Reuven Rasooly and his colleagues at ARS’s Western Regional Research Center in Albany, Calif., developed the toxin detection system which is used to measure Shiga toxin activity. Shiga toxin, a product of E. coli O157:H7, causes an estimated 73,000 cases of food poisoning and more than 60 deaths in the United States each year. ARS explained that it is critical to be able to determine toxin activity, however current immunological tests cannot distinguish between the active and inactive form of Shiga toxin. The inactive form is nontoxic, but the active form poses a health threat to humans.
Researchers constructed a fluorescence detection system using a $300 digital camera and a light source to measure toxicity in a food sample contaminated with Shiga toxin. Researchers obtained fluorescence measurements by taking a picture with the camera and analyzing the image with free, open-source computer software. When compared with a commercial fluorometer, both methods had the same toxin detection level, ARS said. However, a fluorometer, which is generally used to detect toxins, costs approximately $35,000.