Chlamydia has been UK’s most common sexually transmitted infection for several years now. With more than 200.000 new cases reported annually, chlamydia amounts for almost 50% of all STI cases in the country. In this article we will dive into the trends and statistics regarding this bacterial STI in England. At the very beginning, let’s take a look at the key facts.
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Chlamydia in England: Key facts
The number of new cases of chlamydia reported each year reached roughly 200.000 diagnoses in 2015 and remained on more or less the same level ever since. At the same time, certain variations, like the fact that in 2014 more cases were reported as opposed to 2015 (208.638) are related to changes in the rate of STI testing among the general population and not the actual number of cases. Estimates about general prevalence are always made judging on both the number of reported cases and rate of STIs. However, as staggering as the numbers sound now, 2011 is still the year when chlamydia peaked, reaching maximum annual spread with 236.595 cases reported that year.
While chlamydia can affect anyone who is sexually active, it seems that this condition is most prevalent in the age group comprised of people aged 20 to 24. In addition to this, it is also much more commonly diagnosed in women than in men.
Chlamydia in the UK
When it comes to prevalence of different STIs in England, chlamydia is still firmly set on the first place, despite the fact that the number of diagnoses for both syphilis and gonorrhoea is on the rise, while chlamydia is, on the contrary, in decline. However, due to the extreme prevalence of chlamydia, even if this trend continues, it will be several years before chlamydia loses its title of the most common STD in the UK.
According to Public Health England, there is a drop from 99.785 to 93.036 diagnoses in community-based settings, linking this fact to the gradual decrease in chlamydia prevalence. At the same time, they also noticed that fewer and fewer heterosexual women is being tested in such setting, possibly leading to a drop in number of men being tested at sexual health clinics.
By 2015, chlamydia amounted for 46% of all reported STI cases in England. However, by this time, chlamydia prevalence was already in decline – this bacterial STI was on the rise from 2007 until it peaked in 2011 after which steady, but slow decline begun.
We can found even more precise and localized data in the research conducted by The Family Planning Association. According to them, in 2014, distribution of chlamydia cases was as follows:
- 320 cases reported in Scotland
- 452 cases reported in Wales
- 868 cases reported in Northern Ireland
- 638 cases were reported in England
- In total, 232.278 chlamydia cases were reported within the UK as a whole in 2014
However, at the same time the FPA noted that the perceived decline of chlamydia prevalence might be explained by a decline in testing rates. For example, if we just take a look at the age group 15-24, we can notice a drop of 9.500 diagnoses, which certainly is an improvement. But at the same time, in this very group, there were 127.000 less tests taken as opposed to the previous year.
Chlamydia trends in Europe and the US
Additional data about chlamydia trends and statistics in the Europe and the US can be obtained from their respective health services and agencies. When it comes to Europe, we can gain valuable insight from the European Centre for Disease Prevention and Control. According to this institution, United Kingdom still records more chlamydia cases than any other European country – just as was the case ever since 2003.
In 2012, a total of 385.683 chlamydia cases were reported within the European Economic Area with 235.992 of those being diagnosed in the UK. This amounts for about 61% of the total number. However, these statistics can be somewhat distorted since Austria, Czech Republic, Germany and Portugal were not included.
But, while UK might have the highest number of reported chlamydia cases, it does not have the highest chlamydia prevalence per capita. This requires us to consider some additional facts:
- Iceland has the highest number of chlamydia diagnoses per 100.000 inhabitants (677)
- Denmark has the second highest prevalence with 461 cases per 100.000 inhabitants
- Norway holds the third place with 440 cases per 100.000 inhabitants
- The UK, in comparison, has only 369 cases per 100.000 inhabitants
On the other hand, the CDC reports that in the US alone there are more than 1.5 million chlamydia cases reported annually, giving us the number of 478 diagnoses in 100.000 inhabitants.
Tackling the problem on the global scale, certain studies have shown that annually around 68.5 million of women and 62.5 million of men get infected with chlamydia.
Prevalence of chlamydia in different age groups
Both in the United Kingdom and European Union, chlamydia is most common among young people, with the highest rates of prevalence being among the people aged 20 to 24. According to Public Health England, around 62% of all chlamydia cases were diagnosed in people aged 15 to 24.
Similarly to this, the European Centre for Disease Prevention and Control reported that the same age group amounted for roughly 66.2% of all chlamydia cases diagnosed in the European Economic Area. More specifically, 40.6% were recorded among people aged 20 to 24.
This is not surprising since 20-24 age group is the most sexually active in the western countries, with casual sex or having multiple partners being relatively common practices. This is the most likely reason behind the higher prevalence of chlamydia among younger people.
Chlamydia prevalence across genders
Women are more commonly diagnosed with chlamydia than men, and this is true for United Kingdom, European Union and the US. This is explained both by higher susceptibility of women when it comes to chlamydia infection, but also the fact that in all areas of the western world, women are more likely to take STI tests than men, consequently having higher chances to get diagnosed.
Chlamydia and sexual orientation statistics
When it comes to sexual orientation, there is no single group that might be singled out as especially high risk. However, it would seem that the majority of cases have been diagnosed in heterosexual men and heterosexual men. In England alone, men who have sex with men amount for 21% of all diagnosed chlamydia cases or 6% of total chlamydia cases recorded.