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STI Rates in Australia

Counselling about sexually transmitted infections is a basic part of General Practice. It is very useful to be able to explain the risks of various diseases to individual patients to allow them to decide what they might wish to be tested for. For example, many people are very surprised to find that the notifications of new HIV infection in the community is so low.  Sexually transmitted diseases are much more common in rural Australia1,2 in men who have sex with men,2 and in those of Aboriginal and Torres Strait Islander background.2

Chlamydia: This is by far the most common treatable sexually transmitted disease and notifications continue to increase each year. The risk is highest in people aged the 15 to 24 year old and 80% of cases occur in this age group. In 2011, 2,200 women were diagnosed with chlamydia per 100,000 people. It should be noted that approximately 50% of men and 80% of women diagnosed are asymptomatic and so under-reporting is typical.  Women are more likely to be diagnosed than men, but this trend reverses in those over age 30 years.

Gonorrhoea: The rate of gonorrhoea is also increasing annually and in 2011 the rate was 65 people known to be infected per 100,000. Gonorrhoea notifications are over-represented in men, those who have been sexually active in high prevalence countries and in those of Aboriginal and Torres Strait Islander background. However, young women aged 15 to 19 years of age are more likely to be diagnosed than young men in this particular age group. Overall, three quarters of cases occur in the 15 to 34 year old age group.

Syphilis: This is a less common sexually transmitted infection. Interestingly, it is seven times more common in men aged between 40 and 44 years. In this age group, notifications were 23 people per 100,000. Overwhelmingly, men who have sex with men and Indigenous Australians in remote locations comprised new diagnoses.  Syphilis notifications are also increasing.

HIV: Men aged 30 to 34 years of age have the highest new HIV rate at 18 per 100,000. Women are most likely to be diagnosed in the same age group but the rate for women is one fifth as it is for men. Heterosexual transmission appears to comprise a quarter of new diagnoses, the remainder occurring in men who have sex with men. HIV is increasing again in the community.

Genital Herpes: As this is not a notifiable disease the true number of infected individuals is difficult to assess, but it is expected that one in eight people carry the virus.  It is more likely to be identified in women, and type 1 HSV now accounts for at least 50% of cases of genital herpes.

Hepatitis B: This virus is transmitted sexually by acutely or chronically infected individuals. The incidence is highest in rural Indigenous populations and immigrants to Australia arriving from countries where the disease is endemic. The childhood vaccination programme in Australia has reduced the risk of this disease.

Human Papilloma Virus: The prevalence of this infection is reducing dramatically due to HPV vaccination programmes. It is known that genital warts may occur after a long period of latency and so are not confirmation of recent infidelity. As this is not a notifiable disease, the true number of infected individuals is difficult to assess.

Trichomonas:  This bacterial infection mainly occurs in remote and regional northern Australia, and is especially likely to be diagnosed in Indigenous women.

It should be noted that thrush, Hepatitis C and bacterial vaginosis are not considered to be sexually transmitted.

 

1. Australian Bureau of Statistics, Sexually transmissible infections 26 June 2012
http://www.abs.gov.au/AUSSTATS/abs@.nsf/Lookup/4102.0Main+Features10Jun+2012#Bacterial

2. Australian Government Department of Health, Sexually Transmissible Infections 2014
http://www.sti.health.gov.au/internet/sti/publishing.nsf

3. Australasian Sexual Health Alliance, Australian STI Management Guidelines for Use in Primary Care
http://www.sti.guidelines.org.au/