Reliable identification of reovirus-like agent in diarrheal stools.

In recent reports, reovirus-like particles have been identified in stools of children with diarrhea by using several different methods of preparing the stools for electron microscopy. These papers have reported varying incidences of the reovirus-like agent (RLA) in groups of patients with diarrhea. Since no standardized stool processing method has been used, it is difficult to compare the incidence figures which have been published. This study evaluates two commonly used methods to determine which would be more sensitive for use in future clinical studies. Stool samples from 72 Mexican children who had acute-onset diarrhea were processed for reading on the electron microscope by the pseudoreplica technique and by differential centrifugation. Reovirus-like particles were seen in 25 samples (34.7 percent) when the results of both methods were combined. With the pseudoreplica technique 22 samples (30.6 percent) contained the viral particles; with differential centrifugation 21 (29.2 percent) had particles. This study demonstrates that the two methods are equally reliable for demonstrating reovirus-like particles in stool samples. We believe that the pseudoreplica technique, which is quicker and less expensive than differential centrifugation, is the preferred method for clinical studies of diarrhea associated with reovirus-like particles.