Epidemiology of reported cases of leptospirosis in the EU/EEA, 2010 to 2021.

BackgroundLeptospirosis is a zoonotic disease caused by bacteria of the genus Leptospira. Humans are infected by exposure to animal urine or urine-contaminated environments. Although disease incidence is lower in Europe compared with tropical regions, there have been reports of an increase in leptospirosis cases since the 2000s in some European countries.AimWe aimed to describe the epidemiology of reported cases of leptospirosis in the European Union/European Economic Area (EU/EEA) during 2010-2021 and to identify potential changes in epidemiological patterns.MethodsWe ran a descriptive analysis of leptospirosis cases reported by EU/EEA countries to the European Centre for Disease Prevention and Control with disease during 2010-2021. We also analysed trends at EU/EEA and national level.ResultsDuring 2010-2021, 23 countries reported 12,180 confirmed leptospirosis cases corresponding to a mean annual notification rate of 0.24 cases per 100,000 population. Five countries (France, Germany, the Netherlands, Portugal and Romania) accounted for 79% of all reported cases. The highest notification rate was observed in Slovenia with 0.82 cases per 100,000 population. Overall, the notification rate increased by 5.0% per year from 2010 to 2021 (95% CI: 1.2-8.8%), although trends differed across countries.ConclusionThe notification rate of leptospirosis at EU/EEA level increased during 2010-2021 despite including the first 2 years of the COVID-19 pandemic and associated changes in population behaviours. Studies at (sub)national level would help broaden the understanding of differences at country-level and specificities in terms of exposure to Leptospira, as well as biases in diagnosis and reporting.

Salmonellosis outbreak with novel Salmonella enterica subspecies enterica serotype (11:z41:e,n,z15) attributable to sesame products in five European countries, 2016 to 2017.

In spring 2016, Greece reported an outbreak caused by a previously undescribed Salmonella enterica subsp. enterica serotype (antigenic formula 11:z41:e,n,z15) via the Epidemic Intelligence Information System for Food- and Waterborne Diseases and Zoonoses (EPIS-FWD), with epidemiological evidence for sesame products as presumptive vehicle. Subsequently, Germany, Czech Republic, Luxembourg and the United Kingdom (UK) reported infections with this novel serotype via EPIS-FWD. Concerned countries in collaboration with the European Centre for Disease Prevention and Control (ECDC) and European Food Safety Authority (EFSA) adopted a common outbreak case definition. An outbreak case was defined as a laboratory-confirmed notification of the novel Salmonella serotype. Between March 2016 and April 2017, 47 outbreak cases were notified (Greece: n = 22; Germany: n = 13; Czech Republic: n = 5; Luxembourg: n = 4; UK: n = 3). Whole genome sequencing revealed the very close genetic relatedness of isolates from all affected countries. Interviews focusing on sesame product consumption, suspicious food item testing and trace-back analysis following Salmonella spp. detection in food products identified a company in Greece where sesame seeds from different countries were processed. Through European collaboration, it was possible to identify and recall sesame spread as one contaminated food item serving as vehicle of infection and trace it back to its origin.

Salmonella control in poultry flocks and its public health impact.

An increase in confirmed human salmonellosis cases in the EU after 2014 triggered investigation of contributory factors and control options in poultry production. Reconsideration of the five current target serovars for breeding hens showed that there is justification for retaining Salmonella Enteritidis, Salmonella Typhimurium (including monophasic variants) and Salmonella Infantis, while Salmonella Virchow and Salmonella Hadar could be replaced by Salmonella Kentucky and either Salmonella Heidelberg, Salmonella Thompson or a variable serovar in national prevalence targets. However, a target that incorporates all serovars is expected to be more effective as the most relevant serovars in breeding flocks vary between Member State (MS) and over time. Achievement of a 1% target for the current target serovars in laying hen flocks is estimated to be reduced by 254,400 CrI95[98,540; 602,700] compared to the situation in 2016. This translates to a reduction of 53.4% CrI95[39.1; 65.7] considering the layer-associated human salmonellosis true cases and 6.2% considering the overall human salmonellosis true cases in the 23 MSs included in attribution modelling. A review of risk factors for Salmonella in laying hens revealed that overall evidence points to a lower occurrence in non-cage compared to cage systems. A conclusion on the effect of outdoor access or impact of the shift from conventional to enriched cages could not be reached. A similar review for broiler chickens concluded that the evidence that outdoor access affects the occurrence of Salmonella is inconclusive. There is conclusive evidence that an increased stocking density, larger farms and stress result in increased occurrence, persistence and spread of Salmonella in laying hen flocks. Based on scientific evidence, an impact of Salmonella control programmes, apart from general hygiene procedures, on the prevalence of Campylobacter in broiler flocks at the holding and on broiler meat at the end of the slaughter process is not expected.

Evaluation of molecular typing of foodborne pathogens in European reference laboratories from 2012 to 2013.

In 2012, the European Centre for Disease Prevention and Control (ECDC) initiated external quality assessment (EQA) schemes for molecular typing including the National Public Health Reference Laboratories in Europe. The overall aim for these EQA schemes was to enhance the European surveillance of food-borne pathogens by evaluating and improving the quality and comparability of molecular typing. The EQAs were organised by Statens Serum Institut (SSI) and included Salmonella enterica subsp. enterica, verocytotoxin-producing Escherichia coli (VTEC) and Listeria monocytogenes. Inter-laboratory comparable pulsed-field gel electrophoresis (PFGE) images were obtained from 10 of 17 of the participating laboratories for Listeria, 15 of 25 for Salmonella, but only nine of 20 for VTEC. Most problems were related to PFGE running conditions and/or incorrect use of image acquisition. Analysis of the gels was done in good accordance with the provided guidelines. Furthermore, we assessed the multilocus variable-number tandem repeat analysis (MLVA) scheme for S. Typhimurium. Of 15 laboratories, nine submitted correct results for all analysed strains, and four had difficulties with one strain only. In conclusion, both PFGE and MLVA are prone to variation in quality, and there is therefore a continuous need for standardisation and validation of laboratory performance for molecular typing methods of food-borne pathogens in the human public health sector.

Pulsed-field gel electrophoresis proficiency testing trials: toward European harmonization of the typing of food and clinical strains of Listeria monocytogenes.

The European Union Reference Laboratory for Listeria monocytogenes (EURL for Lm) coordinates a European network of 35 National Reference Laboratories (NRLs), most of which perform food, environmental, and veterinary Lm strain surveillance in their respective countries. The EURL activities resulted in the recent creation of a database (EURL Lm DB). Typing and related epidemiological data submitted to the EURL Lm DB will be collected and shared by all the NRLs. For a given NRL, the only criterion required in order to submit pulsed-field gel electrophoresis (PFGE) profiles to the database was the successful participation with at least one EURL PFGE and PFGE profile interpretation Proficiency Testing (PT) trial. In this context, the EURL organized a PT trial in 2012 to evaluate the NRL's ability to perform PFGE and profile interpretation. A total of 18 NRLs took part in this study. Upon request from the Food- and Waterborne Diseases and Zoonoses Programme of the European Centre for Disease Prevention and Control, 10 National Public Health Reference Laboratories (NPHLs) also took part in this PT trial. Of the 28 participating laboratories, 16 obtained results classified as "good" or "satisfactory." These 16 laboratories included 10 NRLs (56%) and 6 NPHLs (60%). Of the 22 NRLs and NHPLs that participated in the part of the PT trial related to PFGE profile interpretation, 11 laboratories obtained good results. These 11 laboratories included eight NRLs, which therefore can now submit profiles to the EURL Lm DB. This PT trial provided a valuable opportunity to facilitate and to stimulate the sharing of reproducible PFGE profiles between human and food reference laboratories.

Pulsed-Field Gel Electrophoresis Proficiency Testing Trials: Toward European Harmonization of the Typing of Food and Clinical Strains of Listeria monocytogenes.

Abstract The European Union Reference Laboratory for Listeria monocytogenes (EURL for Lm) coordinates a European network of 35 National Reference Laboratories (NRLs), most of which perform food, environmental, and veterinary Lm strain surveillance in their respective countries. The EURL activities resulted in the recent creation of a database (EURL Lm DB). Typing and related epidemiological data submitted to the EURL Lm DB will be collected and shared by all the NRLs. For a given NRL, the only criterion required in order to submit pulsed-field gel electrophoresis (PFGE) profiles to the database was the successful participation with at least one EURL PFGE and PFGE profile interpretation Proficiency Testing (PT) trial. In this context, the EURL organized a PT trial in 2012 to evaluate the NRL's ability to perform PFGE and profile interpretation. A total of 18 NRLs took part in this study. Upon request from the Food- and Waterborne Diseases and Zoonoses Programme of the European Centre for Disease Prevention and Control, 10 National Public Health Reference Laboratories (NPHLs) also took part in this PT trial. Of the 28 participating laboratories, 16 obtained results classified as "good" or "satisfactory." These 16 laboratories included 10 NRLs (56%) and 6 NPHLs (60%). Of the 22 NRLs and NHPLs that participated in the part of the PT trial related to PFGE profile interpretation, 11 laboratories obtained good results. These 11 laboratories included eight NRLs, which therefore can now submit profiles to the EURL Lm DB. This PT trial provided a valuable opportunity to facilitate and to stimulate the sharing of reproducible PFGE profiles between human and food reference laboratories.

Iceberg lettuce as suggested source of a nationwide outbreak caused by two Salmonella serotypes, Newport and Reading, in Finland in 2008.

A nationwide outbreak of Salmonella enterica serotypes Newport and Reading occurred between 17 October and 28 November 2008 in Finland. A total of 77 culture-confirmed Salmonella Newport and 30 Salmonella Reading cases, including one case with a double infection, were reported. All strains isolated from the patients were subtyped using serotyping, microbial resistance profiling, and pulsed-field gel electrophoresis (PFGE). Here, the PFGE patterns of the studied Salmonella Newport strains were identical, whereas four different PFGE profiles were found among the Salmonella Reading strains. Two elderly patients died within 2 weeks of the onset of symptoms. Three geographical clusters of cases with an epidemiological link were identified. The traceback investigation suggested that the factor connecting the cases was ready-chopped iceberg lettuce available for mass catering use. However, none of the tested food, environmental samples, or the samples taken from the staff of the processing plant contained Salmonella bacteria. Tracing back to outbreak sources with a short shelf life can be complex.

Yersinia pekkanenii sp. nov.

The taxonomic position of three strains from water, soil and lettuce samples was studied by using a polyphasic taxonomic approach. The strains were reported to lack the virulence-encoding genes inv and virF in a previous study. Controversially, API 20 E and some other phenotypic tests suggested that the strains belong to Yersinia pseudotuberculosis, which prompted this polyphasic taxonomic study. In both the phylogenetic analyses of four housekeeping genes (glnA, gyrB, recA and HSP60) and numerical analyses of HindIII and EcoRI ribopatterns, the strains formed a separate group within the genus Yersinia. Analysis of the 16S rRNA gene sequences showed that the strains were related to Yersinia aldovae and Yersinia mollaretii, but DNA-DNA hybridization analysis differentiated them from these species. Based on the results of the phylogenetic and DNA-DNA hybridization analyses, a novel species, Yersinia pekkanenii sp. nov., is proposed. The type strain is ÅYV7.1KOH2(T) ( = DSM 22769(T)  = LMG 25369(T)).

In search of human-associated bacterial pathogens in Antarctic wildlife: report from six penguin colonies regularly visited by tourists.

We investigated the potential role of Antarctic tourism in the introduction of human-associated pathogens into Antarctic wildlife. We collected and analyzed 233 fecal samples from eight bird species. The samples were collected at six localities on the Antarctic Peninsula, which often is visited by tourists. Every sample was investigated for pathogens of potential human origin: Campylobacter jejuni, Salmonella spp., and Yersina spp. None of these bacteria was found. Our data suggest that the tourism industry so far has achieved its goal of not introducing pathogens into the Antarctic region. There is, however, an urgent need to further investigate the situation in areas closer to permanent Antarctic settlements.

Prevalence and genetic diversity of Listeria monocytogenes in the tonsils of pigs.

This study was set up to establish the prevalence of Listeria monocytogenes in the tonsils of sows and fattening pigs from five Finnish slaughterhouses and to evaluate the genetic similarity of L. monocytogenes strains isolated from the tonsils. A total of 271 pig tonsils (132 tonsils from fattening pigs and 139 from sows) from five different slaughterhouses in various parts of Finland were studied from June 1999 to March 2000. Overall, 14 and 4% of pig tonsils harbored L. monocytogenes and Listeria innocua, respectively. The prevalence of L. monocytogenes in tonsils of fattening pigs (22%) was significantly higher than in sows (6%). The isolates (n = 38) recovered from tonsils showed a wide genetic diversity by means of 24 different pulsed-field gel electrophoresis (PFGE) types presented by the strains. Moreover, in numerical analyses of restriction patterns, no association was found between the clustering of strains and the slaughterhouses, and strains showing a similar PFGE type were recovered from pigs of different slaughterhouses. The high prevalence of L. monocytogenes showing various PFGE types in the tonsils of pigs could indicate a potential source of contamination of pluck sets, carcasses, and the slaughterhouse environment and of subsequent processing steps.

A widespread outbreak of Yersinia pseudotuberculosis O:3 infection from iceberg lettuce.

BACKGROUND: The vehicles and sources of Yersinia pseudotuberculosis infection are unknown. In Finland, clinical microbiology laboratories routinely report Y. pseudotuberculosis isolations and submit isolates for serotype analysis. In October 1998, the number of serotype O:3 infections increased markedly. METHODS: Case patients with culture-confirmed Y. pseudotuberculosis O:3 infection were identified by use of laboratory-based surveillance. We conducted a population-based case-control study. Healthy community control subjects were matched by age, sex, and postal code. Isolates were subtyped by pulsed-field gel electrophoresis (PFGE). RESULTS: Nationwide, 47 case patients were identified (age range, 2-77 years; median, 19 years). One patient with bacteremia died; 5 underwent appendectomies. We enrolled 38 case patients and 76 control subjects in the case-control study. Seventy-one percent of case patients and 42% of control subjects reported having eaten iceberg lettuce (matched odds ratio, 3.8; 95% confidence interval, 1.3-9.4); a dose-response relationship was found for increasing frequency of consumption. Of the 27 isolates obtained from case patients and tested in the analysis, all had indistinguishable PFGE patterns. Four lunch cafeterias that had served iceberg lettuce were associated with clusters of case patients. The lettuce was traced back to originating farms. CONCLUSIONS: Iceberg lettuce was implicated as the vehicle of a widespread foodborne Y. pseudotuberculosis outbreak. Ongoing laboratory-based surveillance and serotype analysis were essential in the rapid detection of infection. Cases of yersiniosis, which appear to be sporadic, may be part of unrecognized outbreaks caused by contaminated fresh produce.

Low prevalence of yadA-positive Yersinia enterocolitica in sows.

Yersinia enterocolitica 4/O:3 is commonly isolated from fattening pigs in Finland, but its prevalence in sows is relatively unknown. The current study determined the prevalence of yadA-positive Y. enterocolitica in sows and fattening pigs with polymerase chain reaction (PCR) and culture methods. The strains were characterized with pulsed-field gel electrophoresis (PFGE) using NotI DNA-restriction enzyme. Pathogenic Y. enterocolitica was detected in only 14% of sow tonsils compared with 56% of tonsils of fattening pigs. The prevalence varied between seven slaughterhouses from 0% to 30% in sows and from 30% to 87% in fattening pigs. A total of 37 NotI profiles were obtained from 148 Y. enterocolitica 4/O:3 strains isolated from 134 tonsil samples: eight profiles were obtained from 26 sow strains and 34 from 122 fattening pig strains. Two types predominated in both sows and fattening pigs. The prevalence of yadA-positive Y. enterocolitica in fattening pigs increased from 1995 versus 1999; the mean prevalence in five slaughterhouses for the 2 years was 33% and 64%, respectively. Seven NotI profiles, including the two common types, were found both years. In conclusion, pathogenic Y. enterocolitica was detected at a significantly lower rate in sows than in fattening pigs. Moreover, the prevalence of this pathogen in fattening pigs was significantly higher in 1999 than in 1995. Some Y. enterocolitica 4/O:3 strains persisting among slaughter swine were demonstrated to be very stable genetically. This study shows that fattening pigs are an important reservoir of different genotypes of Y. enterocolitica 4/O:3 strains.

virF-positive Yersinia pseudotuberculosis and Yersinia enterocolitica found in migratory birds in Sweden.

During spring and autumn migrations, 468 fecal samples from 57 different species of migratory birds were collected in Sweden. In total, Yersinia spp. were isolated from 12.8% of collected samples. The most commonly found species was Yersinia enterocolitica, which was isolated from 5.6% of all collected samples, followed by Y. intermedia (3.8%), Y. frederiksenii (3.0%), Y. kristensenii (0.9%), Y. pseudotuberculosis (0.6%), and Y. rohdei (0.4%). The pathogenic, virF-positive Y. pseudotuberculosis strains were recovered from three thrushes. These strains belonged to the same bioserotype, 1/O:2, but had two different profiles as determined by pulsed-field gel electrophoresis with NotI and SpeI enzymes. In addition, 10 Y. enterocolitica strains, all from barnacle geese, belonged to bioserotype 3/O:3, which is associated with human disease. Two of the strains were pathogenic, carrying the virF gene on their plasmids. All pathogenic Y. pseudotuberculosis and Y. enterocolitica strains were recovered during the spring, and as the birds were caught during active migration they likely became infected at an earlier stage of the migration, thus potentially transporting these bacterial pathogens over long geographical distances.

Yersinia pseudotuberculosis with limited genetic diversity is a common finding in tonsils of fattening pigs.

A total of 425 pig tonsils, including 210 tonsils from fattening pigs and 215 from sows, from seven different abattoirs in Finland were studied for the occurrence of Yersinia pseudotuberculosis from 1999 to 2000. The mean prevalence of Y. pseudotuberculosis in fattening pig tonsils was 4%, varying from 0 to 10% between slaughterhouses. Y. pseudotuberculosis was not recovered from sow tonsils. All 30 Y. pseudotuberculosis isolates from eight pig tonsils were recovered after cold enrichment. Seventeen isolates from seven tonsils were found after cold enrichment for 14 days, followed by alkali treatment. Y. pseudotuberculosis was not isolated after direct plating, overnight enrichment, or selective enrichment. All 30 isolates belonged to bioserotype 2/0:3 and carried the virF gene in the virulence plasmid. The isolates exhibited calcium dependence and Congo red absorption. The pyrazinamidase test gave variable results. All isolates were characterized with pulsed-field gel electrophoresis (PFGE). Using SpeI, NotI, and XbaI enzymes, seven, five, and two different PFGE patterns were obtained, respectively. A total of 11 genotypes, gI to gXI, identified by a combination of the various SpeI, NotI, and XbaI profiles, were detected. Three pigs were found to carry more than one genotype. Overall, variations between PFGE patterns were small, indicating genetic homogeneity among pig strains of bioserotype 2/0:3.