Entity

Time filter

Source Type


Opsteegh M.,National Institute for Public Health and the Environment RIVM | Opsteegh M.,University Utrecht | Teunis P.,National Institute for Public Health and the Environment RIVM | Mensink M.,National Institute for Public Health and the Environment RIVM | And 4 more authors.
Preventive Veterinary Medicine | Year: 2010

Lamb and mutton are considered important sources of human Toxoplasma gondii infections, but actual data on the prevalence of T. gondii in sheep in the Netherlands is lacking. The aim of this study was to investigate the prevalence of T. gondii in slaughtered sheep to get more insight in the importance of sheep as a source of human infection. In addition, regional variation in prevalence was studied, as this may indicate differences in environmental contamination. An in-house ELISA that detects antibodies against T. gondii was developed and used to test 1179 sera collected from sheep presented at 11 Dutch slaughterhouses between October and December 2007. Since validation of the serological assay was hampered by a lack of appropriate reference sera, the diagnostic performance and seroprevalence were estimated by fitting a binormal mixture model. ROC-curve analysis on the fitted distributions showed high discriminatory power (AUC=0.995), and high sensitivity and specificity of the ELISA. The overall prevalence was estimated at 27.8% (25.6-29.9%), but was significantly higher in sheep over 1 year old, and in sheep from the central provinces. The high sensitivity and specificity of the in-house ELISA were confirmed by Bayesian analysis together with three commercially available assays: Toxo-Screen DA (bioMérieux), Chekit Toxotest Antibody ELISA (IDEXX), and Toxoplasmosis serum screening ELISA (Institut Pourquier). In conclusion, the binormal mixture model proved a useful method to obtain estimates of diagnostic performance and seroprevalence without use of reference sera. The seroprevalence in sheep was high, and as sheep with antibodies usually carry tissue cysts, this indicates that undercooked lamb and mutton may indeed be important sources of human toxoplasmosis in the Netherlands. © 2010 Elsevier B.V. Source


Opsteegh M.,National Institute for Public Health and the Environment RIVM | Opsteegh M.,University Utrecht | Teunis P.,National Institute for Public Health and the Environment RIVM | Teunis P.,Emory University | And 4 more authors.
International Journal for Parasitology | Year: 2011

The role of beef in human infections with Toxoplasma gondii is not clear. To get a better understanding of the value of seroprevalence as an indication of the role of beef in human infections with T. gondii we studied the seroprevalence of T. gondii in Dutch cattle and analysed the correlation between detection of antibodies and parasitic DNA. An indirect ELISA was developed and used to test a sample of the Dutch cattle population. Since validation of the ELISA was hampered by a lack of sufficient bovine reference sera, the results were analysed in two different ways: using a cut-off value that was based on the course of the OD in 27 calves followed from birth until 16. months of age, and by fitting a mixture of two normal distributions (binormal mixture model) to the log-transformed ODs observed for the different groups of cattle in the study population. Using the cut-off value, the seroprevalence was estimated at 0.5% for white veal, 6.4% for rosé veal and 25.0% for cattle. However, using the frequency distributions the prevalences were higher: 1.9% for white veal, 15.6% for rosé veal and 54.5% for cattle. Next, for 100 cattle the results with two different serological assays (ELISA and Toxo-Screen DA) were compared with detection of parasites by our recently developed sensitive magnetic capture PCR. Toxoplasma gondii DNA was detected in only two seronegative cattle. This discordance demonstrates that seroprevalence cannot be used as an indicator of the number of cattle carrying infectious parasites. Demonstrating parasitic DNA in seronegative cattle and not in seropositive cattle suggests that only recent infections are detectable. Whether beef from these PCR-positive cattle is infectious to humans remains to be studied. © 2010 Australian Society for Parasitology Inc. Source


de Bruin A.,National Institute for Public Health and the Environment RIVM | de Groot A.,National Institute for Public Health and the Environment RIVM | de Heer L.,National Institute for Public Health and the Environment RIVM | Bok J.,Max Planck Institute for Psycholinguistics | And 4 more authors.
Applied and Environmental Microbiology | Year: 2011

Q fever, caused by Coxiella burnetii, is a zoonosis with a worldwide distribution. A large rural area in the southeast of the Netherlands was heavily affected by Q fever between 2007 and 2009. This initiated the development of a robust and internally controlled multiplex quantitative PCR (qPCR) assay for the detection of C. burnetii DNA in veterinary and environmental matrices on suspected Q fever-affected farms. The qPCR detects three C. burnetii targets (icd, com1, and IS1111) and one Bacillus thuringiensis internal control target (cry1b). Bacillus thuringiensis spores were added to samples to control both DNA extraction and PCR amplification. The performance of the qPCR assay was investigated and showed a high efficiency; a limit of detection of 13.0, 10.6, and 10.4 copies per reaction for the targets icd, com1, and IS1111, respectively; and no crossreactivity with the nontarget organisms tested. Screening for C. burnetii DNA on 29 suspected Q fever-affected farms during the Q fever epidemic in 2008 showed that swabs from dust-accumulating surfaces contained higher levels of C. burnetii DNA than vaginal swabs from goats or sheep. PCR inhibition by coextracted substances was observed in some environmental samples, and 10- or 100-fold dilutions of samples were sufficient to obtain interpretable signals for both the C. burnetii targets and the internal control. The inclusion of an internal control target and three C. burnetii targets in one multiplex qPCR assay showed that complex veterinary and environmental matrices can be screened reliably for the presence of C. burnetii DNA during an outbreak. © 2011, American Society for Microbiology. Source


Hassan Z.H.,Food and Consumer Product Safety Authority VWA | Hassan Z.H.,South Kalimantan Assessment Institute for Agriculture Technology | Zwartkruis-Nahuis J.T.M.,Food and Consumer Product Safety Authority VWA | De Boer E.,Food and Consumer Product Safety Authority VWA
International Food Research Journal | Year: 2012

This study was conducted to determine the prevalence of Vibrio parahaemolyticus in seafood samples in The Netherlands. In total 200 seafood samples, including fish, shrimp, oyster and mussel, collected from the retail market in The Netherlands were examined for the occurrence of V. parahaemolyticus using both a cultural and a direct PCR-based method. Two different selective media, thiosulfate citrate bile salts agar (TCBS) and CHROMagar Vibrio (CV), were evaluated for their efficacy to isolate V. parahaemolyticus from seafood samples. The results showed that there were no differences among the two media to isolate V. parahaemolyticus from all seafood samples (P > 0.05). Using the cultural method, V. parahaemolyticus was isolated from 16 (8%) and 27 (13.5%) samples, on TCBS and CV plates respectively. All the positive samples were mussels and oysters. Of the 43 isolates of V. parahaemolyticus (on TCBS and CV) obtained, none of the isolates was positive for the genes tdh or trh. The PCR-based method was performed at 0 (t=0), 6 (t=6), and 18 (t=18) hours after the enrichment step and allowed the detection of V. parahaemolyticus in 22 (11%) and 38 (19%) samples, with the DNA extracts prepared from the first enrichment (t=6 h) and the second enrichment (t=18 h) respectively. None of the samples were detected to be V. parahaemolyticus-positive when the DNA extracts were prepared from the sample homogenate before the enrichment step (t=0 h). © 2008 IFRJ, Faculty of Food Science & Technology, UPM. Source


Martena M.J.,Food and Consumer Product Safety Authority VWA | van der Wielen J.C.A.,Food and Consumer Product Safety Authority VWA | Rietjens I.M.C.M.,Wageningen University | Klerx W.N.M.,Food and Consumer Product Safety Authority VWA | And 2 more authors.
Food Additives and Contaminants - Part A Chemistry, Analysis, Control, Exposure and Risk Assessment | Year: 2010

Traditional herbal preparations used in Ayurveda, traditional Chinese medicine, traditional Tibetan medicine, and other Asian traditional medicine systems may contain significant amounts of mercury, arsenic or lead. Though deliberately incorporated in Asian traditional herbal preparations for therapeutic purposes, these constituents have caused intoxications worldwide. The aim of this study was therefore to determine mercury, arsenic, and lead levels in Asian traditional herbal preparations on the Dutch market. A total of 292 traditional herbal preparations used in Ayurveda, traditional Chinese medicine, and traditional Tibetan medicine were sampled between 2004 and 2007. Samples were mostly multi-ingredient traditional herbal preparations containing herbs and minerals. The labeling of less than 20% of the traditional herbal preparations suggested the presence of mercury, arsenic or lead. These elements were shown by inductively coupled mass spectrometry (ICP-MS) in 186 (64%) of 292 traditional herbal preparations. Estimated weekly mercury, arsenic, and lead intake levels were calculated for each traditional herbal preparation from the analytically determined concentrations and the recommended dose. A total of 59 traditional herbal preparations (20%) were likely to result in intakes of these elements significantly exceeding safety limits. Of these 59 traditional herbal preparations, intake estimates for 50 traditional herbal preparations significantly exceeded the safety limit for mercury (range = 1.4-1747 mg week-1); intake estimates for 26 traditional herbal preparations significantly exceeded the safety limit for arsenic (range = 0.53-427 mg week-1) and intake estimates for eight traditional herbal preparations were significantly above the safety limit for lead (range = 2.6-192 mg week-1). It is concluded that the mercury, arsenic, and lead contents of traditional herbal preparations used in Ayurveda, traditional Chinese medicine, and traditional Tibetan medicine remain a cause for concern and require strict control. © 2010 Taylor & Francis. Source

Discover hidden collaborations