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Canadian Food Inspection Agency
For the development and successful transfer of the fluorescence polarization assay test for brucellosis in cattle.
Klaus Nielsen / David Gall / Linda Kelly / Walter Kelly / Min Lin / Patricia Smith
Canadian Food Inspection Agency
The ability to quickly detect and diagnose a disease is one of the most important factors in stopping its spread. Yet often, diagnosis relies on expensive tests that take days to return from a lab, prolonging exposure and delaying the control of the disease.
As a front-line weapon in this fight, a dedicated team of scientists and technicians at the Canadian Food Inspection Agency's (CFIA) Ottawa (Fallowfield) laboratory has come up with a compelling solution. The fluorescence polarization assay (FPA) is a 15-second test for detecting brucellosis in cattle. Based on the principle that the smaller the molecule, the faster it rotates in solution, the team developed a test that uses a fluorescent label to measure the time a molecule takes to rotate through a plane of polarized light. If antibodies attach themselves to the molecule (making it larger), the molecule will move more slowly, indicating a positive result. An antibody-free molecule will rotate faster, indicating a negative result.
Such a test is simple, reliable, and does not require a laboratory. Results are obtained in the field, allowing for immediate identification and quarantine of diseased animals. The technology itself is portable, powered by a laptop computer, and able to be loaded onto the back of a donkey if that is the best way to reach remote areas. It is also stable under a wide variety of conditions, having been tested by the intrepid team in temperatures that ranged from +55C degrees in Mexico to -40 degrees in Canada's North. All this, at onetenth the cost of some existing tests.
In Canada, the populations of Canadian cattle and farmed bison have been officially brucellosis-free since 1984. Nonetheless, a reservoir of disease in Canadian wildlife means that Canada must regularly survey its cattle for brucellosis. And while the disease is under control here, it takes a major toll on people and animals in other parts of the world.
Known as "undulant fever" in humans, brucellosis lasts for months, inducing an intermittent fever and debilitating, flu-like symptoms. In developing countries, where dairy products from diseased cattle, sheep and goats are consumed, thousands of cases of human brucellosis still occur. In some parts of Latin America, upwards to 25% of the population is afflicted.
Back in Canada, the potential economic impact of an outbreak of such a disease is frightening. Canada is a major exporter of animals, especially swine and cattle. Dr. Klaus Nielsen, lead scientist for the team, points out, "Our success rests on our ability to claim disease-free animals and products". The good news is that the FPA is now approved as the official test for brucellosis in Canada. It can also be adapted to test for other diseases, such as tuberculosis. From there, it is only a matter of time — and financial support — before similar assays are developed for a range of animal and human diseases.
Yet the journey to developing this into a viable product has had its share of challenges, especially finding a partner to manufacture the unit. The CFIA team searched extensively for a company with the requisite capability, and finally found an American partner, Diachemix, to undertake manufacturing and licensing. The next challenge is to continue to decrease the per unit cost of the equipment, to make it widely affordable to governments around the world.
To date, the test is approved for use in the United States, Mexico and Argentina, and is being evaluated for use in eight European countries. The international animal health organization, Office international des épizooties (OIE), has so far approved the FPA as an alternative test for bovine brucellosis. Once enough member countries have the capability to use the brucellosis FPA, the OIE will move to make it the prescribed test.
From left to right: Min Lin, Walter Kelly, Linda Kelly, Klaus Nielsen, Patricia Smith, David Gall