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Sheep are considered to be one of the main reservoirs forTwo identically managed and naturallyAfter primary vaccination, almost all animals from cohort VAC showed a high IgG Phase I response up until the end of the study period. In cohort CTR, the seropositivity rate varied from 35.1% to 66.3%, and the Phase I and Phase II pattern showed an undulating trend with higher IgG Phase II activity during both lambing seasons. The number of vaginal shedders was significantly reduced in cohort VAC compared to cohort CTR during the lambing season in 2019 (Neither the

INTRODUCTION Study objective was to determine feasibility and compliance with a 3-month exercise intervention in older adults, and if peripheral quantitative computed tomography muscle measures and jumping mechanography could detect changes in muscle mass and function. METHODS A parallel group, nonblinded, pilot trial with individuals 70 yr or older randomized to control group of walking-only (WALK) or an intervention group of walking combined with exercises to improve balance and strength (W + EX). Both groups attended similar weekly nutrition education sessions. Body composition, muscle density, intramuscular adipose tissue area, and muscle function were assessed before and after the intervention using dual-energy x-ray, peripheral quantitative computed tomography, functional tests, and mechanography. RESULTS Eighty-five (90%) of 94 individuals enrolled completed (41WALK, 44W + EX). Eighty-six percent of participants attended seven or more nutrition sessions, and log sheets, used to assess exercise compliance, were returned by 66% of participants, and of those, 88% logged activity on 50%+ days. Sixty-seven percent of participants stated that they increased activity levels, and 82% stated that they felt better overall. Both groups increased lean and lost fat mass, resulting in decreases in fat percentage (all, P < 0.05). Intramuscular adipose tissue area decreased and muscle density increased among WALK (P < 0.05 and P = 0.056, respectively) but were not different between groups. Improvement in force efficiency and chair-rise power were greater among W + EX group than WALK (5.9% ± 1.8% vs -1.2% ± 2.0% [P = 0.01] and 0.25 ± 0.19 W·kg and -0.37 ± 0.23 W·kg [P = 0.04], respectively). Differences in mechanography results became greater in a per-protocol analysis. CONCLUSIONS A larger trial is feasible, and the program was well accepted. Both groups showed improvements, the program that included strength and balance lead to greater jump force efficiency and power than walking only. Whether these differences lead to differences in fall rates need to be determined in a larger trial.

Puumala orthohantavirus (PUUV) is the most important hantavirus species in Europe, causing the majority of human hantavirus disease cases. In central and western Europe, the occurrence of human infections is mainly driven by bank vole population dynamics influenced by beech mast. In Germany, hantavirus epidemic years are observed in 2- to 5-year intervals. Many of the human infections are recorded in summer and early autumn, coinciding with peaks in bank vole populations. Here, we describe a molecular epidemiological investigation in a small company with eight employees of whom five contracted hantavirus infections in late 2017. Standardized interviews with employees were conducted to assess the circumstances under which the disease cluster occurred, how the employees were exposed and which counteractive measures were taken. Initially, two employees were admitted to hospital and serologically diagnosed with hantavirus infection. Subsequently, further investigations were conducted. By means of a self-administered questionnaire, three additional symptomatic cases could be identified. The hospital patients' sera were investigated and revealed in one patient a partial PUUV L segment sequence, which was identical to PUUV sequences from several bank voles collected in close proximity to company buildings. This investigation highlights the importance of a One Health approach that combines efforts from human and veterinary medicine, ecology and public health to reveal the origin of hantavirus disease clusters.

Q fever outbreaks on three dairy goat farms (A–C) were monitored after the animals had been vaccinated with an inactivated Coxiella burnetii phase I vaccine. The antibody response was measured before vaccination by serum samples with two C. burnetii phase-specific ELISAs to characterize the disease status. Shedding was determined by vaginal swabs during three kidding seasons and monthly bulk tank milk (BTM) samples. Dust swabs from one windowsill of each barn and from the milking parlors were collected monthly to evaluate the indoor exposure. These samples were analyzed by qPCR. The phase-specific serology revealed an acute Q fever infection in herd A, whereas herds B and C had an ongoing and past infection, respectively. In all three herds, vaginal shedders were present during three kidding seasons. In total, 50%, 69%, and 15% of all collected BTM samples were C. burnetii positive in herds A, B, and C, respectively. Barn dust contained C. burnetii DNA in 71%, 45%, and 50% of examined swabs collected from farms A, B, and C, respectively. The largest number of C. burnetii positive samples was obtained from the milking parlor (A: 91%, B: 72%, C: 73%), indicating a high risk for humans to acquire Q fever during milking activity.

Q fever outbreaks on three dairy goat farms (A-C) were monitored after the animals had been vaccinated with an inactivated

ZusammenfassungDie Leptospirose ist eine Zoonose, die bei Mensch und Tier eine große Bandbreite von Krankheitssymptomen mit sehr milden bis hin zu sehr schweren Verläufen aufweisen kann. In Deutschland ist der Labornachweis einer akuten Infektion meldepflichtig: beim Menschen gemäß Infektionsschutzgesetz und bei Schweinen und Schafen gemäß der Verordnung über meldepflichtige Tierkrankheiten. Die Übertragung erfolgt über direkten und indirekten Kontakt mit dem Urin infizierter Tiere, wobei Nagetiere als Hauptreservoir gelten. Mit einer durchschnittlichen jährlichen Inzidenz von 0,1 gemeldeten Fällen pro 100.000 Einwohner ist die Leptospirose in Deutschland eine seltene Erkrankung.Im Rahmen des vom Bundesministerium für Bildung und Forschung (BMBF) geförderten Projekts „Verbesserung der Öffentlichen Gesundheit durch ein besseres Verständnis der Epidemiologie nagetierübertragener Krankheiten“ (RoBoPub) werden in diesem Übersichtsartikel aktuelle Kenntnisse zur Leptospirose in Deutschland dargestellt. In einem One-Health-Ansatz werden Informationen zum klinischen Bild, verfügbare Prävalenzdaten bei Mensch und Tier und Erkenntnisse über die Erregerverbreitung, die Wirtsassoziation, die Übertragung des Erregers sowie die Umweltstabilität zusammengefasst. Darüber hinaus werden erste Erkenntnisse zum Einfluss von Populationsschwankungen in Nagetierpopulationen auf das Auftreten der Leptospirose diskutiert. Ziel des Übersichtsartikels ist es, die Wahrnehmung für diese gegenwärtig noch vernachlässigte Erkrankung in Deutschland zu erhöhen.In Zukunft sollten auch die im Zuge des Klimawandels möglicherweise vermehrt auftretenden erhöhten Temperaturen und starken Regenfälle und die damit einhergehende häufigere Exposition des Menschen mit den Erregern berücksichtigt werden.

Q fever is a zoonotic disease caused by the bacterium Coxiella burnetii; Coxiella-infected ruminants are the main reservoir shedding the pathogen during abortion or parturition through birth products. Germany has a long history of small-scale Q fever epidemics in the human population mostly associated with lambing sheep. Therefore, fast and efficient control measures are essentially required to prevent transmission from infected sheep flocks to humans. In our present study, three sheep flocks were vaccinated with an inactivated C. burnetii phase I vaccine after a field infection with C. burnetii was diagnosed. Serum samples and vaginal swabs were collected at different time points to evaluate the extent of the outbreak and the consequences of the vaccination. The serum samples were examined by phase-specific IgG phase I and phase II ELISAs and a commercial ELISA, simultaneously detecting both phase variations. Moreover, vaginal swabs were analysed by qPCR. The fourth flock with no Q fever history and non-vaccinated animals were used as a control group to evaluate the phase-specific ELISAs. The inactivated C. burnetii phase I vaccine induced an IgG phase II response and boosted the humoral immune reaction against natural pre-infections. Furthermore, the longevity of vaccine-induced antibodies seems to depend on previous infections. Around 16 months after primary vaccination, mainly IgG phase I antibodies were detectable. Vaccination did not prevent shedding at the next lambing season. Most interestingly, the phase-specific ELISAs revealed more C. burnetii positive animals than the blended ELISA-Assay. Taken together, phase-specific ELISAs are suitable tools to provide insights into natural- or vaccine-induced humoral immune responses to C. burnetii in sheep.

Q fever is a zoonotic disease caused by the bacterium Coxiella burnetii. Inhalation of contaminated dust particles or aerosols originating from animals (esp. small ruminants) is the main source of human infection. Hence, an active early warning system for Q fever in German small ruminant livestock was conceptualized to prevent human infections. First, we describe the best practice for establishing this system before evaluating its feasibility, as the combination of both evokes conflicts. Vaginal swabs from all husbandry systems with a focus on reproductive females should pooled and investigated by PCR to detect C. burnetii-shedding animals. Multistage risk-based sampling shall be carried out at the flock level and within-flock level. At the flock level, all flocks that are at risk to transmit the pathogen to the public must be sampled. At the within-flock level, all primi- and multiparous females after lambing must be tested in order to increase the probability of identifying a positive herd. Sampling should be performed during the main lambing period and before migration in residential areas. Furthermore, individual animals should be tested before migration or exhibition to ensure a negative status. If a flock tests positive in at least one individual sample, then flock-specific preventive measures should be implemented. This approach implies huge financial costs (sample testing, action/control measures). Hence, taking the step to develop more feasible and affordable preventive measures, e.g., vaccinating small ruminant flocks, should replace testing wherever justifiable.

The main reservoir of Coxiella (C.) burnetii are ruminants. They shed the pathogen through birth products, vaginal mucus, faeces and milk. A direct comparison of C. burnetii excretions between naturally infected sheep and goats was performed on the same farm to investigate species-specific differences. The animals were vaccinated with an inactivated C. burnetii phase I vaccine at the beginning of the study period for public health reasons. Vaginal and rectal swabs along with milk specimens were taken monthly during the lambing period and once again at the next lambing season. To estimate the environmental contamination of the animals’ housings, nasal swabs from every animal were taken simultaneously. Moreover, dust samples from the windowsills and straw beddings were collected. All samples were examined by qPCR targeting the IS1111 gene and the MLVA/VNTR typing method was performed. Whole genome sequencing was applied to determine the number of IS1111 copies followed by a calculation of C. burnetii genome equivalents of each sample. The cattle-associated genotype C7 was detected containing 29 IS1111 copies. Overall, goats seem to shed more C. burnetii through vaginal mucus and in particular shed more and for longer via the rectal route than sheep. This is supported by the larger quantities of C. burnetii DNA detected in caprine nasal swabs and environmental samples compared to the ovine ones. Transmission of C. burnetii from cattle to small ruminants must also be considered.

Infestation with Baylisascaris procyonis, a gastrointestinal nematode of the raccoon, can cause fatal disease in humans. We found that the parasite is widespread in central Germany and can pose a public health risk. The spread of B. procyonis roundworms into nematode-free raccoon populations needs to be monitored.

Leptospirosis is a zoonotic disease with a wide spectrum of clinical symptoms in humans and animals, ranging from subclinical infections to severe signs of multiorgan dysfunction. In Germany, laboratory confirmation of acute human infection is notifiable based on the Protection Against Infection Act. Disease or occurrence of the pathogen in pigs and sheep must be reported according to the regulation on reportable animal diseases. Transmission occurs via direct and indirect contact with the urine of infected animals, with rodents acting as the main reservoir. With an average annual incidence of 0.1 notified cases per 100,000 inhabitants, leptospirosis is a rare disease in Germany.This review article presents the current knowledge on leptospirosis in Germany in the framework of the project "Improving public health through a better understanding of the epidemiology of rodent-transmitted diseases" (RoBoPub) funded by the Ministry of Education and Research. In a One-Health approach, information about clinical manifestation, available prevalence data in humans and animals, knowledge of pathogen distribution, host association, mode of transmission, and survival in the environment is summarized. Preliminary findings on the influence of fluctuations in rodent populations on the occurrence of leptospirosis are also discussed. The aim of the article is to increase the awareness of this currently neglected disease in Germany.In future, higher temperatures and more frequent heavy rainfalls, which could occur due to climate change, should be taken into account.

Animal parasitic nematodes can cause serious diseases and their emergence in new areas can be an issue of major concern for biodiversity conservation and human health. Their ability to adapt to new environments and hosts is likely to be affected by their degree of genetic diversity, with gene flow between distinct populations counteracting genetic drift and increasing effective population size. The raccoon roundworm (Baylisascaris procyonis), a gastrointestinal parasite of the raccoon (Procyon lotor), has increased its global geographic range after being translocated with its host. The raccoon has been introduced multiple times to Germany, but not all its populations are infected with the parasite. While fewer introduced individuals may have led to reduced diversity in the parasite, admixture between different founder populations may have counteracted genetic drift and bottlenecks. Here, we analyse the population genetic structure of the roundworm and its raccoon host at the intersection of distinct raccoon populations infected with B. procyonis. We found evidence for two parasite clusters resulting from independent introductions. Both clusters exhibited an extremely low genetic diversity, suggesting small founding populations subjected to inbreeding and genetic drift with no, or very limited, genetic influx from population admixture. Comparison of the population genetic structures of both host and parasite suggested that the parasite spread to an uninfected raccoon founder population. On the other hand, an almost perfect match between cluster boundaries also suggested that the population genetic structure of B. procyonis has remained stable since its introduction, mirroring that of its raccoon host.

Here, we report a high-quality draft genome sequence of Francisella tularensis subsp. holarctica strain 08T0073, isolated from the cadaver of a wild European hare (Lepus europaeus) found near Helmstedt, Lower Saxony, Germany, in 2007. In Germany, infected hares are a major source of tularemia in humans.

Here, we report a high-quality draft genome sequence of Francisella tularensis subsp. holarctica strain 08T0073, isolated from the cadaver of a wild European hare ( Lepus europaeus ) found near Helmstedt, Lower Saxony, Germany, in 2007. In Germany, infected hares are a major source of tularemia in humans.

The causative agent of Q fever, Coxiella burnetii, is a query agent occurring naturally all over the world. We studied 104 German Coxiella burnetii strains/DNA samples obtained between 1969 and 2011 using a 14 microsatellite marker Multiple-locus variable-number of tandem repeat (VNTR) analysis (MLVA) technique. We were able to divide our collection into 32 different genotypes clustered into four major groups (A-D). Two of these (A and C) formed predominant clonal complexes that covered 97% of all studied samples. Group C consisted exclusively of cattle-associated isolates/DNA specimens, while group A comprised all other affected species including all sheep-derived strains/DNA samples. Within this second cluster, two major genotypes (A1, A2) were identified. Genotype A2 occurred in strains isolated from ewes in northern and central Germany, whereas genotype A1 was found in most areas of Germany. MLVA analysis of C. burnetii strains from neighbouring countries revealed a close relationship to German strains. We thus hypothesize that there is a western and central European cluster of C. burnetii. We identified predominant genotypes related to relevant host species and geographic regions which is in line with findings of the Dutch Q fever outbreak (2007-2010). Furthermore three of our analyzed German strains are closely related to the Dutch outbreak clone. These findings support the theory of predominant genotypes in the context of regional outbreaks. Our results show that a combination of 8 MLVA markers provides the highest discriminatory power for attributing C. burnetii isolates to genotypes. For future epidemiological studies we propose the use of three MLVA markers for easy and rapid classification of C. burnetii into 4 main clusters.

Enteric red-mouth disease, caused by Yersinia ruckeri, is an important disease in rainbow trout aquaculture. Antimicrobial agents are frequently used in aquaculture, thereby causing a selective pressure on bacteria from aquatic organisms under which they may develop resistance to antimicrobial agents. In this study, the distribution of minimal inhibitory concentrations (MICs) of antimicrobial agents for 83 clinical and non-clinical epidemiologically unrelated Y. ruckeri isolates from north west Germany was determined. Antimicrobial susceptibility was conducted by broth microdilution at 22 ± 2 °C for 24, 28 and 48 h. Incubation for 24 h at 22 ± 2 °C appeared to be suitable for susceptibility testing of Y. ruckeri. In contrast to other antimicrobial agents tested, enrofloxacin and nalidixic acid showed a bimodal distribution of MICs, with one subpopulation showing lower MICs for enrofloxacin (0.008–0.015 μg/mL) and nalidixic acid (0.25–0.5 μg/mL) and another subpopulation exhibiting elevated MICs of 0.06–0.25 and 8–64 μg/mL, respectively. Isolates showing elevated MICs revealed single amino acid substitutions in the quinolone resistance-determining region (QRDR) of the GyrA protein at positions 83 (Ser83-Arg or -Ile) or 87 (Asn87-Tyr), which raised the MIC values 8- to 32-fold for enrofloxacin or 32- to 128-fold for nalidixic acid. An isolate showing elevated MICs for sulfonamides and trimethoprim harbored a ∼8.9 kb plasmid, which carried the genes sul2, strB and a dfrA14 gene cassette integrated into the strA gene. These observations showed that Y. ruckeri isolates were able to develop mutations that reduce their susceptibility to (fluoro)quinolones and to acquire plasmid-borne resistance genes.

Cyprinid herpesvirus-3 (CyHV-3, koi herpesvirus, KHV) is the causative agent of an economically important disease in carp. The mode of transmission of this virus, especially how the infectious agent is introduced into ponds de novo, is not known in detail. The aim of this study was to investigate the shedding of CyHV-3 from fish with latent infections, under aquaculture conditions. Ponds in Saxony, Germany, with latently infected carp were examined at different times during the production cycle to investigate the influence of fish farming procedures on virus activation and shedding. Carp and water samples were investigated by quantitative real-time PCR. Some of the latently infected carp shed CyHV-3. Virus shedding was induced mainly when the ponds were drained and the carp either harvested or moved to different ponds, and was independent of the water temperature. This indicated that during these times there was a risk that effluent water from the ponds could disseminate the infectious agent. During summer, on-growing carp are infected with low numbers of CyHV-3. These findings are important for disease management strategies in carp aquaculture and for the design of testing protocols for the detection of latent infection in carp populations.

The raccoon (Procyon lotor) has successfully invaded central Europe, despite the population apparently having been founded by a small number of individuals in two distinct populations in Germany. The ecological success of the invasion has been explained by raccoons being an adaptable, truly omnivorous species. However, the German raccoon population might have a larger number of founders and be more genetically diverse than assumed, as accidental or deliberate releases of household pets or individuals from zoos are relatively common. In the present study, we sequenced a 550-base-pair long fragment of the mitochondrial control region in 193 raccoons from Germany and neighbouring countries. We only identified six different haplotypes; of which, five were limited to Germany. Our results support the notions that the population was founded by a small number of females and that the German raccoons originate from two separate release events in central and eastern Germany. Additionally, however, we provide evidence for the presence of a distinct population in Saxony, eastern Germany. Further studies using different genetic markers are necessary to gain additional information on genetic diversity and population genetic structure.

Infections of common carp Cyprinus carpio and koi, its coloured morphotypes, with the cyprinid herpesvirus 3 (CyHV-3) can induce severe clinical signs and increased mortality in affected stocks. This may significantly challenge the economic basis of carp farming in Central Europe. To limit virus spread in carp farms, effective disinfection measures for ponds stocked with infected populations are required. In the traditional European pond aquaculture of carp, draining and liming of ponds with quicklime (CaO) up to pH 12 is a well-established disinfection measure against various pathogens. The present field study investigated whether these measures are sufficient for the inactivation of CyHV-3 infectivity in carp ponds. After draining and liming, the ponds were stocked with carp fry from a CyHV-3-negative stock, and 2 ponds were examined for the presence of CyHV-3-specific DNA sequences during the growth period of the carp and in the harvested stock. Wild fish (from the ponds, and feeder and drainage canals) and water samples (from the ponds) were also examined for CyHV-3-specific DNA sequences; and naive carp were cohabited with wild fish, or exposed to the pondwater samples, to test for the presence of infectious virus. All examined samples remained negative for CyHV-3 throughout the study. This indicates that draining and liming with quicklime can be a suitable disinfection measure for ponds after a CyHV-3 outbreak in carp aquaculture.

BACKGROUND: Genetically based resistance to anticoagulants has led to increasing difficulties in the control of rodents over recent decades. The possible impact of rodenticide-resistant rats on the infection risk of humans and livestock by zoonotic pathogens is generally unknown. Hence, in a monitoring programme in the German federal states of Lower Saxony and Hamburg, more than 500 Norway rats were analysed for both Tyr139Cys polymorphisms within the VKORC1 gene and zoonotic agents. RESULTS: Evidence of resistance was almost completely restricted to the known resistance area in southern Lower Saxony. Homozygous mutations were only found in urban areas sampled owing to the occurrence of rat control problems and were missing in bycatches of rats by muskrat trappers in rural areas. In more than 25% of the rats, zoonotic bacteria (Leptospira, Salmonella, Yersinia and Coxiella) were detected. There was no obvious correlation between the occurrence of rats carrying zoonotic pathogens and anticoagulant resistance. CONCLUSION: Zoonotic agents and genetically based resistance conferred by the Tyr139Cys polymorphism are both unevenly distributed in Lower Saxony. The study provides the basis for further studies focusing on districts with high levels of pathogens and resistance to assess the potential health risk of their combined occurrence. © 2012 Society of Chemical Industry

In an open observational prospective multicentered study on a cohort of patients with a creatinine clearance ofor = 65 ml/min and diagnosed with the "Esslinger Fall Risk Assessment" to be at an increased risk for falls the effect of daily treatment with 1 microg alfacalcidol (CAS 41294-56-8; Alpha-D3) on muscle power, balance and number of fallers and falls was investigated.In this open prospective study on 237 participants recruited in Germany, 16.9% men and 83.1% women with a mean age of 75.9 years and a mean body mass index (BMI) of 26.3 kg/m2 underwent at the beginning and after 3 and 6 months different muscle strength and balance tests such as the Timed-up and Go Test (TUG), the Tandem Stand Test (TST) and the Chair Rising Test (CRT). A successful performance in these tests has been associated with a significantly lower risk for falls and non-vertebral fractures in elderly patients (successful test performance: TUG12 s, TST10 s, CRT10 s).Controlled for age, gender and BMI, treatment with alfacalcidol was associated with a significantly increased performance in all three muscle and balance tests already after 3 months. This effect increased after six months of therapy and a significant increase in the number of participants who were able to successfully perform the different tests was observed: plus 74.9% for the TUG (p.0001), plus 112% for the TST (p.0001) and plus 108% for the CRT (p.0001). After six months the mean time used for the TUG was decreased by 2.01 s, by 2.29 s for the CRT, and increased by 2.02 s for the TST. Controlled for age, gender, BMI and CrCI, treatment with alfacalcidol for six moths resulted in a significant 48.1% (p _or = .0001) decrease in the absolute number of fallers and a significant 51.3% (p .0001) decrease in the absolute number of falls, compared to the 6 months prior to alfacalcidol therapy.Treatment with alfacalcidol increases muscle power and balance as measured with three different muscle power and balance tests and leads to a highly significant decrease in the number of fallers and falls.

With the side-alternating vibration training, the muscles are trained and treated by vibration. The vibration is reflectively caused in the rhythmic alternation between the left and the right side of the body; the movement pattern is stimulated as it is the case with normal walking. The overview explains the effects of the vibration training and the possible success in practice with the help of studies and the many years of clinical experience of the author with osteoporosis patients.

Francisella tularensis is the aetiological agent of tularemia. Hares, rabbits, and small rodents are the main hosts, but humans can be infected and develop severe clinical symptoms. In Germany, tularemia in humans was a rare disease during the last four decades, but since 2005, this zoonosis seems to be re-emerging. However, only very little is known about the prevalence in the host populations. Therefore, in a study performed from 2006 to 2009, we investigated 2,121 brown hares (Lepus europaeus) and 41 European rabbits (Oryctolagus cuniculus) located in Lower Saxony, Germany for the occurrence of this zoonotic bacterium by PCR and bacterial culture. F. tularensis subsp. holarctica was detected in an average of 1.1% of these animals. Two hot spots were found in northern Lower Saxony indicating outbreaks of tularemia even in hares. This study demonstrates the occurrence of F. tularensis subsp. holarctica within the hare population in Germany. Hunters, medical practitioners, and public health professionals should be aware of the risk which could come from this zoonotic agent especially in the hot spot areas.

Frakturen zu verhindern ist das Ziel jeder Osteoporosebehandlung und -prävention. Da mehr als 90 Prozent der nichtvertebralen Frakturen bei einem Sturz entstehen, gehört es zum Management der Osteoporose auch dazu, Stürze zu verhindern. Um hier erfolgreich zu sein, muss das Sturzrisiko des einzelnen Patienten quantifiziert und gezielt behandelt werden. Eine herkömmliche Nomenklatur spricht einseitig von “osteoporotischen” Frakturen und zählt neben den ertebralfrakturen die Frakturen von hüftnahem Femur, Unterarm und Oberarm als osteoporosebedingt auf. Die vorliegenden Daten verlangen eine Korrektur bzw. eine Ergänzung dieser Sichtweise.

Enteric redmouth disease (ERM), caused by Yersinia ruckeri, is among the most important infectious diseases in rainbow trout Oncorhynchus mykiss aquaculture in Europe. Our aim was to analyse the persistence of Y. ruckeri strains in trout farms in northwest Germany and their dissemination between farms based on a detailed molecular and phenotypical characterisation scheme. The data on identification and characterisation of Y. ruckeri strains and examining the distribution of these strains in the field could serve as a basis for preventive disease monitoring plans. During the observation period from June 2011 until June 2012, we collected 48 Y. ruckeri isolates from 12 different rainbow trout hatcheries. In total, 44 (91.7%) of the isolates were non-motile; in particular, all isolates recovered during the sampling period in winter and early spring were non-motile. In several trout farms, characteristic farm-specific Y. ruckeri isolates from particular typing groups were isolated throughout the year, while in other farms, which had a trading relationship between each other, ERM outbreaks were caused by Y. ruckeri from the same typing group. Our data indicate that in some farms, the causative Y. ruckeri strains persisted in the respective trout farm. The presence of Y. ruckeri from the same typing group in farms with a trading relationship indicates a dissemination of the infection between the farms.