They are young and mostly female: with more than 3.2 million reported cases between 2005 and 2014, chlamydia remains the most commonly reported sexually transmitted infection (STI) across Europe. As chlamydia infection often shows no symptoms, these numbers underestimate the true picture. The updated ECDC guidance Chlamydia control in Europe makes the case for national chlamydia control strategies in the European Union Member States and shows ways to develop, implement or improve national or local control activities.
Rates of chlamydia infection have increased 5% between 2010 and 2014 across the countries of the European Union and European Economic Area (EU/EEA). Young people are particularly affected by this STI with two thirds (63%) of the 396 000 reported cases in 2014 diagnosed among 15 to 24-year-olds.
Across Europe, chlamydia is the only STI which is reported more frequently in women than men. This might be influenced by the fact that women are generally tested more often than men because of the greater risk of complications, which include pelvic inflammatory disease and infertility.
"Chlamydia is straightforward to diagnose and can be effectively treated with antibiotics - but it may also irreversibly damage a woman's reproductive organs. There is no available vaccine and after treatment you can get re-infected if you do not take precautions", stresses ECDC Acting Director Andrea Ammon. The disease can be controlled through prevention and effective treatment of those infected and their partners.
"We looked at the advances in knowledge since the publication of our last guidance in 2009 and propose that every country further develops their national strategies or plans for the control of STI, including chlamydia", explains Ammon.
"Good primary prevention, like health and sex education or condom promotion and distribution, is at the core of STI control. Widespread opportunistic testing or a screening programme should be considered once effective primary prevention activities and case management strategies are in place. And only if sufficient resources are available including for monitoring and evaluation of the programme."
Since the publication of the ECDC guidance in 2009, which offered a stepwise approach to implementation of prevention activities, chlamydia control has improved across the EU/EEA: in 2012, 6 out of 28 Member States reported no organised prevention and control activities (2007: 11/27). Most countries had a surveillance system in place. The overall increase of chlamydia cases across Europe reflects this implementation of national control programmes.
However, consistently high chlamydia infection rates (over 180 per 100 000 population in the last five years) also suggest that the impact of current chlamydia control activities on overall disease burden has been very limited.
The true incidence of chlamydia infection is likely to be substantially higher, due to the asymptomatic nature of the infection. Considerable differences in testing methods, coverage and surveillance systems across Europe also mean that many infections are not being diagnosed or reported.
The latest available data on all five STI under EU surveillance (chlamydia, gonorrhoea, syphilis, congenital syphilis and lymphogranuloma venereum) are now available in the interactive ECDC Surveillance Atlas of Infectious Diseases.