http://repub.eur.nl/res/aut/26718/ List of Publications en http://repub.eur.nl/static-eur/img/logo.png http://repub.eur.nl http://repub.eur.nl/res/pub/26495/ 2011-09-07T00:00:00Z The main objective of this thesis was to investigate the etiology of outbreaks of viral gastroenteritis that remained without diagnosis after testing for common viral pathogens causing gastroenteritis, e.g. noroviruses, rotaviruses, sapoviruses, adenoviruses, and astroviruses. No causative pathogen could be detected in over 10% of these outbreaks. Viral gastroenteritis is about the most frequent disease in humans and this unexplained fraction concerns about 150000 cases in the Netherlands each year. Here, an overview of the state of the art of the literature on viral gastroenteritis is provided. http://repub.eur.nl/res/pub/34096/ 2011-03-01T00:00:00Z Although norovirus infection is generally known to be a mild disease, there is some evidence for severe outcome. An outbreak in a Dutch psychiatric institution, originating from pilgrims returning from Lourdes (France), provided an opportunity for performing a retrospective cohort study in order to identify risk factors for norovirus disease and excess mortality. Relative risks (RR) including 95% confidence intervals (CI) showed that attending the pilgrimage (RR 20, 95% CI 14-30) and age >70 (RR 17, 95% CI 12-22) were risk factors for symptomatic infection. In a subset of patients, for whom more detailed information was available, the use of statins was associated with norovirus disease when adjusted for underlying condition (adjusted odds ratio 39, 95% CI 12-130). Mortality was higher in cases infected during the pilgrimage compared to other residents (RR 209, 95% CI 47-938). Norovirus disease can lead to severe outcome. The newly identified risk of statins for contracting norovirus disease may have considerable consequences for the Western world and needs prospective confirmation. http://repub.eur.nl/res/pub/21512/ 2010-11-01T00:00:00Z http://repub.eur.nl/res/pub/27662/ 2010-06-01T00:00:00Z Sapoviruses (SaVs) belong to the Caliciviridae family and can cause gastroenteritis in humans and swine. Despite extensive testing, human sapoviruses have been found only in sporadic cases and in one mixed outbreak in children between 1994 and 2007 in the Netherlands. Here we describe a change in sapovirus epidemiology in the Netherlands resulting in sapovirus outbreaks and infections in adults. From November 2007 to January 2009, 478 outbreaks of acute gastroenteritis were reported to the National Institute for Public Health and the Environment in the Netherlands as a part of ongoing surveillance. Sapoviruses were found to be the most likely cause of 19 outbreaks (4%). During the same 2-year period, sapovirus infections were reported in Sweden, Slovenia, and Hungary. In the Netherlands, further characterization of outbreak strains showed that 12 (63%) sapovirus outbreaks were caused by genotype I.2 viruses. Most patients were adults older than 60 years (range, 1 to 100 years). Phylogenetic analysis using all presently available SaV sequences showed high homology between genotype I.2 strains detected in different geographical regions (Sweden, Slovenia, Taiwan, Japan, and Russia) since 2007. These first reported outbreaks of sapovirus infections in adults in the Netherlands were remarkable. Detection of identical genotypes in many samples might suggest that these viruses have the same origin, and since the infection is spreading fast, the prevalence of sapovirus infection may be increasing. The incidence of sapovirus infections in these countries suggests that a substantial part of Europe is affected by this virus. Copyright http://repub.eur.nl/res/pub/28193/ 2010-06-01T00:00:00Z The coincidental increase in norovirus outbreaks and Clostridium difficile infection (CDI) raised the question of whether these events could be related, e.g. by enhancing spread by diarrhoeal disease outbreaks. Therefore, we studied the prevalence of C. difficile in outbreaks of viral gastroenteritis in nursing homes for the elderly and characterised enzyme immunoassay (EIA)-positive stool samples. Stool samples from nursing home residents (n=752) in 137 outbreaks of viral aetiology were investigated by EIA for the presence of C. difficile toxins. Positive samples were further tested by a cell neutralisation cytotoxicity test, a second EIA and culture. Cultured isolates were tested for the presence of toxin genes, the production of toxins and characterised by 16S rRNA polymerase chain reaction (PCR) and sequencing. Twenty-four samples (3.2%) tested positive in the EIA. Of these 24 positive samples, only two were positive by cytotoxicity and three by a second EIA. Bacterial culture of 21 available stool samples yielded a toxinogenic C. difficile PCR ribotype 001 in one patient sample only. In conclusion, we found no evidence in this retrospective study for an association between viral gastroenteritis outbreaks and C. difficile. The high rate of false-positive EIA samples emphasises the need for second confirmation tests to diagnose CDI. http://repub.eur.nl/res/pub/24454/ 2009-04-01T00:00:00Z Different viruses belonging to the genus Vesivirus infect a broad range of animals, and cause gastroenteritis, vesicular skin lesions, hemorrhagic disease, respiratory diseases and other conditions. A recent report on Vesivirus viremia, as detected by PCR, in samples from patients with hepatitis of unknown etiology in the USA suggested a zoonotic potential for vesiviruses. These results have not been confirmed by another laboratory. In order to do so, a generic PCR assay on the RNA polymerase region was developed, and validated with RNA from 69 different Vesivirus species. Except SMSV serotype-8, all species tested were detected, including the ones that were suggested to be involved in zoonotic transmission in the USA (SMSV serotype-5). The generic Vesivirus assay was used on RNA extracted from serum samples from patients with hepatitis, stool samples from patients with gastroenteritis, throat-swab specimens of patients with rash illnesses, throat-swab and nose-swabs of patients with acute respiratory diseases, and cell cultures with cytopathologic effect from enterovirus surveillance in which no pathogen was found. None were found positive. In this study a generic Vesivirus assay was developed and it was concluded that vesiviruses are an unlikely cause of common illnesses in humans in the Netherlands.