The number of people living with HIV in Britain will top 100,000 for the first time next year, The Independent on Sunday has learnt. The toll of those infected, to be announced this week by the Health Protection Agency (HPA), is revealed as the world marks 30 years since the first cases of the disease were diagnosed. The growing number of British HIV patients is due to the spread of the disease within the UK, as opposed to infections acquired abroad. The amount of people contracting the disease in Britain each year has doubled in the past decade, with some 3,800 diagnosed last year. Epidemiologists at the HPA now predict that there will be more than 100,000 HIV-positive people – diagnosed and undiagnosed – in Britain by the end of 2012. Health professionals said yesterday that Britain\'s progress towards this figure is more of a cause for optimism than it might first appear. They argued that the high numbers illustrate that in three decades, HIV has moved from something akin to a death sentence to a condition that – if managed – can allow sufferers a normal life expectancy. Dr Valerie Delpech, the HPA\'s head of national HIV surveillance, said: \"It\'s remarkable to be heading towards 100,000 people alive with HIV. In the early days, when we were diagnosing we were also counting as many deaths. That\'s changed dramatically. It\'s an extraordinary leap in medicine, that means we\'ve gone from a fatal disease to a manageable chronic disease with a normal life expectancy – if you catch it early.\" Since the first cases were discovered in Los Angeles 30 years ago, 115,000 people have been diagnosed in the UK. Of these, 27,000 have developed full-blown Aids and 20,000 have died. But prevention is still a cause for concern as the doubling of cases suggests that safe sex campaigns are not hitting home. Despite the increase in the number of diagnoses, the budget for HIV services in London has been cut by 20 per cent: the chief executives of London primary care trusts slashed spending for 2011-12 by £516,000, prompting protests from public health experts. Diane Abbott, Labour\'s spokeswoman on public health, said: \"The situation is very worrying. We\'re cutting services and we could go backwards. We need more outreach and more services, and to work with community groups.\" The majority of new infections are diagnosed in gay men or in people who contracted the disease while abroad, although the number of heterosexuals diagnosed is also increasing. If all the UK-acquired infections were prevented, some £1.2bn could be saved in lifetime treatment costs. Sir Nick Partridge, chief executive of the Terrence Higgins Trust, said: \"Clearly, we want to do better in HIV prevention in the UK, particularly among gay men. The numbers would be much higher if we hadn\'t had the prevention campaigns of the past 25 years, and nine out of 10 gay men now use condoms. \"But in the past 10 years there\'s been a year-on-year decrease in local funding of HIV prevention work. The national programme has been sustained, but cutting local services adds to the invisibility of HIV.\" Although the condition is now manageable if retroviral drugs are available and there is an early diagnosis, a cure is still a long way off, and patients in many countries do not have access to any treatment. On Wednesday, world leaders will gather in New York for the biggest global meeting to tackle the pandemic for a decade. The UN\'s High Level Meeting on Aids will chart progress since a world assembly on the issue 10 years ago and will lay out future plans for eliminating the disease. The global sum given to tackling the disease fell last year for the first time since it was founded. Hopes that Britain might lead the way have been dampened by a position paper published ahead of the meeting by the Department for International Development: the paper does not set any targets for global treatment nor pledge any sums of money. Diarmaid McDonald, co-ordinator of the Stop Aids Campaign, said: \"The paper is indicative of the fact that there\'s been a change of focus within this government. That\'s something we\'re concerned about: no government should feel the war against Aids is won yet. \"In the past, UK governments have played a significant role in driving forward the response to HIV, but we need to see some urgency from this government,\" he added. Stephen O\'Brien, Minister for International Development, said: \"This government is absolutely committed to tackling the devastating scourge of HIV and Aids in developing countries. \"This week, at the UN meeting, I will be working closely with partners to ensure the fight against HIV and Aids remains high on the international development agenda.\"