An outbreak due to a norovirus GII.Pe-GII.4 Sydney_2012 recombinant in neonatal and pediatric intensive care units.

Background: Noroviruses are the major cause of gastroenteritis outbreaks worldwide in all age groups. The several genotypes, mutation, and recombination events guarantee the broad diffusion and maintenance of these viruses in the general human population. We described an outbreak caused by a norovirus recombinant strain screened in samples obtained from children and hospital staff affected in an outbreak of diarrhea at neonatal and pediatric intensive care units in Southeastern Brazil.

Methods: Noroviruses were investigated by PCR and the genotype was determined by sequencing both partial genes regions of RNA-dependent RNA-polymerase (ORF1) and capsid protein (ORF2); the recombination event was performed using SimPlot. Rotaviruses were investigated by real-time PCR targeting the NSP3 gene.

Results: The GII.Pe-GII.4 Sidney_2012 norovirus recombinant was detected in four from among six children with diarrhea and in four symptomatic contacts; the rotavirus was negative in all samples. The virus was introduced by a hospital staff member affecting other staff members and patients of the pediatric intensive care unit. Five days lapsed between the first and last diarrhea case caused by norovirus and the outbreak was restrained through strict hand hygiene, environment disinfection and limiting the contact of infected persons.

Conclusions: The outbreak was due to the GII.Pe-GII.4 Sydney_2012 variant that occurred in the same year of its first description in the world.