The Lab-on-Mobile-Device (LMD) platform can detect aflatoxins as accurately as a laboratory test, but can be carried out anywhere at a fraction of the cost using a smartphone camera, according to Donald Cooper of the University of Colorado, United States, who co-founded a company called Mobile Assay to develop the technology.
Field trials of LMD began in five locations in East Africa last September in collaboration with several regional research universities and research institutions, and with a grant from the Bill & Melinda Gates Foundation.
The fungus that produces aflatoxin grows on various crops — such as maize and peanuts — in warm climates. The problem affects a quarter of food crops worldwide, according to the Food and Agriculture Organization.
Roughly five billion people in the developing world are likely to be exposed to aflatoxins, according to the Partnership for Aflatoxin Control in Africa. The WHO recognises the chemical as a carcinogen.
“You need to be able to couple diagnostics with treatments.”
Efforts to control aflatoxin have been hampered by a lack of adequate diagnostics, says Benoit Gnonlonfin, a food safety researcher working for a research initiative Biosciences eastern and central Africa.
Laboratory tests that can identify the toxin are expensive, costing at least US$15 per test, according to Gnonlonfin, in addition to the challenge of transporting samples from remote areas.
As a result, local regulatory agencies widely use cheaper immunoassay tests, which operate in a similar way to over-the-counter pregnancy tests, for on-location screening. But these can only indicate a positive or negative result via a colour change on test strips or in liquid substrates and so are unable to indicate the level of health threat.
“The immunoassay tests are semi-qualitative techniques and they are not very appropriate for making decisions about whether a batch of food is fit for consumption,” he says. “We need more-advanced technologies that are also affordable.”
Immunoassay tests are also prone to human error as some require precise timing and because low concentrations of aflatoxin might not trigger an obvious coloured response, according to Cooper. He says that LMD reduces these risks by analysing the shades of the coloured bands on test strips via a digital phone image.
After users photograph the test strip with the smartphone, the app then calculates the pixel density of the coloured band. The result shows how much aflatoxin is present, within a certain threshold, rather than merely giving a simple positive or negative result.
LMD is more sensitive than the human eye, boosting the accuracy of traditional immunoassay tests by a factor of 100, according to Cooper.
Data from the tests will also be automatically uploaded online to create real-time, open-access maps of aflatoxin outbreaks for research.“Our goal is to be able to use the big data component of this,” says Cooper. He hopes that, once a critical mass of people are using the app in various regions, he will be able to correlate those findings with other information — such as climate data — to build models that predict aflatoxin prevalence.
Gnonlonfin says it would also be helpful to have a risk map.
Each LMD test will cost about US$2-3, although the need to own a smartphone with a camera means Cooper sees LMD not as a tool for every farmer but rather as a more-accurate, on-site test for agricultural co-operatives and regulatory bodies.
Mobile Assay is also developing a prototype low-energy, lightweight ozone decontamination unit to treat infected crops. Cooper says the technology, often used in organic farming in the United States, can neutralise up to 90 per cent of the aflatoxin in a plant.
“You need to be able to couple diagnostics with treatments,” says Cooper. “It’s one thing to have an easy-to-use and low-cost diagnostic, but then there is the larger question of what to do when you find out that you have a problem. What we’re trying to do is answer both questions.”
This week (5 November), The International Food Policy Research Institute will launch a series of 19 policy briefs on managing aflatoxins.
Several briefs examine effective detection and diagnostic technologies, including one on Blue Boxes, portable grain-testing tools that allow for on-the-spot testing of crops at any stage of the supply chain.
“The series provides a good way of bringing together up-to-date information on aflatoxins by experts,” said Delia Grace, veterinary epidemiologist at the International Livestock Research Institute, in a story posted on IFPRI's website.
See below for a promotional video of the app: