Just two months into her new role, Dr Claire Ryan, 36, a former GUM registrar at Sheffield's Royal Hallamshire Hospital, is still tanned from a four-month expedition to Ethiopia to brush up on her AIDS expertise.

But now, in a dark and spartan room tucked away in the Infirmary's warren of corridors, Dr Ryan is putting her African experience to good use as she takes up the task of tackling a town still tarnished with a taboo disease tag.

"The Doncaster situation is very unusual" said Dr Ryan, referring to the 1998 outbreak of HIV when a state of emergency was declared after HIV-positive nightclub bouncer Steve Robson admitted to health officials he had sex with up to 1,000 women, many of whom he could not remember.

"But what is most unusual about it is that a sudden HIV outbreak triggered by one person could easily happen again and yet there have been very few similar cases. There is no reason why we couldn't see a repeat of this." she said.

There are currently 150 HIV patients being treated by the hospital's GUM clinic but, said Dr Ryan, there are potentially up to another 50 sufferers in Doncaster still undiagnosed.

However, compared to the 60,000 people nationwide now being treated for HIV, Doncaster no longer seems deserving of its tag as an AIDS hot spot.

While the clinic treats a substantial number of gay men and immigrants from south-east Asia and sub-Saharan Africa, what does mark Doncaster out however is a significant number of local white, heterosexual patients.

Some are survivors of the 1998 epidemic but others are newly diagnosed.

Dr Ryan said: "We are still seeing the after effects of 1998 here. HIV affects young people and is transmissible throughout the rest of their lives.

"Although some patients have died, massive progress has been made in drug treatments in the last 10 years which means people with HIV can now practically live a normal life span.

"We use a very aggressive and costly drug treatment to keep the disease at bay but it is cost effective because it enables carriers to continue their lives and to work."

But HIV is not the only concern of Doncaster's GUM consultants.

She said: "We have seen an enormous explosion in all sexual diseases including chlamydia, gonorrhoea and syphilis.

"The world is facing a global epidemic and we have massive chlamydia problems in Doncaster.

"Nationwide as many as one-in-ten under 24-year-olds are currently infected but we know in certain social pockets, including some in Doncaster, this is raised to one-in-five and it is usually in lower socio-economic groups."

While diseases such as gonorrhoea have unpleasant and obvious symptoms, chlamydia is silent but can cause more long-term damage.

"What is essential to tackling the problem is early treatment" said Dr Ryan.

The GUM clinic at the DRI offers tests for all sexually transmitted infections to everyone without the need for a GP referral.