A school outbreak of Norwalk-like virus: evidence for airborne transmission

Abstract

An outbreak of gastroenteritis affected a school attended by children aged 4-11 years. Epidemiological features suggested this was due to Norwalk-like virus (NLV) and this was confirmed by polymerase chain reaction (PCR). Nucleotide sequence analysis of the PCR amplicons revealed identical strains in all five positive stool samples. Pupils were significantly more likely to become ill following an episode of vomiting within their classroom (adjusted odds ratio 4.1, 95% CI 1.8-9.3). The times from exposure to illness were consistent with direct infection from aerosolized viral particles where exposure to vomiting was high. Cleaning with quaternary ammonium preparations made no impact on the course of the outbreak. However, the outbreak stopped after the school closed for 4 days and was cleaned using chlorine-based agents. This study confirms the importance of vomiting in the transmission of NLV and provides evidence that direct infection with aerosolized viral particles occurs.

Genetic diversity of noroviruses in Brazil

“…GII.6 circulated in PE (Northeast Region), ES, MG, RJ and SP (Southeast Region) from 2003(Castilho et al 2006, Barreira et al 2010.…”

“…It is transmitted faeco-orally by ingesting contaminated food and water. However, infection can also occur through person-person contact, fomites or by aerosols produced during vomiting (Fankhauser et al 2002, Lopman et al 2002, Marks et al 2003. These infections are often reported in nursing homes, kindergartens, hospitals, schools, cruise ships, restaurants, military installations and resorts (Leuenberger et al 2007, Podewils et al 2007, Rizzo et al 2007, Verhoef et al 2008.…”

Hospitalization due to norovirus and genotypes of rotavirus in pediatric patients, state of Espírito Santo

“…Although NoV is primarily transmitted by the fecaloral route, vomit carries the additional risk for nosocomial transmission through generation of infectious aerosol, an important airborne source of transmission (Marks et al 2003). Four cases positive for NoV occurred in children admitted to the hospital for causes other than gastroenteritis, suggesting nosocomial transmission.…”

Genetic Analysis of Noroviruses in Chiba Prefecture, Japan, between 1999 and 2004

“…They are one of the most common causes of gastroenteritis and have been detected in fecal samples from both humans (12,15,28) and animals (20,30,37). Human-associated NV outbreaks resulting from ingestion of contaminated water or food, such as oysters (4,5,18,23), and outbreaks in public places, particularly hospitals, schools, and cruise ships (9,11,22,36), pose an important public health problem.Reverse transcription-PCR (RT-PCR) and sequencing of the partial viral genome are the most popular and useful procedures for obtaining epidemiological and genetic information on NVs. Human NVs can be divided into two genogroups, genogroups GI and GII, by genetic analysis of the RNA polymerase and capsid regions (1, 15), with several genotype classifications having been reported independently (1,16,33).…”

“…They are one of the most common causes of gastroenteritis and have been detected in fecal samples from both humans (12,15,28) and animals (20,30,37). Human-associated NV outbreaks resulting from ingestion of contaminated water or food, such as oysters (4,5,18,23), and outbreaks in public places, particularly hospitals, schools, and cruise ships (9,11,22,36), pose an important public health problem.…”