LAUSR

To determine norovirus frequency, seasonal trends, disease severity and nosocomial acquisition in a region of Ireland. From November 18th 2016 to November 18th 2017, all children up to 3 y of age who presented to Mayo University Hospital with vomiting and diarrhea, had their stool tested for norovirus and other viruses. Each week of the year was studied in relation to the total number of stool samples requested for norovirus testing, the number of positive stool samples, the calculated median of positive stool samples in two consecutive weeks and their calculated median percentage of positive stool samples in each two consecutive week period. During the study period, norovirus was the third leading cause of gastroenteritis (12%), norovirus G2 was the predominant strain; 61% were male; 56% older than 1 y, 78% of cases were severe. No nosocomial disease was detected. The fifth week of January was the week peak. Viral Co- infection was confirmed in four cases of which astrovirus was confirmed in two cases. Three seasons of norovirus gastroenteritis and four short episodes of norovirus infection were noted during 2016/2017. Norovirus is a predominant cause of gastroenteritis. Co- infection with other viruses, mainly astrovirus may occur. Norovirus infections occur throughout the year with a peak in winter.