The number of people infected with HIV in the UK rose last year to an estimated 58,300 and almost a third of those may not know they are carrying the disease, a report said on Thursday.
Most new cases were diagnosed in heterosexuals and nearly three-quarters of those were probably contracted in Africa.
The Health Protection Agency (HPA) said the number of HIV sufferers had risen last year from an estimated 53,000 who were thought to be infected in 2003.
The report revealed that during 2004 there were 7,275 new HIV infections in the UK, up slightly from 7,217 in 2003. Of those, 4,287 were in heterosexuals, with 73 percent of these most likely to have been acquired in Africa.
The report said up to a third of the cases—some 19,700 people—were thought to be undiagnosed, meaning they could be spreading the disease without knowing. "There is no part of the UK that remains unaffected by HIV or sexually transmitted infections," said Barry Evans, an HIV expert at the agency.
"Our report 'Mapping the Issues' coincides with the World Aids Day and allows us to take stock of the progress made in our efforts to prevent the spread of HIV."
Nick Partridge, CEO of Terrence Higgins Trust, a sexual health charity trust, said Britain was in danger of having the worst sexual health record in Western Europe. "It will be the same story year after year unless the recent Government funding to improve sexual health services is spent wisely."
"That's why we're calling for Primary Care Trusts to commit publicly, today, to spend their share of the 250 million pounds funding on the front-line sexual health services that need it so desperately, he said.
"We're at a crossroads—if we don't concentrate on prevention and access to services now, we will continue to have ever-increasing rates of HIV and the worst sexual health in Western Europe," he added.