Rates of sexually transmitted infections have doubled among the over 45 population in less than a decade, reveals research in the journal Sexually Transmitted Infections.

Sexual behavior studies tend to ignore older age groups and focus on young people, say the authors. The period of analysis spanned eight years between 1996 and 2003 inclusive. Researchers monitored the numbers of sexually transmitted infections (STI) diagnosed in 19 sexual health clinics and reported to the Health Protection Agency's Regional Surveillance Unit in the West Midlands.

In total, 4445 STI episodes were identified among people aged 45 and older during that time. Most of these were in straight men and women.

The most commonly diagnosed infection among the over 45s was genital warts, accounting for almost half (45%) of the episodes. Herpes was the next most common, accounting for almost one in five (19%).

Men and those between the ages of 55 and 59 were significantly more likely to have an STI than anyone else.

Among women, rates were highest among those aged 45 to 54; among men, rates were highest among those aged 55 to 60 plus.

Cases of Chlamydia, herpes, warts, gonorrhoea and syphilis all rose sharply. And the cumulative rate of infections more than doubled from 16.7 per 100, 000 of the population in 1996 to 36.3 per 100,000 of the population in 2003.

And in 1996, this age group comprised 3.9% of all clinic visits; by 2003, this had risen to 4.5%.

While the numbers of infections identified in younger age groups rose 97% during the period of the study, those identified in the over 45s rose 127%.

Programmes aimed at preventing sexually transmitted infections should be tailored towards different age groups and do more to dispel myths and assumptions about the level of sexual activity among older age groups, say the authors.

"Indeed, it may be argued that older people are more susceptible [to sexually transmitted infections] as they are less likely to use condoms than younger people," they say, adding that as successive waves of people with more liberal sexual attitudes and behaviours age, the problem is likely to worsen.