Noroviruses as cause of gastroenteritis in elderly patients.

BACKGROUND AND AIMS: Gastroenteritis is one of the infections which are particularly important in elderly people. Knowledge of the main pathogens causing gastroenteritis in this group of patients, whose number will dramatically increase in coming decades, is essential. The contribution of group A rotavirus, adenovirus types 41 and 42, norovirus and astrovirus as causes of gastroenteritis among patients of all ages, especially those with over 65 was evaluated over an extended time period. METHODS: A total of 4024 fecal samples, collected during seven seasons (October 2000 to September 2007), were tested with a commercial immunoassay (rotavirus) and an "in house" nested RT-PCR (adenovirus, norovirus and astrovirus). RESULTS: Although norovirus was the second most common cause of gastroenteritis (7.9%) in the total population, it was predominant in the age group over the age of 6, causing 7.2% of gastroenteritis in the 6-16-year-old group, 8.6% in the 16-64-year-old group, and 11.1% in the >65-year group (p=0.001). In the last age group, norovirus was the most frequently detected (11.1%), followed by adenovirus (7.4%), astrovirus (3.6%) and rotavirus (3.3%) (p<0.0001). In addition, norovirus was rarely found in association with other viruses. CONCLUSIONS: Our data suggest that the elderly are highly vulnerable to certain infections, and indicate the need to introduce simple tests for an early identification of norovirus in cases of gastroenteritis affecting elderly patients, improving patient care by reducing unnecessary treatments and hospital stays.