Stacking the odds to detect dengue from saliva.

Saliva-based tests are not new. The Chinese used saliva for an ancient polygraph called the rice test, in which an interrogator placed grains of dry rice into the mouth of a suspect and asked the suspect to spit out the rice. If the grains of rice stuck to the mouth of the suspect, stressinduced xerostomia was assumed—and therefore the suspect was guilty. Fortunately, over the past 3000 years, we have made progress in salivary diagnostics. One of the latest advances is the design of a new paper-based immunoassay by Jackie Y. Ying, executive director of the Institute of Bioengineering and Nanotechnology in Singapore.