Tick-Borne Encephalitis Virus: A General Overview

Tick-borne encephalitis (TBE) virus is classified as one species with three subtypes, namely the European subtype, the Siberian subtype and the Far Eastern subtype. TBE is distributed in an endemic pattern of so-called natural foci over a wide geographical area from Western Europe to the northern part of Japan. It is the most important flavivirus infection of the central nervous system in Europe and Russia, with about 13,000 estimated human cases per year. The epidemiology of TBE is closely related to the ecology and biology of ixodid ticks. In nature, TBE virus is propagated in a cycle involving permanently infected ticks and wild vertebrate hosts. Currently, the diagnosis of TBE is mainly based on the detection of specific antibodies in serum and cerebrospinal fluid. No specific treatment for the disease is available to date, but it can be prevented by active immunization

First international diagnostic accuracy study for the serological detection of West Nile virus infection

<p>Abstract</p> <p>Background</p> <p>The diagnosis of an acute or convalescent West Nile (WN) virus infection can be confirmed by various serological assays such as enzyme immunoassay (EIA), immunofluorescence assay (IFA), or neutralisation test (NT) which are conducted by a growing number of laboratories. However, as the degree of proficiency may vary between laboratories, quality control measures for laboratory diagnostics are essential.</p> <p>Methods</p> <p>We have performed an external quality assurance (EQA) programme for the serological detection of WN virus infection to assess the diagnostic quality of laboratories. The participating laboratories received a proficiency panel of 10 coded lyophilised test samples comprising four antisera positive for WN antibodies as positive controls, three antisera positive for antibodies against other heterologous flaviviruses plus one multireactive unspecific serum as specificity controls, and two negative serum samples.</p> <p>Results</p> <p>Twenty-seven laboratories from 20 different countries in Europe, the Middle East, the Americas and Africa participated in this EQA programme. Applying the proficiency criteria of this study, only eight laboratories correctly analysed all samples with their respective EIA, IFA or NT methods. Eighteen laboratories correctly identified between 77.8 and 90% of the samples, and one laboratory identified only 70% correctly with a clear need to eliminate cross-reactivity with other antisera, particularly those elicited by yellow fever virus. Differentiation between the results for IgM and IgG was considered separately and revealed that IgM-antibodies were detected less frequently than IgG-antibodies (p < 0.001). However, the assay used was not a significant technical factor influencing laboratory performance.</p> <p>Conclusion</p> <p>The EQA programme provides information on the quality of different serological assays used by the participating laboratories and indicates that most need to improve their assays, in particular to avoid cross-reactions with antibodies to heterologous flaviviruses.</p

International External Quality Assessment of Molecular Detection of Rift Valley Fever Virus

Rift Valley fever (RVF) is a viral zoonosis that primarily affects animals resulting in considerable economic losses due to death and abortions among infected livestock. RVF also affects humans with clinical symptoms ranging from an influenza-like illness to a hemorrhagic fever. Over the past years, RVF virus (RVFV) has caused severe outbreaks in livestock and humans throughout Africa and regions of the world previously regarded as free of the virus. This situation prompts the need to evaluate the diagnostic capacity and performance of laboratories worldwide. Diagnostic methods for RVFV detection include virus isolation, antigen and antibody detection methods, and nucleic acid amplification techniques. Molecular methods such as reverse-transcriptase polymerase chain reaction and other newly developed techniques allow for a rapid and accurate detection of RVFV. This study aims to assess the efficiency and accurateness of RVFV molecular diagnostic methods used by expert laboratories worldwide. Thirty expert laboratories from 16 countries received a panel of 14 samples which included RVFV preparations representing several genetic lineages, a specificity control and negative controls. In this study we present the results of the first international external quality assessment (EQA) for the molecular diagnosis of RVF. Optimal results were reported by 64% of the analyses, 21% of the analyses achieved acceptable results and 15% of the results revealed that there is need for improvement. Evenly good performances were achieved by specific protocols which can therefore be recommended as an accurate molecular protocol for the diagnosis of RVF. Other protocols showed uneven performances revealing the need for improved optimization and standardization of these protocols

Rickettsia aeschlimannii in Hyalomma marginatum Ticks, Germany

To the Editor: Rickettsia spp. of the spotted fever group cause worldwide emerging human infections known as tick-borne rickettsioses (1). Data on the occurrence and prevalence of Rickettsia in Germany are still limited (2). Six Rickettsia species have been reported to date (2). R. helvetica, R. felis, R. massiliae, and R. monacensis were detected with a relatively low prevalence in Ixodes ricinus ticks collected in southern Germany (2); R. raoultii was identified with high prevalence in the rapidly expanding area where D. reticulatus ticks are found (2). R. raoultii was recently recognized as an agent of tick-borne lymphadenopathy/Dermacentor-borne necrosis and erythema lymphadenopathy (3). Low prevalence of another tick-borne lymphadenopathy agent, R. slovaca, in Dermacentor marginatus ticks collected in southern Germany was recently reported (4)

Second External Quality Assurance Study for the Serological Diagnosis of Hantaviruses in Europe

Peer reviewe

Importance of external quality assessment for SARS-CoV-2 antigen detection during the COVID-19 pandemic

Background: Antigen testing has become an essential part of fighting the ongoing COVID-19 pandemic. With the continual increase in available tests, independent and extensive comparative evaluations using data from external quality assessment (EQA) studies to evaluate test performance between different users are required.Objectives: An EQA scheme was established to assess the sensitivity of antigen tests and the potential impact of circulating SARS-CoV-2 strains on their performance.Study design: Panels were prepared for three challenges in 2021 containing inactivated SARS-CoV-2-positive samples of various genetic strains (including variants of concern, VOCs) at different concentrations, and negative samples. Data was analysed based on qualitative testing results in relation to the antigen test used. Results: Participants registered for each individual challenge in any combination. In total, 258 respondents from 27 countries worldwide were counted submitting 472 datasets. All core samples were correctly reported by 76.7 to 83.1% at participant level and by 73.5 to 83.8% at dataset level. Sensitivity differences could be shown in viral loads and SARS-CoV-2 strains/variants including the impact on performance by a B.1.1.7-like mutant strain with a deletion in the nucleoprotein gene. Lateral flow rapid antigen tests showed a higher rate of false negatives in general compared with automated point-of-care tests and laboratory ELISA/immunoassays.Conclusions: EQA schemes can provide valuable data to inform participants about weaknesses in their testing process or methods and support ongoing assay evaluations for regulatory approval or post-market surveillance

2nd International External Quality Control Assessment for the Molecular Diagnosis of Dengue Infections

Dengue viruses (DENV) are the most widespread arthropod-borne viruses which have shown an unexpected geographic expansion, as well as an increase in the number and severity of outbreaks in the last decades. In this context, the accurate diagnosis and reliable surveillance of dengue infections are essential. The laboratory diagnosis of dengue relies on the use of several methods detecting markers of DENV infection present in patient serum. Molecular diagnosis methods are usually rapid, sensitive, and simple when correctly standardized. Moreover, PCR-based diagnosis techniques are able to readily detect DENV during the acute phase of the disease and may assume an important role in dengue diagnosis and surveillance. Different reverse transcriptase PCR (RT-PCR) methods have been developed and are currently available and should be standardized in each laboratory to maintain high quality performance. In this work an External quality assessment (EQA) activity has been carried out to evaluate the accuracy and quality of laboratory data for the molecular diagnosis and surveillance of dengue, which involved worldwide dengue reference laboratories. In conclusion, RT-PCR techniques for dengue diagnosis applied by the participating laboratories demonstrated the need of further improvement in most laboratories

First International External Quality Assessment Study on Molecular and Serological Methods for Yellow Fever Diagnosis

Objective: We describe an external quality assurance (EQA) study designed to assess the efficiency and accurateness of molecular and serological methods used by expert laboratories performing YF diagnosis. Study Design: For molecular diagnosis evaluation, a panel was prepared of 14 human plasma samples containing specific RNA of different YFV strains (YFV-17D, YFV South American strain [Brazil], YFV IvoryC1999 strain), and specificity samples containing other flaviviruses and negative controls. For the serological panel, 13 human plasma samples with anti-YFVspecific antibodies against different strains of YFV (YFV-17D strain, YFV IvoryC1999 strain, and YFV Brazilian strain), as well as specificity and negative controls, were included. Results: Thirty-six laboratories from Europe, the Americas, Middle East, and Africa participated in these EQA activities. Only 16% of the analyses reported met all evaluation criteria with optimal performance. Serial dilutions of YFV-17D showed that in general the methodologies reported provided a suitable sensitivity. Failures were mainly due to the inability to detect wild-type strains or the presence of false positives. Performance in the serological diagnosis varied, mainly depending on the methodology used. Anti-YFV IgM detection was not performed in 16% of the reports using IIF or ELISA techniques, although it is preferable for the diagnosis of YFV acute infections. A good sensitivity profile was achieved in general; however, in the detection of IgM antibodies a lack of sensitivity of anti-YFV antibodies against the vaccine strain 17D was observed, and of the anti-YFV IgG antibodies against a West African strain. Neutralization assays showed a very good performance; however, the unexpected presence of false positives underlined the need of improving the running protocols. Conclusion: This EQA provides information on each laboratory’s efficacy of RT-PCR and serological YFV diagnosis techniques. The results indicate the need for improving serological and molecular diagnosis techniques and provide a follow-up of the diagnostic profiles

Arboviral Encephalitis – Epidemiology, Diagnostics and Surveillance in the Face of Changing Environments

The habilitation thesis focuses on arbovirus-induced disease of the central nervous system, with emphasis on those agents important and emerging in Europe, by giving an overview of their epidemiology, diagnostics, and surveillance. These are: West Nile virus (WNV), Toscana virus (TOSV), and tick-borne encephalitis virus (TBEV). The published studies selected are all part of activities within the European Network for Diagnostics of ‘Imported’ Viral Diseases (ENIVD) and/or the German Consultant Laboratory for Tick-borne encephalitis and further flaviviruses

Prävalenz kardiotroper Viren im humanen Herzgewebe

Virusinfektionen sind eine häufige Ursache von entzündlichen Erkrankungen am menschlichen Herzen, wie z.B. der akuten und chronischen Myokarditis, dilatativen Kardiomyopathie oder der koronaren Herzkrankheit, und gelten daher weltweit als eine der Hauptursachen für Morbidität und Mortalität bei kardiovaskulären Erkran-kungen. Des Weiteren sind Virusinfektionen im transplantierten Myokard an kardialen Ereignissen beteiligt, die bis zum Transplantatverlust führen können. In der vorlie-genden, derzeitig umfangreichsten Prävalenzstudie für kardiotrope Viren wurden mit Hilfe der PCR Herzgewebeproben (sowohl Myokard- als auch Herzklappengewebe) aus Herztransplantatempfängern (HTx-Patienten) und Herzspendern untersucht, um die Häufigkeit einzelner in Frage kommender viralen Erreger in erkrankten bzw. ge-sunden Herzen zu klären. In der Studie eingeschlossen wurden a) kardiotrope virale Erreger, für die ein ätiologischer Zusammenhang mit entzündlichen Herzerkrankun-gen belegt worden ist wie Enteroviren (EV), Adenoviren (ADV), humanes Zytomega-lievirus (HCMV), Parvovirus B19 (PVB19) und Influenzavirus (Typ A und B) sowie b) virale Erreger mit bisher unbekanntem Risiko wie die – erst kürzlich in schwedischen Mäusepopulationen beschriebenen – Ljunganviren (LV) und Hantaviren (Typ Puuma-la und Dobrava). Die Untersuchung von insgesamt 449 Myokardproben hat hierbei ergeben, dass 34 von 73 HTx-Patienten (47 %) und 48 von 80 Herzspendern (60 %) positiv für min-destens einen der untersuchten Viren waren. Virale Nukleinsäuresequenzen wurden signifikant häufiger in Spendern mit einem Spenderalter über 65 Jahren nachgewie-sen als in HTx-Patienten (P= 0,005) oder Spendern mit einem Spenderalter unter 65 Jahren (P= 0,02). Des Weiteren konnte erstmalig auch ein hoher Befall von subval-vulärem Myokardgewebe (64 %) und Herzklappen (53 %) in 30 Herzklappen-spendern nachgewiesen werden. Insgesamt wurde eine hohe Prävalenz von EV (vor allem Coxsackievirus B-ähnlichen Viren) und ADV festgestellt. Weniger häufig wur-den HCMV und PVB19 nachgewiesen, denen jedoch ebenfalls eine Bedeutung als kardiotrope Erreger zugeschrieben wird. Keine der hier untersuchten Proben war positiv für Influenza-, Ljungan- oder Hantaviren, was eher darauf hinweist, dass die Prävalenz dieser Erreger in humanen Herzgewebe deutlich geringer ist als die anderer Viren und dass diese Erreger wahrscheinlich eher eine Rolle bei akuten Infektionen spielen, die nicht den Hauptbestandteil in unserem Patientenkollektiv bildeten. In 88 % der untersuchten Fälle wurde eine hohe Korrelation zwischen den PCR-Befunden und histopathologischen Ergebnissen gezeigt. Im Gegensatz dazu waren die serologischen Ergebnisse der zum Einsatz gekommenen kommerziellen ELISA-Teste weitgehend diskordant (zwischen 4 % und 27 %) hinsichtlich des Nach-weises von IgG-Antikörpern, wodurch die potenziell virale Ursache chronischer Krankheitsverläufe übersehen werden kann. Die Beobachtung, dass Herzexplantate durch verschiedene virale Erreger persistent infiziert sein können, ist sowohl für die Diagnostik und Therapie von entzündlichen Herzerkrankungen von Bedeutung als auch für die Prävention von Komplikationen, die, bedingt durch die im Transplantat vorhandenen Viren, nach einer Transplanta-tion möglicherweise auftreten können. Die sensitive PCR-Technik könnte in Zukunft hilfreich sein, das Risiko einer Virusübertragung vom Spender auf den Empfänger näher zu untersuchen. Die hier beschriebenen Daten sind auch bezüglich der Spen-derauswahl von Bedeutung, da bedingt durch das limitierte Angebot geeigneter Spenderorgane die Kriterien zur Spenderauswahl zunehmend gelockert werden. So wird z.B. die Altersbegrenzung der Spender immer mehr angehoben, wodurch immer häufiger Spenderorgane älterer Spender transplantiert werden, die, wie hier gezeigt werden konnte, eine signifikant höhere Prävalenz möglicher Virusinfektionen im Her-zen aufweisen als bisher vermutet. Zur Verbesserung des Qualitätsmanagements bei Transplantaten wird ein kombiniertes Verfahren aus PCR-Diagnostik und histo-pathologischer Evaluierung zur Untersuchung von Biopsiematerialien bzw. Myokard-proben auf die Präsenz viraler Erreger vorgeschlagen. Die Virusdiagnostik sollte nach den in dieser Studie belegten neueren Erkenntnissen generell die bekannten kardiotropen viralen Erreger wie EV, ADV, HCMV und PVB19 berücksichtigen sowie weitere virale Erreger, die im Zusammenhang von Spender-bezogenen Infektionen in Allotransplantaten beschrieben worden sind, z.B. Hepatitis B-, Hepatitis C- und Ep-stein-Barr-Virus.Virus infections are implicated in the etiology of cardiovascular diseases like acute and chronic myocarditis, dilated cardiomyopathy (DCM) or coronary heart disease (CHD), which are the leading causes of heart failure with a high morbidity and morta-lity worldwide. Affected individuals may require long-term medical therapy for chronic heart failure with a high economic burden including cardiac transplantation costs. In Germany almost 60 percent of all indications for cardiac transplantation are due to DCM and 27 percent due to CHD. Furthermore, virus infections of the heart have been reported to be potentially implicated in atherosclerosis, coronary vasculopathy, lymphoproliferative disease and graft loss after cardiac allograft transplantation, developments which limit the survival of recipients. Although laboratory diagnosis of viral heart disease has improved in recent years due to molecular techniques such as polymerase chain reaction (PCR) and in situ hybridization, these techniques are not yet widely applied. Due to few or controversial data regarding the prevalence of the different possible viral agents in these heart diseases, the aim of this presently most extensive study was to examine myocardial and heart valve tissue samples from explanted hearts of heart transplant (HTx) recipients and heart donors for nucleic acids of myocardiotropic viruses. To assess the prevalence, myocardial and heart valve tissue samples were analyzed by different PCR methods for screening of viral agents which were linked to inflam-matory heart disease, like enteroviruses (EV), adenoviruses (ADV), human cyto-megalovirus (HCMV), parvovirus B19 (PVB19) and influenza viruses (type A and B). Additionally, screening was also performed for the newly described Ljungan viruses and the also rodent-derived Hanta viruses (type Puumala and Dobrava) which are suspected to be involved in human heart disease. PCR analysis of 449 myocardial tissue samples from explanted hearts indicated infection in 34 of 73 HTx-recipients (47 percent) and 48 of 80 donors (60 percent). The prevalence of virus infection in donors aged over 65 years was significantly higher than that in HTx-recipients (P= 0.005) or donors aged under 65 years (P= 0.02). Furthermore, high prevalence of viral DNA could be shown for the first time in subvalvular myocardial tissue (64 percent) and non-coronary valve samples (53 percent) from 30 heart valve donors. The most frequently detected viruses were EV (group B coxsackieviruses) and ADV. HCMV and PVB19 were found less frequently but these viruses should also be recognized as potential cardiotropic pathogens in patients of all ages. All tested samples were negative for influenza, Ljungan or hanta viruses, indicating low prevalence of these viral agents in human heart tissue compared to the other viruses. Maybe these viruses play only a role in early acute heart diseases, but the majority of the patients tested in our heart study presented diseases with chronic course like DCM and CHD. This should be taken into consideration for future study design and patient selection. While the serological findings and PCR results for different viruses were discordant in 4 to 27 percent of the cases, there was a high correlation (88 percent) between PCR and histopathological findings. The serological results indicated a risk of overlooking the potential viral cause of chronic inflammatory heart disease by using commercial ELISA tests. The observation that heart explants may be persistently infected by different viral agents is of importance not only for the diagnosis of inflammatory cardiac disease, but also for the prevention of post-transplantation complications. The highly sensitive PCR technique as shown here seems helpful in estimating the risk of virus transmission from donor to recipient. The obtained data are important for virological safety aspects in donor selection, because the criteria for donor selection have become looser, e.g. the age limit of donors was reduced, allowing transplantation of donor organs from older people which, as shown here, demonstrated a significantly higher prevalence of virus infection in the heart. For improvement of virus safety in cardiac transplantation and homograft banking it should be recommended to screen the donor organs and tissues with a multi-technology approach, using PCR in addition to or instead of serological analysis together with histological evaluation. Viral diagnostics should include the known cardiotropic viruses like EV, ADV, HCMV, PVB19, as done in this study, and viral agents of general importance for donor-associated infection in allograft transplantation (e.g. HBV, HCV, and EBV)