Background STI are a significant cause of morbidity in Europe, particularly among young adults and men who have sex with men (MSM). Monitoring the spread of STI across key populations allows development of targeted prevention interventions.

Methods Surveillance for chlamydia, gonorrhoea and syphilis in the European Union (EU/EEA) is coordinated by the European Centre for Disease Prevention and Control since 2009. Data reported by Member States covering the period 1990–2011 were analysed.

Results In 2011, 346911 cases of chlamydia (rate: 175 per 100000 population) were reported compared to 39179 cases of gonorrhoea (12.6/100000) and 19798 cases of syphilis (4.9/100000). Chlamydia was more frequently reported among women (male-to-female ratio: 0.7) in contrast to gonorrhoea and syphilis (male-to-female ratios: 2.7 and 3.9 respectively). The highest age and gender-specific rates were observed among 15–19 year old females for chlamydia (1748); 20–24 year-old males for gonorrhoea (71) and 25–24 year-old males for syphilis (16.1). Young adults (15–24 years) accounted for 73% of chlamydia, 42% of gonorrhoea and 16% of syphilis cases. Transmission among MSM was more frequently reported for syphilis (42%) and gonorrhoea (33%) cases than for chlamydia (5%). HIV co-infection was reported among 11% of gonorrhoea and 28% of syphilis cases. Rates of chlamydia have increased by 133% between 2000 and 2011 among countries reporting consistently. Gonorrhoea rates have increased by 27% since 2008 and syphilis rates increased by 10% in 2011.

Conclusion Surveillance data shows diversity in reported rates and trends across the EU/EEA. Increasing rates of chlamydia reflect strengthened case detection and improved diagnostics. Young adults constitute a large proportion of cases of chlamydia and gonorrhoea. Transmission among MSM accounts for the majority of syphilis and, increasingly, gonorrhoea spread. Both key populations need to be better targeted through specific prevention and control measures.