Practice parameters for diagnosing and managing iodinated contrast media hypersensitivity.

Immediate and nonimmediate hypersensitivity reactions to iodinated contrast media (ICM) have been reported to occur in a frequency of about 0.5%-3% of patients receiving nonionic ICM. The diagnosis and management of these patients vary among guidelines published by various national and international scientific societies, with recommendations ranging from avoidance or premedication to drug provocation test. This position paper aims to give recommendations for the management of patients with ICM hypersensitivity reactions and analyze controversies in this area. Skin tests are recommended as the initial step for diagnosing patients with immediate and nonimmediate hypersensitivity reactions; besides, they may also help guide on tolerability of alternatives. Re-exposition or drug provocation test should only be done with skin test-negative ICMs. The decision for performing either re-exposition or drug provocation test needs to be taken based on a risk-benefit analysis. The role of in vitro tests for diagnosis and pretreatment for preventing reactions remains controversial.

Peanut-induced anaphylaxis in children and adolescents: Data from the European Anaphylaxis Registry.

BACKGROUND: Peanut allergy has a rising prevalence in high-income countries, affecting 0.5%-1.4% of children. This study aimed to better understand peanut anaphylaxis in comparison to anaphylaxis to other food triggers in European children and adolescents. METHODS: Data was sourced from the European Anaphylaxis Registry via an online questionnaire, after in-depth review of food-induced anaphylaxis cases in a tertiary paediatric allergy centre. RESULTS: 3514 cases of food anaphylaxis were reported between July 2007 - March 2018, 56% in patients younger than 18 years. Peanut anaphylaxis was recorded in 459 children and adolescents (85% of all peanut anaphylaxis cases). Previous reactions (42% vs. 38%; p = .001), asthma comorbidity (47% vs. 35%; p < .001), relevant cofactors (29% vs. 22%; p = .004) and biphasic reactions (10% vs. 4%; p = .001) were more commonly reported in peanut anaphylaxis. Most cases were labelled as severe anaphylaxis (Ring&Messmer grade III 65% vs. 56% and grade IV 1.1% vs. 0.9%; p = .001). Self-administration of intramuscular adrenaline was low (17% vs. 15%), professional adrenaline administration was higher in non-peanut food anaphylaxis (34% vs. 26%; p = .003). Hospitalization was higher for peanut anaphylaxis (67% vs. 54%; p = .004). CONCLUSIONS: The European Anaphylaxis Registry data confirmed peanut as one of the major causes of severe, potentially life-threatening allergic reactions in European children, with some characteristic features e.g., presence of asthma comorbidity and increased rate of biphasic reactions. Usage of intramuscular adrenaline as first-line treatment is low and needs to be improved. The Registry, designed as the largest database on anaphylaxis, allows continuous assessment of this condition.

Management of allergy transfer upon solid organ transplantation.

Allergy transfer upon solid organ transplantation has been reported in the literature, although only few data are available as to the frequency, significance, and management of these cases. Based on a review of 577 consecutive deceased donors from the Swisstransplant Donor-Registry, 3 cases (0.5%) of fatal anaphylaxis were identified, 2 because of peanut and 1 of wasp allergy. The sera of all 3 donors and their 10 paired recipients, prospectively collected before and after transplantation for the Swiss Transplant Cohort Study, were retrospectively processed using a commercial protein microarray fluorescent test. As early as 5 days posttransplantation, newly acquired peanut-specific IgE were transiently detected from 1 donor to 3 recipients, of whom 1 liver and lung recipients developed grade III anaphylaxis. Yet, to define how allergy testing should be performed in transplant recipients and to better understand the impact of immunosuppressive therapy on IgE sensitization, we prospectively studied 5 atopic living-donor kidney recipients. All pollen-specific IgE and >90% of skin prick tests remained positive 7 days and 3 months after transplantation, indicating that early diagnosis of donor-derived IgE sensitization is possible. Importantly, we propose recommendations with respect to safety for recipients undergoing solid-organ transplantation from donors with a history of fatal anaphylaxis.

Fiction, Falsehoods, and Few Facts: Cross-Sectional Study on the Content-Related Quality of Atopic Eczema-Related Videos on YouTube.

BACKGROUND: In recent years, YouTube has become a recognized source of medical information for health care consumers. Although YouTube has advantages in this context, there are potential dangers as videos may contain nonscientific, misleading, or even harmful information. OBJECTIVE: As little is known about YouTube as a source of information on atopic dermatitis (AD), we investigated the content-related quality of AD videos and their perception among YouTube users. METHODS: The quality of the 100 most viewed AD videos was assessed by using the Global Quality Scale (GQS) and the DISCERN instrument. Videos were classified as "useful," "misleading," and "potentially harmful," and the correlations of viewers' ratings (likes) with the GQS and DISCERN scores were assessed. RESULTS: Among the 100 videos, 68.0% (68/100) and 62.0% (62/100) were of poor and very poor scientific quality, respectively. Additionally, 32.0% (32/100) of the videos were classified as useful, 48.0% (48/100) were classified as misleading, and 34.0% (34/100) were classified as potentially harmful. Viewers' ratings did not correlate with the GQS and DISCERN scores. Overall, 50.0% (50/100) of the videos were posted by private individuals and promoters of complementary/alternative treatments, 42.0% (42/100) by therapeutical advertisers, and only 8.0% (8/100) by nonprofit organizations/universities. CONCLUSIONS: Our study demonstrated that two-thirds of the videos analyzed were below acceptable medical quality standards and that many videos were disseminating misleading or even dangerous content. Subjective and anecdotal content was overrepresented, and viewers did not appear to be able to distinguish between high- and low-quality videos. Health promotion strategies by professional medical organizations are needed to improve their presence and visibility on YouTube.

An EAACI position paper on the investigation of perioperative immediate hypersensitivity reactions.

Perioperative immediate hypersensitivity reactions are rare. Subsequent allergy investigation is complicated by multiple simultaneous drug exposures, the use of drugs with potent effects and the many differential diagnoses to hypersensitivity in the perioperative setting. The approach to the investigation of these complex reactions is not standardized, and it is becoming increasingly apparent that collaboration between experts in the field of allergy/immunology/dermatology and anaesthesiology is needed to provide the best possible care for these patients. The EAACI task force behind this position paper has therefore combined the expertise of allergists, immunologists and anaesthesiologists. The aims of this position paper were to provide recommendations for the investigation of immediate-type perioperative hypersensitivity reactions and to provide practical information that can assist clinicians in planning and carrying out investigations.

The use of drug provocation testing in the investigation of suspected immediate perioperative allergic reactions: current status.

Suspected perioperative allergic reactions are often severe. To avoid potentially life-threatening re-exposure to the culprit drug, establishing a firm diagnosis and identifying the culprit is crucial. Drug provocation tests are considered the gold standard in drug allergy investigation but have not been recommended in the investigation of perioperative allergy, mainly because of the pharmacological effects of drugs such as induction agents and neuromuscular blocking agents. Some specialised centres have reported benefits of provocation testing in perioperative allergy investigation, but the literature on the subject is limited. Here we provide a status update on the use of drug provocation testing in perioperative allergy, including its use in specific drug groups. This review is based on a literature search and experiences of the authors comprising anaesthesiologists and allergists with experience in perioperative allergy investigation. In addition, 19 participating centres in the International Suspected Perioperative Allergic Reaction Group were surveyed on the use of provocation testing in perioperative allergy investigation. A response was received from 13 centres in eight European countries, New Zealand, and the USA. Also, 21 centres from the Australian and New Zealand Anaesthetic Allergy Group were surveyed. Two centres performed provocation routinely and seven centres performed no provocations at all. Nearly half of the centres reported performing provocations with induction agents and neuromuscular blocking agents. Drug provocation testing is being used in perioperative allergy investigation in specialised centres, but collaborations between relevant specialties and multicentre studies are necessary to determine indications and establish common testing protocols.

Management of suspected immediate perioperative allergic reactions: an international overview and consensus recommendations.

Suspected perioperative allergic reactions are rare but can be life-threatening. The diagnosis is difficult to make in the perioperative setting, but prompt recognition and correct treatment is necessary to ensure a good outcome. A group of 26 international experts in perioperative allergy (anaesthesiologists, allergists, and immunologists) contributed to a modified Delphi consensus process, which covered areas such as differential diagnosis, management during and after anaphylaxis, allergy investigations, and plans for a subsequent anaesthetic. They were asked to rank the appropriateness of statements related to the immediate management of suspected perioperative allergic reactions. Statements were selected to represent areas where there is a lack of consensus in existing guidelines, such as dosing of epinephrine and fluids, the management of impending cardiac arrest, and reactions refractory to standard treatment. The results of the modified Delphi consensus process have been included in the recommendations on the management of suspected perioperative allergic reactions. This paper provides anaesthetists with an overview of relevant knowledge on the immediate and postoperative management of suspected perioperative allergic reactions based on current literature and expert opinion. In addition, it provides practical advice and recommendations in areas where consensus has been lacking in existing guidelines.

C-Reactive Protein and Procalcitonin in Case Reports of Drug Reaction with Eosinophilia and Systemic Symptoms (DRESS) Syndrome.

BACKGROUND: The spectrum of inflammatory marker response in DRESS (drug reaction with eosinophilia and systemic symptoms) syndrome has not been systematically characterized. METHODS: An epidemiological biomarker study of C-reactive protein (CRP) and procalcitonin (PCT) values in patients with DRESS syndrome reported at 2 regional pharmacovigilance centers in Switzerland or published in the medical literature 2008-2016 was performed. RESULTS: Ninety-four DRESS cases were studied. All cases showed a CRP value > 10 mg/L (the upper limit of normal). The mean CRP value was 109.2 ± 79.4 mg/L. CRP values were significantly higher in 22 cases where a cause of inflammation besides DRESS could not be excluded (mean 162.1 vs. 92.9 mg/L; p = 0.003). Receiver operator characteristics curve analysis showed a moderate performance with a CRP cut-off value of 99.4 mg/L (AUC 0.717) to distinguish between patients with and without a possible additional cause of inflammation. The mean and median PCT values were 2.44 ± 5.94 and 0.69 ng/mL, respectively (n = 25 patients). Patients in whom an additional cause of inflammation besides DRESS could not be excluded showed a median PCT of 1.37 ng/mL (n = 9) versus 0.67 ng/mL (n = 16) in patients with DRESS only. PCT values were above the normal cut-off of 0.1 ng/mL, suggestive of bacterial infection in all but 1 case. Furthermore, there was a correlation between PCT values and hepatic enzyme measurements. CONCLUSIONS: Evaluating CRP and PCT values might be of use in helping physicians to distinguish between cases of DRESS syndrome with and without concurrent infection or other causes of inflammation. Further prospective investigation is required to define the use of these inflammatory markers in the management of DRESS.

Anaphylaxis in children and adolescents: The European Anaphylaxis Registry.

BACKGROUND: Anaphylaxis in children and adolescents is a potentially life-threatening condition. Its heterogeneous clinical presentation and sudden occurrence in virtually any setting without warning have impeded a comprehensive description. OBJECTIVE: We sought to characterize severe allergic reactions in terms of elicitors, symptoms, emergency treatment, and long-term management in European children and adolescents. METHODS: The European Anaphylaxis Registry recorded details of anaphylaxis after referral for in-depth diagnosis and counseling to 1 of 90 tertiary allergy centers in 10 European countries, aiming to oversample the most severe reactions. Data were retrieved from medical records by using a multilanguage online form. RESULTS: Between July 2007 and March 2015, anaphylaxis was identified in 1970 patients younger than 18 years. Most incidents occurred in private homes (46%) and outdoors (19%). One third of the patients had experienced anaphylaxis previously. Food items were the most frequent trigger (66%), followed by insect venom (19%). Cow's milk and hen's egg were prevalent elicitors in the first 2 years, hazelnut and cashew in preschool-aged children, and peanut at all ages. There was a continuous shift from food- to insect venom- and drug-induced anaphylaxis up to age 10 years, and there were few changes thereafter. Vomiting and cough were prevalent symptoms in the first decade of life, and subjective symptoms (nausea, throat tightness, and dizziness) were prevalent later in life. Thirty percent of cases were lay treated, of which 10% were treated with an epinephrine autoinjector. The fraction of intramuscular epinephrine in professional emergency treatment increased from 12% in 2011 to 25% in 2014. Twenty-six (1.3%) patients were either admitted to the intensive care unit or had grade IV/fatal reactions. CONCLUSIONS: The European Anaphylaxis Registry confirmed food as the major elicitor of anaphylaxis in children, specifically hen's egg, cow's milk, and nuts. Reactions to insect venom were seen more in young adulthood. Intensive care unit admissions and grade IV/fatal reactions were rare. The registry will serve as a systematic foundation for a continuous description of this multiform condition.

Immediate Type Hypersensitivity to Heparins: Two Case Reports and a Review of the Literature.

Immediate type hypersensitivity reactions due to heparins are rare, and the exact immunologic pathomechanism has not been identified so far. In our 2 case reports, we describe first a 50-year-old female who received dalteparin (Fragmin®) and developed signs of an immediate type hypersensitivity reaction. The personal history revealed a previous application of dalteparin (Fragmin®). Evaluation with a skin prick test showed positive results for dalteparin. The second case deals with a 73-year-old female with a suspected immediate type reaction after the administration of dalteparin (Fragmin®). A skin prick test was negative but intracutaneous tests showed a positive reaction to the causative agent. Both cases indicated cross-reactivity reactions for low-molecular-weight heparin (LMWH) but not for unfractioned heparin (UFH) or fondaparinux. In conclusion, our case reports including a review of published cases of immediate type hypersensitivity reactions after the application of heparins illustrate this rare complication. Mostly, the causative agent can be identified with a skin test, which is highly suggestive of an IgE-mediated reaction. Therapeutic alternatives for patients with sensitization to an LMWH are UFH and fondaparinux. Both agents have a small risk of cross-reactivity compared to heparins of the same substance class.

Nanometric molecular separation measurements by single molecule photobleaching.

Although considerable progress has been made in imaging distances in cells below the diffraction limit using FRET and super-resolution microscopy, methods for determining the separation of macromolecules in the 10-50 nm range have been elusive. We have developed fluorophore localisation imaging with photobleaching (FLImP), based on the quantised bleaching of individual protein-bound dye molecules, to quantitate the molecular separations in oligomers and nanoscale clusters. We demonstrate the benefits of using our method in studying the nanometric organisation of the epidermal growth factor receptor in cells.

Determining the geometry of oligomers of the human epidermal growth factor family on cells with <10 nm resolution.

There is a limited range of methods available to characterize macromolecular organization in cells on length scales from 5-50 nm. We review methods currently available and show the latest results from a new single-molecule localization-based method, fluorophore localization imaging with photobleaching (FLImP), using the epidermal growth factor (EGF) receptor (EGFR) as an example system. Our measurements show that FLImP is capable of achieving spatial resolution in the order of 6 nm.

A series of flexible design adaptations to the Nikon E-C1 and E-C2 confocal microscope systems for UV, multiphoton and FLIM imaging.

Multiphoton microscopy is widely employed in the life sciences using extrinsic fluorescence of low- and high-molecular weight labels with excitation and emission spectra in the visible and near infrared regions. For imaging of intrinsic and extrinsic fluorophores with excitation spectra in the ultraviolet region, multiphoton excitation with one- or two-colour lasers avoids the need for ultraviolet-transmitting excitation optics and has advantages in terms of optical penetration in the sample and reduced phototoxicity. Excitation and detection of ultraviolet emission around 300 nm and below in a typical inverted confocal microscope is more difficult and requires the use of expensive quartz optics including the objective. In this technical note we describe the adaptation of a commercial confocal microscope (Nikon, Japan E-C1 or E-C2) for versatile use with Ti-sapphire and OPO laser sources and the addition of a second detection channel that enables detection of ultraviolet fluorescence and increases detection sensitivity in a typical fluorescence lifetime imaging microscopy experiment. Results from some experiments with this setup illustrate the resulting capabilities.

Desensitization in patients with hypersensitivity to platinum and taxane in gynecological cancers.

BACKGROUND: Exposure to paclitaxel and carboplatin has the risk of developing hypersensitivity reactions (HSRs), which could necessitate using less effective treatments to avoid anaphylaxis. Desensitization to platinum and taxane HSRs can be used to complete chemotherapy according to the standard regimen; therefore, this study investigated rates and benefits of successful desensitization in patients with gynecologic cancers (GC). METHODS: We collected data from 241 patients with GC who had at least one cycle of platinum or taxane chemotherapy. The rate of HSRs and successful desensitization were evaluated, and an outcome analysis was conducted. RESULTS: The rate of HSRs to platinum and taxane was 6.39% and 13.07%, respectively. We observed a 100% success rate of desensitization in our cohort. Patients with HSR were significantly younger (57.1 vs. 64.9 years, p = 0.030) in the taxane cohort. Importantly, the overall survival (OS) of patients with platinum and taxane HSRs who underwent desensitization was comparable to that of patients with no HSRs (platinum vs. controls; median OS 60.36 vs. 60.39 months, p = 0.31; taxane vs. controls; OS 80.29 vs. 60.00 months, p = 0.59). CONCLUSION: Thus, we show that desensitization for platinum and taxane HSRs is safe and effective, resulting in an outcome that is well comparable to patients without HSR. Based on these observations, desensitization procedures might be considered as standard of care before switching to less effective treatment for patients with GC.

Analysis of an unusual cluster of systemic reactions to subcutaneous specific immunotherapy with respiratory allergens in one allergy center.

Systemic reactions to subcutaneous immunotherapy occur despite all necessary precautions and experienced staff and should prompt a search for causative factors. We present an analysis of 11 reactions, 8 of them within a short period. The patients and reactions were evaluated regarding extract errors (composition, concentration), dosing errors, ignored contraindications to specific subcutaneous immunotherapy, introductions versus maintenance phase and accidental intravascular injection. No single or common cause could be identified. Statistical analysis suggests that exceptional clusters of systemic reactions such as these may be just random cumulations without identifiable cause.

Allergic complications from orthopaedic joint implants: the role of delayed hypersensitivity to benzoyl peroxide in bone cement.

BACKGROUND: Orthopaedic implants and osteosynthesis materials are increasingly being used. Complications include mainly physical-mechanical problems and infections. Uncommonly, an allergic reaction towards an alloy metal or a bone cement component has been implicated. Potential bone cement allergens include acrylates, benzoyl peroxide, N,N-dimethyl-p-toluidine, and gentamicin. Typical symptoms are pain, swelling, inflammatory skin reactions, implant loosening, and fistula formation. OBJECTIVES: To report on 5 patients with complications from a knee or a shoulder joint implant in whom a relevant sensitization to benzoyl peroxide was shown. METHODS: Patch tests were performed with the European baseline series, an extended metal series, and a bone cement series. Patch tests with benzoyl peroxide were performed twice in all patients. A bone cement-free replacement was chosen in sensitized patients. RESULTS: In 4 patients sensitized to benzoyl peroxide, a bone cement-free replacement resulted in a considerable decrease or disappearance of pain and swelling, and complete clearing of cutaneous symptoms. CONCLUSIONS: Components of bone cement, such as benzoyl peroxide, may rarely cause allergic complications. However, because of the irritant potential of these substances, careful performance, reading and interpretation of the patch tests is required.

Contact dermatitis to para-phenylenediamine in hair dye following sensitization to black henna tattoos - an ongoing problem.

BACKGROUND: The increased frequency of case reports of allergic contact dermatitis from non-permanent black henna tattoos in recent years shows the popularity of this form of body painting. PATIENTS AND METHODS: Seven patients presented with allergic contact dermatitis after initial hair or eyelash dyeing. They all had a history of a previous reaction from a black henna tattoo. All were patch tested with the European standard patch test series and the standard supplemental series, as well as special series for dyes and hairdressers. RESULTS: All seven patients showed a positive reaction in patch testing with para-phenylenediamine (PPD) (0.3 % and/or 1.0 % in pet.). Five patients also had positive reactions to other dyes such as aminophenol, para-toluene diamine, disperse orange and yellow and four patients reacted to benzocaine. These were interpreted as cross-reactions. The time from sensitization by the black henna tattoo to the onset of allergic contact dermatitis after hair dyeing was an average of 6.2 years. CONCLUSIONS: The most common cause of allergic contact dermatitis after black henna tattoos is PPD. Both the long skin contact and the high concentrations of PPD increase the risk of sensitization. Allergic contact dermatitis may be followed by post-inflammatory hyper- or hypopigmentation, scarring and lifelong sensitization, which can have occupational impact, especially for hair dressers and cosmeticians.

Provoking allergens and treatment of anaphylaxis in children and adolescents--data from the anaphylaxis registry of German-speaking countries.

Anaphylaxis is the most severe reaction of an IgE-mediated hypersensitivity. Data about affected patients may help to improve our knowledge of anaphylaxis and its medical care. We analysed data from the anaphylaxis registry of German speaking countries with regard to the provoking allergens and treatment modalities of anaphylaxis in children and adolescents. Inclusion criteria were severe systemic allergic reactions with concomitant pulmonary and/or cardiovascular symptoms. The data are collected by a password-controlled online-questionnaire. For this analysis, data of 197 reported anaphylactic reactions from children and adolescents registered between 2006 and 2009 were included. The data show that within the registered cases the most frequently affected organ systems for children and adolescents were the skin (89%) and the respiratory tract (87%) followed by symptoms of the cardiovascular system (47%) and the gastrointestinal tract (43%). The most frequent elicitors were food allergens accounting for 58% of cases, followed by insect venom (24%) and drugs (8%). The most frequent food allergens were peanuts followed by tree nuts and animal related food products. In 18% aggravating factors such as physical exercise were noted by the clinicians. 26% of the analysed patients had experienced more than one reaction. The data regarding the emergency treatment show that antihistamines (87%) and corticosteroids (85%) were often used but that adrenaline was rarely used (22% of the registered cases). Taken together these data show that the analysis of anaphylaxis by registration of affected individuals can provide data about provoking allergens and treatment measures but also suggest the impact of aggravating factors on anaphylactic reactions. The under-represented usage of adrenaline indicates the need of educational measures for patients and their physicians.

Failure of omalizumab (Xolair®) in the treatment of a case of solar urticaria caused by ultraviolet A and visible light.

Solar urticaria is a rare photodermatosis probably caused by a chromophore, that - if activated by light of a specific spectrum - binds to mast cell-bound IgE and elicits degranulation. In our patient an action spectrum in ultraviolet A and visible light range was found, in the autologous serum test the presence of a serum chromophore for the same action spectra could be demonstrated, which may underline this pathogenetic hypothesis. Symptoms did not improve using antihistamines and sun protection. Photo hardening was denied from the patient, immunosuppression and plasmapheresis were discussed but not considered. So a treatment with Omalizumab was started that recently was successfully used in 4 case reports. After 3 doses of Xolair® there was no changing in the phototesting results and after 4 doses no subjective improvement.

Food-borne norovirus-outbreak at a military base, Germany, 2009.

BACKGROUND: Norovirus is often transmitted from person-to-person. Transmission may also be food-borne, but only few norovirus outbreak investigations have identified food items as likely vehicles of norovirus transmission through an analytical epidemiological study.During 7-9 January, 2009, 36 persons at a military base in Germany fell ill with acute gastroenteritis. Food from the military base's canteen was suspected as vehicle of infection, norovirus as the pathogen causing the illnesses. An investigation was initiated to describe the outbreak's extent, to verify the pathogen, and to identify modes of transmission and source of infection to prevent further cases. METHODS: For descriptive analysis, ill persons were defined as members of the military base with acute onset of diarrhoea or vomiting between 24 December 2008, and 3 February 2009, without detection of a pathogen other than norovirus in stools. We conducted a retrospective cohort study within the headquarters company. Cases were military base members with onset of diarrhoea or vomiting during 5-9 January. We collected information on demographics, food items eaten at the canteen and contact to ill persons or vomit, using a self-administered questionnaire. We compared attack rates (AR) in exposed and unexposed persons, using bivariable and multivariable logistic regression modelling. Stool specimens of ill persons and canteen employees, canteen food served during 5-7 January and environmental swabs were investigated by laboratory analysis. RESULTS: Overall, 101/815 (AR 12.4%) persons fell ill between 24 December 2008 and 3 February 2009. None were canteen employees. Most persons (n = 49) had disease onset during 7-9 January. Ill persons were a median of 22 years old, 92.9% were male. The response for the cohort study was 178/274 (72.1%). Of 27 cases (AR 15.2%), 25 had eaten at the canteen and 21 had consumed salad. Salad consumption on 6 January (aOR: 8.1; 95%CI: 1.5-45.4) and 7 January (aOR: 15.7; 95%CI: 2.2-74.1) were independently associated with increased risk of disease.Norovirus was detected in 8/28 ill persons' and 4/25 canteen employees' stools, 6/55 environmental swabs and 0/33 food items. Sequences were identical in environmental and stool samples (subtype II.4 2006b), except for those of canteen employees. Control measures comprised cohort isolation of symptomatic persons, exclusion of norovirus-positive canteen employees from work and disinfection of the canteen's kitchen. CONCLUSIONS: Our investigation indicated that consumption of norovirus-contaminated salad caused the peak of the outbreak on 7-9 January. Strict personal hygiene and proper disinfection of environmental surfaces remain crucial to prevent norovirus transmission.