Koen De Schrijver
University of Antwerp
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Featured researches published by Koen De Schrijver.
Journal of Clinical Virology | 2009
Emmanuel Robesyn; Koen De Schrijver; Elke Wollants; G Top; Jannick Verbeeck; Marc Van Ranst
BACKGROUND In July 2004, a sharp increase of hepatitis A, a notifiable disease in Belgium, was detected. OBJECTIVES We investigated the outbreak in order to identify the source and take appropriate action. STUDY DESIGN We conducted an outbreak investigation which included a matched case-control study to analyse the association with a range of food items and food providers. A phylogenetic analysis was used to study the relation between the outbreak cases and the identified source. RESULTS We registered 269 cases of hepatitis A. Consumption of raw beef (OR 16.0; 95% CI 2.1-120.7) was the most probable way of infection. A food handler working at an epidemiologically linked meat distribution plant had contracted hepatitis A 1 month before the start of the outbreak. HAV strains from the food handler and the patients involved in the outbreak were monophyletically related. CONCLUSIONS Since serological immunity in Belgium is decreasing over time, foodborne outbreaks of hepatitis A are a substantial risk. In this outbreak, a single food handler, at the level of the distribution chain, has been identified as the most likely source, through cross-contamination of raw beef. This outbreak investigation suggests the need to consider vaccination against hepatitis A in food handlers.
European Journal of Epidemiology | 2003
Koen De Schrijver; I Maes
In 2001 an outbreak of Neisseria menigitidis serogroup C occurred in the province of Antwerp (Belgium). Over a year the incidence rate of meningococcal disease (MD) increased from 3.9 per 100,000 to 9.1 per 100,000 with a shift from serogroup B (87%) in 2000 to serogroup C (66%) in 2001. The most prominent phenotype was C:2a:P1.2,5. The incidence rate for serogroup C MD increased from 0.4 per 100,000 to 4.5 per 100,000 in 2001. The case fatality rate was 6.7% in 2001. After the introduction of a mass vaccination campaign with a conjugated vaccine against serogroup C MD the incidence of serogroup C MD fell from 4.5 to 1.8 per 100,000. As a result of the analysis of this outbreak, it was proposed to offer a vaccine against serogroup C to all people under 19 years of age. Part of this plan has been implemented to date in Belgium.
Value in Health | 2011
Jeroen Luyten; Christiaan Marais; Niel Hens; Koen De Schrijver; Philippe Beutels
OBJECTIVES To explore the impact of applying different non-standardized analytical choices for quality of life measurement to obtain quality-adjusted life years (QALYs). In addition to more widely discussed issues such as the choice of instrument (e.g. EQ-5D or SF-6D?) researchers must also choose between different recall periods, scoring algorithms and interpolations between points of measurement. METHODS A prospective survey was made among 114 Belgian patients with acute hepatitis A illness. Using non-parametric tests and generalized linear models (GLMs), we compared four different methods to estimate QALY losses, two based on the EQ-5D (administered during the period of illness without recall period) and two based on the SF-6D (administered after illness with 4 weeks recall period). RESULTS We found statistically significant differences between all methods, with the non-parametric SF-6D-based method yielding the highest median QALY impact (0.032 QALYs). This is more than five times as high as the EQ-5D-based method with linear health improvement, which yields the lowest median QALY impact (0.006 QALYs). CONCLUSIONS Economic evaluations of health care technologies predominantly use QALYs to quantify health benefits. Non-standardised analytical choices can have a decision-changing impact on cost-effectiveness results, particularly if morbidity takes up a substantial part of the total QALY loss. Yet these choices are rarely subjected to sensitivity analysis. Researchers and decision makers should be aware of the influence of these somewhat arbitrary choices on their results.
Vaccine | 2012
Jeroen Luyten; Stefaan Van de Sande; Koen De Schrijver; Pierre Van Damme; Philippe Beutels
Hepatitis A vaccination targeting adults (or adult risk-groups like e.g. travellers, health care workers, soldiers or teachers) could be considered an alternative to a universal infant or adolescent vaccination program in low endemic countries. We estimated the current disease burden of hepatitis A in Belgium, and evaluated whether adult vaccination is cost-effective. We used a Markov cohort model to simulate the costs and effects of (1) vaccination of adults and (2) serological screening of adults and vaccination of susceptibles and compared these with the current situation. The results indicated that these expanded vaccination strategies are not cost-effective in the epidemiological circumstances of a typical low-endemic western country. In order to gain 1 quality-adjusted life year the health care payer would have to pay 185,000€ for vaccination and 223,000€ for screening and vaccination of seronegatives. For adult vaccination to be cost-effective, risk-groups would need to be exposed to a force of infection that is 3.5-4 times higher than currently estimated in the general population; or the total costs of vaccination would have to drop with approximately 75%.
Tijdschrift Voor Bedrijfs- En Verzekeringsgeneeskunde | 2016
Koen De Schrijver; Francis Vercammen; Yves Alen
SamenvattingVier (4/9; 44,4%) van de negen dierenverzorgers van de zoo van Planckendael (België) die instonden voor het onderhoud van de kooien van recent aangekomen lori’s of die werkten op de quarantaine-afdeling, maakten in mei 2014 psittacose door. De evolutie van de met ELISA bepaalde antistoffen (IgM, IgG) tegen C. psittaci was kenmerkend voor een recent doorgemaakte infectie. In de positieve vogelmengmestmonsters (4/32; 12,5%) die getest werden via PCR kwam C. psittaci voor. Hetzelfde gold voor de positieve leverweefselmonsters (6/38; 15,8%). Naast de behandeling van de vogels, de quarantaine, de desinfectie en het onderhoud van de kooien en de surveillance via PCR op vogelmest en leverweefselmonsters, berustte de preventie van deze infectie op het voorkomen van stofvorming en inademing van aerosols van excreta van de vogels. Het dragen van een FFP2-masker en het niet gebruiken van hogedrukreinigers en stofzuigers en het nat schoonmaken van de kooien droegen bij tot de indijking.SummaryFour out of nine (4/9; 44.4%) zoo workers who were exposed to newly arrived lories by cleaning cages and working at the quarantine unit of the zoo of Planckendael (Belgium), tested positive on C. psittaci, and developed clinical psittacosis in May 2014. They presented significantly rising titers (IgM, IgG) tested positive with ELISA to C. psittaci in paired sera. C. psittaci was found in several avian faecal samples (4/32; 12.5%) and in avian liver specimens (6/38; 15.8%) by PCR. Risk prevention comprised quarantine of incoming birds and sick birds, treatment of the birds, disinfection and regular cleaning of cages, frequent wet-mopping of the floor, surveillance by PCR on bird droppings and liver specimens and prevention of dust formation and aerosolization of bird excreta. Wearing protective FFP2 masks and avoidance of use of high pressure ventilators and aspirators had attributed in control of transmission.
Journal of Medical Microbiology | 2005
K Dirven; Margareta Ieven; Marcel F. Peeters; Anneke van der Zee; Koen De Schrijver; Herman Goossens
Archive | 2008
Philippe Beutels; Jeroen Luyten; Olivier Lejeune; Niel Hens; Joke Bilcke; Koen De Schrijver; Stefaan Van de Sande; Koen Van Herck; Pierre Van Damme
Travel Medicine and Infectious Disease | 2007
Koen De Schrijver; Hilde Boeckx; G Top; An Mertens; Patrick De Mol
Vlaams Infectieziektebulletin | 2012
Koen De Schrijver; Toon Braeye; Daniël Van den Branden; Sander Vanwanrooy; Guy E. Boeckxstaens; Marc Van Ranst
Bulletin Infectieziekten | 2010
Emmanuel Robesyn; Koen De Schrijver; Sophie Quoilin; Daniel Reynders; Marc Van Ranst