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HIV test performed by USB stick
November 29, 2016, 1:44 pm
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Scientists at the Imperial College in London have developed a type of HIV test on a USB stick. The device uses a drop of blood to detect HIV, and then creates an electrical signal that can be read by a computer, laptop or handheld device. The disposable test could be used by HIV patients to monitor their own treatment and could enable such patients to be managed more effectively, especially in remote locations.

Early diagnosis of the infection using HIV tests and anti-retroviral treatment has over the last 20 years resulted in reducing virus levels to near zero, and most HIV patients can now have normal life expectancy. Regular monitoring of viral levels is crucial in order to enable healthcare teams to check whether a patient is taking their medication, or that the medication is working as intended.

Stopping medication mid-way through the treatment fuels HIV drug-resistance, where the virus develops resistance to the drug being administered and renders the treatment ineffective. The first indication of this is a rise in virus levels in the patient’s bloodstream.

However, routine HIV tests can only identify whether a person has been infected, it cannot detect the viral levels.  At the moment, testing for viral levels often requires costly and complex equipment that can take a couple of days to produce a result.

The new USB technology could allow patients to regularly monitor their virus levels in much the same way that people with diabetes check their blood sugar levels. The technology could be particularly powerful in remote regions in sub-Saharan Africa, which may not have easy access to testing facilities. Finding out quickly if a patient, particularly a baby, is infected with the virus is crucial to their long term health and survival.

The device, which uses a mobile phone chip, just needs small sample of blood. This is placed onto a spot on the USB stick. If any HIV virus is present in the sample, this triggers a change in acidity which the chip transforms into an electrical signal. This is sent to the USB stick, which produces the result in a program on a computer or electronic device.

In the latest research, the technology tested 991 blood samples with 95 percent accuracy. The average time to produce a result was 20.8 minutes.

The team behind the technology is also investigating whether the device can be used to test for other viruses such as hepatitis and for detecting bacterial and fungal sepsis and antibiotic resistance.

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