What is HIV?
HIV is a retrovirus that is transmitted through blood or sexual contact. Initial symptoms vary and can include flu-like symptoms and fever, although most infected people will not have any symptoms at all.
During the later stages of infection, the immune system will become significantly weakened. This is because the virus gradually destroys a section of the immune system called T-cells. These cells are crucial for the body to fight infection. At the later stages, HIV can develop into Acquired Immunodeficiency Syndrome (AIDS) and other infections, such as severe pneumonia, can occur.
Eventually, without the proper treatment, the loss of the immune cells will pass beyond a critical level and can be fatal.
The 1980s saw the emergence of HIV and the AIDS pandemic. The following years since then have seen an incredible output of research into the virus and its subsequent characterisation and treatment. Global scale-up of antiretroviral therapy has been the primary contributor to a 48 per cent decline in deaths from AIDS-related causes,1 however there is still a long way to go towards the eradication of HIV.
Why do we need research into early detection systems for HIV?
The health economic benefits of widening access to testing was shown in the Health Protection Agency Report (now Public Health England) in 2011. This has led to new legislation to widen access to testing outside hospital settings, in both developed and developing countries. Self-testing became legal in the UK in 2014.
Finding out early that people have HIV is crucial for starting treatment before their immune system is irreversibly damaged. Today, diagnosis is made by sophisticated laboratory tests and patients have to visit a clinic to have a test done.
Early detection in non-hospital settings is problematic for rapid-tests, since they typically rely on antibody detection; these antibodies cannot be detected until three weeks to six months after the exposure. Moreover, antibody detection is sometimes inaccurate, for example it cannot be used to diagnose infants under 18 months of age as their mothers’ antibodies may cause false positive results.
Biomarkers for early detection are of interest to try and close this window period - the time between onset of infection and detection. Directly detecting parts of the virus such as the p24 antigen, an important protein in HIV, can help detect the virus at early stages. This does present challenges due to the very low concentration of these proteins in the blood.
As testing becomes necessary in non-clinical settings, data-linkage becomes increasingly important too; both to keep people linked into follow-up care and for public health efforts. The low-cost and widespread availability of mobile phones in developing countries offers tremendous opportunities for testing in remote settings. Geographically linked information could help support better access to follow-up care and public health interventions, to prevent the spread of HIV.