Infection of exposed patients during norovirus outbreaks – Are there predictive parameters?

Summary Background Norovirus outbreak management comprises isolation and cohorting of patients. In this context, exposed patients are preferably cohorted separately from symptomatic and unexposed asymptomatic patients, since they potentially develop symptoms of norovirus gastroenteritis. Whether routinely examined clinical or laboratory parameters can help predicting occurrence of gastroenteritis symptoms in those patients has not yet been examined. Aim To evaluate routinely examined clinical and laboratory parameters as predictive values for the development of norovirus symptoms in exposed patients during outbreaks. Methods Exposed patients during norovirus outbreaks were observed throughout a two year period in the university hospital of Muenster. The development of laboratory confirmed norovirus gastroenteritis symptoms was examined in exposed patients and clinical as well as laboratory parameters prior to onset of the outbreak were compared in exposed symptomatic and asymptomatic patients. Findings We detected 42 exposed patients within 10 outbreaks. Of these, 33 remained asymptomatic, while nine patients developed norovirus gastroenteritis. Exposed symptomatic patients were significantly older (50 ± 10.51 years vs. 28 ± 4.68 years), had significantly higher blood sodium concentration (142.5 ± 1.48 mmol/l vs. 138.8 ± 0.47 mmol/l) and higher systolic blood pressure (119.3 ± 3.84 mmHg vs. 108.5 ± 2.41 mmHg). Development of symptoms among exposed patients was significantly associated with blood type 0 (75% vs. 20%). Conclusions In order to minimize patient-to-patient transmission within norovirus outbreaks in hospital, risk stratification of exposed patients is helpful. To achieve this, routinely detected clinical and laboratory parameters can be useful to predict development of symptoms in these patients.