Detection of norovirus in mouthwash samples from patients with acute gastroenteritis

Background: Norovirus infection is characteristically associated with vomiting which is known to contain a high concentration of viral particles. The oral cavity is therefore likely to become contaminated with norovirus during episodes of gastroenteritis. Objective: To investigate the oral detection of norovirus in patients with norovirus gastroenteritis. Study design: Faecal and oral mouthwash samples were collected in two separate settings. In the first setting, samples were collected repeatedly over a 3-week period from six family members experiencing a domestic outbreak of norovirus gastroenteritis. Secondly, samples were collected at a single time point following disease onset from 59 patients hospitalised with norovirus gastroenteritis. Norovirus detection in oral and faecal samples was undertaken by RT-PCR. Results: In the family study, norovirus was detected in early morning mouthwash samples for 10-15 days following disease onset from each of six family members. In the hospital study, 14/59 hospitalised adults with norovirus infection had norovirus detected in mouthwashes (24%; 14-37% 95% C. I.). For the hospitalised adults, the detection of norovirus in mouthwash samples was associated with the presence of vomiting (p = 0.1); and in those patients with norovirus infection whose mouthwash samples were collected within 24 h of the onset of vomiting, 59% (10/17) had norovirus detected. Conclusions: Oral mouthwashes may provide an adjunct to faecal sampling to support the diagnosis of norovirus infection. The detection of norovirus in orally-derived material raises the possibility of oral-to-oral norovirus transmission, and that this potential for transmission may extend beyond the immediate symptomatic period. (C) 2010 Elsevier B. V. All rights reserved.