Cases of syphilis in New Zealand continue to increase, with new ESR data showing 548 reported for the 12 months ended March 2019 and these cases concentrated among men aged 20 to 39.
The number of syphilis cases is up from 527 for the 12 months ended December 2018, and from a total of 82 reported cases five years earlier (based on data available for the 12 months ended December 2013.
Data for the latest 12 months show infectious syphilis to be most commonly reported in men who have sex with men, this group accounting for 350 of the total 548 cases. Of all male syphilis cases, the majority were reported in men aged 20-39 years. There was also an increase in cases in heterosexual women aged 20-39 years.
ESR reports this data in its new quarterly surveillance Dashboard on Sexual Transmitted Infections (STIs), which provides information on trends in syphilis, gonorrhoea and chlamydia in New Zealand. ESR’s dashboard report on STI surveillance can be found here.
The increase in total syphilis cases includes a recent rise in congenital syphilis (confirmed and probable) to three cases during the 2018 calendar year, with two additional cases still under investigation, and a further two cases reported so far in 2019. Congenital syphilis is a serious multi-system infection caused by the bacterium Treponema pallidum which is passed from mother to developing foetus during pregnancy. This results in miscarriage or still birth in about half of cases.
ESR Public Health Physician Jill Sherwood comments: “The increasing proportion of cases reported in heterosexual males and females and the rise in cases of congenital syphilis suggest increasing transmission of this STI in groups that have not been seen as high risk in recent years. Strategies to increase awareness about the changing risk groups, as outlined in the new Ministry of Health National Syphilis Action Plan, will be useful to address these concerns. I note that screening for syphilis is provided during routine antenatal care and that the Ministry strongly advises women to have this test.”
The ESR data show gonorrhoea rates have increased significantly in recent years, with 117 cases per 100,000 of the New Zealand population reported for the 12 months ended March 2019. The rate for the 12 months ended December 2017 was 99, and for the 12 months ended December 2013 it was 77.
Gonorrhoea rates have increased significantly since 2015 with the highest rates reported in men aged 20-29 years. The increase in the national rate is largely driven by cases reported from the Auckland region where male rates continue to be well above the national average.
A new questionnaire was completed for about 30% of cases notified from October 2018 to March 2019. Of these cases, 34% were reported in men who have sex with men, while a further 21% were in heterosexual men and 23% in heterosexual women.
Dr Sherwood comments: “The differing patterns of disease across geographical settings and in reported sexual behaviour suggest that a range of strategies is needed to control gonorrhoea.”
Chlamydia rates have changed little in the past two years but chlamydia continues to be the most commonly reported STI in New Zealand with the highest number of cases and rates reported in females aged 15−29 years. In the 12 months ended March 2019, there were 653 cases per 100,000 population, compared with 644 in the 12 months ended December 2017.
Dr Sherwood comments: “That the majority of cases of chlamydia reported are among females is probably due to lower testing rates among males, and this raises the concern that many infections in males are going undiagnosed and untreated.”