Experts have warned of a “silent epidemic” of sexually transmitted infections as new data shows that one in every 25 people globally are carrying an STI.
Two of the most common infections – gonorrhoea and syphilis – are causing particular concern because they are becoming resistant to antibiotics, making them all but impossible to treat.
A review of the four most common STIs shows that in 2016 there were 127 million new cases of chlamydia, 87 million new cases of gonorrhoea, 6.3 million cases of syphilis and 156 million of trichomoniasis – an STI spread by a parasite.
These figures equate to one in 25 people in the world having at least one STI at any one time and a million new cases being diagnosed every day.
The study, published in the Bulletin of the World Health Organization, highlights how STIs have a serious impact on the health of adults and children and, if untreated, can lead to infertility, stillbirths, increased risk of HIV and even cardiovascular and neurological complications.
Syphilis is a particular problem for pregnant women with around 200,000 stillbirths and deaths of newborn babies every year linked to the infection.
The study brings together hundreds of pieces of research and shows that since the last large-scale analysis of global infection data was published in 2012 the number of infections contracted annually remains stubbornly high.
In Britain the number of people being infected is rising, with three cases of super gonorrhoea reported since last April.
The new figures are published in the week that data from Public Health England showed that there were around 448,000 cases of STIs diagnosed in 2018, an increase of five per cent from 2017.
The figures do not highlight drug-resistant infections separately but Teodora Wi, WHO medical officer specializing in sexual health, warned of the rise of STIs that may one day be impossible to treat.
Last year a man from the UK picked up a case of “super-gonorrhoea” in south east Asia. And earlier this year two women picked up the drug-resistant form in the UK.
Dr Wi said that WHO had also detected cases of drug-resistant syphilis – a particular concern because the disease in some people has no symptoms and, if left untreated, can lead to long-term neurological and cardiac problems. She also warned of the resistant form of an emerging STI, Mycoplasma genitalium.
One of the report’s authors, Matthew Chico, said urgent action was needed.
“These STIs are preventable and treatable. However, the global threat of antibiotic resistance looms large, highlighted by the almost unthinkable: a world without a cure for gonorrhoea in the not too distant future.
“Alongside promoting sexual health education and effective condom use, efforts to improve STI surveillance, and develop new treatments and diagnostics, must be a top public health priority,” said Dr Chico, assistant professor at the London School of Hygiene and Tropical Medicine.
Dr Tim Jinks, head of the Wellcome Trust’s drug resistant infection programme, said the high numbers were alarming, given that some STIs were becoming impossible to treat.
“We do not know what the burden of super-gonorrhoea is in low and middle-income countries, but with a broader rise in gonorrhoea cases, we can expect to see drug-resistant forms of the disease become more common all over the world,” he said.
The WHO African region had the highest prevalence of chlamydia in men, gonorrhoea in women and men, trichomoniasis in women and syphilis in men and women.
In the European region the most common STI was chlamydia, with 3.2 per cent of women and 2.2 per cent of men estimated to have contracted the infection in 2016. These rates have both increased since 2012.
In Europe rates of gonorrhoea among women and men have stayed broadly the same – at 0.3 per cent.
However the authors warn that there was a striking lack of data on men – the figures on syphilis, for example, which show that women have higher rates than men in practically all regions of the world, are predominantly based on studies of pregnant women.
Melanie Taylor, author of the study and a medical epidemiologist at the WHO, stressed that these figures did not include viral STIs such as herpes, HIV and the human papillomavirus (HPV) which causes cervical cancer.
New estimates on herpes and HPV will be published within the next six months.
Dr Taylor added that STIs were often symptomless so could be easily transmitted to sexual partners or to babies by their mothers.
“These infections are associated with stigma, they’re associated with shame… We do consider this a hidden epidemic, a silent epidemic, a dangerous epidemic. And it’s persistent, globally and persistent within populations, families and relationships and quite damaging to all,” she said.
Dr Wi said that the widespread use of dating apps, declining fears over contracting HIV and the advent of pre-exposure prophylaxis – a pill that can prevent HIV – were contributing to the high rates of STIs.
“STIs are everywhere, they are more common that you think but they are not given enough attention. We continue to stigmatise people living with STIs and we neglect to care,” she said.
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