Age range chart
More than 80% of chlamydia infections occur in people <29 years of age.9 Screening for chlamydia infection in all sexually active people up to 29 years of age is recommended because of increased prevalence and risk of complications.10 In asymptomatic, sexually active people up to 29 years of age, the overall absolute risk of infection is approximately 5% for chlamydia and 0.5% for gonorrhoea.
The ranked risk for specific infections per 100,000 in general population/Aboriginal and Torres Strait Islander populations:11
- Chlamydia (371/1341)
- Gonorrhoea (49/858)
- Hepatitis B (23/50)
- Syphilis (8/32)
- HIV (4/6)
A large proportion of young people will attend primary care clinics each year, and this presents the opportunity to normalise sexual health care as part of usual general practice.10 Younger sexually active youths should not be excluded from case finding, or identifying any safety or abuse issues. This may involve a complete psychosocial (HE2ADS3)12 risk assessment as discussed in Table 3.2.
Women with untreated chlamydia infections have a 2–8% risk of infertility.13 Other STIs to consider screening for in higher risk individuals are gonorrhoea, HIV and syphilis.14 The risk for gonorrhoea, HIV and syphilis is low for heterosexuals in all major cities in Australia and New Zealand,15 but rates of gonorrhoea and syphilis are higher among MSM. The individual’s age and sexual habits, and community STI prevalence all influence the level of risk and should guide STI testing recommendations for patients (refer to Tables 18.104.22.168 and 22.214.171.124 for guidance).
MSM should be screened for gonorrhoea, chlamydia, syphilis and HIV every 12 months. Screening should be performed more often if they have multiple sexual contacts. Most MSM with STIs have no symptoms.16
Aboriginal and Torres Strait Islander peoples are at higher risk and should also be screened for gonorrhoea, chlamydia, syphilis and HIV.
Screening for hepatitis C should be provided if the patient is HIV positive or there is a history of injecting drug use, as this increases the risk of transmission.16
All pregnant women should be screened for hepatitis B, C, HIV and syphilis.14,17,18 Consider screening pregnant women up to 29 years of age for chlamydia (and also gonorrhoea, if the patient is at high risk).17–20
Sexually transmissible infections: Identifying risks
Tests to detect sexually transmissible infections
Chlamydia is the most common and curable STI in Australia. Notification rates per 100,000 increased from 35.4 in 1993 to 363 in 2011, and has been steady since; 78% of those infected are aged 15–29 years.11Young Aboriginal and Torres Strait Islander peoples have higher infection rates especially in regional and remote areas, with a substantially increased risk of chlamydia, gonorrhoea and syphilis.10
Screening sexually active women <25 years of age for chlamydia on an annual basis has been shown to halve the infection and complication rates.11,13,35
Treatment of partners and contact tracing
All partners of those infected should be tested and treated presumptively. A systematic review has shown that providing patient-delivered partner therapy to index cases is more effective in reducing infection rates than paper-based methods of contact tracing.36 There is no single optimal strategy for contact tracing. Getting assistance from the local sexual health services is recommended for HIV and syphilis because it leads to more contacts being tested and treated.35 Referral to sexual health services should be considered for problematic or repeated infections.37
It is important to ensure current sexual partners are treated simultaneously. Untreated pregnant women infected with chlamydia have a 20–50% chance of infecting their infant at delivery.38