Norovirus is a leading cause of acute gastroenteritis (AGE) in all age groups. Although at least 28 different genotypes infecting humans have been reported, most outbreaks over the last 15 years have been caused by genogroup II (GII) viruses, of which GII.4 viruses have caused more than 50%. Since clinical differences between different genotypes are poorly understood, we sought to compare clinical characteristics in children infected with GII.4 and non-GII.4 viruses.
Children between 15 days and 17 years who presented with AGE defined as diarrhea (≥3 loose stools in a 24 hour period) or vomiting (≥1 episodes in a 24 hour period) within 10 days duration were recruited in outpatient, emergency, and inpatient settings in Nashville, TN, during 2012-2015. Stool specimens were tested by RT-qPCR for GI and GII norovirus. Norovirus-positive specimens were genotyped by sequencing of a partial region of the capsid gene. In this study, we excluded children infected with GI, mixed GI/GII and non-typeable GII viruses.
Of 3705 AGE subjects enrolled, 2892 (78%) specimens were collected, 637 (22%) tested norovirus-positive (567 [89%] GII, 62 [10%] GI, and 8 [1%] mixed GI/GII). Of the 567 GII viruses, 461 (81%) were able to be genotyped and of those 238/461(51.6%) were typed as GII.4 and 223/461(48.3%) were typed as other GII genotypes (non-GII.4, primarily GII.3 [65/ 461, 14.1%], GII.6 [48/461, 10.4%] and GII.7 [36/461, 7.8%]. Over three AGE seasons, GII.4 represented 64/117 (54%), 79/178 (44%), and 71/166 (57%), of the GII infections, respectively. Compared to non-GII.4 subjects, GII.4 subjects were more likely to be younger (15.5 vs. 21.3 months, p<0.01), and less likely to attend daycare (23% vs. 39%, p<0.01). GII.4 subjects also were more likely to present with diarrhea (75% vs. 57%, p<0.01) and had higher median modified Vesikari score (7 vs. 6, p<0.01).
Children infected with GII.4 viruses were younger, less likely to attend child care, more likely to present with diarrhea, and had a more severe illness compared to those with non-GII.4 infections. These data provide important information on the genotype distribution of norovirus in children with AGE in Tennessee and highlight GII.4 as the most prevalent strain.
B. Piya, None
L. Stewart, None
J. D. Chappell, None
J. Dunn, None
D. C. Payne, None
M. E. Wikswo, None
J. Vinjé, None
A. J. Hall, None
N. Halasa, Sanofi Pasteur: Investigator , Research support . GSK: Consultant , Consulting fee . Moderna: Consultant , Consulting fee .