CARTRIDGE used in the experimental GeneXpert system is about as tall as an adult's thumb (left). Inside, sound waves bombard material to be tested, causing any cells to break open and release their DNA. If a pathogen of interest is present, its DNA will be amplified in the arrow-shaped reaction tube (protrusion), and the edges of the arrowhead will fluoresce. The micrograph (right) shows the remains of a cell that has disgorged its contents.
IMAGE: COURTESY OF CEPHEID Image:
If a terrorist group spread anthrax spores into the open air, the release could affect large numbers of people but would probably go unnoticed until victims showed up at hospitals. Many would undoubtedly seek help too late to be saved by current therapies. Much illness could be prevented, however, if future defenses against anthrax attacks included sensors that raised an alarm soon after spores appeared in the environment. The needed instruments are not yet ready for deployment, but various designs that incorporate cutting-edge technology are being developed.
Environmental sensors must discriminate between disease-causing agents (pathogens) and the thousands of similar but harmless microorganisms that colonize air, water and soil. Most of the tools being investigated work by detecting unique molecules on the surface of the pathogens of interest or by picking out stretches of DNA found only in those organisms.