Northern Territory Sexual Health and Blood Borne Virus Unit Surveillance Update
Department of Health and Families, Vol. 10 No. 1,
Jan-Mar 2009 & Apr-Jun 2009
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 the first two quarters of 2009. It also presents the results of gonococcal sensitivity surveillance for 2008.
The data used for this report include surveillance data extracted from the Northern Territory Notifiable Diseases System (NTNDS), 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 System1 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. 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.
The notification rates for the two quarters and 6-month periods presented in this report are crude annualised rates. There is often a small proportion of notifications categorised as ‘interstate’ or of unknown residence locations. Due to this, 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.
As notification rates of STIs can 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. This 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, Jan-Jun 2009
Gonorrhoea Chlamydia Syphilis Trichomoniasis Quarter
Cases Rate Cases Rate Case Rate Case Rate 2009
Jan-Mar 398 740.7 581 1081.3 39 72.6 430 800.3 Apr-Jun 505 939.8 678 1261.8 46 85.6 469 872.8 Total 903 840.3 1,259 1171.5 85 79.1 899 836.6 2008
Jan-Jun 900 837.5 1261 1173.4 137 127.5 1217 1132.5
Figure B.1.1 Notification rates of gonorrhoea, chlamydia, syphilis and trichomoniasis, NT, Jan- Jun, 2005-2009
0 200 400 600 800 1000 1200 1400
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, Jan-Jun 2009
Gonorrhoea Chlamydia Syphilis Trichomoniasis Gender
Cases Rate Cases Rate Cases Rate Cases Rate Males
Jan-Mar 192 702.0 220 804.4 17 62.2 33 120.7
Apr-Jun 258 943.4 211 771.5 26 95.1 29 106.0
Total 450 822.7 431 788.0 43 78.6 62 113.3 Females
Jan-Mar 206 813.6 361 1425.8 22 86.9 397 1568.0 Apr-Jun 247 975.6 466 1840.5 20 79.0 439 1733.9 Total 453 894.6 827 1633.2 42 82.9 836 1651.0 Unknown
Jan-Mar 0 0 0 0
Apr-Jun 0 1 0 1
Total 0 1 0 1
Figure B.1.2 Notification rates of gonorrhoea, chlamydia, syphilis and trichomoniasis by gender, NT, Jan-Jun, 2005-2009
Male
0 500 1000 1500 2000 2500
2005 2006 2007 2008 2009
Year Notification Rate (per 100,000 population)
Gonorrhoea Chlamydia Syphilis Trichomoniasis
Female
0 500 1000 1500 2000 2500
2005 2006 2007 2008 2009
Year 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, Jan-Jun 2009
Ethnicity Gonorrhoea Chlamydia Syphilis Trichomoniasis Quarter Cases Rate Cases Rate Cases Rate Cases Rate Aboriginal
Jan-Mar 365 2196.1 323 1943.4 34 204.6 400 2406.7 Apr-Jun 462 2779.7 451 2713.5 36 216.6 447 2689.4 Total 827 2487.9 774 2328.4 70 210.6 847 2548.1 Non-Aboriginal
Jan-Mar 21 54.8 211 550.4 4 10.4 17 44.3
Apr-Jun 40 104.3 178 464.3 9 23.5 19 49.6
Total 61 79.6 389 507.4 13 17.0 36 47.0 Unknown
Jan-Mar 12 47 1 13
Apr-Jun 3 49 1 3
Total 15 96 2 16
Figure B.1.3 Notification rates of gonorrhoea, chlamydia, syphilis and trichomoniasis by ethnicity, NT, Jan-Jun, 2009
0 500 1000 1500 2000 2500 3000
Gonorrhoea
Chlam ydia
Syphilis
Trichomoniasis Disease
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, Jan-Jun 2009
Gonorrhoea Chlamydia Syphilis Trichomoniasis District Cases Rate Cases Rate Cases Rate Cases Rate Darwin
Jan-Mar 78 227.7 254 741.4 16 46.7 143 417.4 Apr-Jun 59 172.2 249 726.8 25 73.0 124 361.9 Total 137 199.9 503 734.1 41 59.8 267 389.7 Katherine
Jan-Mar 56 1168.1 61 1272.4 10 208.6 63 1314.1 Apr-Jun 73 1522.7 60 1251.6 3 62.6 82 1710.5 Total 129 1345.4 121 1262.0 13 135.6 145 1512.3 East Arnhem
Jan-Mar 32 788.2 60 1477.9 3 73.9 75 1847.4
Apr-Jun 28 689.7 38 936.0 1 24.6 70 1724.2
Total 60 739.0 98 1207.0 4 49.3 145 1785.8 Barkly
Jan-Mar 20 1261.6 19 1198.5 0 0.0 24 1514.0
Apr-Jun 13 820.1 13 820.1 3 189.2 16 1009.3
Total 33 1040.8 32 1009.3 3 94.6 40 1261.6 Alice Springs
Jan-Mar 191 1862.6 172 1677.3 10 97.5 113 1102.0 Apr-Jun 324 3159.6 312 3042.6 12 117.0 175 1706.6 Total 515 2511.1 484 2359.9 22 107.3 288 1404.3
Figure B.1.4 Notification rates of gonorrhoea, chlamydia, syphilis and trichomoniasis by district, NT, Jan-Jun 2009
0 500 1000 1500 2000 2500 3000
Darwin Katherine East Arnhem Barkly Alice Springs
Notification rate (per 100,000 population)
Gonorrhoea Chlamydia Syphillis Trichomoniasis
Table B.1.5 Number and rate of gonorrhoea, chlamydia, syphilis and trichomoniasis notifications by 5-year age group, Jan-Jun 2009
Gonorrhoea Chlamydia Syphilis Trichomoniasis Age
group Cases Rate Cases Rate Cases Rate Cases Rate
<10 1 5.6 5 28.1 0 0.0 0 0.0
10-14 26 311.2 29 347.1 0 0.0 15 179.6
15-19 266 3234.4 365 4438.2 2 24.3 144 1751.0 20-24 231 2589.5 398 4461.6 9 100.9 154 1726.4 25-29 159 1644.7 228 2358.4 5 51.7 125 1293.0 30-34 88 961.6 101 1103.6 12 131.1 108 1180.1 35-39 73 800.1 61 668.6 13 142.5 115 1260.5 40-44 36 442.6 34 418.0 12 147.5 96 1180.4
45-49 7 88.2 21 264.7 10 126.0 62 781.5
50-54 10 142.7 7 99.9 9 128.5 51 727.9
55-59 3 51.0 8 136.0 6 102.0 15 255.0
60-64 3 72.6 1 24.2 1 24.2 6 145.3
65+ 0 0.0 1 17.9 6 107.4 8 143.2
Total 903 821.6 1259 1145.5 85 77.3 899 817.9
Figure B.1.5 Notification rate of gonorrhoea, chlamydia, syphilis and trichomoniasis notifications by age group, Jan-Jun 2009
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
The annualised rate of gonorrhoea for this six-month period, 840.3 per 100,000, remained at about the same level as that for the same period of the last two years.
(see Table B.1.1 and Figure B.1.1). The population rate of gonorrhoea for Australia was 35.7 per 100000 in 2008.
Compared with the 2008 rate for Jan-Jun, the rate for Jan-Jun this year was at about the same level for both sexes (see Figure B.1.2). The male to female rate ratio was 1:1.1 (see Table B.1.2). About 92% of all cases were recorded in the Aboriginal population, and the Aboriginal rate was 31 times the non-Aboriginal rate (see Table B.1.3). The non-Aboriginal rate for the NT, 79.6 per 100000, was still more than double the rate for Australia quoted above.
Alice Springs district recorded the highest number and rate of notifications among all districts (see Table B.1.4). In this 6-month period, about 57% of all notified cases were from Alice Springs. As reported before, this proportion is usually higher in the first half of the year due to the local annual sexual health screen being conducted in the second quarter each year.
The highest notification rates continued to be recorded in the 15-19 and 20-24 years age groups, which accounted for 55% of all notifications during this reporting period (Table B.1.5 and Figure B.1.5). One case was reported in the under 10 year age group and 26 cases in the 10-14 year age group.
B.2 Genital Chlamydia
The annualised notification rate of genital chlamydia for Jan-Jun remained at about the same level as those of 2007 and 2008 (see Figure B.1.1 and Table B.1.1).
The notification rate for females continued to be higher than the male rate with a male to female rate ratio of 1:2.1 (see Table B.1.2). The male rate declined slightly in this reporting period as compared with the same period of the last two years while the female rate continued its upward trend noted in the past five years (see Figure B.1.2).
About 61% of the notifications were Aboriginal, compared with the 92% for gonorrhoea. However, the notification rate for Aboriginals was still much higher, about 4.6 times the non-Aboriginal rate (see Table B.1.3). Both Aboriginal and non- Aboriginal rates were considerably higher than the national notification rate (270.6 per 100000 in 2008).
The highest rate of notification were recorded in the Alice Springs District, followed by Katherine (see Table B.1.4). However, Darwin recorded the highest number of notifications, representing 40% of all cases.
The 15-19 and 20-24 year age groups continued to record the highest age-specific rates (Table B.1.5). Together these two age groups accounted for 61% of all notifications. There were 5 cases reported in the under 10 year age group and 29 cases in the 10-14 year age group.
B.3 Syphilis
The annualised notification rate for syphilis for the Jan-Jun continued to decline in this year. This was a continuation of the decreasing trend noted in 2006-2008 (see Table B.1.1 and Figure B.1.1). Compared with the 137 notifications in Jan-Jun 2008, the 85 cases recorded during the same time this year represents a considerable 38%
decrease.
The number and rate of notification for females were at similar levels as those for males (see Table B.1.2). Compared with the corresponding annualised rates for 2008, the 2009 rate for this reporting period decreased by 40% in males and 30% in females (see Figure B.1.2).
About 82% of all notifications were recorded in the Aboriginal population and the Aboriginal rate was about 12 times the non-Aboriginal rate (see Table B.1.3). The Aboriginal status was reported in about 98% of all notifications.
The highest number of notifications was recorded in Darwin District, which
represented about 48% of all notifications (see Table B.1.4). However, 31 out of the 41 notifications were categorised as ‘syphilis of greater than 2 years duration or unknown duration’. The highest notification rate was recorded in Katherine, but 11 out of the 13 notifications of Katherine were also categorised as ‘syphilis of greater than 2 years duration or unknown duration.’
Notifications of syphilis were relatively less concentrated in one or two age groups, compared with those for gonorrhoea and chlamydia (see Table B.1.5). Highest rates were recorded in the 35-39 and 40-44 year age groups.
Two congenital syphilis cases were notified in this reporting period, one in Alice Springs and the other in Katherine.
B.4 Trichomoniasis
The notification rate of trichomoniasis declined by 26% in this reporting period compared with the same period of 2008 (see Figure B.1.1).
Table B.4.1 Number of trichomoniasis notifications by diagnostic method, Jan-Jun 2007-2009
Diagnostic method 2007 2008 2009
Microscopy 466 479 401
Nucleic acid testing 850 897 598 Culture and other methods 16 25 38
Total* 1332 1401 1037
* A notification of trichomoniasis can come with more than one diagnostic test result. Therefore the total numbers of diagnoses in this table were greater than the numbers shown in Table B.1.1.
Table B.4.2 Number of tests and positivity rate for the nucleic acid test for trichomoniasis, Jan- Jun 2007-2009
Testing data 2007 2008 2009
Total number of tests 4221 5848 5870 Positivity rate 18.6% 14.9% 12.6%
Further analysis was undertaken examining the number of notifications by diagnostic tests and the laboratory testing data of the nucleic acid test for trichomonas. This was performed in order to explore the reason for this significant decrease. Table B.4.1 shows that the number of diagnoses by nucleic acid testing had decreased by 33.3%
in 2009 compared with the same period in 2008. During the period, the number of diagnoses by microscopy decreased by 16.3%. Furthermore, the total number of nucleic tests performed in this period was at virtually the same level as that of 2008 while the positivity rate (the proportion of positive test) decreased by 15.6% (see Table B.4.2). It is clear that the significant decrease in notification in this reporting period was not the result of decreased testing, but is likely due to decreased prevalence.
The majority (93%) of all notifications were female and 94% of them were Aboriginal (see Table B.1.2 and Table B.1.3). The Aboriginal rate was 54 times the non-
Aboriginal rate.
The highest rate was recorded in East Arnhem although the Alice Springs recorded the highest number of notifications (see Table B.1.4).
The highest rates continued to be recorded in the 15-19 and 20-24 year age groups (see Table B.1.5). These two age groups accounted for about 33% of all notifications.
There were 15 cases recorded in the 10-14 year age group.
B.5 Donovanosis
There were no notifications of donovanosis in this reporting period.
B.6 Other Sexually Transmitted Infections
There were no notifications of chancroid or lymphogranuloma venereum in this reporting period.
B.7 Hepatitis C
A total of 102 notifications of hepatitis C virus (HCV) infection was reported in this reporting period, which represented a 15% decrease compared with the number for 2008 (see Table B.7.1). They were evenly distributed over the two quarters and male cases more than doubled female cases (male: female=2.2:1). For Aboriginal cases, the male to female ratio was about 1:1. There were three ‘newly acquired’ cases, two males and one female. Unspecified cases represented 96% of all cases (see Table B.7.2 and Table B.7.3). About 76% of cases were non-Aboriginal. Notably, 20% of all cases were identified as Aboriginal.
About 63% of all cases were recorded in Darwin, followed by 18% in Alice Springs.
(see Table B.7.4). Darwin also recorded the highest rate among all districts. The highest age-specific rates were recorded in the relatively older age groups in both sexes (50-54 and 55-59 year age groups, see Figure B.7.1).
Table B.7.1 Number of hepatitis C notifications by gender, NT, Jan-Jun, 2005-2009 Gender 2005 2006 2007 2008 2009
Female 50 44 43 44 32
Male 94 106 79 76 70
Total 144 150 122 120 102
Enhanced surveillance was conducted for 43 cases for which there were no previous notification data recorded in the NT. Two out of the three cases categorised as ‘newly acquired’ cases were current injection drug users (IDUs) while the other case
reported having sex with a HCV positive partner as the only risk factor. Of the 40 cases categorised as ‘unspecified’, 14 (35%) were previously diagnosed elsewhere, and hence not new diagnoses; 18 (45%) admitted to be either current or previous IDUs.
Aboriginal status was unknown in 7% of the notifications, compared with 9% and 13% during the same period in 2007 and 2008, respectively.
Table B.7.2 Number and rate of hepatitis C by gender and ethnicity, NT, Jan-Jun 2009
Aboriginal
Non-
Aboriginal Unknown Total Case Rate Case Rate Case Case Rate Quarter Gender
Jan-Mar Female 6 71.0 8 44.4 2 16 60.5
Male 7 85.7 26 127.9 2 35 122.8
Total 13 78.2 34 88.7 4 51 92.8
Apr-Jun Female 4 47.3 12 66.6 0 16 88.9
Male 3 36.7 29 142.7 3 35 172.2
Total 7 42.1 41 107.0 3 51 92.8
Jan-Jun Female 10 59.2 20 55.5 2 32 60.5
Male 10 61.2 55 135.3 5 70 122.8
Total 20 60.2 75 97.8 7 102 92.8
Table B.7.3 Number of hepatitis C notifications by gender, ethnicity and disease categories, NT, Jan-Jun 2009
Category Gender Ethnicity
Aboriginal
Non-
Aboriginal Unknown
Total %
Female 0 1 0 1
New Male 1 1 0 2 3%
Unspecified Female 10 19 2 31
Male 9 54 5 68 97%
Total 20 75 7 102
% 20% 74% 7%
Table B.7.4 Number and annualised rate of hepatitis C notifications by gender and district, NT, Jan- Jun 2009
District Darwin Katherine
East
Arnhem Barkly
Alice Springs
Quarter Gender
Case Rate Case Rate Case Rate Case Rate Case Rate
Jan-Mar Female 8 49.4 2 84.8 1 50.9 0 0 3 57.9
Male 21 116.2 3 123.1 1 47.7 0 0.0 7 138.0 Apr-Jun Female 10 61.8 1 42.4 0 0.0 1 130.4 4 77.2
Male 25 138.3 0 0.0 0 0.0 1 122.2 4 78.9
Total Jan-Jun
2009 64 93.4 6 62.6 2 12.3 2 63.1 18 87.8
63% 6% 2% 2% 18%
Figure B.7.1 Annualised notification rate of hepatitis C by age groups, NT, Jan-Jun 2009
0 50 100 150 200 250 300 350 400 450 500 550
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)
Table B.8.1 HIV notifications by sex and ethnicity, NT, Jan-Jun 2008 & 2009
2009 2008
Category
Jan-Jun % Jan-Jun % Sex
Male 5 50 5
Female 5 50 1
Ethnicity
Aboriginal 0 0 1 17
Non-Aboriginal 10 100 5 83
Caucasian 7 4
Other 3 1
Figure B.8.1 HIV notifications by sex, NT, Jan-Jun 2004-2009
0 2 4 6 8 10 12
2004 2005 2006 2007 2008 2009
Number of notifications
Female Male
Table B.8.2 HIV notifications by exposure category and source of infection, NT, Jan-Jun 2009
Category Male Female Total %
Exposure
Male homosexual
contact 2 0 2 20
Heterosexual contact 3 5 8 80
Source of infection
Local transmission 3 3 6 60
Immigrant 1 1 2 20
Overseas travel 1 1 2 20
A total of ten notifications were recorded in this reporting period, including five males and five females (see Table B.8.1). Compared with the same period of the last five years (mean=5.4), the number of notifications for this year represents a considerable increase (see Figure B.8.1). All ten cases were Australian residents and notified in Darwin. None of them were Aboriginal. Three out of the ten cases were categorised as ‘newly acquired’ cases (two females and one male), compared with the total of 281 cases for Australia in 2008. The crude notification rate of newly acquired HIV for
Eighty per cent of the cases contracted HIV via heterosexual contact, and the rest through male homosexual contact (see Table B.8.2). The median age was 30 years of age in females and 50 in males (for all cases, 48). With regard to source of infection, 60% of the cases acquired HIV from local contacts. Notably, two cases (one male and one female) acquired the infection while travelling overseas, both were diagnosed as ‘newly acquired’ cases.
C. Surveillance of antimicrobial
sensitivity of N. gonorrhoeae, 2008
Ongoing active surveillance of the antimicrobial sensitivity of N. gonorrhoeae is essential to the control of gonorrhoea. This is of particular importance in the NT for two reasons. Firstly, the NT is the only State/Territory where inexpensive oral penicillin can be used to satisfactorily treat locally acquired genital gonorrhoea.
Secondly, as the NT continues to record very high rates and disease burden of gonorrhoea, any change in the overall antimicrobial sensitivity that leads to a change to the recommended treatment from oral penicillin to more expensive regimens will have serious public health and financial implications. Therefore, measures such as enhanced surveillance, active case management and contact tracing have been undertaken for all resistant gonorrhoea cases in order to maintain the favourable therapeutic situation against this STI.
The 2008 consolidated gonococcal sensitivity data for the NT 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.
In 2008, a total of 403 isolates from the NT were received and tested, compared with 404 in 2007 and 549 in 2006 (see Table C.1). Of these, 266 were from males and 137 from females, giving a male to female ratio of1.9:1. The majority of isolates came from urethra in males (96.6%) while 95.6% of female specimens were from cervix.
Table C.1 Specimen site of N. Gonorrhoeae isolates from the NT by sex, 2008
Male Female
Site
Number % Site
Number % Urethra 257 96.6 Cervix 131 95.6
Rectal 1 0.4 Other/NS* 6 4.4
Other/NS* 8 3.0
Total 266 Total 137
* NS: Not specified
The overall percentage of penicillin resistant gonococcal strains was 3.7% (4.1% in 2007, 4.6% in 2006), including 11 penicillinase-producing isolates (PPNG, 2.7%) and 4 with chromosome-mediated resistance (CMRNG, 1.0%). All of these isolates resistant to penicillin were sensitive to Ceftriaxone, the antibiotic currently recommended for gonococcal infections acquired from people from interstate or overseas.
This low level of penicillin resistance provides good evidence to support the continued use of the current treatment recommendations for genital gonorrhoea contained in NT Guidelines for the Management of Sexually Transmitted Infections in the Primary Health Care Setting. However, it is worth noting that four PPNG and two CMRNG cases were diagnosed in Central Australia where there used to be very few such diagnoses (although these 6 cases were all non-Aboriginal). As the Aboriginal rate of gonorrhoea remained high in this region, it is important for clinicians to specifically order culture for gonorrhoea for symptomatic clients and for those who
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: [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. 1.
