Sexually transmitted infections (STIs) are soaring among young people, with chlamydia the most virulent, health officials have warned.
Nearly half a million people were diagnosed with STIs last year, with those aged under-25 experiencing the highest rates of infection, according to new figures released today.
Health experts have warned that the rise in STIs shows too many young people are still putting themselves at risk by failing to practice safe-sex.
Last year there were 448,422 diagnoses, which was a rise of five per cent from 2011, said Public Health England (PHE).
Almost half of all infections were chlamydia, amounting to 46 per cent of total STI diagnoses.
The number of new gonorrhoea diagnoses increased by 21 per cent, which is a particular cause for concern among health officials as the global threat of antibiotic resistance grows.
People aged under-25 accounted for 64 per cent of all chlamydia and 54 per cent of genital warts diagnoses in 2012.
Dr Gwenda Hughes, PHE head of STI surveillance, said: "Too many people are continuing to have unsafe sex, put themselves at risk of STIs and the serious consequences associated with infection, including infertility."
Health officials recommend sexually active young people and gay men have a chlamydia test every year and whenever they change partners.
If chlamydia – which is just as common for men to get as it is for women – remains untreated, it can cause infertility in women and joint problems in men.
Whilst gonorrhoea can be treated by an injection, it can cause serious health problems such as pelvic inflammatory diseases in women.
"There have been significant improvements in screening in recent years, so we are diagnosing and treating more infections than ever before." said Dr Hughes. "On-going investment in programmes to increase sexual-health awareness, condom use and testing, particularly for groups at most risk, is vital,"
Dr Hughes said: "We must also ensure chlamydia screening remains widely available.
"Local authorities should continue to integrate chlamydia screening into broader health services for young adults.
"This will also help this age group develop positive relationships with services, enabling them to develop and maintain good sexual-health throughout their lives."
Professor Kevin Fenton, PHE director of health and wellbeing, said: "We are committed to improving the nation's sexual health, with a focus on the groups most at risk.
"We will provide local authorities and clinical commissioning groups with data on local health needs, coupled with evidence-based advice on STI prevention and sexual-health promotion approaches, to improve risk awareness and encourage safer sexual behaviours."