Chlamydia
What is it?
Chlamydia is New Zealand’s most common STI, typically spread through unprotected vaginal, anal, or oral sex. Symptoms can include unusual discharge, bleeding, lower abdominal pain, and painful urination—but most people experience no symptoms at all. It’s easily treated with antibiotics, but if left untreated, it can lead to infertility in severe cases.
Where is it?
From September 2023 to September 2024, ESR surveillance found the highest chlamydia rates in the Tairāwhiti (Gisborne), Lakes (Rotorua), and Hawke’s Bay regions, with rates of 814, 741, and 626 cases per 100,000 people, respectively. In comparison, Auckland and Wellington reported 607 and 523 cases per 100,000. The lowest rates were recorded on the South Island’s West Coast (170), South Canterbury (276), and Nelson-Marlborough (293).
Who’s most affected?
Chlamydia rates remain significantly higher in women than men, likely due to more frequent screening opportunities. In the 12 months to September 2023, the rolling average was 648 cases per 100,000 women compared to 415 per 100,000 men. By age group, the highest rates were among those aged 20–24, followed by 15–19-year-olds. In 2023, Māori and Pacific people had chlamydia rates approximately 3.5 times higher than those of European or other ethnic groups, with no sign of this disparity improving.
What’s the big picture?
After a slight increase in 2023, chlamydia rates remained relatively stable in 2024, with a rolling average of 533 cases per 100,000—similar to figures from five years ago.
Gonorrhoea
What is it?
Gonorrhoea, caused by the bacterium Neisseria gonorrhoeae, spreads easily through unprotected sex and can lead to serious health complications if untreated. Symptoms include unusual discharge, bleeding, stomach pain, swollen testicles, and painful urination. Public health experts are increasingly concerned about the bacteria’s growing resistance to the two main antibiotics used to treat it.
Where is it?
Over half of all gonorrhoea cases reported in the 12 months to September were in Auckland, but the Tairāwhiti and Lakes regions again showed disproportionately high rates. Lakes recorded 165 cases per 100,000 people, while Tairāwhiti had 154. Auckland and Wellington reported rolling averages of 224 and 142 cases per 100,000, respectively, while Waikato had a similarly high rate of 144. The South Island’s West Coast had the lowest rate, at just 14 cases per 100,000.
Who’s most affected?
Gonorrhoea is more common in men, particularly those who have sex with other men. In 2023, 28% of cases were among men who have sex with men, while 25% involved men who have sex with women. Most affected individuals were aged 20–40, with the highest numbers in their 30s. Just over half of cases were in people of European or other descent, while Māori and Pacific people made up about a quarter of infections.
What’s the big picture?
After a decline between 2021 and 2022, gonorrhoea cases have risen slightly over the past three years, reaching 146 notifications per 100,000 as of September.
Syphilis
What is it?
Syphilis is a highly infectious STI spread through close sexual contact. In its early stages, it causes sores or ulcers at the infection site—usually the genitals, anus, or mouth. If untreated, it progresses to symptoms such as rashes, swollen lymph nodes, warty growths, fatigue, fever, and hair loss. Late-stage syphilis can damage the heart, brain, nerves, eyes, liver, and bones. Untreated syphilis also increases the risk of contracting HIV.
Where is it?
In 2023, Auckland accounted for 56% of infectious syphilis cases, followed by Waikato (13%), Canterbury (9%), and Wellington (8%). Over the 12 months to September, ESR reported 352 cases in Auckland, 91 in Waikato, 82 in Wellington, and 105 in Canterbury.
Who’s most at risk?
The highest case numbers are in people in their 30s, though rates have recently risen among those in their 40s. Cases in 2023 were predominantly among men—59% involved men who have sex with men, while 20% involved men who have sex with women. European or other ethnicities accounted for about 40% of cases, while Māori and Pacific people were disproportionately affected, making up 23% and 10% of cases, respectively. Māori and Pacific communities also face higher rates of congenital syphilis—when the infection is passed to babies during pregnancy—highlighting inequities in antenatal and sexual healthcare access.
What’s the big picture?
As seen globally, New Zealand experienced a 45% surge in syphilis cases between 2022 and 2023, primarily due to increased infections among men who have sex with men and a rebound from lower case numbers during the COVID-19 pandemic. Since then, case numbers have stabilized, with 753 cases reported in the 12 months to September.
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