UNIVERSAL screening for HIV could form a cornerstone of the Scottish government's revised action plan against the virus, according to a spokesman for NHS Lothian.

Jim Sherval, a specialist in public health, told the Sunday Herald proposals to implement automatic screening were "currently under active discussion" with the Scottish government, which is set to deliver its HIV action plan in the spring.

Fears over undiagnosed HIV have led the UK Health Protection Agency (HPA) to back the British HIV Association's calls for automatic screening of anyone aged 15 to 59 when they register with a GP or are admitted to hospital in areas where HIV prevalence is two or more per 1000. The proposal received a boost on Wednesday when the medical journal the Lancet reported a World Health Organisation study. It used mathematical modelling to forecast that universal testing - followed by immediate antiretroviral therapy - could reduce new HIV cases by 95% within 10 years.

While no health board in Scotland meets the British HIV Association's criteria for prevalence, NHS Lothian's rates of diagnosed HIV - at 1.5 to 1.99 per 1000 - are twice those of any other area. According to Medical Research Council data, Glasgow has the highest levels of undiagnosed HIV in the UK.

Alarmingly, the HPA says around 28% of carriers do not know they are infected. The figure correlates with a study among gay men in Edinburgh earlier this month by the HIV charity the Terrence Higgins Trust. It found that more than a third of those who tested postive did not know their status.

Between 1988 and 2001, annual HIV diagnoses seemed to have plateaued at 150. Since then figures have tripled and, since 2004, have exceeded the previous peak of 1988.

In 1988 gay men accounted for 47% of diagnoses (IDUs) and injecting drug users, 46%. Twenty years on, heterosexuals make up 47% - compared to 42% gay men - while IDUs have fallen to 7%.

David Johnston, director of Edinburgh HIV charity Waverly Care, said: "It may well be the GP practices in some areas should definitely be looking at proactively offering an HIV test to every new patient that registers, and I think that would be a helping way forward in terms of thinking about how to maximise people's chances of living well with HIV."