0 per 100,000), which represented a
76.9% increase compared with the corresponding rate for 2009 (1277.5 per 100,000).
The 15-19 and 20-24 year age groups continued to record the highest age-specific rates (Table B.1.5), in which about 60% of all notifications were recorded. Notably, eight cases were recorded in the age group of under 10 years and 28 in the 10-14 year age groups.
B.3 Infectious Syphilis
Sixteen cases of infectious syphilis were notified in this six-month period, compared with 16 cases diagnosed in the same period in 2009. (Table B.1.1 and Figure B.1.1) A total of 42 cases were notified in 2010, giving a notification rate of 18.7 per
100,000, which was close to the rate for 2009 (16.9 per 100,000).
Unlike other bacterial STIs, there were more male notifications than female ones.
About two-thirds of the cases for both this reporting period and the whole year of 2010 were male (Table B.1.2). Fourteen out of the 16 cases in this period were Aboriginal (87.5%, Table B.1.3). The annual rate for Aboriginals (57.5 per 100,000) was 43 times that for the non-Aboriginal population. There were five or less
notifications in each district in this period (Table B.1.4). In terms of age-specific rates, the highest was recorded in the 20-24 year age group.
As illustrated in Figure B.3.1, the rate of notification has been decreasing in both categories since 2007.
Figure B.3.1 Rate of syphilis notifications by category, NT, 2006-2010
0 50 100 150
2006 2007 2008 2009 2010
Year Notification rate per 100000 population
Less than 2 years duration Greater than 2 yrs or unknown duration
There were no congenital syphilis cases notified in 2010, compared with 3 cases in 2009.
B.4 Trichomoniasis
The number of notifications in this reporting period, 1,348, represented a 55.1%
increase over the same period in 2009. The total of 2,413 notifications in 2010 is the highest ever annual number of trichomoniasis notifications in the NT so far. (Table B.1.1 and Figure B.1.1). If the decrease in 2009 is viewed as a variant, then this 2010 figure is consistent with an existing increasing trend since 2005.
The vast majority of notifications (90.2%) were recorded in females (Table B.1.2).
About 95.0% of notifications were recorded in the Aboriginal population in this reporting period (Table B.1.3). The adjusted Aboriginal rate for 2010 was about 71.8 times the non-Aboriginal rate. Alice Springs 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 36.1% of all notifications were recorded (Table B.1.5). One case was recorded in the age group of under 10 years and 39 in the 10-14 year age group.
B.5 Donovanosis
There were no donovanosis notifications recorded in 2010.
B.6 Other Sexually Transmitted Infections
There were no notifications of chancroid or lymphogranuloma venereum recorded in 2010.
B.7 Hepatitis C
A total of 122 cases were notified in this reporting period, 89 (73.0%) in males and 33 (27.0%) in females (Table B.7.1). All were categorised as ‘unspecified’ (Table B.7.2).
The majority of notified cases (76.2%) were non-Aboriginal, and the ethnicity was unknown in 8.2% of notifications. The notification rate for males was about 2.5 times the female rate, while the non-Aboriginal rate was about 2.3 times the Aboriginal rate.
Figure B.7.1 Number of hepatitis C notifications by sex, NT, 2005-2010
0 20 40 60 80 100 120 140 160 180 200
2005 2006 2007 2008 2009 2010
Number of notifications
Female Male
Table B.7.1 Number and rate of hepatitis C by sex and ethnicity, NT, Jul-Dec 2010 Quarter Sex Aboriginal Non-Aboriginal Unknown Total Case Rate Case Rate Case Case Rate
Jul-Sep Female 2 23.2 8 43.4 1 11 40.7
Male 5 60.0 30 144.0 3 38 130.3
Total 7 41.3 38 96.8 4 49 87.2
Oct-Dec Female 6 69.6 13 70.6 3 22 81.4
Male 6 71.9 42 201.6 3 51 174.8
Total 12 70.8 55 140.1 6 73 129.9
Jul-Dec Female 8 46.4 21 57.0 4 33 61.0
Male 11 66.0 72 172.8 6 89 152.5
Total 19 56.0 93 118.5 10 122 108.5
2010
Total Female 17 49.3 41 55.6 8 66 61.0
Male 14 42.0 121 145.2 11 146 125.1
Total 31 45.7 162 103.2 19 212 94.3
Table B.7.2 Number of hepatitis C notifications by sex, ethnicity and disease categories, NT, Jul-Dec 2010
Type Gender Indigenous status
Aboriginal
Non-
Aboriginal Unknown
Total %
Female 0 0 0 0
Newly
acquired Male 0 0 0 0 0%
Unspecified Female 8 21 4 33
Male 11 72 6 89 100%
Total 19 93 10 122
% 15.6% 76.2% 8.2%
Table B.7.3 Number and annualised rate of hepatitis C notifications by gender and district, NT, Jul-Dec 2010
Case Rate Case Rate Case Rate Case Rate Case Rate
Jul-Sep Female 7 42.3 1 41.5 0 0.0 0 0 3 56.6
Male 18 97.2 5 200.5 1 46.8 1 119.2 8 154.2
Oct-Dec Female 15 90.6 4 166.2 0 0.0 1 127.6 2 37.7
Male 34 183.6 3 120.3 0 0.0 2 238.3 11 212.1
Jul-Dec 2010 74 105.5 13 132.6 1 12.1 4 123.2 24 114.4
60.7% 10.7% 0.8% 3.3% 19.7%
Quarter Sex
District
Darwin Katherine East Arnhem Barkly Alice Springs
Figure B.7.2 Annualised notification rate of hepatitis C by age groups, NT, Jul-Dec 2010
0 20 40 60 80 100 120 140 160 180
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
Enhanced surveillance data:
In 2010, there were 212 notifications of unspecified hepatitis C infection. Among them, 159 (75.0%) were new to the NTNDSS and were therefore investigated by the enhanced surveillance system. Collection of enhanced surveillance data was
successful for 91 of these cases investigated (response rate=57.2%).
Among the 91 cases with enhanced data, 33 (36.2%) indicated that they were
previously diagnosed (in or outside of the NT). This leaves 57 being truly unspecified cases. The data on risk factors for these two groups are summarised in Table B.7.4.
Notably, injection drug use information was not known in over 40% of unspecified cases, compared with just over 20% among those previously diagnosed with hepatitis C infection.
Table B.7.4 Demographic and injection drug use data for those notified for hepatitis C infection investigated by the enhanced surveillance system in the NT, 2010
Category Unspecified Previously diagnosed Sex
Female 14 24.1% 11 33.3%
Male 44 75.9% 22 66.7%
Injection drug use
<two years 3 5.2% 1 3.0%
>two years 17 29.3% 19 57.6%
unknown 23 39.7% 7 21.2%
never 14 24.1% 6 18.2%
not answered 1 1.7% 0 0.0%
B.8 Human Immunodeficiency Virus (HIV)
Two new notifications of HIV were recorded in this 6-month period, giving a total of 7 cases for 2010. Demographic details of these cases are summarised in Table 8.1.
Two cased diagnosed in 2010 were classified as ‘newly acquired HIV’ cases, and both of them were men who have sex with men. One female case was not an Australian resident and was an imported case from another country. Other demographic details of these notifications and those from January to June are summarised in Table B.8.1. Notably, there was one Aboriginal case notified in 2010, and male homosexual contact has become the most common exposure category this year. One case acquired the infection while travelling overseas. (Table B.8.2).
The annual number of HIV notifications had remained low in the last five years (see Figure B.8.1).
Table B.8.1 Demographics and exposure categories for HIV cases, NT, 2010
Category Jan-Jun Jul-Dec Total %
Sex
Male 4 1 5 71%
Female 1 1 2 29%
Total 5 2 7
Ethnicity
Aboriginal 1 0 1 8%
Non-Aboriginal 4 2 6 86%
Exposure category
Male homosexual contact 4 0 4 57%
Male homosexual / bisexual
contact 0 1 1 14%
Heterosexual contact 1 1 2 29%
Injecting drug user 0 0 0 0%
Table B.8.2 Place of infection by sex for HIV cases notified in 2010, NT Place of infection Female Male Total
Interstate 0 1 1
NT 0 2 2
Immigrants/travellers with HIV 2 0 2
Overseas travel 0 1 1
Unknown 0 1 1
Total 2 5 7
Figure B.8.1 HIV notifications in the NT, 2006-2010
0 5 10 15 20
2006 2007 2008 2009 2010
Number of notifications
Male Female
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 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. Sexual Health and Blood Borne Viruses Unit Surveillance Update. 2010; Vol. 11, No. 2.
