06/09/11

Test could give HIV diagnosis ‘in minutes’

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[KIGALI] An easy-to-use diagnostic chip could be a game changer in the field of cheap diagnostics for remote regions, claim the researchers who developed it.

Tests of the ‘mChip’ on blood samples collected in Rwanda showed that it can diagnose HIV/AIDS and detect 100 per cent of cases in just 15 minutes — with the same accuracy as standard laboratory tests that can take weeks to give a result.

The chip is roughly the size of a postage stamp and can be cheaply mass produced. Researchers say that the same technology could be used to diagnose other diseases, such as malaria and hepatitis.

It combines microfluidics, an interdisciplinary field of science that deals with tiny amounts of fluids, with nanotechnology in a single, hand-held device. The resulting chip is essentially a miniature ELISA (enzyme-linked immunosorbent assay) test, a standard laboratory diagnostic test based on detecting molecules.

It needs a drop of blood, which is treated with pre-loaded reagents within the chip that produce a visual result that can be read off directly or using a mobile-phone sized device.

Each test would cost around US$1 and the full device US$100.

"Lack of early diagnosis among people living with HIV/AIDS has always been described as a major challenge in accessing cheap medicines in developing countries," Lambert Mwambaragwe, a health researcher at Project Ubuzima, in Rwanda, and a co-author of the study, told SciDev.Net.

"Making medical diagnosis cheaper and affordable will reduce the high risk of infectious diseases to vulnerable groups," he added.

The chip has been specifically designed for use in remote regions of the developing world, said the study.

"The devices are portable, simple, and robust enough for community healthcare workers to use in places beyond the reach of clinics or hospitals," said George Whitesides, a professor at Harvard University, United States.

Jean Bosco Kayiranga, a medical doctor in Rwanda, said that in order for the device to work in the field, countries will also need a large number of healthcare practitioners trained in using this technology.

David Bell, head of the malaria diagnostics programme at the Foundation for Innovation Diagnostics, told SciDev.Net: "This new test requires blood and various reagents aspirated through a tube with air bubbles between them, which is intrinsically more complicated [than some existing rapid tests for HIV]. Whether it is good for a community-level [setting] will depend on whether the method can be made extremely simple to do, which will probably need some sort of automation.

"The test may be appropriate for a district or a hospital level," Bell said. "And that would still be a big step forward."

The findings were published in Nature Medicine (31 July).

References

Nature Medicine doi:10.1038/nm.2408 (2011)

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