Northern Territory Sexual Health and Blood Borne Virus Unit Surveillance Update
Centre for Disease Control
Department of Health
Northern Territory Government
Vol. 12, No. 1
A. Introduction
This surveillance update is published twice a year to present the quarterly statistics for notifiable sexually transmissible infections (STIs) and blood borne viruses (BBVs) in the Northern Territory (NT). This issue presents the statistics for the period January to June 2011. It also presents the results of gonococcal sensitivity surveillance in the NT for 2010.
The notification data used in this report are extracted from the Northern Territory Notifiable Diseases System (NTNDS). The extraction of notification data was carried out in early October 2011. As the official data cleaning process for data of this year is usually carried out in the next year, the data published in this report are not final.
Other data also used include HIV and AIDS data from the HIV/AIDS database maintained by the NT 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 2011’
published by the Kirby Institute. The gonococcal sensitivity surveillance data are provided by the Australian Gonococcal Sensitivity Programme. Population data used for rate calculation are estimated resident population prepared and provided by the Health Gains Planning unit, which are derived from the Census data retrieved from the Australian Bureau of Statistics. Population data for 2010 were used for calculating 2011 rates as the data for 2011 are not available yet.
The quarterly rates of notification presented in this report are crude annualised rates per 100,000 population. As there is often a small proportion of notifications categorised as ‘interstate’ or of unknown residence locations, the sum of district- specific notifications presented in this report may be lower than the total number of notifications shown in other tables.
It has been widely reported that in areas where the prevalence is high, notification rates of common bacterial STIs (such as gonorrhoea and chlamydia) are often influenced by the amount of testing. Therefore, caution should be taken when interpreting the statistics reported in this publication because the STI rates have been high in the NT, and a change in notification rates can often be related to a change in the testing amount. For example, the randomised community trial entitled STRIVE commenced this year is aimed at promoting STI testing in most at risk young age groups in remote communities and this is expected to significantly increase testing amount, and hence an increase in notifications.
B. Quarterly Statistics
Table B.1.1 Number and rate of gonorrhoea, chlamydia, infectious syphilis and trichomoniasis notifications, NT, Jan-Jun 2011
Quarter Gonorrhoea Chlamydia
Infectious
syphilis Trichomoniasis Cases Rate Cases Rate Case Rate Case Rate 2011
Jan-Mar 533 928.3 687 1196.5 17 29.6 619 1078.0 Apr-Jun 522 909.1 661 1151.2 8 13.9 721 1255.7 Jan-Jun total 1055 918.7 1348 1173.8 25 21.8 1340 1166.9 2010
Jan-Mar 414 721.0 649 1130.3 10 8.7 530 468.7 Apr-Jun 495 862.1 628 1093.7 16 13.9 531 469.6 Jan-Jun total 909 791.6 1277 1112.0 26 11.3 1061 469.1
Figure B.1.1 Annualised notification rates of gonorrhoea, chlamydia, infectious syphilis and trichomoniasis, NT, Jan-Jun 2007-2011
0 200 400 600 800 1000 1200
Gonorrhoea Chlamydia Infectious Syphilis
Trichomoniasis
Disease
Notification rate (per 100,000 population)
2007 2008 2009 2010 2011
Table B.1.2 Number and rate of gonorrhoea, chlamydia, infectious syphilis and trichomoniasis by sex, NT, Jan-Jun 2011
Gender Gonorrhoea* Chlamydia Syphilis Trichomoniasis Cases Rate Cases Rate Cases Rate Cases Rate Males
Jan-Mar 250 840.0 263 883.6 8 26.9 68 228.5
Apr-Jun 242 813.1 252 846.7 3 10.1 110 369.6
Total 492 826.5 515 865.2 11 18.5 178 299.0 Females
Jan-Mar 283 1023.3 424 1533.1 9 32.5 551 1992.4
Apr-Jun 279 1008.8 409 1478.9 5 18.1 611 2209.3
Total 562 1016.1 833 1506.0 14 25.3 1162 2100.8
* There was one notification with sex being unknown.
Figure B.1.2 Annualised notification rates of gonorrhoea, chlamydia, infectious syphilis and trichomoniasis by gender, NT, Jan-Jun 2007-2011
0 400 800 1200 1600 2000 2400
2007 2008 2009 2010 2011 2007 2008 2009 2010 2011 Male Female
Notification Rate (per 100,000 population)
Gonorrhoea Chlamydia Syphilis Trichomoniasis
Table B.1.3 Number and rate of gonorrhoea, chlamydia, infectious syphilis and trichomoniasis notifications by ethnicity, NT, Jan-Jun 2011
Ethnicity Gonorrhoea Chlamydia
Infectious
Syphilis Trichomoniasis Quarter Cases Rate Cases Rate Cases Rate Cases Rate Aboriginal
Jan-Mar 488 2825.6 431 2495.6 14 81.1 592 3427.8 Apr-Jun 484 2802.5 402 2327.7 7 40.5 684 3960.5 Total 972 2814.0 833 2411.6 21 60.8 1276 3694.2 Non-Aboriginal
Jan-Mar 34 84.7 217 540.5 3 7.5 15 37.4
Apr-Jun 27 67.3 213 530.5 1 2.5 22 54.8
Total 61 76.0 430 535.5 4 5.0 37 46.1
Unknown
Jan-Mar 11 39 0 12
Apr-Jun 11 46 0 15
Total 22 85 0 27
Figure B.1.3 Annualised notification rates* of gonorrhoea, chlamydia, infectious syphilis and trichomoniasis by ethnicity, NT, Jan-Jun 2011
0 500 1000 1500 2000 2500 3000 3500 4000
Gonorrhoea Chlamydia Syphilis Trichomoniasis
Notification rate (per 100000 population)
Aboriginal Non-Aboriginal
* Adjusted rates after allocating notifications of unknown ethnicity to Aboriginal and non-Aboriginal categories according to their proportions based on notifications of known ethnicity.
Table B.1.4 Number and rate of gonorrhoea, chlamydia, infectious syphilis and trichomoniasis notifications by district, NT, Jan-Jun 2011
Gonorrhoea Chlamydia Infectious Syphilis Trichomoniasis District Cases Rate Cases Rate Cases Rate Cases Rate Darwin
Jan-Mar 102 290.9 318 907.0 2 5.7 139 396.5
Apr-Jun 89 253.8 295 841.4 1 2.9 204 581.8
Total 191 272.4 613 874.2 3 4.3 343 489.2
Katherine
Jan-Mar 80 1632.5 64 1306.0 3 61.2 163 3326.2
Apr-Jun 80 1632.5 58 1183.6 2 40.8 130 2652.8
Total 160 1632.5 122 1244.8 5 51.0 293 2989.5 East Arnhem
Jan-Mar 42 1014.2 65 1569.7 2 48.3 99 2390.7
Apr-Jun 40 966.0 55 1328.2 0 0.0 98 2366.6
Total 82 990.1 120 1448.9 2 24.1 197 2378.7
Barkly
Jan-Mar 29 1786.8 11 677.8 5 308.1 41 2526.2
Apr-Jun 29 1786.8 16 985.8 4 246.5 31 1910.0
Total 58 1786.8 27 831.8 9 277.3 72 2218.1
Alice Springs
Jan-Mar 270 2574.7 218 2078.8 4 38.1 167 1592.5
Apr-Jun 273 2603.3 228 2174.2 1 9.5 248 2364.9
Total 543 2589.0 446 2126.5 5 23.8 415 1978.7
Figure B.1.4 Annualised notification rates of gonorrhoea, chlamydia, infectious syphilis and trichomoniasis by district, NT, Jan-Jun 2011
0 500 1000 1500 2000 2500 3000
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 of gonorrhoea, chlamydia, infectious syphilis and trichomoniasis notifications by 5-year age group, Jan-Jun 2011
Gonorrhoea Chlamydia
Infectious
Syphilis Trichomoniasis Age
group Cases Rate Cases Rate Cases Rate Cases Rate
<10 3 16.5 0 0.0 0 0.0 2 11.0
10-14 40 477.3 40 477.3 0 0.0 32 381.8
15-19 300 3562.1 390 4630.7 5 59.4 229 2719.1 20-24 270 2849.3 396 4179.0 9 95.0 216 2279.4 25-29 197 1865.4 263 2490.3 3 28.4 235 2225.2 30-34 109 1154.4 109 1154.4 1 10.6 157 1662.8
35-39 62 667.4 55 592.1 3 32.3 152 1636.3
40-44 34 399.9 45 529.3 1 11.8 132 1552.7
45-49 21 260.3 29 359.5 3 37.2 95 1177.7
50-54 9 123.7 13 178.6 0 0.0 52 714.6
55-59 7 112.7 3 48.3 0 0.0 22 354.2
60-64 1 21.3 1 21.3 0 0.0 8 170.6
65+ 2 31.4 4 62.9 0 0.0 8 125.8
Total 1055 918.7 1348 1173.8 25 21.8 1340 1166.9
Figure B.1.5 Notification rate of gonorrhoea, chlamydia, infectious syphilis and trichomoniasis notifications by age group, Jan-Jun 2011
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
Notification rate (per 100,000 population) Gonorrhoea Chlamydia Infectious Syphilis Trichomoniasis65+
B.1 Gonorrhoea
The annualised rate of gonorrhoea for this six-month period, 918.7 per 100,000, represents a considerable increase compared with the same period for the previous 4 years (Table B.1.1 and Figure B.1.1). It is 21 times the Australian rate of 43.5 per 100,000 in 2010.
As shown in Figure B.1.2, the rate increase occurred in both sexes, although the increase was greater in females. The male to female rate ratio of case number was 1:1.14 (Table B.1.2). This was different from the usual pattern in the NT in which male notifications were more than female ones. As was the case in previous years, over 90% of all cases were recorded in the Aboriginal population, and the Aboriginal rate was about 37 times the non-Aboriginal rate (Table B.1.3). The NT Aboriginal and non-Aboriginal rates were both considerably higher than their corresponding rates for Australia (804 and 30 per 100,000, respectively) in 2010.
The highest district-specific rate was recorded in Alice Springs district, followed by Barkly (see Table B.1.4). In this 6-month period, 51.5% of all notified cases were recorded in Alice Springs.
The highest age-specific notification rate was recorded in the 15-19 year age group, followed by 20-24; these two age groups recorded 52.0% of all notifications (Table B.1.5 and Figure B.1.5). There were 3 cases recorded in the under 10 year age group, and 40 in the 10-14 year age group.
B.2 Genital chlamydia
Compared with the corresponding rate for 2010, the annualised rate of genital chlamydia for this reporting period showed a slight increase (5.6%), but was at about the same level as 2007 and 2008 rates (Figure B.1.1 and Table B.1.1).
The notification rates did not show significant changes in either sex when compared with the same rates for previous four years. The rate for females continued to be considerably higher than the rate for males (higher by 74.1%, see Table B.1.2).
About 61.8% of all notifications were recorded in the Aboriginal population and 31.9%
in non-Aboriginal (Table B.1.3). The proportion of notifications with Aboriginal status being unknown was 6.3%, compared with 2.1% for gonorrhoea. This may be due to the higher proportion of non-Aboriginal notifications, which were more likely to be notified by urban-based GPs, and the fact that the Aboriginal status was more likely not be unknown for cases notified by GPs. The notification rate for the Aboriginal population was about 4.5 times the non-Aboriginal rate. Both Aboriginal and non- Aboriginal rates were considerably higher than the corresponding rates for Australia (1257 and 340 per 100000 in 2010 respectively).
The highest district-specific rate was recorded in the Alice Springs district, followed by East Arnhem (Table B.1.4). However, it was the Darwin district that recorded the highest number of notifications, representing 45.5% of all notifications.
The 15-19 year age group recorded the highest notification rate, followed by the 20- 24 year age group (Table B.1.5). These two age groups accounted for 58.3% of all notifications. Notably, a total of 40 cases were notified in the 10-14 year age group, but none in the under 10 year age group.
B.3 Infectious syphilis
The number and rate of notifications in this reporting period were about the same as those in 2010 (Table B.1.1). The annualised rate (21.8 per 100,000) was considerably higher than the Australian rate of 5 per 100,000 in 2010.
There were slightly more female cases than in males (Table B.1.2). The annualised rates remained at about the same level as previous two years in both sexes (Figure B.1.2).
Twenty-one out of the 25 cases (84.0%) notified in this reporting period were Aboriginal; the Aboriginal rate was about 12.2 times the non-Aboriginal rate (Table B.1.3). The reporting of Aboriginal status was 100% in this 6-month period for infectious syphilis.
Barkly district recorded the highest number and rate of notification (Table B.1.4). The majority of the cases came from a small outbreak which started in October 2010 and was successfully contained in January. The number of notifications was 5 or lower in all other districts. Like chlamydia and gonorrhoea, the highest number and rate of notification were recorded in the 15-19 and 20-24 year age groups (Table B.1.5).
There were no notifications of congenital syphilis in this reporting period.
B.4 Trichomoniasis
The number and rate of notification for trichomoniasis in this reporting period was the highest in the recent five years; the rate increased by 26.3% compared with the same rate for 2010 (Table B.1.1).
The majority (86.7%) of all notifications were female and 95.2% of them were Aboriginal (Table B.1.2 and Table B.1.3). The Aboriginal rate was 80.2 times the non- Aboriginal rate.
The rate was substantially higher in mainly remote districts than in the mainly urban Darwin district. Katherine district recorded the highest rate, but the highest number of notifications was recorded in the Alice Springs district (Table B.1.4).
The highest rates continued to be recorded in the 15-19 and 20-24 year age groups (Table B.1.5), but it was the 25-29 year age group that recorded the highest number of cases. These three age groups accounted for just over half of all notifications (50.7%). Notably, 2 cases were recorded in the age group of under 10 years and 32 in the 10-14 year age group.
B.5 Donovanosis and other sexually transmitted infections
There were no notifications of donovanosis, chancroid or lymphogranuloma venereum in this reporting period.
B.7 Hepatitis C
The number of hepatitis C notifications increased by 15.6% in this reporting period compared with the same rate of 2010 (Figure B.7.1). It represented a reverse of the decreasing trend noted in recent years up to 2010. The increase occurred mainly in males. The cause of the increase is unknown. The annualised notification rate for this 6-month period was 90.6 per 100,000, compared with the Australian rate of 50.1 per 100,000 in 2010. Only 1 case out of the 104 was categorised as newly acquired Table B.7.2)
As was usually the case, there were considerably more male cases than female ones (male: female=2.2:1, see Table B.7.1). About 74% of all notifications were non-
Aboriginal. Aboriginal status was unknown in 6.7% of the notifications.
The Darwin district recorded the highest number and rate of notification (66.3% of all cases, see Table B.7.3). The highest age-specific rates were recorded in the
relatively older age groups in both sexes (50-54 and 45-49 year age groups, see Figure B.7.1).
Figure B.7.1 Number of hepatitis C notifications by gender, NT, Jan-Jun, 2007-2011
0 20 40 60 80 100 120 140
2007 2008 2009 2010 2011
Number of notifications
Female Male Total
Table B.7.1 Number and rate of hepatitis C notifications by gender and ethnicity, NT, Jan-Jun 2011
Quarter Sex Aboriginal Non-Aboriginal Unknown Total
Case Rate Case Rate Case Case Rate
Jan-Mar Female 4 45.5 11 58.3 1 16 57.9
Male 6 70.7 25 117.5 2 33 110.9
Total 10 57.9 36 89.7 3 49 85.3
Apr-Jun Female 4 45.5 11 58.3 2 17 61.5
Male 6 70.7 30 141.0 2 38 127.7
Total 10 57.9 41 102.1 4 55 95.8
Jan-Jun Female 8 45.5 22 58.3 3 33 59.7
Male 12 70.7 55 129.2 4 71 119.3
Table B.7.2 Number of hepatitis C notifications by gender, ethnicity and disease categories, NT, Jan-Jun 2011
Type Gender Indigenous status
Total %
Aboriginal
Non-
Aboriginal Unknown
Newly acquired
Female 0 1 0 1
1%
Male 0 0 0 0
Unspecified
Female 8 21 3 32 99%
Male 12 55 4 71
Total 20 77 7 104
% 19.2% 74.0% 6.7%
Table B.7.3 Number and annualised rate of hepatitis C notifications by gender and district, NT, Jan- Jun 2009
Quarter Sex
District Darwin Katherine
East
Arnhem Barkly
Alice Springs Case Rate Case Rate Case Rate Case Rate Case Rate Jan-
Mar Female 11 65.0 1 40.7 0 0.0 0 0 4 73.8
Male 22 116.4 3 118.0 3 137.9 0 0.0 4 75.7
Apr-Jun Female 8 47.2 1 40.7 0 0.0 0 0.0 6 110.7
Male 28 148.1 4 157.3 1 46.0 0 0.0 4 75.7
Jan-Jun 2011
Female 19 2 0 0 10
Male 50 7 4 0 8
Total 69 96.3 9 90.0 4 47.4 0 0.0 18 84.1
Figure B.7.1 Annualised notification rate of hepatitis C by age groups, NT, Jan-Jun 2011
0 60 120 180 240 300 360
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)
There were 5 notifications of HIV in this reporting period. All of them were male and one was an Aboriginal case (Table B.8.1). One out of the five was a newly acquired case.
Table B.8.1 HIV notifications by sex and ethnicity, NT, Jan-Jun 2010 & 2011
Category 2010 2011
Jan-Jun % Jan-Jun % Sex
Male 4 75.0 5 75.0
Female 1 25.0 0 25.0
Ethnicity
Aboriginal 1 25.0 1 25.0
Non-Aboriginal 4 75.0 4 75.0
Figure B.8.1 HIV notifications by sex, NT, Jan-Jun 2007-2011
0 2 4 6 8 10
2007 2008 2009 2010 2011
Number of notifications
Male Female
Table B.8.2 HIV notifications by exposure category and source of infection, NT, Jan-Jun 2011
Exposure category No. %
Male homosexual contact 1 20.0%
Male homosexual / bisexual contact 1 20.0%
Heterosexual contact 2 40.0%
Undetermined 1 20.0%
Place of infection
NT 2 40.0%
Imported 2 40.0%
Unknown 1 20.0%
Total 5
Two acquired the infection through heterosexual contact while two others did so through male homosexual contact. Two cases acquired the infection before they arrived in Australia either as immigrants or temporary residents. Two cases acquired
C. Surveillance of antimicrobial
sensitivity of N. gonorrhoeae, 2010
The continuous surveillance of the antimicrobial sensitivity of N. gonorrhoeae is essential to the control of gonorrhoea. This is especially important for the NT as has been explained in our previous issues (for instance, Vol.10 No.1).
The consolidated antimicrobial sensitivity data for N. gonorrhoeae for the NT for 2010 were provided by the Australian Gonococcal Surveillance Programme (AGSP). For a detailed description of the NT’s collaboration with the AGSP, please refer to Vol.9, No.1 issue of this publication.
A total of 448 isolates from the NT were received by the AGSP for 2010. This represents a considerable increase compared with the 387 isolates in 2009 and 403 in 2008. Of these, 312 were from males (about 70%) and 136 from females (about 30%), giving a male to female ratio of 2.3:1 (Table C.1). This is considerably higher than the ratios in recent years, which was usually below 2:1. The majority of isolates in men were taken from urethra (95.2%) while 93.4% of isolates from women were taken from the cervix.
After deducting 36 non-viable isolates, a total of 412 isolates were subjected to sensitivity analysis. Of these, 9 isolates were classified as chromosome-mediated penicillin resistant (CMRNG, 2.2%) and 6 as penicillinase-producing penicillin resistant (PPNG, 1.5%), giving an overall proportion of isolates resistant to penicillin of 3.8%, which was the lowest in the recent five years (4.2% in 2009, 3.9% in 2008, 4.1% in 2007, 4.6% in 2006). All isolates resistant to penicillin were sensitive to Ceftriaxone, the antibiotic currently recommended for gonococcal infections acquired from contact with people from interstate or overseas.
Furthermore, of the 15 cases infected with strains of N. gonorrhoeae resistant to penicillin, only one acquired the infection locally (6.7%, from an unknown person in Darwin), and two from interstate (13.3%), and all the others acquired the infection while travelling overseas (80.0%).
Table C.1 Specimen sites of N. Gonorrhoeae isolates from the NT by sex, 2010
Site Male
Site Female
Number % Number %
Urethra 297 95.2% Cervix 127 93.4%
Rectal 3 1.0% Rectal 0 0.0%
Pharynx 0 0.0% Pharynx 0 0.0%
DGI 10 3.2% DGI 8 5.9%
Other/Unknown 2 0.6% Other/Unknown 1 0.7%
Total 312 Total 136
Table C.2 Penicillin sensitivity for N. Gonorrhoeae isolates* from the NT by region, 2010
Sensitivity
result Top End % Central
Australia % Total %
Fully sensitive 0 0.0% 1 0.3% 1 0.2%
Less sensitive 111 91.7% 285 97.9% 396 96.1%
CMRNG 4 3.3% 5 1.7% 9 2.2%
PPNG 6 5.0% 0 0.0% 6 1.5%
Total 121 291 412
* included only viable isolates
The proportion for the Central Australia region was low at 1.7% (Table C.2). Although the proportion of isolates resistant to penicillin was higher than 5% in the Top End region (8.3%), only one case was likely to be infected by a local resident.
Furthermore, all NT isolates, including the ones resistant to penicillin, were sensitive to the second line antibiotic recommended, Ceftriaxone. Considering all these statistics, it is appropriate to maintain the current treatment recommendations for genital gonorrhoea contained in NT Guidelines for the Management of Sexually Transmitted Infections in the Primary Health Care Setting.
In Jan-Jun 2011, five cases of PPNG were notified. All of them were male and acquired the infection overseas. None of them reported having local contacts before being detected and treated. All were treated with antibiotics effective for the identified strains.
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) 8922 8874 Fax: (08) 8922 8809
Email:
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:
Suggested citation:
Northern Territory Department of Health. Sexual Health and Blood Borne Viruses Unit Surveillance Update. 2011; Vol. 12, No. 1.
