Norovirus. Photo: CDC/ Charles D. Humphrey, PhD

New method reveals where viruses hide

Tuesday 12 Jul 16


Anna Charlotte Schultz
Senior Researcher
National Food Institute
+45 35 88 73 56

A method that can detect different disease-causing viruses on surfaces like countertops and fixtures, has been developed in a project at the National Food Institute, Technical University of Denmark. The method can be used to test for the presence of viruses in the environment in places like childcare centres, nursing homes, hospitals and food production premises. Test results make it possible to focus cleaning on the places that are the biggest sources of infection.

Viruses are the cause of many of the gastrointestinal and respiratory infections, which cause thousands of Danes to get sick each year. In addition to direct transfer of infection between people many viruses are probably transferred via infected surfaces such as hands, sinks and tables. However, effective methods to test this presumption have been limited.

A method to detect different disease-causing viruses on surfaces has now been developed in a project at the National Food Institute.

Method makes targeted cleaning possible

The method makes it possible for e.g. childcare centres, nursing homes, hospitals and food production premises to test for the presence of viruses. The test results make it possible to focus cleaning on the surfaces that are at greatest risk of transmitting infection.

Among the food sources that most often cause norovirus in people is food prepared in institutions, restaurants or catering companies. This is partly because food handlers themselves are infected or via their relatives carry the virus while they are working, and partly because they return to work after having recovered from symptoms, although they still in fact are carriers of the infection by continuous viral shedding.

The test method from the National Food Institute can be used e.g. in the regular cleaning control system of the institution or food establishment, or after an employee or a guest has vomited to check whether the subsequent cleaning has been sufficient to stop the virus from spreading.

Broad application

Norovirus has been used as the model virus in this method development. This is partly because norovirus is one of the most significant causes of gastrointestinal infections worldwide, and partly because it is so contagious that just a few virus particles can make a person sick. Studies have furthermore shown that norovirus can be transferred to virtually any surface and survive there for weeks at room temperature, months at refrigeration temperatures and years at freezer temperatures.

The method can also be applied to a number of other viruses.

The National Food Institute is constantly working to further develop this and other methods that can be used to detect viruses in food products and in environmental samples such as water, air and on surfaces. The aim is to use the methods to generate data from monitoring, disease outbreaks and intervention studies in order to better understand the risk posed by the various transmission routes.

Collected data are also used in risk assessments which regulators and industry can use to improve efforts to control and reduce virus contamination.

Read more

The work to develop and validate the new method is described in further detail in a scientific article in the Journal of Hospital Infection: Test and validation of methods to sample and detect human virus from environmental surfaces using norovirus as a model virus (pdf). The work has been carried out in cooperation with researchers from Rigshospitalet, as part of Tobias Ibfelt’s PhD project and with Senior Researcher Anna Charlotte Schultz from the National Food Institute as external supervisor.

The National Food Institute has extensive expertise in detecting virus in food and environmental samples. The institute has a history of carrying out the viral analyses of suspected food and environmental samples during the investigation of water and foodborne disease outbreaks in Denmark. In April 2016 the National Food Institute played a pivotal role in establishing that Lollo Bionda lettuce from France was the cause of one of Denmark’s biggest outbreaks of norovirus in recent years.

Visit the National Food Institute’s website for more information on the institute’s work to develop fast, reliable and cost-effective methods to test for the presence of unwanted microorganisms: Molecular diagnostics.