Outbreaks of so-called winter vomiting disease, caused by norovirus, have a significant impact on health services at a time when they are least able to bear the strain. Now, rapid diagnostics from R-Biopharm Rhône have come to the rescue.
Norovirus is a genetically diverse group of single-stranded RNA, non-enveloped viruses belonging to the Caliciviridae family. Five genogroups have been identified (Gl, Gll, Glll, GlV and GV), and the groups commonly isolated in cases of acute gastroenteritis belong to genogroups GI and GII. Strains belonging to one particular cluster (GII.4) are those frequently associated with outbreaks in closed or semiclosed environments. The infective dose is as little as 10–100 virus particles and is transmitted by direct contact with infected persons, or from contaminated surfaces or food.
Outbreaks are most common during the winter months of October to March, but low-level occurrence can be seen throughout the year. According to the Health Protection Agency (HPA), laboratory reported cases represent only a fraction of the true number of cases that occur, as many people who have gastroenteritis do not go to their doctor.
In most individuals, the infection is self-limiting and lasts for two to three days. Symptoms present as watery diarrhoea and projectile vomiting. A 2001–2006 study of gastroenteritis in the elderly in England and Wales1 suggests that 20% of deaths in persons aged 65 and older with infectious gastroenteritis other than that caused by Clostridium difficile were associated with norovirus, and that a further 13% of non-infectious disease was associated with norovirus. The study concluded that a possible 80 deaths each year in persons of 65 years and over may be associated with norovirus infection. In 2001 it was estimated that infectious disease accounted for 26% of deaths worldwide.2
In January 2009 the HPA introduced a web-based voluntary reporting system. In the first six months a total of 350 outbreaks were recorded. Of these, 290 (81%) resulted in ward closures, with 50 NHS trusts reporting an average of seven outbreaks each. Furthermore, 42 NHS trusts experienced either full or partial closure to new admissions, with wards closed for an average of 7.2 days and 3.2 bed-days lost per day of closure.
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