ESR data shows congenital syphilis on the rise and ongoing inequities in burden of disease of Sexually Transmitted Infection

Source: ESR

Newly released data from ESR’s ‘New Zealand Sexually Transmitted Infection (STI) Surveillance Dashboard(external link),’ highlights increased cases of congenital syphilis and higher rates of STIs for Māori and Pacific communities than for other ethnic groups.

The latest dashboard, which is released every quarter, shows an overall decline in the number of reported cases of syphilis, gonorrhoea and chlamydia in New Zealand for the 12 months to March 2021.

The Institute of Environmental Science and Research (ESR) Team Leader, Epidemiology Dr Andrea says congenital syphilis is a disease that occurs when syphilis is passed from mother to child during pregnancy.

Eight cases were reported for the period, compared with one in 2016, with nearly all these cases from Māori or Pacific Communities. When untreated, syphilis can lead to miscarriage, stillbirth, or congenital infection, but it often causes few or no symptoms in adults, so pregnant women may not know they have the infection.

“The good news is congenital syphilis is preventable through antenatal care, with testing and treatment for syphilis in pregnancy,” says Dr McNeill.

In comparison to the previous 12-month period, the 12 months to March 2021 saw a 26 percent decrease in reported cases of syphilis (169), a 19 percent decline in cases of chlamydia (6,053) while cases of gonorrhoea remained stable with 35 fewer cases reported over the period.

Dr McNeill advised caution interpreting the decline in cases reported over the period as they were likely to have been impacted by the COVID-19 pandemic which saw a rapid change in the epidemiology of many infectious diseases, including STIs.  

“It’s likely the data will have been impacted by changes in the availability of testing, changes in health-seeking behaviour and the societal changes caused by COVID-19.”

“The information also shows Māori and Pacific peoples continue to suffer much higher rates of gonorrhoea and chlamydia than other ethnic groups. And while cases of syphilis among people of European ethnicity have decreased noticeably over the past 12 months, case numbers within Māori and Pacific communities have remained consistent.”

Syphilis

There were 476 cases of infectious syphilis in the 12 months ended 31 March 2021. This compares with 645 for the same period last year. Dr McNeill said most cases of syphilis continue to be reported in males aged 20–39 years with the majority of European/other ethnicities.

“While we have seen a substantial decline from 436 reported cases of syphilis in the 12 months to 31 March 2020 to 265 in the 12 months to 31 March 2021 among those of European/other ethnicities, there has been no corresponding drop in overall cases among Māori (127 in quarter 1 2021 and 123 in quarter 1 2020) and Pacific (42 in both quarter 1 2021 and quarter 1 2020) communities.”

Auckland (191) and Wellington (89) account for the majority of notified cases.  The proportion of cases reporting men who have sex with men (MSM) sexual behaviour has steadily decreased from 85 percent in 2014 to 57 percent for the past 12 months. In contrast the proportion of notified cases reporting heterosexual behaviour has increased from 14 percent in 2014 to 39 percent in 2021, and this increase was more marked for Māori and Pacific people.

Chlamydia

Chlamydia is the most commonly reported STI in New Zealand and quarterly rolling 12-month rates were relatively stable from 2013 to late 2019 before declining in 2020 into 2021.

Dr McNeill says limited screening tests for people without symptoms during the COVID-19 pandemic is likely to have contributed to the decrease in rates.

“The majority of cases are consistently reported in females aged 15−29 years. The lower male rate is probably due to lower testing rates in males, suggesting that many infections in males remain undiagnosed and untreated.”

Lakes, Tairāwhiti and Hawke’s Bay DHBs continue to have the highest chlamydia rates by region. While nationally there were 501 cases of chlamydia per 100,000 people, rates were significantly higher in Māori (1,029 per 100,000 Māori) and Pacific peoples (1,087 per 100,000 Pacific peoples) indicating a need for more equitable access to care for these groups.

Dr McNeill says cases reported include approximately 70 cases in infants each year.

Gonorrhoea

A total of 7,392 cases (or 145 cases per 100,000) of Gonorrhoea of the New Zealand population were reported for the 12 months ended 31 March.

Dr McNeill says COVID-19 may have also resulted in an increase in the number of undiagnosed cases due to interruptions in access to care and testing of case numbers over the period.

“It is likely the alert level restrictions will have decreased the number of face-to-face consultations, and therefore the opportunity for testing. For approximately six weeks from late March 2020 restrictions on asymptomatic testing for gonorrhoea and chlamydia were employed to prioritise COVID-19 testing. As a result, overall testing and diagnosed case numbers decreased and positivity rates increased during this period.”

The latest data continue the trend of the highest rates being reported among males. For males, most cases are aged 20–29 years and for females 15–29 years with Māori and Pacific peoples suffering much higher rates of disease than other ethnic groups. Tairāwhiti has recorded the highest rates in the 12 months to the end of 2021 Q1, closely followed by the Auckland and Lakes regions, although Auckland reports more than half the number of cases (3,844) in New Zealand.

Dashboard summary

Rates(cases) based on ethnicity for the period April 2020 to March 2021

Total cases per region for period April 2020 to March 2021

 Additional information:  
 
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 anonymous 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. 

The dashboard utilises quarterly rolling 12-month case counts (rates per 100,000) which provides insight into slow-moving trends

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