This finding has important public health implications for a substantial group of HIV infected people, at risk of transmitting HIV to their sexual partners if they do not realise they have the infection, raising the issue that more work must be done to prevent others from becoming infected.
The study, funded by the MRC and led by Dr Anne Presanis at the MRC Biostatistics Unit in Cambridge, estimates that the number of HIV positive people living in England and Wales aged 15-44, including both diagnosed and undiagnosed cases, to have increased from 32,400 in 2001 to 54,500 in 2008. Much of the rise is attributable to an increase in the number of undiagnosed individuals seeking testing.
While it is encouraging to see the estimated upwards shift in the proportion of HIV infections diagnosed from 58 per cent in 2001 to 71 per cent in 2008, the researchers were disappointed to note that there was no corresponding drop-off in the estimated number of people with HIV without diagnosis, implying that the ongoing spread of HIV infection has not yet subsided.
Lead author Dr Anne Presanis from the MRC Biostatistics Unit in Cambridge says:
“HIV remains an important public health problem. As long as a large number of people continue to be unaware of their condition, the infection will continue to pass from person to person. These findings highlight the need for continued public health policies aimed at both reducing further HIV transmission and encouraging individuals to get tested and access the help and services they need.”
Study co-author Professor Noel Gill, head of the Health Protection Agency’s HIV & STI department, said:
“The findings of this paper reveal the need to focus efforts on reducing transmission of HIV if we are to bring the overall number of cases down. Early diagnosis of HIV infection will give individuals access to treatment, improve their survival and reduce the risk of transmission to partners. The HPA recommends that people at higher risk of HIV, such as men who have sex with men, should test at least annually for HIV and that everyone should use a condom with all new or casual sexual partners – it is the surest way to ensure you do not become infected with a serious sexually transmitted infection such as HIV.”
The results are published online today in the journal AIDS.
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3. The researchers estimated trends in diagnosed and undiagnosed prevalence by synthesising data: on exposure group sizes from behavioural surveys and the population census; on prevalence of total and undiagnosed infection and proportions of infections diagnosed from unlinked anonymous seroprevalence surveys and community surveys; and on the total number diagnosed from an annual survey of individuals with diagnosed HIV infection. This was achieved through a form of statistical “triangulation” of the available data known as Bayesian multi-parameter evidence synthesis.
4. The Health Protection Agency is an independent UK organisation set up by government in 2003 to protect the public from threats to their health. The HPA identifies and responds to health hazards and emergencies caused by infectious disease, hazardous chemicals, poisons or radiation. It also ensures the safety and effectiveness of biological medicines such as vaccines and blood products. The HPA gives advice to the public on how to stay healthy and avoid health hazards, provides data and information to the government, and advises people working in healthcare.
5. It also makes sure the nation is ready for future threats to health that could happen naturally, accidentally or deliberately. ww.hpa.org.uk For more information on and the latest data on HIV please visit http://www.hpa.org.uk/Topics/InfectiousDiseases/InfectionsAZ/HIV/