Clap is rising on a relentless scale - there has been an 87 per cent increase in gonorrhoea since 1996. Last week, middle England, and its many media representatives, immediately pointed a finger at their favourite culprits: rampant teenagers allegedly bonking like bunnies, living for today in a condom-free zone. How disgusting is that?

'Sexual health crisis blamed on teen promiscuity', read a not untypical headline in the Daily Mail, reporting on an article written by Professor Michael Adler, who advises the National Health Service on its sexual health strategy. The strategy, now in its third year, has the aim of reducing the diagnoses of HIV and gonorrhoea by 25 per cent in four years.

So far, even to an optimist, the chances of succeeding don't appear good. Attendances at genitourinary medicine clinics have doubled in the last decade with one million people now seen by sexually transmitted diseases (STD) departments. HIV, running at 3,500 cases in 2000, will probably reach 6,500 this year.

The cases of chlamydia, the so-called silent infection because the symptoms are often non-existent, have doubled to 71,225 since 1996, while syphilis, once virtually eradicated, is also rapidly re-emerging. But is it really all the fault of the young?

Professor Adler, writing in the medical journal, Sexually Transmitted Infections, has cogently argued that we face not a crisis in teenage sexual behaviour but a deterioration in the entire nation's sexual health. 'Sexual health is not an NHS or political priority,' he writes. 'Until it becomes so, we will witness further failure upon further failure.'

Part of this failure surely also lies in the determined effort of both government and the media to focus the cause primarily on what the under-twenties do. This has a double consequence. First, it narrows down the solutions, leaving most of the problem unresolved. (Warning against being part of a sexual lottery in the lads' mag FHM is hardly going to persuade the 60-year-old businessman to put a condom on it when he pays for his pleasure with an eastern European call-girl.) Second, grown-up sexual behaviour is allowed to remain in the place it loves most - the dark.

The Department of Health is a prime propounder of this skewed analysis. For instance, it says, correctly, that 42 per cent of females with gonorrhoea and 36 per cent of females with chlamydia infection are under 20. Yes, a minority of teenagers are becoming sexually active at a very young age, sometimes for all the wrong reasons such as emotional neediness, lack of aspiration, booze and coercion, but what of the conduct of the 58 per cent of much older women with gonorrhoea and the 64 per cent with chlamydia? What's their justification for taking risks?

STD clinics, for instance, report a significant rise in the post-divorce thirty- and fortysomethings, primarily women, coming for treatment. Often, it's precisely because they had so little sexual experience in their teens that they now obey the advertisers' diktat and 'go for it'. What is described as promiscuity in a teenager is concurrence in a grown-up; both risk infertility. Among men, too, the majority of cases of sexually transmitted diseases are among older, not younger, age groups.

We all know we live in a highly sexualised age. As soon as a toddler can switch on the telly, he or she is bombarded with the message that almost every activity in life is wrapped around 'doing it'. Ice cream, cars, underwear, pop stars singing their latest hit - all are intertwined with having sex.

Against this setting, the small miracle is not how many, but how relatively few young people have multiple partners. The majority delay making their sexual debut until 16 or 17. Could they actually be heeding sex and relationship education in schools - poor as it so often is?

Anita Weston, nurse consultant in genitourinary medicine at Guy's and St Thomas', echoes the view of other clinics, that increasing numbers of young people are behaving responsibly, by having 'a sexual MOT'. They do so if they change partners or they are in a long-term relationship and they plan to dispense with a condom; the couple often attend the clinic together.

Here, perhaps, is the real reason for middle England's fulminations. It's not unprotected sex that raises their indignation - it's the fact that teenagers are having sex at all. Some will, some won't, but it's difficult to deliver the message that positive sexual health matters when so many adults, including many GPs, prefer to pretend that physical desire in the under-21s is an unnatural activity.

Dr George Kinghorn is a consultant genitourinary physician in Sheffield. He argues that a change of culture is required, a 'mindset' removed: 'Sexual health should be considered as much of a priority as heart disease and cancer.' He points out that while the Government has provided £47.5 million for its sexual health strategy, that is barely enough to cover screening for chlamydia.

Clinics are overstretched. Anita Weston's was designed to treat 9,000 patients a year - and now deals with 35,000. Dr Kinghorn estimates between £150m and £200m is required over the next five years to improve clinics while more than 200 consultants need to be recruited. It is telling that in the new GPs' contract, the Government has introduced no obligation to undergo training to deal with sexually transmitted diseases.

For all but the dedicatedly monogamous (and that means 15 per cent of the population), sexual screening should become as automatic as a dental check. What is also required is a public-health campaign that eschews the propaganda of youth attack in favour of straight facts.

Chlamydia can cause infertility for women and men. A penis infected by gonorrhoea is not a pretty sight. Syphilis can kill. An HIV patient costs £150,000 a year to keep alive. We should cease being obsessed with the sex lives of the young - many are already on the learning curve. The real worry is how we teach new tricks to the old dogs.

The Observer NHS debate www.observer.co.uk/nhs