Britain recorded almost half a million new cases of sexually transmitted infections (STIs) last year, with teenagers and those aged under 25, especially young women, particularly affected, figures showed.
Health officials said the rise in STIs in young women was partly due to their reluctance to insist on using condoms.
Overall, 482,696 new STIs were diagnosed in 2009, an increase of 12,000 cases from the previous year, and continuing an upward trend seen over the last decade, the Health Protection Agency (HPA) said.
Two-thirds of the new STIs in women were diagnosed in those aged 15 to 24, with more than half of new cases for men falling in the same age group.
There were also high rates of STI diagnoses among gay men.
Poor sexual health
"These latest figures show that poor sexual health is a serious problem among the UK's young adults and men who have sex with men," said Dr Gwenda Hughes, head of the HPA's STI section.
"These figures also highlight the vulnerability of young women. Many studies have shown that young adults are more likely to have unsafe sex and they lack the skills and confidence to negotiate safe sex."
In women, 73% of new cases of gonorrhea and 66% of new genital wart cases were in those under 25, while 88% of female chlamydia diagnoses were in this age bracket.
The peak age for an STI in women is between 19 and 20, and 20 to 23 for men, the HPA said.
Re-infection also a problem
Re-infection was also a problem with one in 10 of those aged 15-24 diagnosed with an STI becoming re-infected within a year.
"The numbers we're seeing in teenagers are of particular concern as this suggests teenagers are repeatedly putting their own, as well as others', long term health at risk from STIs," Hughes said.
Overall cases of chlamydia were up by 7%, gonorrhoea diagnoses increased by 6% and genital herpes cases rose by 5%.
Hughes said better testing accounted for some of the rises, but added they were also due to unsafe sexual behaviour.
"It's staggering that almost half a million people each year are affected by preventable sexually transmitted infections," said Nick Partridge, chief executive of sexual health charity the Terrence Higgins Trust.
"Until we improve sex education and give extra support to young people they will continue to take avoidable risks with their sex lives." - (Reuters Health, August 2010)
STIs and safer sex