Helen Bernard

Epidemic Profile of Shiga-Toxin–Producing Escherichia coli O104:H4 Outbreak in Germany

BACKGROUND We describe an outbreak of gastroenteritis and the hemolytic-uremic syndrome caused by Shiga-toxin-producing Escherichia coli in Germany in May, June, and July, 2011. The consumption of sprouts was identified as the most likely vehicle of infection. METHODS We analyzed data from reports in Germany of Shiga-toxin-producing E. coli gastroenteritis and the hemolytic-uremic syndrome and clinical information on patients presenting to Hamburg University Medical Center (HUMC). An outbreak case was defined as a reported case of the hemolytic-uremic syndrome or of gastroenteritis in a patient infected by Shiga-toxin-producing E. coli, serogroup O104 or serogroup unknown, with an onset of disease during the period from May 1 through July 4, 2011, in Germany. RESULTS A total of 3816 cases (including 54 deaths) were reported in Germany, 845 of which (22%) involved the hemolytic-uremic syndrome. The outbreak was centered in northern Germany and peaked around May 21 to 22. Most of the patients in whom the hemolytic-uremic syndrome developed were adults (88%; median age, 42 years), and women were overrepresented (68%). The estimated median incubation period was 8 days, with a median of 5 days from the onset of diarrhea to the development of the hemolytic-uremic syndrome. Among 59 patients prospectively followed at HUMC, the hemolytic-uremic syndrome developed in 12 (20%), with no significant differences according to sex or reported initial symptoms and signs. The outbreak strain was typed as an enteroaggregative Shiga-toxin-producing E. coli O104:H4, producing extended-spectrum beta-lactamase. CONCLUSIONS In this outbreak, caused by an unusual E. coli strain, cases of the hemolytic-uremic syndrome occurred predominantly in adults, with a preponderance of cases occurring in women. The hemolytic-uremic syndrome developed in more than 20% of the identified cases.

Large multistate outbreak of norovirus gastroenteritis associated with frozen strawberries, Germany, 2012

From 20 September through 5 October 2012, the largest recorded food-borne outbreak in Germany occurred. Norovirus was identified as the causative agent. We conducted four analytical epidemiological studies, two case–control studies and two surveys (in total 150 cases) in secondary schools in three different federal states. Overall, 390 institutions in five federal states reported nearly 11,000 cases of gastroenteritis. They were predominantly schools and childcare facilities and were supplied almost exclusively by one large catering company. The analytical epidemiological studies consistently identified dishes containing strawberries as the most likely vehicle, with estimated odds ratios ranging from 2.6 to 45.4. The dishes had been prepared in different regional kitchens of the catering company and were served in the schools two days before the peaks of the respective outbreaks. All affected institutions had received strawberries of one lot, imported frozen from China. The outbreak vehicle was identified within a week, which led to a timely recall and prevented more than half of the lot from reaching the consumer. This outbreak exemplifies the risk of large outbreaks in the era of global food trade. It underlines the importance of timely surveillance and epidemiological outbreak investigations for food safety.

Epidemiology of norovirus gastroenteritis in Germany 2001-2009: eight seasons of routine surveillance.

We analysed data on laboratory or epidemiologically confirmed cases (n = 856,539) and on outbreaks (n = 31,644) notified during week 31 (2001) to week 30 (2009), and performed molecular typing of specimens from 665 outbreaks. We aimed at identifying demographic and molecular characteristics to inform on potential additional approaches to prevent disease spread in the population. The mean incidence by norovirus season (week 31 in one year to week 30 in the following year) was 130 (range 19-300) cases/100,000 population and was highest in persons aged <5 years (430/100,000) and ≥ 75 years (593/100,000). The proportion hospitalized in community-acquired cases was 8-19% per season. The mean norovirus-associated mortality was 0.05/100,000 per season and 0.5/100,000 in the ≥ 75 years age group. Most outbreaks with known setting (75%) occurred in hospitals (32%), nursing homes (28%), households (24%) and childcare facilities (10%). GII strains dominated in the outbreak specimens. GII.4 strains were found in 82% of nursing home outbreaks, 85% of hospital outbreaks, and 33% of childcare facility and school outbreaks. Cases in younger individuals were notified earlier during the season than adult cases, and outbreaks in childcare facilities and schools preceded those in nursing/residential homes, hospitals and private households. We suggest future studies to investigate more closely potential transmission patterns between children and adults.

A multi-country outbreak of Salmonella Newport gastroenteritis in Europe associated with watermelon from Brazil, confirmed by whole genome sequencing: October 2011 to January 2012

In November 2011, the presence of Salmonella Newport in a ready-to-eat watermelon slice was confirmed as part of a local food survey in England. In late December 2011, cases of S. Newport were reported in England, Wales, Northern Ireland, Scotland, Ireland and Germany. During the outbreak, 63 confirmed cases of S. Newport were reported across all six countries with isolates indistinguishable by pulsed-field gel electrophoresis from the watermelon isolate.A subset of outbreak isolates were whole-genome sequenced and were identical to, or one single nucleotide polymorphism different from the watermelon isolate.In total, 46 confirmed cases were interviewed of which 27 reported watermelon consumption. Further investigations confirmed the outbreak was linked to the consumption of watermelon imported from Brazil.Although numerous Salmonella outbreaks associated with melons have been reported in the United States and elsewhere, this is the first of its kind in Europe.Expansion of the melon import market from Brazil represents a potential threat for future outbreaks. Whole genome sequencing is rapidly becoming more accessible and can provide a compelling level of evidence of linkage between human cases and sources of infection,to support public health interventions in global food markets.

An outbreak of Salmonella Newport associated with mung bean sprouts in Germany and the Netherlands, October to November 2011.

The largest Salmonella enterica serovar Newport outbreak (n=106) ever reported in Germany occurred in October and November 2011. Twenty associated cases were reported in the Netherlands. The outbreak investigation included an analytical epidemiological study, molecular typing of human and food isolates and food traceback investigations. Unspecified Salmonella had been detected in samples of mung bean sprouts at a sprout producer (producer A) in the Netherlands and mung bean sprouts contaminated with S. Newport had been found during routine sampling at a sprout distributor in Germany. Therefore, we tested the hypothesis of sprouts being the infection vehicle. In a case-control study, we compared 50 notified adult S. Newport cases with 45 Salmonella enterica serovar Enteritidis cases regarding their food consumption in the three days before illness. In multivariable logistic regression analysis, only sprout consumption was significantly associated with S. Newport infection (odds ratio: 18.4; 95% confidence interval: 2.2-150.2). Molecular typing patterns of human isolates were indistinguishable from a mung bean sprouts isolate. Traceback of sprouts led to distributors and producer A in the Netherlands. Since sprouts are frequently contaminated with microorganisms, consumers need to be aware that consumption of raw or insufficiently cooked sprouts may pose a health risk.

Mumps outbreak in the Republic of Moldova, 2007-2008

Background: Moldova experienced a nationwide mumps outbreak between 2007 and 2008. Single-dose monovalent mumps vaccination at 15 to 18 months was introduced in 1983, replaced by a 2-dose MMR schedule at age 1 and 6 to 7 years in 2002. We investigated the outbreak to quantify its extent, explore the role of primary and secondary vaccine failure, and provide control recommendations. Methods: We analyzed national mumps surveillance and vaccination coverage data to estimate vaccine effectiveness (VE) using the screening method. A retrospective cohort study in 5 educational institutions was conducted to determine age-specific attack rates (ARs) and VE. We compared vaccine strain-specific ARs. Isolation and genotyping of mumps virus strains were performed. Results: Of 31,142 cases reported during October 2007 and July 2008, 80% were in 15- to 24-year-olds. Of cases with information (66%), 92% were vaccinated once, 4% twice. One-dose mumps VE estimates based on surveillance data over 1997–2001 declined from 91% (95% CI: 88%–92%) in 2-year-olds to 72% (70%–74%) in 15- to 19-year-olds. In the cohort study (n = 1589), VE was −40% (−120% to 20%) for 1 dose. For 2 doses it was 62% (−43% to 90%) in 13- to 15-year-olds. ARs were higher in individuals vaccinated with Urabe strains (43%) than with Leningrad-Zagreb strains (14%, P < 0.001). Mumps virus genotype G5 was identified. Conclusions: Low effectiveness of single-dose mumps vaccination was the main cause of the outbreak. Waning immunity may have contributed to this. The risk of mumps in 2-dose vaccinees was low. Other countries in which large population groups have received <2 doses of mumps vaccine may face similar outbreaks.

Phylogenetic structure of European Salmonella Enteritidis outbreak correlates with national and international egg distribution network

Outbreaks of Salmonella Enteritidis have long been associated with contaminated poultry and eggs. In the summer of 2014 a large multi-national outbreak of Salmonella Enteritidis phage type 14b occurred with over 350 cases reported in the United Kingdom, Germany, Austria, France and Luxembourg. Egg supply network investigation and microbiological sampling identified the source to be a Bavarian egg producer. As part of the international investigation into the outbreak, over 400 isolates were sequenced including isolates from cases, implicated UK premises and eggs from the suspected source producer. We were able to show a clear statistical correlation between the topology of the UK egg distribution network and the phylogenetic network of outbreak isolates. This correlation can most plausibly be explained by different parts of the egg distribution network being supplied by eggs solely from independent premises of the Bavarian egg producer (Company X). Microbiological sampling from the source premises, traceback information and information on the interventions carried out at the egg production premises all supported this conclusion. The level of insight into the outbreak epidemiology provided by whole-genome sequencing (WGS) would not have been possible using traditional microbial typing methods.

Associations of Age and Sex With the Clinical Outcome and Incubation Period of Shiga toxin–producing Escherichia coli O104:H4 Infections, 2011

We pooled data on adults who reported diarrhea or developed life-threatening hemolytic uremic syndrome (HUS) in any of 6 closed cohorts from 4 countries (1 cohort each in Denmark, France, and Sweden and 3 in Germany) that were investigated during a large outbreak of Shiga toxin-producing Escherichia coli (STEC) O104:H4 infection in 2011. Logistic regression and Weibull regression for interval censored data were used to assess the relation of age and sex with clinical outcome and with incubation period. Information on the latter was used in a nonparametric back-projection context to estimate when adult cases reported in Germany were exposed to STEC O104:H4. Overall, data from 119 persons (median age, 49 years; 80 women) were analyzed. Bloody diarrhea and HUS were recorded as the most severe outcome for 44 and 26 individuals, respectively. Older age was significantly associated with bloody diarrhea but not with HUS. Woman had nonsignificantly higher odds for bloody diarrhea (odds ratio = 1.81) and developing HUS (odds ratio = 1.83) than did men. Older participants had a statistically significantly reduced incubation period. The shortest interval that included 75% of exposures in adults spanned only 12 days and preceded outbreak detection. In conclusion, the frequency of bloody diarrhea but not of HUS and the length of the incubation period depended on the age of individuals infected with STEC O104:H4. A large number of people were exposed to STEC O104:H4 for a short period of time.

Erratum to: Ergebnisbericht der Task Force EHEC zur Aufklärung des EHEC O104:H4 Krankheitsausbruchs in Deutschland

Im Folgenden wird uber die Ergebnisse der Arbeit der Task Force EHEC bei der lebensmittelseitigen Aufklarung des EHEC O104:H4 Krankheitsausbruchs in Deutschland berichtet. In der ersten Phase der Ausbruchsaufklarung ging es darum, das mit EHEC O104:H4 behaftete Lebensmittel zu identifizieren. Hierbei wurden von der Task Force parallel zwei Strategien verfolgt. Zum einen wurde fur funf ausgewahlte Ausbruchsorte mit mehreren Erkrankten eine detaillierte Ruckverfolgung fur dort abgegebene Salatbestandteile und rohes Gemuse durchgefuhrt, um Gemeinsamkeiten von Lebensmitteln und Lieferketten aufzudecken. Zum anderen wurden Sprossenlieferungen eines Gartenbaubetriebes in Niedersachsen verfolgt um zu ermitteln, ob Ausbruchsorte mit diesen beliefert wurden. Beide strategische Ansatze haben zur Erkenntnis gefuhrt, dass mit EHEC O104:H4 kontaminierte Sprossen aus einem Gartenbaubetrieb in Niedersachsen mit hoher Wahrscheinlichkeit den Krankheitsausbruch verursacht haben. In der zweiten Phase der Ausbruchsaufklarung wurde die Quelle des Ausbruchserregers gesucht. Die Task Force EHEC formulierte Empfehlungen zum Eliminieren der Ausbruchsquelle und wertete epidemiologische Informationen zur Eingrenzung des Zeitraums, in welchem die Quelle aktiv war, aus. Weiterhin wurde die Ruckverfolgung von verdachtigen Samenarten, die bei der Sprossenproduktion im niedersachsischen Gartenbaubetrieb eingesetzt wurden, initiiert. Diese Ermittlungsergebnisse flossen als Grundlage in die von der Europaischen Behorde fur Lebensmittelsicherheit koordinierte Ruckverfolgung von Sprossensamen im Rahmen der Ausbruchsaufklarung in Frankreich und Deutschland ein, welche aus Agypten importierte Bockshornkleesamen als vermutliche gemeinsame Ursache der Ausbruche identifizierte. Die von der Task Force EHEC entwickelte neue Strategie fur die Ausbruchsaufklarung mit der engen Zusammenarbeit von Bundes- und Landesbehorden und zwischen Gesundheitsbehorden, Lebensmitteluberwachungsbehorden und Wissenschaftlern ist ein Erfolgsmodell mit Zukunft.

Experiences from the Shiga toxin-producing Escherichia coli O104:H4 outbreak in Germany and research needs in the field, Berlin, 28–29 November 2011

This report presents the main findings from an international workshop on Shiga toxin-producing Escherichia coli (STEC), held on 28-29 November 2011, organized by the Robert Koch Institute [1]. The workshop assembled over 100 experts in clinical medicine, epidemiology, public health, microbiology, food safety, and environmental science from various countries