Analysis: Electronics backed to cut STD spread

E&T describes how a new generation of bio-electronic devices could reduce the transmission of infectious diseases.

The UK's Technology Strategy Board is trying to fast-track the development of bio-electronic point-of-care devices to speed up the diagnosis and treatment of infectious diseases, with sexual diseases one of the priority areas. Almost across the board, diagnoses of sexually transmitted diseases (STDs) have increased in the UK in the past ten years, with syphilis cases rising close to 20-fold.

The TSB has set up three funding tracks for new devices, two aimed at moving devices to production quickly. A feasibility track is for companies that have an existing biochemical sensor that could be deployed as a point-of-care unit. "If you have a device but have never looked at an infectious agent then we will support you to do that," said Penny Wilson, innovation-platform leader for the TSB.

A fast-track programme is intended to take devices designed for handling infectious diseases on the government's priority list to the point where they can be used in clinical trials.

Tariq Sadiq, consultant physician at St George's Hospital, University College, London, explained that although cases of gonorrhoea dropped in 2008 after being targeted by the Department of Health, the UK has the worst record for sexually transmitted infections in Western Europe. "There has been a thousand per cent increase in syphilis in the past decade," he said.

A major problem for doctors trying to treat patients is the time it takes to get an accurate diagnosis. Today, samples have to be sent to a laboratory for analysis, so the patient has to return to the clinic or hospital at a later date for treatment, which many fail to do, and so continue to spread the condition. If accurate diagnoses can be made while the patient is in the treatment room, then the vital 'return rate' rises from as low as 50 per cent to 100 per cent.

"Point-of-care diagnostics have the potential to impact on the spread of disease. If you find them, get to them, diagnose and treat them as well as their partners, you reduce the size of that pool of infection," Sadiq explained.

The statistical trade-off is one of immediacy versus accuracy. Lab tests are already very accurate but lose on the return rate. In principle, a point-of-care device can be far less accurate than a lab test and still deliver better results in terms of infection control.

"If the rate of return for a lab test is as low as 50 per cent, then one argument is that it doesn't matter how accurate the point-of-care test is. That is the scientist's view. But it's not that of the politician," said Ben Arlett, product development director for diagnostics start-up Atlas Genetics.

With sexual diseases in particular, false positives present major problems on a social level. And false negatives will increase the number of infections before the patient is finally diagnosed correctly.

"Gonorrhoea can be diagnosed by a test we have had for many years but it is not very sensitive, especially in women. People don't want to go back to their partner and say 'I think I might...'," said Sadiq, adding that the ideal would be to test for many conditions at once.

One of the problems with existing tests that are suitable for point-of-care diagnosis is that they depend on chemical markers that can show positive for a variety of reasons. A test that looks for the telltale DNA signature of a virus, for example, is what today's lab tests can offer and where some of the work on point-of-care testing is focusing.

Atlas Genetics is one of the companies preparing for this shift. Speaking at an event organised for potential investors by university consortium SetSquared, Arlett said: "We have to make a lab-quality test. But those molecular tests are very difficult. We have integrated all the steps of a molecular assay onto a card. All the end user has to do is take the sample."

The card goes into a machine the size of a toaster which then performs the chemical processes normally carried out manually in a lab to amplify the DNA, extract a portion if the infectious agent is present and match it against a probe. Because the probes select for sequences of DNA, the device can, in principle, test for multiple infections.

"We have met all the targets in terms of specificity and sensitivity with the prototype. Now we want to do the design for manufacture," said Arlett.

Atlas and others are being joined by larger technology players vying for a place in what could be a gigantic global market. IBM researchers in Zurich are aiming for a similar goal with a microfluidic card that embeds antibodies for specific conditions in a tree of capillaries, designed to allow a reader device that is simpler than the one made by suppliers such as Atlas, to register whether an infectious agent is present.

IBM researcher Emmanuel Delamarche used a term from horse-racing to describe the significance of the development. "This point of care test has achieved the trifecta for medical staff in that it is portable, fast and requires a very small volume of sample," he commented.

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