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Norovirus monitored worldwide

Erasmus MC's Department of Viroscience monitors the norovirus worldwide in close collaboration with the Dutch National Institute for Public Health and the Environment (RIVM) and other scientists within the Global NoroNet.

The norovirus causes 685 million cases of gastrointestinal infections each year and just like the influenza virus it has many strains and changes continuously. People are infected by three different genogroups, which in turn can be classified into 40 genotypes. Most infections in humans are caused by norovirus GII.4 and this virus changes over time by means of mutations. Therefore in order to develop a good vaccine, the norovirus must be closely monitored so that new strains can be responded to in good time.

Janko van Beek makes this recommendation in an article published in Lancet Infectious Diseases. Van Beek, who will defend his doctoral thesis on 11 April 2018 at Erasmus MC, compared data about the norovirus from the past 10 years. This revealed, for example, that 26 different genotypes have been detected based on differences in the capsid protein and that currently a new recombinant is circulating under the name GII.P16-GII.4 Sydney 2012.

Vomiting and diarrhoea
The norovirus causes almost one fifth of all gastrointestinal infections. As previously stated, the norovirus is responsible for 685 million cases per year worldwide of which 200 million cases in young children. For healthy people, the infection lasts a few days and causes diarrhoea and vomiting. But in vulnerable elderly people and people with a low resilience, the clinical picture can be far worse and persist for longer. The severe diarrhoea and vomiting can cause dehydration, which in turn can result in death.

It is therefore important that the norovirus is carefully monitored so that changes in the genetic properties can be detected in time. This is possible with the Global NoroNet, an enormous database containing information about the norovirus in relation to humans. Global NoroNet has existed since 2002 and accurately records worldwide outbreaks and mutations. It is maintained by the Department of Viroscience Erasmus MC, RIVM and partners in Asia, Europe, Oceania and Africa. By using Global NoroNet, all of these researchers can keep abreast of what is happening in other countries. The database records which type of norovirusses cause outbreaks, when the majority of outbreaks occur and where (nursing home, day nursery, office, cruise ship, et cetera). The Global NoroNet data revealed that in Europe and Asia, the majority of GII.4 norovirus outbreaks occur in the winter, whereas in New Zealand most of the infections occur in spring. It also revealed that GII.4 norovirus is relatively more often responsible for outbreaks in nursing homes compared to other norovirus variants.

Global Noronet also explores the genetic diversity and changes in the viruses over the years. With this information the researchers hope to gain an idea about which norovirus is the most important pathogen and how the virus evolves and spreads.

During the past two years, major advances have been made in research into the norovirus because the virus can now be successfully cultivated. This means that steps can now be taken to realise a thorough analysis of the virus and it will be simpler to test medicines and vaccines. Researcher Miranda de Graaf is leading this research within the Department of Viroscience and she also coordinates the international activities of Global Noronet in collaboration with RIVM.

Want to know more?
- Publication Lancet
Department of Viroscience
- Global Noronet

gepubliceerd: 4 oktober 2018

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