Experimentally induced infections of European eel <i>Anguilla anguilla</i> with <i>Anguillicola crassus</i> (Nematoda, Dracunculoidea) and subsequent migration of larvae

Migration patterns of third-stage Anguillicola crassus larvae, and pathogenesis of the lesions induced by third-stage larvae, was investigated in European eel Anguilla anguilla L. Young elvers (1g) were fed infected Paracyclops fimbriatus (Copepoda). Eel samples were collected and examined histologically at varying intervals during 6 mo post-infection period. Third-stage larvae (L-III) migrated directly through the intestinal wall and body cavity to the swimbladder within 17h post-infection. L-IV larvae were detected 3 mo post-infection, and immature adults were detected within 4 mo post-infection. The parasites occasionally showed aberrant migration paths. Pathological effects caused by the parasite were less severe after experimentally induced infections than those detected in some natural infections

Gebruik van de Diagnostische Tussentijdse Toets voor opbrengstgericht werken op scholen

FdR – Publicaties zonder aanstelling Universiteit Leide

Genotoxic effects of neutrophils and hypochlorous acid

n/

Co-infections and multiple stressors in fish

Fish are typically exposed to multiple physical, chemical and biological stressors. The cumulative impact of co-infections between parasites, bacteria, viruses and (a)biotic environmental pressures may trigger complex interactions, eliciting different pathological and immunological outcomes than those classically assessed. New cross-disciplinary studies attempt to measure the impact of environmental stressors in modulating the host response to pathogens. Scientific advances are needed to reduce pressure on natural populations, improve fish stock management, and to design more efficient diagnostic tools or vaccination strategies. An EAFP-promoted workshop, held on 10th September 2019 in Porto, Portugal, was dedicated to sharing research experiences on the interaction between heterogenous pathogens and multiple stressors in fish. The workshop involved around 200 attendants, opened by a keynote talk (Fast), and followed by a further twelve oral presentations, including three in the format of lash poster presentations. Contributions illustrated cross-disciplinary approaches to study complex host-pathogen and stressors interactions

Monitoring the spread of meticillin-resistant Staphylococcus aureus in The Netherlands from a reference laboratory perspective

SummaryBackgroundIn The Netherlands, efforts to control meticillin-resistant Staphylococcus aureus (MRSA) in hospitals have been largely successful due to stringent screening of patients on admission and isolation of those that fall into defined risk categories. However, Dutch hospitals are not free of MRSA, and a considerable number of cases are found that do not belong to any of the risk categories. Some of these may be due to undetected nosocomial transmission, whereas others may be introduced from unknown reservoirs.AimIdentifying multi-institutional clusters of MRSA isolates to estimate the contribution of potential unobserved reservoirs in The Netherlands.MethodsWe applied a clustering algorithm that combines time, place, and genetics to routine data available for all MRSA isolates submitted to the Dutch Staphylococcal Reference Laboratory between 2008 and 2011 in order to map the geo-temporal distribution of MRSA clonal lineages in The Netherlands.FindingsOf the 2966 isolates lacking obvious risk factors, 579 were part of geo-temporal clusters, whereas 2387 were classified as MRSA of unknown origin (MUOs). We also observed marked differences in the proportion of isolates that belonged to geo-temporal clusters between specific multi-locus variable number of tandem repeat analysis (MLVA) clonal complexes, indicating lineage-specific transmissibility. The majority of clustered isolates (74%) were present in multi-institutional clusters.ConclusionThe frequency of MRSA of unknown origin among patients lacking obvious risk factors is an indication of a largely undefined extra-institutional but genetically highly diverse reservoir. Efforts to understand the emergence and spread of high-risk clones require the pooling of routine epidemiological information and typing data into central databases

Phylogeny of the Viral Hemorrhagic Septicemia Virus in European Aquaculture

<p>One of the most valuable aquaculture fish in Europe is the rainbow trout, Oncorhynchus mykiss, but the profitability of trout production is threatened by a highly lethal infectious disease, viral hemorrhagic septicemia (VHS), caused by the VHS virus (VHSV). For the past few decades, the subgenogroup Ia of VHSV has been the main cause of VHS outbreaks in European freshwater-farmed rainbow trout. Little is currently known, however, about the phylogenetic radiation of this Ia lineage into subordinate Ia clades and their subsequent geographical spread routes. We investigated this topic using the largest Ia-isolate dataset ever compiled, comprising 651 complete G gene sequences: 209 GenBank Ia isolates and 442 Ia isolates from this study. The sequences come from 11 European countries and cover the period 1971-2015. Based on this dataset, we documented the extensive spread of the Ia population and the strong mixing of Ia isolates, assumed to be the result of the Europe-wide trout trade. For example, the Ia lineage underwent a radiation into nine Ia clades, most of which are difficult to allocate to a specific geographic distribution. Furthermore, we found indications for two rapid, large-scale population growth events, and identified three polytomies among the Ia clades, both of which possibly indicate a rapid radiation. However, only about 4% of Ia haplotypes (out of 398) occur in more than one European country. This apparently conflicting finding regarding the Europe-wide spread and mixing of Ia isolates can be explained by the high mutation rate of VHSV. Accordingly, the mean period of occurrence of a single Ia haplotype was less than a full year, and we found a substitution rate of up to 7.813 × 10^-4 nucleotides per site per year. Finally, we documented significant differences between Germany and Denmark regarding their VHS epidemiology, apparently due to those countries' individual handling of VHS.</p