Human noroviruses (HuNoVs) are a leading cause of foodborne gastroenteritis worldwide and spread easily among humans via the faecal-oral route. A low infective dose, a high viral load in the vomit and faeces of infected persons, a lack of long-term immunity following previous infection, and a high environmental stability of the viruses all enhance the spreading of HuNoV in the population.

The aim of this doctoral thesis is to investigate the prevalence of HuNoVs on environmental surfaces and to observe and measure virus transfer during manual food preparation. A method for the detection of HuNoV is optimized and used in the laboratory and also in field studies, both in a resort and in food preparation premises. Finally, ultraviolet light irradiation (UV) is tested as a means to inactivate the HuNoVs from environmental surfaces.

HuNoV and its surrogate murine norovirus (MuNoV) were detected from environmental surfaces by swabbing, after which the viruses were eluted from the swabs and their genomes were extracted by a commercial kit. HuNoV and MuNoV genomes were detected using reverse transcription quantitative polymerase chain reaction (RT-QPCR) method using specific primers and probes. The effects of UV on the viruses were investigated both by viability assays (MuNoV) and by RT-QPCR (MuNoV and HuNoV). An enzymatic pre-PCR treatment was conducted before RT-QPCR detection to distinguish infective viruses from non-infective viruses.

Out of the four swab materials tested for swabbing HuNoV on surfaces, the recovery rates of the viruses were highest for swabs made of microfiber and polyester. When stored at 4⁰C, HuNoV persisted well in swabs, whereas at 22⁰C, viruses persisted better on swabs moistened by phosphate buffered saline (PBS, pH 7.2) than by glycine buffer pH 9.5.

HuNoV and MuNoV transferred easily from the hands to the gloves when gloving. The viruses were also repeatedly transferred to the first recipient surface (left hand, cucumber, and knife) during the sandwich preparation process. Virus-contaminated gloves were estimated to spread HuNoV to the food servings more efficiently than a single contaminated cucumber can during handling.

In a resort, where a gastroenteritis outbreak had taken place, HuNoV was detected in 10/36 swabs (27.8%) taken from environmental surfaces and further genotyped as a new variant, GII.4 Sydney_2012. In the field study that was conducted in three food-processing companies with no recently reported outbreaks of gastroenteritis, 5/90 swabs (5.6%) in 2010, 4/168 swabs (2.4%) in 2011, and 7/82 swabs (8.5%) in 2012 were found to be HuNoV GII-positive. The positives were detected in a production line and from the food handlers break room and restroom areas.

UV was observed as a potential inactivation method for HuNoV: a loss of infectivity and a 4 log10 reduction of HuNoV surrogate MuNoV were observed when the virus-containing surfaces were exposed to UV dose of 60 mJ/cm2 or higher. Methods based on genome detection seemed to overestimate HuNoV persistence even when samples were pre-treated before the RT-QPCR was conducted.

As seen in the studies included in the thesis, HuNoV is transmitted very easily from hands to food and environmental surfaces. Proper hand hygiene combined with effective measures to inactivate HuNoV from surfaces, such as UV, is needed to manage the transmission of the virus. Adequate monitoring of the environment for virus contamination in potential fountainheads of gastroenteritis outbreaks, such as in hospitals and restaurants serving RTE foods, could prevent or restrict HuNoV outbreaks.

DVM Maria Rönnqvist will defend her doctoral dissertation entitled “Noroviruses on surfaces: Detection, transfer and inactivation” in the Faculty of Veterinary Medicine, University of Helsinki, on Friday 24th October 2014 at 12. The public examination will take place at the Walter Hall, EE Building, Agnes Sjöbergin katu 2, Helsinki.

Docent Veli-Jukka Anttila, will serve as the opponent, and Professor Marja-Liisa Hänninen as the custos.

Textbook Meat Inspection and Control in the Slaughterhouse was published in August 2014. It is a up-to-date reference book, which responds the changing needs of meat inspection and control.

The book is targeted at international use, primarily for veterinary students and vocational post-graduate degree students, but the book is also suitable for other meat inspection and control experts. Food safety, infectious diseases of animals, and animal welfare meet at the slaughterhouses, and that the book dealt with in many ways.

The authors are international experts in the field. The book is edited by DVM Thimjos Ninios, DVM, PhD, Docent  Janne Lundén, Professor Hannu Korkeala and Professor Maria Fredriksson-Ahomaa.

The book presentation can be found in publisher’s page: http://eu.wiley.com/WileyCDA/WileyTitle/productCd-1118525868.html.

The Second International Meeting on Food Control Research” was held in Latvia, Riga on April, 9th-11th, 2014. The meeting discussed widely food control from the surveillance of food-borne diseases to the disclosure of food control inspections.

“Food control research is a central research area in environmental health control, which is gaining increasingly more visibility around the world. “Those who carry out food control appreciate that food control organizations and methods are exposed to research so that food control can be developed” tells Janne Lundén, who examines the efficiency of food control.

The meeting was attended by about 50 food control researchers from eleven different countries, including the United States, Ireland, the UK, Germany, Sweden, and Denmark.

Department of Food Hygiene and Environmental Health was strongly represented at the meeting, the meeting was attended by Professor Hannu Korkeala, University Lecturers Mari Nevas and Janne Lundén, as well as Doctoral Students Karoliina Kettunen, Jenni Luukkanen, Tiina Läikkö- Roto, and Satu Tähkäpää.

Department’s researchers presented the following lectures at the meeting:

• Introduction by Mari Nevas
• Food control methods by Janne Lundén
• Use of enforcement measures in the local food control units in Finland by Karoliina Kettunen
• Distribution of meat inspection tasks in the high-capasity slaughterhouses by Jenni Luukkanen
• Consistency in the inspection processes of food control officials as the disks by Tiina Läikkö-Roto
• Patterns of food frauds by Satu Tähkäpää.

The meeting was arranged by the Institute of Food Safety, Animal Health and Environment (BIOR) in collaboration with the Department of Food Hygiene and Environmental Health, Faculty of Veterinary Medicine, University of Helsinki, Latvia University of Agriculture, Ministry of Agriculture of Latvia, Food and Veterinary Service.

The meeting was the second in order. The first meeting was held in Helsinki in 2008, and it was organized by the Department of Food Hygiene and Environmental Health. The next meeting will be held in Ireland 2017.

The homepage of the meeting: http://www.bior.gov.lv/en/left-menu/news/meeting-2014

DVM Sonja Virtanen will defend the doctoral dissertation entitled “Epidemiology of Yersinia enterocolitica on pig farms” in the Faculty of Veterinary Medicine, University of Helsinki, on 21st February 2014 at 12:00. The public examination will take place at the following address: Biokeskus 2, auditorium 1041, Viikinkaari 5.

Professor Mikael Skurnik, University of Helsinki, will serve as the opponent, and Professor Hannu Korkeala as the custos.

The dissertation is also available in electronic form through the http://urn.fi/URN:ISBN:978-952-10-9745-4.