Our paper on rates of norovirus disease in the community and presenting to primary care in the UK has just been published in the Journal of Infectious Diseases. This is part of a special supplement on norovirus, including a number of articles covering research expenditure on norovirus, norovirus epidemiology, control of hospital outbreaks and new research developments.
Norovirus is the most common cause of viral gastroenteritis worldwide and causes frequent outbreaks in healthcare settings and other closed environments, such as long-term care homes and cruise ships. It is also responsible for a tremendous burden of disease in the community. We have previously estimated that in the UK alone, there are approximately 3 million cases of norovirus gastroenteritis each year. About 128,000 result in consultations to primary care. Most of this disease is mild and self-limiting, but results in a substantial economic burden, as well as a burden on health services.
For this paper, we estimated the rates of norovirus disease in the UK for different age groups, both in the community and presenting to primary care. This is one of only a few studies reporting empirical estimates of age-specific rates of norovirus. The reason for this is that very few prospective studies in the community have been done that allow for such estimates. For our analysis, we used data from the Second Study of Infectious Intestinal Disease in the UK (IID2). We conducted this study in 2008-9 and recruited over 6000 participants of all age groups who reported on a weekly basis whether or not they had symptoms of gastroenteritis. Those who reported being ill also provided samples for laboratory analysis, to help us find out what caused their illness. Based on our analysis we found that children under 5 years have the highest rates of norovirus disease; about 14% of children will experience an episode of norovirus gastroenteritis in a given year. This is about 10 times higher than older individuals. About 10% of these children will see a doctor for their illness.
These results indicate that, unlike the burden of norovirus outbreaks, which falls predominantly among elderly individuals in healthcare settings, the burden of non-outbreak related norovirus disease in the community falls predominantly on children. This has been understood for some time, although empirical data to demonstrate this have been lacking. It also has important implications for understanding the epidemiology of norovirus, for example, to what extent transmission in the community and in institutions is related. With the advent of promising norovirus vaccines, these data will also be useful for informing vaccination strategies in the community, and mathematical models to study the potential impact of vaccination programmes.