A four-year study conducted by Japanese scientists focused on the occurrence of rotavirus diarrhea among adults. Nearly 700 adults were studied and examined for the presence of group A rotavirus using Rotaclone, an enzyme linked immunosorbent assay kit. The virus was detected in 108 of the patients, but further testing eliminated 11 of those people who had pathogenic bacteria including Vibrio parahemolyticus and Campylobacter jejuni, leaving 14 percent of the entire patient pool infected with rotavirus. To eliminate the possibility that rotavirus was not causing the diarrheal symptoms, the authors obtained and tested stool samples from 115 hospital patients who exhibited other gastrointestinal symptoms other than acute diarrhea. The samples showed that 5 percent of the patients were found to be shedding rotavirus, indicating a significant enough increase in the virus appearing in adults during the study. "Unlike rotavirus diarrhea in infants and young children, which shows a significant winter seasonality, the distribution of rotavirus-positive cases were deviated toward warmer months and showed a seasonality in which peak incidence occurs in mid-April," the authors note. The researchers conclude that not only is it vital to recognize rotavirus in elderly patients, but physicians should regard rotavirus as a cause of diarrheal diseases in adults, with variations in degree by age and season, as it does in infants and children.