Reported cases of syphilis, gonorrhoea and chlamydia dropped slightly in the third quarter of 2021, but Māori, Pacific, young people, and Men who have sex with men (MSM) continue to be disproportionately affected.
ESR is the crown research Institute responsible for surveillance and reporting of a range of communicable diseases, including sexually transmitted infections (STIs). The STI dashboard(external link), which reports information on trends in syphilis, gonorrhoea and chlamydia in New Zealand has been updated to include data up to 30 September 2021.
Dr Andrea McNeill, ESR Technical Lead Epidemiology, says that while a reduction in sexually transmitted infections (STIs) reported is always encouraging, it’s likely the results are still being influenced by the COVID-19 response. “During the COVID-19 response there has been limited access to healthcare, reduced testing and behavioural changes, which have had an influence on the number of reported STIs”, says Dr McNeill.
Despite the general decline in reported cases, STI rates in New Zealand continue to be significantly higher in Māori, Pacific, young people, and MSM.
There were 463 cases of infectious syphilis in the 12 months ending 30 September 2021, a continuation of the overall decline in cases since mid-2019.
Most syphilis cases continue to be in males. Men who have sex with men are much more likely to be infected with to syphilis (53% of cases despite being a much lower proportion of populations), but an increasing proportion of syphilis cases are people reporting heterosexual behaviour. Among heterosexual female cases, Māori women are disproportionately impacted.
One case of congenital syphilis was reported in this period, and cases of congenital syphilis continue to be regularly reported. Antenatal care is essential for the prevention of congenital syphilis: testing for syphilis is routinely available in the first trimester of pregnancy.
Chlamydia is still the most reported STI in New Zealand, with the majority of cases being females aged 15-29 years. There were 525 cases of chlamydia per 100,000 of the New Zealand population reported for the 12 months ending 30 September 2021. Males have much lower rates of testing for chlamydia suggesting many infections remain undiagnosed and untreated.
Chlamydia rates have been impacted by the COVID-19 pandemic response. In quarter two of 2021, chlamydia rates increased for the first time since late 2019, but then decreased again in quarter three of 2021, likely influenced by changes to the COVID-19 alert levels.
Chlamydia rates are consistently much higher among Māori and Pacific peoples. As chlamydia is not a notifiable infection, information about chlamydia is based on laboratory surveillance only.
Cases of gonorrhoea decreased this quarter. 139 cases of gonorrhoea per 100,000 of the New Zealand population were reported for the 12 months ended 30 September 2021. This rate of infection is closer to that reported in quarter three of 2019.
Gonorrhoea rates have also been impacted by COVID-19, and rates of reported cases continue to fluctuate. The highest rates are consistently reported among males, with the highest proportion among MSM compared to other sexual behaviour groups. For males, most cases are aged 20-29 years and for females 15-29 years.
Gonorrhoea rates are consistently much higher amongst Māori and Pacific peoples.
How STI surveillance works in New Zealand
ESR operates the following surveillance systems for gonorrhoea, chlamydia and syphilis:
- For gonorrhoea and chlamydia, a laboratory-based surveillance system is in place whereby all laboratory results for gonorrhoea and chlamydia are sent to ESR along with demographic information (age, sex, ethnicity and geographic region). For gonorrhoea, there is also an online clinician notification system in place to collect additional information for cases including risk factor information such as sexual behaviour.
- For syphilis, there is a clinician notification system in place to collect demographic, laboratory and risk factor information.
ESR’s STI Dashboard uses quarterly rolling 12-month case counts (rates per 100,000) which provide insight into slow-moving trends. For this reason, COVID-19 restrictions may also affect subsequent dashboard releases for the next 12 months. Further interpretation of this data in the context of COVID-19 has been provided in addition to the dashboard(external link).