Diarrhea is a common symptom among patients from middle- and long-term facilities.
Clostridium difficile and Norovirus are the main causes of epidemic gastroenteritis.
Preemptive measures (geographic isolation, specific precautions) are infrequent.
A 2-step laboratory-based polymerase chain reaction approach using a new Norovirus assay is efficient.
Beyond this pilot study the impact on outbreak prevention should be evaluated.