Nosocomial Norovirus Outbreaks Research Articles

Nosocomial Norovirus Outbreak Associated with Persistent Norovirus Excretion in a Patient Receiving Corticosteroid Therapy

Nosocomial Norovirus Outbreak Associated with Persistent Norovirus Excretion in a Patient Receiving Corticosteroid Therapy

Nosocomial Transmission of Norovirus Is Mainly Caused by Symptomatic Cases

Nosocomial norovirus (NoV) infection is common and may increase the burden of disease in healthcare settings, particularly in vulnerable hospitalized patients. Implementing effective infection control during and after admission may limit further spread, but evidence-based measures are lacking. In this study, we performed a systematic evaluation of sources and modes of transmission during NoV outbreaks within 2 types of healthcare facilities. An outbreak protocol was developed to sample all patients and healthcare workers (HCWs) with and without symptoms on wards involved in outbreaks. Data on clinical history and possible high-risk exposures were collected. Five outbreaks were investigated, involving 28 patients with recognized symptomatic NoV infection. Enhanced sampling, however, yielded 65 additional cases, of whom 14% (n = 9) were asymptomatic patients, 57% (n = 37) were symptomatic HCWs, and 17% (n = 11) were asymptomatic HCWs. For 12% (n = 8), clinical data were not provided (2 HCWs and 6 patients). On the basis of the shedding kinetics, the onset of infection was estimated for each case. The generation interval was then used to construct plausible transmission pathways and reproduction numbers for symptomatic and asymptomatic patients and HCWs. We found that symptomatic patients and HCWs were more often involved in transmission events than asymptomatic shedders. Asymptomatic HCWs rarely contributed to transmission, despite high levels of fecal virus shedding.

A review of nosocomial norovirus outbreaks: infection control interventions found effective

The purpose of this study was to review documented outbreaks of enteric illness associated with nosocomial norovirus infections and to identify modes of transmission, morbidity and mortality patterns, and recommendations for control. Searches of electronic databases, public health publications, and federal, state/provincial public health websites were completed for 1 January 2000 to 31 December 2010. Computer-aided searches of literature databases and systematic searches of government websites identified 54 relevant outbreak reports. Transmission routes included person-to-person (18.5%), foodborne (3.7%) and in the majority (77.8%) the route was unknown. Actions taken during the outbreak to control infection included restricting the movements of patients and staff (22.5%), enhanced environmental cleaning (13.6%) and hand hygiene (10.3%). Rapid identification of norovirus outbreaks in hospitals is vital for the immediate implementation of infection control measures and isolation of infected individuals in this mainly immunocompromised population. Studies that statistically evaluate infection control measures are needed.

Investigation and Control of a Nosocomial Norovirus Outbreak in a Long-Term Care Facility

Investigation and Control of a Nosocomial Norovirus Outbreak in a Long-Term Care Facility

Electronic outbreak surveillance in Germany: a first evaluation for nosocomial norovirus outbreaks.

BackgroundIn Germany, surveillance for infectious disease outbreaks is integrated into an electronic surveillance system. For 2007, the national surveillance database contains case-based information on 201,224 norovirus cases, three-quarters of which are linked to outbreaks. We evaluated the data quality of the national database in reflecting nosocomial norovirus outbreak (NNO) data available in 19 Hessian local public health authorities (LPHAs) and the influence of differences between LPHA's follow-up procedures for laboratory notifications of Norovirus positive stool samples on outbreak underascertainment.MethodsData on NNO beginning in 2007 and notified to the 19 LPHAs were extracted from the national database, investigated regarding internal validity and compared to data collected from LPHAs for a study on NNO control. LPHAs were questioned whether they routinely contacted all persons for whom a laboratory diagnosis of norovirus infection was notified. The number of outbreaks per 1,000 hospital beds and the number of cases within NNOs for acute care and rehabilitation hospitals were compared between counties with and without complete follow-up.ResultsThe national database contained information on 155 NNOs, including 3,115 cases. Cases were missed in the national database in 58 (37%) of the outbreaks. Information on hospitalisation was incorrect for an estimated 47% of NNO cases. Information on county of infection was incorrect for 24% (199/820) of cases being forwarded between LPHAs for data entry. Reported NNO incidence and number of NNO cases in acute care hospitals was higher in counties with complete follow-up (incidence-rate ratio (IRR) 2.7, 95% CI 1.4–5.7, p-value 0.002 and IRR 2.1, 95% CI 1.9–2.4, p-value 0.001, respectively).ConclusionsMany NNOs are not notified by hospitals and differences in LPHA procedures have an impact on the number of outbreaks captured in the surveillance system. Forwarding of case-by-case data on Norovirus outbreak cases from the local to the state and national level should not be required.

Two nosocomial norovirus outbreaks in the neonatal intensive and intermediate care unit

Norovirus is one of the major causes of non-bacterialacute gastroenteritis worldwide. Diagnostic methods in-clude electron microscopy, enzyme-linked immunosorbentassay (ELISA) and reverse-transcription polymerase chainreaction (RT-PCR) [1]. Electron microscopy has previous-ly been regarded as the gold standard for the diagnosis ofnorovirus, but RT-PCR appears to be a more sensitiveassay (36 to 58% versus 94 to 98%), with similarspecificity(96to98%and92to100%)[2, 3]. Studieson the sensitivity and specificity of the RIDASCREENenzyme immunoassay reported a broad range of 36 to 59%and73to100%,respectively[4, 5] (CDC, Atlanta, GA,USA). However, data for preterm and term born babies israre. Recent studies of norovirus in very young infantshave presumed many false-positive results and havequestioned the high specificity of enzyme immunoassay[2, 6]. The aim of this report is to characterise twooutbreaks of norovirus in neonatal nurseries by raisingquestions about the performance of diagnostic assays fornorovirus and the clinical presentation of norovirusinfectioninveryyounginfants.Faecal specimens of all tested persons were sent to theInstitute of Hygiene, Microbiology and EnvironmentalMedicine of the Medical University of Graz immediatelyafter collection or on the following day. Analysis wasdone for norovirus, adenovirus and rotavirus using anenzyme immunoassay (RIDASCREEN Norovirus ELISAkit, 3rd Generation) and/or real-time PCR (ANDIATECNorovirus real-time PCR kit, Bioproducts Company,designed to detect norovirus genotypes I and II). There-fore, stool cultures on bacteria and parasites were alsodone. To assess the clinical severity of disease, a 14-pointscoring system by Colomba et al. [7] was used. Duringboth outbreaks, the clinical records of all patients werecarefully documented and strict hygienic measures, in-cluding the cohorting of patients, mandatory use of glovesand gowns, and hand washing with disinfecting agents(Skinman® Soft N, Ecolab, Vienna, Austria), wereimplemented at the particular unit. Approval by theEthical Review Board was not necessary since the studywas performed by means of prospective surveillanceinvolving both outbreaks.First outbreak: January to March 2007In January 2007, a neonatologist on duty developedsymptoms of gastroenteritis, including fever, vomiting anddiarrhoea. The day after, the index patient (see Table 1),hospitalized at the Neonatal Intensive Care Unit (NICU) ofthe Pediatric Department of the Medical University Hospi-tal of Graz, Austria, recalled symptoms of bloody tingedstools for one day (14-point severity score: 6). Faecalspecimens of this infant and of the staff member were testedon virus, bacteria and parasites, and turned out to bepositive for norovirus tested by ELISA. Subsequently,faecal specimens of all neonates admitted to and treated atthe NICU were routinely tested three times a week byELISA and, due to repeatedly positive results, some of thespecimens were additionally tested by RT-PCR.

Clinical characteristics of nosocomial norovirus outbreaks in Hong Kong

Norovirus outbreaks occur worldwide every year and have become more frequent over the last few years. There were extensive outbreaks in Hong Kong from May to July 2006 and our aim was to describe nosocomial outbreaks from 1 May 2006 to 31 July 2006 in this retrospective observational study. A total of 38 confirmed norovirus outbreaks involving 218 patients were identified. Most of these patients were elderly with a mean age of 74.5 years (range: 3 months to 97 years); 62% of them were either totally or partially dependent for help with daily activities, 83.9% had underlying chronic medical problems and 56% had limited mobility. In all, 97.2% of individuals presented with diarrhoea and only 46.3% of them had vomiting. The median duration for diarrhoea was 3 days and the longest 24 days. The median duration of vomiting was one day and the longest 15 days. Fever occurred in one-third of all cases. Reverse transcriptase-polymerase chain reaction was positive for norovirus in 72.6% cases. We conclude that nosocomial norovirus infection often involves frail elderly patients with limited mobility and that these patients may have more prolonged symptoms.

Two nosocomial norovirus outbreaks at the neonatal intensive and intermediate care unit

Objective: Norovirus infection in preterm and term neonates rarely has been described. We report on two nosocomial norovirus outbreaks at the neonatal intensive care unit (NICU) and the Neonatal Intermediate Care Unit of the Paediatric Department of the Medical University Graz, Austria. Methods: Observational study on two nosocomial outbreaks of norovirus disease. Symptoms of infection in preterm and term neonates are described. Norovirus was detected in faecal specimen by ELISA and/or PCR technique. Results: Episode I at the NICU: Between January and March 2007, 22 of 44 preterm infants were tested positive for norovirus. Out of 174 faecal specimen 63 (36%) tested positive by ELISA, thirteen specimen tested additionally by PCR were negative. Only the index patient developed symptoms with bloody stools for one day. Viral shedding longer than two weeks was observed in six (27%) patients with maximum 39 days. Episode II at the Neonatal Intermediate Care Unit: Between December 2007 and January 2008 five of 36 neonates were tested positive for norovirus. All had clinical symptoms including vomiting and mild diarrhea in one patient and short-lasting diarrhea in four patients. Isolation of the infants and strict hygiene measures hardly stopped spread of disease. By discharge four of five patients still showed viral shedding. Conclusion: Although spread of disease is difficult to confine, symptoms of disease are generally mild and self-limited in this population. However, we question the reliability of the norovirus-specific antigen assay by the fact of negative PCR testing during the first episode

Outbreak Management and Implications of a Nosocomial Norovirus Outbreak

Noroviruses are enterically transmitted and are a frequent cause of gastroenteritis, affecting 23 million people annually in the United States. We describe a norovirus outbreak and its control in a tertiary care hospital during February-May 2004. Patients and health care workers met the case definition if they had new onset of vomiting and/or diarrhea during the outbreak period. Selected stool samples were tested for norovirus RNA. We also determined outbreak costs, including the estimated lost revenue associated with unit closures, sick leave, and cleaning expenses. We identified 355 cases that affected 90 patients and 265 health care workers and that were clustered in the coronary care unit and psychiatry units. Attack rates were 5.3% (7 of 133) for patients and 29.9% (29 of 97) for health care workers in the coronary care unit and 16.7% (39 of 233) for patients and 38.0% (76 of 200) for health care workers in the psychiatry units. Thirteen affected health care workers (4.9%) required emergency department visits or hospitalization. Detected noroviruses had 98%-99% sequence identity with representatives of a new genogroup II.4 variant that emerged during 2002-2004 in the United States (e.g., Farmington Hills and other strains) and Europe. Aggressive infection-control measures, including closure of units and thorough disinfection using sodium hypochlorite, were required to terminate the outbreak. Costs associated with this outbreak were estimated to be $657,644. The significant disruption of patient care and cost of this single nosocomial outbreak support aggressive efforts to prevent transmission of noroviruses in health care settings.

院内感染早期探知のための症候群サーベイランスの基礎的研究

To detect nosocomial outbreaks early we construct syndromic surveillance for inpatients with fever, respiratory symptoms, diarrhea, vomiting, or rash and evaluate it statistically. In hospital using electronic medical records since August 1999, we studied the number of inpatients with a certain symptoms from 1999 to 2005. To prospectively detect outbreaks after January 1, 2005, we first estimated the baseline using data from August 1, 1999 to the day before any given day. We then predicted the number of patients on the day and judge whether an outbreak has occurred, evaluating this by checking it sensitivity and specificity to detect outbreaks other than those with previous patterns. From August 1999 to December 2005, 115,532 patients had fever, 126,443 respiratory symptoms, 87,923 diarrhea, 32,858 vomiting, and 11,212 In 2005, in prospective detection, 23,617 had fever, 23,698 respiratory symptoms, 14,671 diarrhea, 5,893 vomiting, and 2,486 rash. This hospital had a nosocomial Noro virus outbreak on January 27, 2005. Syndromic surveillance identified an outbreak of vomiting at a 0.1% criterion. Our system thus detects nosocomial outbreaks and is of practical use. The next step will be ward-by-ward examination, after which we will experiment with rapid information collection, analysis, reports of results, and investigation by infection control teams.

Impact of an Outbreak of Norovirus Infection on Hospital Resources

To describe a nosocomial norovirus outbreak, its management, and its financial impact on hospital resources. A matched case-control study and microbiological investigation. We compared 16 patients with norovirus infection with control-patients matched by age, gender, disease category, and length of stay. Bed occupancy-days during the peak incidence period of the outbreak were compared with the corresponding periods in 2001 and 2002. Expenses due to increased workload were calculated based on a measuring system that records time spent for nursing care per patient per day. The attack rates were 13.9% among patients and 29.5% among healthcare workers. The median number of occupied beds was significantly lower due to bed closure during the peak incidence in 2003 (29) compared with the median number of occupied beds in 2001 and 2002 combined (42.5). Based on this difference and a daily charge of 562.50 dollars per patient, we calculated a revenue loss of 37,968 dollars. Additional expenses totaled 10,300 dollars for increased nursing care. Extra costs for microbiological diagnosis totaled 2707 dollars. Lost productivity costs due to healthcare workers on sick leave totaled 12,807 dollars. The expenses for work by the infection control team totaled 1408 dollars. The financial impact of this outbreak on hospital resources comprising loss of revenue and extra costs for microbiological diagnosis but without lost productivity costs, increased nursing care, and expenses for the infection control team totaled 40,675 dollars. Nosocomial norovirus outbreaks result in significant loss of revenue and increased use of resources. Bed closures had a greater impact on hospital resources than increased need for nursing care

Evaluation of the Impact of the Source (Patient Versus Staff) on Nosocomial Norovirus Outbreak Severity

To study the dependence of infection risk and outbreak size on the type of index case (i.e., patient or staff). Nosocomial outbreaks were reviewed and categorized into those started by patients and those started by staff. Infection risks and outbreak sizes were evaluated taking into account the index case category. Of the 30 nosocomial outbreaks of norovirus with person-to-person transmission, 20 (67%) involved patients as the index cases. Patient-indexed outbreaks affected significantly more patients than did staff-indexed outbreaks (difference in means, 16.25; 95% confidence interval [CI95], 5.1 to 27.0). For the numbers of affected staff, no dependence on the index case category was detectable (difference in means, -1.05; CI95, -9.0 to 6.9). For patients exposed during patient-indexed outbreaks, the risk of acquiring a norovirus infection was approximately 4.8 times as high as the corresponding risk for patients exposed during staff-indexed outbreaks (odds ratio [OR], 4.79; CI95, 1.82 to 8.28). The infection risk for exposed staff during patient-indexed outbreaks was approximately 1.5 times as high as the corresponding risk during staff-indexed outbreaks (OR, 1.51; CI95, 0.92 to 2.49). Patient-indexed norovirus outbreaks generally affect more patients than do staff-indexed outbreaks. Staff appear to be similarly affected by both outbreak index category groups. This study demonstrates the importance of obtaining complete outbreak data, including the index case classification as staff or patient, during norovirus outbreak investigations. Such information may be useful for further targeting prevention measures