Yersinia ruckeri Infection and Enteric Redmouth Disease among Endangered Chinese Sturgeons, China, 2022.

During October 2022, enteric redmouth disease (ERM) affected Chinese sturgeons at a farm in Hubei, China, causing mass mortality. Affected fish exhibited characteristic red mouth and intestinal inflammation. Investigation led to isolation of a prominent bacterial strain, zhx1, from the internal organs and intestines of affected fish. Artificial infection experiments confirmed the role of zhx1 as the pathogen responsible for the deaths. The primary pathologic manifestations consisted of degeneration, necrosis, and inflammatory reactions, resulting in multiple organ dysfunction and death. Whole-genome sequencing of the bacteria identified zhx1 as Yersinia ruckeri, which possesses 135 drug-resistance genes and 443 virulence factor-related genes. Drug-susceptibility testing of zhx1 demonstrated high sensitivity to chloramphenicol and florfenicol but varying degrees of resistance to 18 other antimicrobial drugs. Identifying the pathogenic bacteria associated with ERM in Chinese sturgeons establishes a theoretical foundation for the effective prevention and control of this disease.

Epidemiological cut-off values for Yersina ruckeri disc diffusion data generated by a standardised method.

In order to establish the meaning of data generated in antimicrobial agent susceptibility tests, it is necessary to develop internationally harmonised interpretive criteria. Currently, such criteria have not been developed for data generated in studies of the susceptibility of the fish pathogen Yersinia ruckeri. This work generated the data that would be required to set epidemiological cut-off values for the susceptibility data of this species that had been generated using a standardised disc diffusion method that specified the use of Mueller Hinton agar and incubation at 22°C for 24-28 h. Using this method, sets of inhibition zones data for 4 antimicrobial agents were generated by 3 independent laboratories. The data from these laboratories were aggregated and analysed using the statistically based normalised resistance interpretation. For ampicillin, florfenicol, oxytetracycline and trimethoprim-sulfamethoxazole the cut-off values calculated by this analysis were ≥16, ≥23, ≥24 and ≥30 mm, respectively. Evidence is presented demonstrating that the data for these 4 agents was of sufficient quantity and quality that they could be used by the relevant authorities to set internationally harmonised, consensus epidemiological cut-off values for Y. ruckeri.

Co-existence of two Yersinia ruckeri biotypes and serotype O1a retrieved from rainbow trout (Oncorhynchus mykiss) farmed in Puno, Peru.

Yersinia ruckeri causes important economic losses for rainbow trout (Oncorhynchus mykiss) farms worldwide. This bacterial disease is likely the most common among trout in Peru; however, no commercial vaccine is available nationally, which is, in part, due to a lack of information on the bacterium. The aim of the current study was to characterize 29 Y. ruckeri isolates sampled from seven cage-reared farms in the Puno Region, the focal point for aquaculture activities in Peru. For this, samples were taken from fish with clinical signs (i.e. haemorrhages, uni- or bilateral exophthalmia, hyphaemia and/or melanosis). Notable among our findings was the existence of both Y. ruckeri biotype 1 (9 isolates) and biotype 2 (20 isolates; negative for sorbitol and Tween 80). The isolates further differed in API profiles 5307100 (21 isolates), 1307100 (4 isolates), 1305100 (2 isolates), 1307120 (1 isolate) and 5305100 (1 isolate), with the main differences being in the tests for lysine decarboxylase, gelatine hydrolysis and D-saccharose fermentation. Despite these differences, all isolates shared identical ERIC-PCR and REP-PCR profiles and belonged to the O1a serotype. Fingerprints were identical to the reference strain CECT 955 (serotype O1a). The information obtained will be used for epidemiological purposes by health authorities and for the development of a vaccine against Y. ruckeri, a prominent request made by fish farmers in Peru.

Forgotten but not gone: Yersinia infections in England, 1975 to 2020.

BackgroundYersiniosis is one of the most common food-borne zoonoses in Europe, but there are large variations in the reported incidence between different countries.AimWe aimed to describe the trends and epidemiology of laboratory-confirmed Yersinia infections in England and estimate the average annual number of undiagnosed Yersinia enterocolitica cases, accounting for under-ascertainment.MethodsWe analysed national surveillance data on Yersinia cases reported by laboratories in England between 1975 and 2020 and enhanced surveillance questionnaires from patients diagnosed in a laboratory that has implemented routine Yersinia testing of diarrhoeic samples since 2016.ResultsThe highest incidence of Yersinia infections in England (1.4 cases per 100,000 population) was recorded in 1988 and 1989, with Y. enterocolitica being the predominant species. The reported incidence of Yersinia infections declined during the 1990s and remained low until 2016. Following introduction of commercial PCR at a single laboratory in the South East, the annual incidence increased markedly (13.6 cases per 100,000 population in the catchment area between 2017 and 2020). There were notable changes in age and seasonal distribution of cases over time. The majority of infections were not linked to foreign travel and one in five patients was admitted to hospital. We estimate that around 7,500 Y. enterocolitica infections may be undiagnosed in England annually.ConclusionsFindings suggest a considerable number of undiagnosed yersiniosis cases in England, with possibly important changes in the epidemiology. The apparently low incidence of yersiniosis in England is probably due to limited laboratory testing.

Mesenteric Lymphadenitis and Terminal Ileitis is Associated With Yersinia Infection: A Meta-analysis.

BACKGROUND: Yersinia infection affects terminal ileum and lymph nodes and could therefore mimic the symptoms of appendicitis. We aimed to systematically characterise the suspected or confirmed abdominal diseases and/or surgeries associated with Yersinia infection. MATERIALS AND METHODS: This systematic review and meta-analysis was reported following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. A protocol (CRD42016053252) was uploaded to PROSPERO. The searches were conducted in PubMed and EMBASE on October 2, 2020. Original reports on patients with abdominal surgical diseases were included. The primary outcome was to characterise suspected or confirmed abdominal surgical diseases and/or surgeries associated with Yersinia infection, while the secondary outcomes were the positive rate of Yersinia species for each disease and surgery, and to investigate the rate of Yersinia spp. in different geographic regions. We calculated the weighted mean prevalence of positive tests for Yersinia spp. for the different diseases and surgeries according to the detection method and for subgroups based on geographic region. RESULTS: From the search, 33 studies were included in the systematic review and 18 in the meta-analysis. Across geographic regions, the weighted mean prevalence for Yersinia spp. was 51% (95% CI 34%-69%) in mesenteric lymphadenitis, 65% (95% CI 45%-85%) in terminal ileitis, and 8% (95% CI 2%-15%) in normal appendices. CONCLUSIONS: Around half of the patients with mesenteric lymphadenitis and terminal ileitis were serologically positive for infections with Yersinia spp. Yersinia infection may cause unnecessary surgery for suspected appendicitis due to symptoms from mesenteric lymphadenitis or terminal ileitis.

Detection, characterization, and antimicrobial susceptibility of Yersinia enterocolitica in different types of wastewater in the Czech Republic.

AIMS: The purpose of the study was to evaluate the occurrence of Yersinia enterocolitica in different types of wastewater and to characterize the isolates by biotyping, serotyping, and antimicrobial susceptibility testing. In addition, cultivation protocols were evaluated. METHODS AND RESULTS: The occurrence of Y. enterocolitica was determined in treated and untreated municipal wastewater, as well as in hospital, slaughterhouse, and cowshed wastewater. Y. enterocolitica was detected in 84.1% of the wastewater samples, while the main sources were untreated municipal and slaughterhouse wastewater. In contrast, the lowest incidence was found in hospital wastewater. An exclusive occurrence of biotype 1A (98.3%) was detected. Pathogenic bio-serotypes 4/O:3 and 3/O:3 were isolated only from slaughterhouse wastewater. The highest resistance rates were observed for ampicillin (92.5%) and amoxicillin-clavulanic acid (36.8%). CONCLUSIONS: Y. enterocolitica was commonly detected in wastewater, although the prevalence varied depending on the origin of the wastewater. No single cultivation protocol was able to recover Y. enterocolitica isolates from such a complex matrix as wastewater. SIGNIFICANCE AND IMPACT OF THE STUDY: Our study provided data that can contribute to the evaluation of wastewater as a source of Y. enterocolitica and to understanding the threat of wastewater isolates to human health.

Biotyping reveals loss of motility in two distinct Yersinia ruckeri lineages exclusive to Norwegian aquaculture.

Non-motile strains of Yersinia ruckeri, known as Y. ruckeri biotype 2, now dominate amongst clinical isolates retrieved from rainbow trout internationally. Due to an acute increase in the number of yersiniosis cases in Norway in recent years, followed by introduction of widespread intraperitoneal vaccination against the disease, an investigation on the prevalence of Y. ruckeri biotype 2 in Norwegian aquaculture was conducted. We biotyped 263 Y. ruckeri isolates recovered from diseased salmonids in Norway between 1985 and 2020. A total of seven biotype 2 isolates were identified, four of which were collected between 1985 and 1987, and three of which belong to the current epizootic clone, isolated from two different sea-farms in 2017. Whole-genome sequencing revealed single non-synonymous nucleotide polymorphisms in the flagellar genes flhC in isolates from the 1980s, and in fliP in isolates from 2017. In both variants, motility was restored both by complementation with wild-type alleles in trans and via spontaneous mutation-driven reversion following prolonged incubation on motility agar. While biotype 2 strains do not yet seem to have become broadly established in Norwegian aquaculture, the seven isolates described here serve to document a further two independent cases of Y. ruckeri biotype 2 emergence in salmonid aquaculture.

qPCR screening for Yersinia ruckeri clonal complex 1 against a background of putatively avirulent strains in Norwegian aquaculture.

Although a number of genetically diverse Yersinia ruckeri strains are present in Norwegian aquaculture environments, most if not all outbreaks of yersiniosis in Atlantic salmon in Norway are associated with a single specific genetic lineage of serotype O1, termed clonal complex 1. To investigate the presence and spread of virulent and putatively avirulent strains in Norwegian salmon farms, PCR assays specific for Y. ruckeri (species level) and Y. ruckeri clonal complex 1 were developed. Following extensive screening of water and biofilm, the widespread prevalence of putatively avirulent Y. ruckeri strains was confirmed in freshwater salmon hatcheries, while Y. ruckeri clonal complex 1 was found in fewer farms. The formalin-killed bacterin yersiniosis vaccine was detected in environmental samples by both PCR assays for several weeks post-vaccination. It is thus important to interpret results from recently vaccinated fish with great care. Moreover, field studies and laboratory trials confirmed that stressful management procedures may result in increased shedding of Y. ruckeri by sub-clinically infected fish. Analysis of sea water sampled throughout thermal delousing procedures proved effective for detection of Y. ruckeri in sub-clinically infected populations.

Overview of basic epidemiological characteristics and descriptive analysis of the incidence of human yersiniosis in the Czech Republic in 2018-2020.

OBJECTIVE: The aim was to provide an overview of the basic epidemiological characteristics of human yersiniosis and to analyze the reported epidemiological data on the incidence of this disease in the Czech Republic (CZ) in 2018-2020. METHODS: A descriptive analysis was performed of cases of yersiniosis captured in the Infectious Disease Information System (ISIN) in the CZ in 2018-2020. MS Excel 2010 was used for data processing and sorting. RESULTS: In the CZ, a total of 1,686 cases of yersiniosis were reported in 2018-2020 (average annual incidence of 5/100,000 population). The highest average age-specific incidence was recorded in the age group 1-4 years (31.3/100,000), followed by 0-year-olds (26.9/100,000). In the study period, 942 cases were male and 744 cases were female, with the respective incidences of 6.0 /100,000 and 4.6/100,000. By administrative region, the highest average annual incidences were recorded in the South Moravian (9.1/100,000) and Moravian-Silesian (7.5/100,000) Regions. Hospital admission was required for 14.3% (n = 241) of reported cases. No death or outbreak was reported during the study period. A total of 31 cases were imported from usual recreational destinations. No seasonality was detected in the CZ; however, more cases always occur in January and in the second half of the year. Over the last three years, a stagnant trend in the incidence of the disease has been observed in the CZ. CONCLUSIONS: In 2018 and 2019, yersiniosis (caused by Y. enterocolitica and rarely Y. pseudotuberculosis) was the fourth most commonly reported zoonosis in humans in the European Union (EU), with a stable trend in 2014-2019. The CZ reports an incidence up to three times higher but a 2.5 lower share of hospitalized patients compared to the EU average, which probably indicates that the CZ has an effective surveillance system in place. The trend in the incidence of the disease has stagnated in the CZ and the EU in recent years. The most common vehicle for transmission of yersiniosis to humans is contaminated food, especially undercooked pork, less often vegetables or water. Contamination of products from home slaughtered animals intended for private consumption is likely and would also explain the increased incidence of the disease, particularly in the winter months.

Yersiniosis in Poland in 2018-2020.

AIM: The aim of the study was to assess the epidemiological situation of yersiniosis in Poland in 2018-2020 and compare it to previous years. MATERIAL AND METHODS: To assess the epidemiological situation of yersiniosis in Poland, data from individual case reports prepared by Sanitary Epidemiological Stations as part of routine epidemiological surveillance were used. Incidence, number of cases and data on hospitalizations by voivodship included in the bulletins "Infectious Diseases and Poisons in Poland" for 2015-2020 were also used. RESULTS: In 2018-2020, a total number of 542 cases of yersiniosis were registered, including 456 intestinal and 86 extraintestinal forms. The incidence in 2018 was 0.53/100,000 in 2019 0.59/100,000 and in 2020 0.29/100,000. The number of cases in 2020 compared to 2019 decreased by 52%, and compared to 2018 by 45.8%. The percentage of hospitalizations in each year was at a similar level of 65.5% in 2018, 62.4% in 2019, and 60% in 2020. The highest incidence was noted in the 0-4 age group at 44.7% of cases in 2018, 42.9% in 2019 and 55.6% in 2020, respectively (all cases of the intestinal form). The predominant species was Y. enterocolitica in both intestinal and extraintestinal forms. The most common serotype was serotype O:3, which was identified in 34 isolates in 2018, 43 isolates in 2019 and 9 isolates in 2020. SUMMARY AND CONCLUSIONS: Since 2009, Poland has had a decreasing trend in the incidence of yersiniosis. In 2020, both Poland and Europe saw a sharp decline in the number of cases compared to previous years. This is a result of the occurrence of the COVID-19 pandemic in March 2020, during which many measures were introduced to limit the spread of the SARS-CoV-2 virus, which may also have affected the number of other infections. Although the numbers of cases and incidence of yersiniosis among children under the age of 5 are the highest compared to other age groups, the highest number of hospitalizations was reported in the 10-19 age group, which most likely reflects the decreasing number of laboratory tests ordered on an outpatient basis with age and the significant underreporting of cases in this and older age groups.

Yersinia enterocolitica Outbreak Associated with Pasteurized Milk.

In July 2019, we investigated a cluster of Yersinia enterocolitica cases affecting a youth summer camp and nearby community in northeastern Pennsylvania. After initial telephone interviews with camp owners and community members, we identified pasteurized milk from a small dairy conducting on-site pasteurization, Dairy A, as a shared exposure. We conducted site visits at the camp and Dairy A where we collected milk and other samples. Samples were cultured for Y. enterocolitica. Clinical and nonclinical isolates were compared using molecular subtyping. We performed case finding, conducted telephone interviews for community cases, and conducted a cohort study among adult camp staff by administering an online questionnaire. In total, we identified 109 Y. enterocolitica cases. Consumption of Dairy A milk was known for 37 (34%); of these, Dairy A milk was consumed by 31 (84%). Dairy A had shipped 214 gallons of pasteurized milk in 5 weekly shipments to the camp by mid-July. Dairy A milk was the only shared exposure identified between the camp and community. Y. enterocolitica was isolated from Dairy A unpasteurized milk samples. Five clinical isolates from camp members, two clinical isolates from community members, and nine isolates from unpasteurized milk were indistinguishable by whole-genome sequencing. The risk for yersinosis among camp staff who drank Dairy A milk was 5.3 times the risk for those who did not (95% confidence interval: 1.6-17.3). Because Dairy A only sold pasteurized milk, pasteurized milk was considered the outbreak source. We recommend governmental agencies and small dairies conducting on-site pasteurization collaborate to develop outbreak prevention strategies.

Evaluating sub-typing methods for pathogenic Yersinia enterocolitica to support outbreak investigations in New Zealand.

Incidence of human yersiniosis in New Zealand has increased between 2013 and 2017. For surveillance and outbreak investigations it is essential that an appropriate level of discrimination between pathogenic Yersinia enterocolitica isolates is provided, in order to support epidemiological linking of connected cases. Subtyping of 227 Y. enterocolitica isolates was performed using a range of different typing methods, including biotyping, serotyping and seven loci multiple-locus variable-number tandem-repeat analysis (MLVA). In addition, core genome single-nucleotide polymorphism (core SNP) analysis and multi-locus sequence typing were performed on a subset of 69 isolates. Sixty-seven different MLVA types were identified. One MLVA profile was associated with an outbreak in the Bay of Plenty region, supported by epidemiological data. Core SNP analysis showed that all the outbreak-related isolates clustered together. The subtyping and epidemiological evidence suggests that the outbreak of yersiniosis in the Bay of Plenty region between October and December 2016 could be attributed to a point source. However, subtyping results further suggest that the same clone was isolated from several regions between August 2016 and March 2017. Core SNP analysis and MLVA typing failed to differentiate between Y. enterocolitica biotype 2 and biotype 3. For this reason, we propose that these biotypes should be reported as a single type namely: Y. enterocolitica biotype 2/3 and that the serotype should be prioritised as an indicator of prevalence.

Cross-border outbreak of Yersinia enterocolitica O3 associated with imported fresh spinach, Sweden and Denmark, March 2019.

In April 2019, a cross-border outbreak of Yersinia entercolitica O3 was identified in Sweden and Denmark and confirmed using whole genome sequencing. Close cross-border collaboration with representatives from human and food authorities helped direct resources and investigations. Combined epidemiological and trace-back investigations pointed to imported fresh spinach as the outbreak vehicle and highlight that other vehicles of Y. enterocolitica outbreaks than pork should be considered.

Prevalence and Dynamics of Pathogenic Yersinia enterocolitica 4/O:3 Among Finnish Piglets, Fattening Pigs, and Sows.

Pigs are considered the main reservoir of Yersinia enterocolitica, and hence, understanding the ecology of this foodborne pathogen at the farm level is crucial. We calculated Bayesian estimates for the ability of a commercial enzyme-linked immunosorbent assay (ELISA) diagnostic test kit to detect antibodies against pathogenic Yersinia in pigs. The sensitivity and specificity of the test were 75.4% and 98.1%, respectively. We also studied the dynamics of Y. enterocolitica infection in 3 farrow-to-finish pig farms by following the same 30 pens of pigs through their lifetime from farrowing unit to slaughterhouse. Each farm was sampled 4 times, and 864 fecal and 730 serum samples were collected altogether. Pathogenic Y. enterocolitica 4/O:3 was isolated from 31.6% of the fecal samples by culturing, and Yersinia antibodies were detected in 38.2% of the serum samples with the commercial ELISA test. The pathogen was not isolated from farrowing units or all-in/all-out weaning units. However, in the weaning and fattening units using continuous management systems, the pathogen was isolated from every pen at some point of the study. After the pigs were transported into slaughterhouse, 150 tonsils were collected and 96.7% were positive by culturing. Among the strains isolated from feces and tonsils, 56 different genotypes of pathogenic Y. enterocolitica 4/O:3 were found by multilocus variable-number tandem-repeat analysis (MLVA). Finally, we collected tonsils of 266 sows from 115 farrowing farms, and Y. enterocolitica 4/O:3 was detected in 6.0% of the samples by the culture method, whereas 77.1% of the tonsils were serologically positive; the estimate for true seroprevalence was 95.8%. In conclusion, sows may not be the main source of Y. enterocolitica for piglets, although sows may still play a role in maintaining Y. enterocolitica in pig farms. Instead, pigs appear to get this foodborne pathogen mainly during the fattening period, especially if continuous management is applied.

[The surveillance of Yersiniosis among children in central area of Beijing from 2011 to 2018].

Objective: To illuminate the epidemic characteristics of Yersiniosis among children in the central city of Beijing and the accuracy of current clinical diagnosis towards Yersiniosis. Methods: Etiological surveillance of diarrheal patients, a total of 3 493 cases, was performed in a children hospital in central area of Beijing from 2011 to 2018 continuously. Collected the epidemiological and clinical information of the cases, analyzed the clinical and etiological diagnosis for Yersiniosis and bacterial dysentery and compared the distribution of Yersiniosis cases with the different symptoms. Results: A total of 3 493 acute diarrhea cases distributed from the age of 6 months to 13 years old, M (P(25), P(75)) was 1.50 (0.75, 3.17) years old. The 28 cases were isolated Yersinia enterocolitica (isolation rate of 0.80%) and they could be diagnosed as Yersiniosis by etiology. The isolation peaked in May and February. A total of 85.71% (24/28) of Yersiniosis cases were under 5-year old. The children of 3-4 age group had the highest isolation rate (1.52%) while the rate (0.18%) of 0-1 age group was the lowest (P=0.025). The Yersinia enteroclitica isolation rates of diarrheal patients with the symptoms including mucus feces, fever, white blood cell (WBC) and red blood cell (RBC) in feces were higher than the patients without these symptoms (P>0.05). The 9 of 28 Yersiniosis cases by etiology diagnosis were clinical diagnosed as bacillary dysentery. Conclusion: The infants and young children under 5-year old were the main population of Yersiniosis adolescent patients under 14-year old. The typical symptoms characterized with mucus stool, fever, WBC and RBC by routine microscopic examination. The preliminary clinical diagnosis of Yersiniosis is easily confused with bacterial dysentery.

Yersiniosis in Poland in 2017

AIM: The aim of the study is to assess epidemiological situation of yersiniosis in Poland in 2017 in comparison to previous years. MATERIAL AND METHODS: The evaluation is based on analysis of data from the annual bulletins "Infectious diseases and poisoning in Poland", information from individual yersiniosis case reports entered and shared by local sanitary-epidemiological stations through Electronic Registry of Epidemiologic Forms (SRWE), information from individual extraintestinal case reports fulfilled by local sanitary-epidemiological station and sent to the Departments of Epidemiology, National Institute of Public Health - National Institute of Hygiene by regional sanitary-epidemiological stations, information on outbreaks shared through the Electronic Registry of Epidemic Outbreaks (ROE) and data on deaths from the Department of Demographic Studies of the Central Statistical Office. RESULTS: In 2017 255 cases of yersiniosis, including 191 intestinal and 64 extraintestinal were registered. Incidence in 2017 was 0.66/100 000 population. Number of cases registered in 2017 was higher than in 2015 and 2016 (for both years 205 cases with incidence 0.53/100 000 was observed) and similar to the one in 2014 (244 cases, incidence 0.63/100 000). In 2017 all intestinal yersiniosis cases met criteria for confirmed case. Around 35% of cases were registered in mazowieckie voivodship where incidence was similar to the one in European Union. Among Y. enterocolitica isolates, serotype was determined in 62 cases what stands for only 28.7% of all cases. Predominant serotype was 03, it was identified in 81% of serotyped cases. Most of intestinal yersiniosis cases occurred among children under 4 years (54.5% of all registered cases). CONCLUSIONS: In 2017 increase in number of cases was observed. Yersiniosis in Poland is rarely diagnosed, incidence in Poland is more than twice time lower than in European Union.

Low occurrence of pathogenic Yersinia enterocolitica in pig tonsils at slaughter in Southern Brazil.

Yersinia enterocolitica is a foodborne pathogen and pigs are the main reservoir of it in their tonsils. As Brazil is a large producer and exporter of pork meat and information regarding this pathogen is still quite scarce, this study aimed at evaluating the direct detection of Y. enterocolitica followed by pathogenic Y. enterocolitica (PYE) determination in tonsils of slaughtered pigs. For this purpose, 400 pig tonsils were collected from 15 farms in four federally certified slaughterhouses in Southern Brazil. Initially, samples were screened using conventional PCR targeting of the 16sRNA gene, followed by multiplex PCR (mPCR) in order to detect three virulence genes (ail, yadA, and virF) and quantitative real-time PCR (qPCR) for the detection of the ail gene. One hundred and one (25.2%) of the samples tested positive for the 16sRNA gene. However, a PYE was detected in one out of the 101 Y. enterocolitica positive samples. The three virulence genes were determined by mPCR and confirmed by partial DNA sequencing. Thus, a significant occurrence of Y. enterocolitica was observed in pig tonsils from federally inspected slaughterhouses in Brazil, although the presence of pathogenic strains was quite low.

Yersiniosis in Poland in 2015 and 2016

OBJECTIVE: The aim of this study is to assess the epidemiological situation of yersiniosis in Poland in 2015 and 2016 in comparison to the previous years. MATERIAL AND METHODS: The evaluation is based on analysis of data from the annual bulletins "Infectious diseases and poisoning in Poland" (4,5), information from individual yersiniosis case reports sent to the Department of Epidemiology of Infectious Diseases and Surveillance, NIPH-NIH by regional sanitaryepidemiological stations, information on outbreaks delivered by local sanitary-epidemiological stations through the system "Rejestr Ognisk Epidemicznych" (Electronic Registry of Epidemic Outbreaks) and data on deaths from the Department of Demographic Studies of the Central Statistical Office. RESULTS: The number of registered yersiniosis cases in Poland in 2015 and 2016 was the same ­ 205 cases, corresponding to annual incidence of 0.53/100 000. Among them in 2015 there were 172 intestinal yersiniosis cases and 33 extraintestinal yersiniosis cases and in 2016 ­ 167 intestinal yersiniosis cases and 38 extraintestinal yersiniosis cases. In 2015 and 2016 all intestinal yersiniosis cases met the criteria for confirmed case. In turn, among extraintestinal yersiniosis cases in 2015 26 cases met criteria for probable case and 7 for confirmed case and in 2016 ­ 32 for probable and 6 for confirmed case. Both in 2015 and in 2016 the incidence in mazowieckie voivodeship (1.61/100 000 in 2015 and 1.55/100 000 in 2016) largely exceeded the average incidence in Poland. The overall proportion of hospitalizations, 59.5% in 2015 and 58% in 2016, remained at the level similar to the preceding years. Serotype of the isolated Yersinia enterocolitica in 2015 in Poland was determined in 59 cases (32% of all Y. enterocolitica isolates). In 2016 serotype was determined in 47 cases of Y. enterocolitica infections (27% of all Y. enterocolitica isolates). Predominant serotype was O3. As in the previous years about 1/3 of infections occurred among children aged 0-4 (110 cases, 34.9% in 2015 and 92 cases, 30.9% in 2016). In 2015 there were no yersiniosis outbreaks, in 2016 there was one outbreak caused by Y. enterolitica. CONCLUSION: Yersiniosis in Poland is rarely diagnosed and is likely underreported. The percentage of serotyped isolates continues to be low.

Prevalence of Yersinia enterocolitica Bioserotype 3/O:3 among Children with Diarrhea, China, 2010-2015.

Yersinia enterocolitica is thought to not significantly contribute to diarrheal disease in China, but evidence substantiating this claim is limited. We determined the prevalence of Y. enterocolitica infection and strain types present among children <5 years of age with diarrhea in China. The overall prevalence of pathogenic isolates was 0.59%. Prevalence of pathogenic bioserotype 3/O:3 varied geographically. In this population, the presence of fecal leukocytes was a characteristic of Y. enterocolitica infection and should be used as an indication for microbiological diagnostic testing, rather than for the diagnosis of bacillary dysentery. In contrast with Y. enterocolitica isolates from adults, which were primarily biotype 1A, isolates from children were primarily bioserotype 3/O:3. Most pathogenic isolates from children shared pulsed-field gel electrophoresis patterns with isolates from pigs and dogs, suggesting a possible link between isolates from animals and infections in children. Our findings underscore the need for improved diagnostics for this underestimated pathogen.

Lectin pathway factors in patients suffering from juvenile idiopathic arthritis.

Both complement activation and certain infections (including those with Yersinia sp.) may contribute to the pathogenesis of juvenile idiopathic arthritis (JIA). We investigated factors specific for the lectin pathway of complement: mannose-binding lectin (MBL), ficolins and MBL-associated serine protease-2 (MASP-2), in 144 patients and 98 controls. One hundred and six patients had oligoarticular disease and 38 had polyarticular disease. In 51 patients (out of 133 tested), Yersinia-reactive antibodies were found (JIA Ye+ group). MBL deficiency was significantly more frequent in the JIA Ye+ group than in patients without Yersinia-reactive antibodies or in controls. Median serum ficolin-2 level was significantly lower (and proportion of values deemed ficolin-2 insufficient greater) in JIA patients irrespective of their Yersinia antibody status. The minority (C) allele at -64 of the FCN2 gene was less frequent among JIA patients than among control subjects. No differences were found in the frequency of FCN3 gene +1637delC or MASP2 +359 A>G mutations nor for median values of serum ficolin-1, ficolin-3 or MASP-2. However, high levels of serum ficolin-3 were under-represented in patients, in contrast to MBL. MBL, ficolin-1, ficolin-2, ficolin-3 and MASP-2 were also readily detectable in synovial fluid samples but at a considerably lower level than in serum. Our findings suggest a possible role for the lectin pathway in the pathogenesis of JIA, perhaps secondary to a role in host defence, and indicate that investigations on the specificity of lectin pathway recognition molecules towards specific infectious agents in JIA might be fruitful.