New figures from the Finnish Institute for Health and Welfare (THL) show that chlamydia infections in Finland have decreased for the first time in nearly 30 years, marking a potential turning point in the country’s fight against sexually transmitted infections (STIs).
Chlamydia trend reversed after decades of growth
According to THL data, around 14,350 chlamydia infections were reported in 2024, which represents a 20 percent drop compared to the previous year. This is the first decline since 1995, interrupting a long-standing upward trend in reported cases.
Chlamydia has consistently been the most common bacterial STI in Finland, particularly among young adults. The infection often presents no symptoms but can lead to serious health complications if left untreated, including infertility.
Experts cautious about the causes of the drop
Eija Hiltunen-Back, a specialist in dermatology and STIs, stated that there is no clear explanation for the decrease. “We don’t know why the numbers have started to fall. The same trend is visible internationally,” she told Yle News.
Some experts suggest that changes in testing behaviour, sexual health education, or shifts in sexual activity patterns may play a role, but further research is needed.
Gonorrhoea cases on the rise
While chlamydia is declining, the number of gonorrhoea infections is rising. In 2024, 1,850 cases were recorded in Finland, compared to 1,300 the previous year—an increase of over 40 percent. The rise was especially marked among women, reversing previous patterns in STI demographics.
Gonorrhoea, like chlamydia, is a bacterial infection but is becoming increasingly difficult to treat due to growing antibiotic resistance, making surveillance and prevention more urgent.
Public health implications and next steps
The reversal in chlamydia trends provides a rare opportunity to study what works in STI prevention and where efforts can be intensified. At the same time, the rise in gonorrhoea underscores the need for comprehensive sexual health strategies, including accessible testing, public awareness campaigns, and antibiotic stewardship.
THL and public health agencies will continue to monitor STI trends closely to inform evidence-based policy and ensure timely responses to shifting epidemiological patterns.
