Delivering a Healthy WA
Disease WAtch

Increasing gonorrhoea notifications among non-Aboriginal Western Australians

Western Australia has consistently reported the second highest notification rate for gonorrhoea of all jurisdictions, after the Northern Territory. Historically, high rates in WA have reflected the large number and proportion of cases (~80%) reported among Aboriginal people, mostly from rural and remote regions, in the past resulting in rates over 100 times higher than in non-Aboriginal people.

In 2012, a record high of 2,102 gonococcal infections were notified among Western Australians. From 2009 (when the increase commenced) to 2012, the WA gonococcal notification rate increased by 47%, and a doubling in rates was observed in the non-Aboriginal population and in the Perth metropolitan region. Because the recent rise in gonorrhoea in WA can be attributed mostly to increases among non-Aboriginal people, this article highlights changes in the epidemiology of gonorrhoea in this group.

Figure 1 shows gonorrhoea notification numbers and rates among Aboriginal and non-Aboriginal Western Australians for the period 2007 to 2012. Among Aboriginal people, there was an overall decline in the number and rate of notifications, by 14% and 20% respectively. Among non-Aboriginal people, however, the number and rate of notifications increased by 230% and 200% respectively, albeit from a much lower base. Despite an apparent convergance of rates, the Aboriginal rate was 36 times higher than the non-Aboriginal rate in 2012 (1,485 versus 41 per 100,000 population).

Notification rates (per 100,000 population) for gonorrhoea in Aboriginal and non-Aboriginal Western Australians, 2007 to 2012 (note the different scales)

Number of gonorrhoea notifications in Aboriginal and non-Aboriginal Western Australians, 2007 to 2012

Figure 1 – Line graph: Notification rates (per 100,000 population) for gonorrhoea in Aboriginal and non-Aboriginal Western Australians, 2007 to 2012 (note the different scales)
Bar graph: Number of gonorrhoea notifications in Aboriginal and non-Aboriginal Western Australians, 2007 to 2012

Sex

From 2007–2012, gonorrhoea notification rates among non-Aboriginal males were, on average, three times that of their female counterparts. There were marked increases in notification rates over this period for both sexes, with the increase occurring one year earlier in males (2010 vs 2011). However, between 2009 and 2012, the gonorrhoea notification rate increased more in females (2.7 times) than in males (2 times).

Figure 2 – Notification rates (per 100,000 population) for gonorrhoea in non-Aboriginal Western Australians by sex, 2007 to 2012

Figure 2 – Notification rates (per 100,000 population) for gonorrhoea in non-Aboriginal Western Australians by sex, 2007 to 2012

Region

In 2012, the majority (84%) of non-Aboriginal people notified with gonorrhoea resided in the Perth metropolitan region. From 2009 to 2012, notification rates in non-Aboriginal people doubled in both metropolitan and non-metropolitan regions. While notification rates in males increased 2-fold in both the metropolitan and non-metropolitan regions, rates in females increased 2.8 and 2.5 times, respectively.

Age

Among non-Aboriginal people, older teenagers and young adults (aged 15–24 years) continued to have the highest gonorrhoea notification rates; and these doubled between 2011 and 2012. In 2012, 40% of notifications were in this age group (up from 29% in 2011) , followed by adults aged 25–34 years (34% of notifications) in whom rates had increased steadily since 2009 (Figure 3). Increases in those aged 35 years and above were less dramatic.

Figure 3 – Age-specific notification rates (per 100,000 population) for gonorrhoea in non-Aboriginal Western Australians, 2007 to 2012

Figure 3 – Age-specific notification rates (per 100,000 population) for gonorrhoea in non-Aboriginal Western Australians, 2007 to 2012

Sex of partner

Information on "sex of partner" was available for 90% of non-Aboriginal gonorrhoea cases reported in 2012, with the presumed source of infection attributed to heterosexual males (42% of cases), heterosexual females (31%) and men who have sex with men (MSM) (26%). Numbers increased in all three categories over time, most evident in the Perth metropolitan area, with little change in country areas (Figure 4).

Figure 4 – Number of gonorrhoea notifications in non-Aboriginal Western Australians, 2007 to 2012, by region of residence and sex of partner

Figure 4 – Number of gonorrhoea notifications in non-Aboriginal Western Australians, 2007 to 2012, by region of residence and sex of partner

Place of acquisition

In 2012, the majority of gonococcal infections among non-Aboriginal Western Australians were acquired in WA (75%), followed by overseas (19%) and interstate (4%). From 2009 to 2012, there was a greater increase in the number of locally acquired infections (269% increase) compared to overseas-acquired infections (62%) (Figure 5). Of the 178 cases acquired overseas in 2012, the vast majority were male (87%) and the most commonly reported countries of acquisition were Thailand and Indonesia (30% each), followed by the Philippines (11%).

In 2012, the majority of gonococcal infections among non-Aboriginal Western Australians were acquired in WA (75%), followed by overseas (19%) and interstate (4%). From 2009 to 2012, there was a greater increase in the number of locally acquired infections (269% increase) compared to overseas-acquired infections (62%) (Figure 5). Of the 178 cases acquired overseas in 2012, the vast majority were male (87%) and the most commonly reported countries of acquisition were Thailand and Indonesia (30% each), followed by the Philippines (11%).

Figure 5 – Number of gonorrhoea notifications in non-Aboriginal Western Australians, 2007 to 2012, by sex and place of acquisition

Figure 5 – Number of gonorrhoea notifications in non-Aboriginal Western Australians, 2007 to 2012, by sex and place of acquisition

Conclusion

The recent sharp increase in gonorrhoea infections among non-Aboriginal Western Australians, particularly in younger heterosexual adults and including females, is of concern. The increase indicates a possible decline in safe sex practices and the establishment of gonorrhoea transmission among young non-Aboriginal people. Gonorrhoea is a significant public health concern, not only because of its long-term impact on fertility, but also because of decreasing sensitivity to the current suite of antimicrobial drugs (including the cephalosporins in some countries) and the increased risk of HIV transmission associated with the presence of another sexually transmitted infection.

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