Norovirus is aptly called the winter vomiting disease because of its symptoms (vomiting and diarrhoea) and its seasonality, although it can strike any time of the year. It is highly contagious and outbreaks have occurred in hospitals, nursing homes, schools and cruise ships.
Although the illness can be quite unpleasant, it should only last a few days. Advice is to rest, keep hydrated and try not to infect anyone else. Prevention is better than cure so good hygiene is important. Although there is very little probiotic research on norovirus, a trial has been conducted with L. casei Shirota.
Study: Norovirus in an elderly cohort
Effect on illness associated with norovirus gastroenteritis (elderly residents) - Nagata et al. (2011) Brit J Nutr 106(4):549-56.
Method: This open label study of seventy-seven subjects (mean age 84 years) was conducted in a residential home in Japan during winter. Intervention was an L. casei Shirota fermented milk drink given to 39 residents; a control group of 38 did not receive the probiotic. Efficacy was assessed by looking at records of illness for the month of December when there were norovirus cases.
Results: The mean duration of fever >37 °C after onset of illness was 1.5 days (SD 1.7) in the probiotic group compared to 2.9 days (SD 2.3) in the control group, which was a significant reduction (P < 0.05). There was, however, no significant difference in incidence of norovirus gastroenteritis during this month.
Faecal analysis of a sub-group of subjects found a significant increase in numbers of Bifidobacterium (P < 0.05) and Lactobacillus (P < 0.01) after one month on the probiotic. After two months there was a significant decrease in levels of Enterobacteriaceae and Pseudomonas (P < 0.05).