Acute gastroenteritis and enteric viruses: Impact on the detection of norovirus

Norovirus is the second cause of acute viral gastroenteritis in infants after rotavirus. However, its prevalence is underestimated because a specific diagnosis is not usually performed. The comparative study of microbiological diagnostics, performed before and after the implementation date of a test for detecting a particular microorganism, allows the estimation of the percentage of cases not properly diagnosed earlier (for non-implementation of the test) and those that would be left to diagnose if the test is removed. In this paper we study the epidemiology of acute gastroenteritis virus before and after the implantation of the Norovirus GI+GII CerTest. An observational retrospective cohort study was conducted on patients under 15 years old with acute gastroenteritis, from January 2013 to April 2015. The sample was divided into two groups. In the first group, the search was limited to adenovirus and rotavirus, and in the second one, the determination of norovirus became part of the systematic diagnosis. The study included 604 patients, 313 in the first group and 291 in the second one. Demographic characteristics were similar in both groups. In the first group, 58/313 (18.5%) enteric viruses were identified and in the second group, 97/291 (33.3%). In the second group, 31 positive cases for norovirus were identified, but only 12 (4.1%) of them were positive exclusively for this virus. No significant differences were found in clinical features of intestinal viruses. An actual increase of 4.1% was observed in the cases with an identified aetiological agent after implementing the Norovirus GI+GII CerTest diagnostic technique. The most common cause of acute gastroenteritis is rotavirus, closely followed by norovirus.