Mobile health check

The excruciating wait to find out whether you have bird flu or just the common cold could be eliminated by a new rapid disease detection device.

A 20-strong team at technology company Avacta is developing a hand-held device that can detect and diagnose disease pathogens quickly in the field, removing the need to take samples to the laboratory for testing, which could take days.

According to Avacta, by using a dual detection assay method, the technology will be able reduce the number of false positives by diagnosing a suspect sample using immuno assays, which detect proteins, and polymerase chain reaction (PCR) assays, which detect DNA or RNA. This would allow viruses or bacteria, such as salmonella, which has protein in its cell wall and DNA in its nucleus, to be identified more accurately.

‘The detector is unique in that there is nothing out there that is hand-held that would be able to do both assays in one device,’ said Prof Alastair Smith, chief executive of Avacta.

Avacta has been awarded funding from the InterAct project Proof of Concept fund to work with the Health Protection Agency (HPA) and the Central Science Laboratory (CSL), which will provide pathogen samples and their mutations to enable Avacta to develop the new technology.

Smith explained why there was a need for a hand-held disease detector that could be used in the field.

‘If a body such as the HPA wants to determine whether there is a pathogen on a farm or in a water supply, they would take a sample and take it back to the laboratory and test it, and the results could take a day or two.

‘If you take the foot-and-mouth outbreak in 2001, a quarter of the animals were unnecessarily slaughtered as they didn’t have the disease, but there wasn’t a method of quickly testing those animals, and in the two or three days it takes to test the animals, they would have all infected each other.’

Avacta’s detecting system will contain a disposable chip to facilitate the safe testing of samples in the field.

‘You would place your sample into a plastic device, or chip, and then put that plastic chip into the machine, like a cassette into a tape recorder,’ said Smith. ‘This means that only the chip, and not the machine, gets contaminated. The assay is then done on the fluids that move around on the chip, and the detection mechanism inside the technology will see if it is a positive or a negative.’

The diagnostic reading would then be taken from an electronic screen.

Smith suggested another application could be in the event of a terrorist attack. Emergency services using the device would be able to rule out, in less than an hour, the presence of biological weapons such as anthrax, so they can deal with injured people safely.

The HPA and CSL will allow Avacta to test the device with real-life pathogens to which the private company would not normally have access. When viruses change their nature through mutation, the device will need to be configured to recognise the new forms, and part of the laboratories’ work is to develop reagents (substances that help create mutated forms of a known pathogen) and new methodologies for detecting new pathogens as they occur.

‘It is extremely difficult for private companies to develop reagents rapidly enough to respond to new pathogens,’ said Smith. ‘We would not even be allowed to handle extremely dangerous organisms in our own facilities, but the HPA and CSL can, so we can access real pathogens and real systems, not just models.’

The project team is about to develop a working prototype of the detector into a hand-held device, which is expected to be delivered to the HPA for testing with real pathogens, within the next 12 months. So far, it has tested only harmless model pathogen systems in its own laboratories.

Avacta has also signed an agreement with Retroscreenvirology, a European clinical virology organisation that specialises in respiratory diseases such as SARS and influenza, which will develop reagents to complement its technological developments.

Smith said he hoped to develop the product so it could eventually be used in more day-to-day situations.

‘In future, strategy is to take technology from the defence and homeland security area into clinical diagnostics,’ he said. ‘So, if you can detect viruses in the field, you can also use the technology for rapid detection of diseases in a GP’s clinic, for example. However, there are lots of regulatory hurdles to clear before you can go into clinical settings.’