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Abstract: The European Virus Archive (EVA) was conceived as a direct response to the need for a coordinated and readily accessible collection of viruses that could be made available to academia, public health organisations and industry, initially within Europe, but ultimately throughout the world. Although scientists worldwide have accumulated virus collections since the early twentieth century, the quality of the collections and the viruses collected may vary according to the personal interests and agenda of the scientists. Moreover, when laboratories are re-organised or closed, collections are no longer maintained and gradually cease to exist. The tragedy of 9/11 and other disruptive activities have also meant that some previously available biological reagents are no longer openly exchanged between countries. In 2008, funding under the FP7–EU infrastructure programme enabled the initiation of the EVA. Within three years, it has developed from a consortium of nine European laboratories to encompass associated partners in Africa, Russia, China, Turkey, Germany and Italy. There is every reason to believe that EVA will continue to expand and ultimately exist as a globally networked, quality-controlled non-profit archive for the benefit of science. Organizations or individuals who would like to be considered as contributors are invited to contact the EVA coordinator, Jean–Louis Romette, at jean-louis.romette@univmed.fr. [Copyright &y& Elsevier]

Tick-borne encephalitis (TBE) is a viral zoonotic disease endemic in many regions of Eurasia. The definition of TBE risk areas is complicated by the focal nature of the TBE virus transmission. Furthermore, vaccination may reduce case numbers and thus mask infection risk to unvaccinated persons. Therefore, additional risk indicators are sought to complement the current risk assessment solely based on human incidence. We reviewed studies published over the past ten years investigating potential new sentinels of TBE risk to understand the advantages and disadvantages of the various sentinel animal surveys and surrogate indicator methods. Virus prevalence in questing ticks is an unsuitable indicator of TBE infection risk as viral RNA is rarely detected even in large sample sizes collected at known TBE endemic areas. Seroprevalence in domestic animals, on the other hand, showed good spatial correlation with TBE incidence in humans and might also uncover presently unknown TBEV foci., (Copyright © 2015 Elsevier GmbH. All rights reserved.)

On August 8 2014, the World Health Organization (WHO) declared the outbreak of Ebola Virus Disease (EVD) evolving in West Africa since December 2013, a Public Health Emergency of International Concern (PHEIC). It is expected that the outbreak of Ebolavirus Disease (EVD) in West Africa will lead to increased testing of individuals in Europe for EVD. The severity of the situation in West Africa warranted a critical appraisal of the laboratory preparedness and response for EVD, with a focus on information needs for laboratories involved in diagnostics of rare viral diseases associated with the European Network for the Diagnostics of "Imported" Viral Diseases", ENIVD. Essential knowledge and knowledge gaps for an adequate laboratory response focusing on virus properties, infection kinetics, tests specifics and field performances were identified. An inventory of the laboratory capacity for EVD diagnostics among ENIVD laboratories was made.

Crimean-Congo haemorrhagic fever (CCHF) is an infectious viral disease that has (re-)emerged in the last decade in south-eastern Europe, and there is a risk for further geographical expansion to western Europe. Here we report the results of a survey covering 28 countries, conducted in 2012 among the member laboratories of the European Network for Diagnostics of 'Imported' Viral Diseases (ENIVD) to assess laboratory preparedness and response capacities for CCHF. The answers of 31 laboratories of the European region regarding CCHF case definition, training necessity, biosafety, quality assurance and diagnostic tests are presented. In addition, we identified the lack of a Regional Reference Expert Laboratory in or near endemic areas. Moreover, a comprehensive review of the biosafety level suitable to the reality of endemic areas is needed. These issues are challenges that should be addressed by European public health authorities. However, all respondent laboratories have suitable diagnostic capacities for the current situation.

Tick-borne encephalitis (TBE) is a zoonotic disease, transmitted mainly by the bite of ticks. The TBE virus (TBEV) belongs to the family Flaviviridae, genus Flavivirus and is able to cause meningoencephalitis. For serological TBEV detection, the neutralization test (NT) is the most specific assay available. Different NT protocols are used in the laboratories, and until now the performance of these NTs has never been tested in an external quality assessment (EQA). In this EQA, we compared the results of eight European laboratories in detecting 17 samples (11 TBEV positive, five flavivirus cross reactive, and one negative sample) by NT. Furthermore, 14 of these EQA samples and 15 additional samples were tested in different commercial assays: 15 immunoglobulin G (IgG) enzyme-linked immunosorbent assays (ELISAs) and an immunofluorescence assay (IFA). Four laboratories showed a good NT EQA performance, whereas four laboratories had some sensitivity problems. Additionally, two of these laboratories showed a lack in specificity, misidentifying a dengue-positive sample as TBEV positive. The comparison of the commercial ELISAs revealed a high sensitivity in all assays, but as expected for IgG, the ELISAs showed a high degree of flavivirus cross reactivity. The assessment of Vienna Units in some of the ELISAs revealed deviations in the standards used by the different companies. Therefore, these standards should be revised. Generally, in this EQA, we found that reliable NT protocols are used in most of the laboratories, and the evaluation of the IgG ELISAs and the IFA showed a good agreement.

Public Health is defined as an interdisciplinary multilevel approach that deals with questions of preventing diseases at the population level. In this context, this paper focuses on vector-borne diseases as an important threat with an increasing impact on human and animal health. Emphasis is laid on an integrated health approach ('One-Health' initiative) as it recognizes the interrelated nature of both human and animal health. The importance of vector-borne diseases to new and emerging diseases in Europe was demonstrated, for example, by the recent outbreak of West Nile virus infections in Greece, Northern Italy and Hungary; the spread of Crimean-Congo haemorrhagic fever virus across Turkey, south-western countries of the former USSR and the Balkans; the dramatic increase in hantavirus infections in Germany in 2012; and the dengue virus outbreak in Portugal in the same year. This paper provides a systematic approach for the analysis, assessment and governance of emerging health risks attributed to vector-borne diseases by using a holistic approach developed by the International Risk Governance Council (IRGC), called the 'IRGC Risk Governance Framework'. It can be used by decision-makers and general Public Health authorities in order to evaluate the situation regarding any specific pathogen or Public Health risk and to decide if additional measures should be implemented., (© 2013 Blackwell Verlag GmbH.)

West Nile virus (WNV), a mosquito-borne flavivirus in the Japanese encephalitis antigenic group, has caused sporadic outbreaks in humans, horses and birds throughout many of the warmer regions of Europe for at least 20 years. Occasional cases of West Nile encephalitis have also been associated with infected blood transfusions and organ donations. Currently, WNV appears to be expanding its geographical range in Europe and causing increasing numbers of epidemics/outbreaks associated with human morbidity and mortality. This brief review reports on the current epidemic situation regarding WNV in Europe, highlighting the clinical, diagnostic and preventive measures available for controlling this apparently emerging human pathogen., (© 2013 The Authors Clinical Microbiology and Infection © 2013 European Society of Clinical Microbiology and Infectious Diseases.)

Hantaviruses are endemic throughout the world and hosted by rodents and insectivores. Two human zoonoses, hemorrhagic fever with renal syndrome (HFRS) and hantavirus pulmonary syndrome (HPS), are caused by hantaviruses and case fatality rates have reached 12% for HFRS and 50% for HPS in some outbreaks. Symptomatic hantavirus infections in Europe are summarised as HFRS mainly due to Puumala, Dobrava-Belgrade and Saaremaa virus. While HFRS has an overall low incidence in Europe, the number of cases varies from 100 per year in all Eastern and Southern Europe up to 1,000 per year only in Finland. To assess the quality of hantavirus diagnostics, the European Network for the Diagnostics of "Imported" Viral Diseases (ENIVD) organised a first external quality assurance (EQA) in 2002. The purpose of this second EQA study is to collect updated information on the efficiency and accurateness of hantavirus serological methods applied by expert laboratories. A serum panel of 14 samples was sent to 28 participants in Europe of which 27 sent results. Performance in hantavirus diagnosis varied not only on the method used but also on the laboratories and the subclass of antibodies tested. Commercial and in-house assays performed almost equally. Enzyme immunoassays were mainly used but did not show the best performances while immunoblot assays were the less employed and showed overall better performances. IgM antibodies were not detected in 61% of the positive IgM samples and IgM detection was not performed by 7% of the laboratories indicating a risk of overlooking acute infections in patients. Uneven performances using the same method is indicating that there is still a need for improving testing conditions and standardizing protocols.

In the last several years, West Nile virus (WNV) was proven to be present especially in the neighboring countries of Austria, such as Italy, Hungary, and the Czech Republic, as well as in eastern parts of Austria, where it was detected in migratory and domestic birds. In summer 2010, infections with WNV were reported from Romania and northern Greece with about 150 diseased and increasingly fatal cases. We tested the sera of 1,607 blood donors from North Tyrol (Austria) and South Tyrol (Italy) for antibodies against WNV by using IgG enzyme-linked immunosorbent assay (ELISA). Initial results of the ELISA tests showed seroprevalence rates of 46.2% in North Tyrol and 0.5% in South Tyrol, which turned out to be false-positive cross-reactions with antibodies against tick-borne encephalitis virus (TBEV) by adjacent neutralization assays. These results indicate that seropositivity against WNV requires confirmation by neutralization assays, as cross-reactivity with TBEV is frequent and because, currently, WNV is not endemic in the study area.

Usutu virus (USUV) is an African mosquito-borne flavivirus, member of the Japanese encephalitis antigenic group. This avian virus is transmitted by arthropod vectors (mainly mosquitoes of the Culex pipiens complex). It is well known that free-living birds, including migratory species, have the potential to disperse certain pathogenic microorganisms. Usutu virus has recently been introduced to Europe and is spreading through Austria, Hungary, Italy, Spain and Switzerland, causing disease in birds and humans. Like West Nile virus, USUV may become a resident pathogen in Europe and the consequences for public health should be considered. Many different biotic and abiotic factors affect the survival of the virus in a new environment and influence the efficiency of its geographical dispersal. In this article, we consider the possibility of including USUV infections among the vector-borne diseases to be monitored in Europe.

Understanding epidemiology of the tick-borne pathogens requires the accurate identification of the vector ticks. Morphological analysis of ticks is difficult and often leads to misidentification. Molecular techniques offer an alternative approach of tick identification. To date, no practical and reliable molecular assays for discrimination of Euro-Asian ticks are available. Our aim was to develop such an assay for discrimination between four Euro-Asian tick species of high medical importance such as Ixodes ricinus, Ixodes persulcatus, Ixodes hexagonus, and Dermacentor reticulatus. As a basis, we have chosen conventional species-specific polymerase chain reaction (PCR), a technique providing a good combination of simplicity and reliability. The DNA information available on ticks was searched for orthologous loci containing stretches of sequence dissimilarity sufficient for designing species-specific primers. ITS2 locus (second internal transcribed region of the rRNA gene cluster) was found to be the most favorable for primer design. Finally, for each of the three Ixodes species a PCR was developed amplifying only for the targeted species. One PCR amplified the entire ITS2 locus of the four species and allowed discrimination of D. reticulatus from the Ixodes species on the basis of the size difference of the respective PCR products. This PCR system was successfully tested for discrimination of the ticks at different maturation stages (larva, nymph, and adult) in engorged and unfed conditions, and therefore it may be useful for large-scale epidemiological studies. Differentiation between the closely related I. ricinus and I. persulcatus, the two species most often occurring in the tick-borne diseases in Eurasia, is of special importance.

Background: Dengue viruses (DENV) are the most widespread arthropod-borne viruses, which have shown an unexpected geographic expansion, as well as an increase in number and severity of outbreaks in the last decades. Although the emergence of dengue is considered to be due to a number of complex factors, epidemiological studies have shown that some strains of dengue might be associated with increased severity and higher transmission rates than others. In this context, surveillance and identification of the appearance or introduction of more virulent strains, along with fluctuation of DENV among endemic areas are now considered essential public health activities., Methods: Samples from travelers returning from the tropics with acute dengue infections were analyzed to obtain up-dated information on circulating dengue strains. A short nucleotide fragment located in the carboxyl terminus of the dengue E gene was used for the characterization of DENV strains and the identification of their sero- and genotype., Results: One hundred eighty-six new dengue strains have been classified into 12 distinct genotype groups within the four dengue serotypes. The identification of the emergence of different sero- and genotypes, the appearance of new clades correlating with outbreaks, and the identification of a dengue-4 genotype not previously reported have been achieved. Interestingly, African strains characterized in this study have provided valuable data on dengue circulation on the continent., Conclusions: This work demonstrates the convenience of routine application of molecular epidemiology analyses in dengue diagnosis laboratories. The use of molecular epidemiology tools on the analysis of imported dengue infections strengthens data acquisition on dengue strain movements correlating with epidemiological changes. The importance of surveillance of imported diseases contributing data for the epidemiological knowledge of infectious diseases in endemic areas has been once more demonstrated., (© 2011 International Society of Travel Medicine.)

Bats may host emerging viruses, including coronaviruses (CoV). We conducted an evaluation of CoV in rhinolophid and vespertilionid bat species common in Europe. Rhinolophids carried severe acute respiratory syndrome (SARS)-related CoV at high frequencies and concentrations (26% of animals are positive; up to 2.4×10(8) copies per gram of feces), as well as two Alphacoronavirus clades, one novel and one related to the HKU2 clade. All three clades present in Miniopterus bats in China (HKU7, HKU8, and 1A related) were also present in European Miniopterus bats. An additional novel Alphacoronavirus clade (bat CoV [BtCoV]/BNM98-30) was detected in Nyctalus leisleri. A CoV grouping criterion was developed by comparing amino acid identities across an 816-bp fragment of the RNA-dependent RNA polymerases (RdRp) of all accepted mammalian CoV species (RdRp-based grouping units [RGU]). Criteria for defining separate RGU in mammalian CoV were a >4.8% amino acid distance for alphacoronaviruses and a >6.3% distance for betacoronaviruses. All the above-mentioned novel clades represented independent RGU. Strict associations between CoV RGU and host bat genera were confirmed for six independent RGU represented simultaneously in China and Europe. A SARS-related virus (BtCoV/BM48-31/Bulgaria/2008) from a Rhinolophus blasii (Rhi bla) bat was fully sequenced. It is predicted that proteins 3b and 6 were highly divergent from those proteins in all known SARS-related CoV. Open reading frame 8 (ORF8) was surprisingly absent. Surface expression of spike and staining with sera of SARS survivors suggested low antigenic overlap with SARS CoV. However, the receptor binding domain of SARS CoV showed higher similarity with that of BtCoV/BM48-31/Bulgaria/2008 than with that of any Chinese bat-borne CoV. Critical spike domains 472 and 487 were identical and similar, respectively. This study underlines the importance of assessments of the zoonotic potential of widely distributed bat-borne CoV.

Background: Currently dengue viruses (DENV) pose an increasing threat to over 2.5 billion people in over 100 tropical and sub-tropical countries worldwide. International air travel is facilitating rapid global movement of DENV, increasing the risk of severe dengue epidemics by introducing different serotypes. Accurate diagnosis is critical for early initiation of preventive measures. Different reverse transcriptase PCR (RT-PCR) methods are available, which should be evaluated and standardized. Epidemiological and laboratory-based surveillance is required to monitor and guide dengue prevention and control programmes, i.e., by mosquito control or possible vaccination (as soon as an effective and safe vaccine becomes available)., Objective: The purpose of the external quality assurance (EQA) study described is to assess the efficiency and accuracy of dengue molecular diagnosis methods applied by expert laboratories., Study Design: A panel of 12 human plasma samples was distributed and tested for DENV-specific RNA. The panel comprised 9 samples spiked with different DENV serotypes (DENV-1 to DENV-4), including 10-fold dilution series of DENV-1 and DENV-3. Two specificity controls consisted of a sample with a pool of 4 other flaviviruses and a sample with chikungunya virus. A negative control sample was also included., Results: Thirty-seven laboratories (from Europe, Middle East Asia, Asia, the Americas/Caribbean, and Africa) participated in this EQA study, and reports including 46 sets of results were returned. Performance among laboratories varied according to methodologies used. Only 5 (10.9%) data sets met all criteria with optimal performance, and 4 (8.7%) with acceptable performance, while 37 (80.4%) reported results showed the need for improvement regarding accomplishment of dengue molecular diagnosis. Failures were mainly due to lack of sensitivity and the presence of false positives., Conclusions: The EQA provides information on each laboratory's efficacy of RT-PCR techniques for dengue diagnosis and indicates for most laboratories an urgent need to improve sensitivity and specificity.

During the last decade Crimean-Congo hemorrhagic fever (CCHF) emerged and/or re-emerged in several Balkan countries, Turkey, southwestern regions of the Russian Federation, and the Ukraine, with considerable high fatality rates. Reasons for re-emergence of CCHF include climate and anthropogenic factors such as changes in land use, agricultural practices or hunting activities, movement of livestock that may influence host-tick-virus dynamics. In order to be able to design prevention and control measures targeted at the disease, mapping of endemic areas and risk assessment for CCHF in Europe should be completed. Furthermore, areas at risk for further CCHF expansion should be identified and human, vector and animal surveillance be strengthened.

Ticks can transmit a variety of viruses, bacteria or parasites that can cause serious infections or conditions in humans and animals. While tick-borne diseases are becoming an increasing and serious problem in Europe, tick-borne diseases are also responsible for major depressions in livestock production and mortality in sub-Saharan Africa, Latin America and Asia. This review will focus on the most important circulating tick-transmitted pathogens in Europe (Borrelia spp., Anaplasma phagocytophilum, Babesia spp., tick-borne encephalitis virus, Rickettsia spp. and Crimean-Congo hemorrhagic fever virus).

A preformulated chikungunya virus real-time reverse transcription-PCR, quality-confirmed oligonucleotides, and noninfectious virus controls were distributed by the European Network for the Diagnosis of Imported Viral Diseases. An international proficiency study with 31 participants demonstrated that ad hoc implementation of molecular diagnostics was feasible and successful.

Background: In 1999-2000, reports of fatalities after vaccination with 17D-derived yellow fever vaccine (YEL) focused mainly on cases of YEL-associated adverse events (YEL-AEs) and YEL-associated viscerotropic disease (YEL-AVD). Here, we investigated 6 recent European cases to provide insight regarding immune response involvement and to identify potential risk factors., Methods: Clinical, microbiological, molecular biological, and immunological assays were performed on serum from 6 patients with YEL-AEs, including 5 with YEL-AVD and 1 with YEL-associated neurotropic disease (YEL-AND)., Results: The levels of 3 liver enzymes associated with infection were clearly increased in all patients with YEL-AVD, but no elevations were observed in the patient with YEL-AND. In the patients with severe YEL-AVD, platelet counts were markedly reduced (< 100,000 cells/microL). The only patient with fatal YEL-AVD exhibited a cytokine profile comparable to that seen in YF: high levels of interleukin (IL)-6, IL-8, monocyte chemotactic protein (MCP)-1, monokine induced by interferon-gamma, and growth-related oncogene (GRO). The other patients with YEL-AVD exhibited similar but less severe cytokine profiles. The patient with YEL-AND exhibited a cytokine profile similar to that found in vaccinees without YEL-AEs: elevated levels of RANTES and low levels of GRO, MCP-1, transforming growth factor-beta1, and tumor necrosis factor-beta., Conclusions: On the basis of these results, we conclude that elevations in cytokine levels and reductions in platelet counts are suitable surrogate markers for patients likely to experience severe adverse reactions to YEL.

The European Network for Diagnostics of "Imported" Viral Diseases (ENIVD) is finalising a project to improve the diagnostic and monitoring of encephalitis viruses in Europe. Part of this study was to analyse the present surveillance situation for tick-borne encephalitis (TBE), which is the most important flavivirus infection of the central nervous system in the European Union (EU) and Russia. A questionnaire was mailed to contact points in all Member States of the EU and three non-EU countries (Norway, Russia and Switzerland) to summarise their TBE surveillance and prevention activities. Information was requested on case definition, type of laboratory tests for TBE diagnostics, investigations regarding tick-transmitted diseases, mapping of endemic foci, vaccination programmes, and recommendations for travellers. The survey gives an overview of the existing epidemiological and laboratory sources of information and the number of TBE cases from 2004 until 2007, but also showed that, in particular, case definitions, diagnostic assays for confirmation, and methods/indicators for mapping risk areas differ widely across the participating countries. The data will help to develop recommendations for the standardisation and quality control or TBE surveillance and diagnostics.

Infective processes in the brain, spinal cord and meninges are considered to be the main causes of encephalitis, myelitis and meningitis. However, most cases remain unexplained. The incidence of different viral aetiologies (zoonotic and non-zoonotic) is especially poorly estimated, due to the lack of a standard case definition and of agreed diagnostic algorithms, including harmonised diagnostic methods and sample collection. It is important to clarify the incidence of viral encephalitis/meningitis and to optimise the diagnosis of infectious neurological illness, particularly to ensure early recognition of outbreaks or emerging infectious such a West Nile encephalitis. The European Network for Diagnostics of 'Imported' Viral Diseases (ENIVD) has analysed the present surveillance situation for viral encephalitis/meningitis in Europe. Here we give an overview of the existing epidemiological sources of information in European Union (EU) Member States, mapping the laboratory capacity and identifying key requirements for a possible future surveillance study at European level. The data presented will help design a harmonised/standardised Europe-wide surveillance study investigating patients with encephalitis and/or meningitis in order to obtain more information on the role of infections in these rarely analysed syndromes, both from a clinical and an epidemiological perspective.

Background: Reverse transcriptase-polymerase chain reaction (RT-PCR) is an efficient method for the early detection of tick-borne encephalitis virus (TBEV) RNA in blood and serum samples taken prior to the appearance of antibodies. Improved diagnostics are critical for optimally detecting and managing TBE infections and quality control measures are therefore essential., Objective: To assess the diagnostic quality of laboratories by performing an external quality assurance (EQA) programme for the molecular detection of TBE infections., Study Design: A panel of 12 prepared human plasma samples were distributed and tested for the presence of TBEV-specific RNA. The panel comprised eight samples spiked with different TBEV strains of European, Siberian and Far Eastern subtypes, and included a 10-fold dilution series. Two specificity controls consisted of a sample with Louping ill virus (LIV) and a sample with a pool of four other flaviviruses, and two negative control samples were further included., Results: Twenty-three laboratories from 16 European and 2 non-European countries participated in this EQA programme. Only two participants correctly identified all samples. Nine laboratories correctly identified 75.0-91.7% of the samples; seven laboratories correctly identified 54.5-66.7% and five laboratories correctly identified < or =50%., Conclusions: The EQA programme provides information on the quality of the RT-PCR methods used by the participating laboratories and indicates that most of these need to improve sensitivity and specificity of their molecular assays for TBEV.

The threat posed by emerging and re-emerging communicable diseases and, more recently, by the intentional release of infectious agents in a susceptible population, has been receiving considerable attention at the national and international levels. Public health efforts to strengthen disease detection, surveillance and control have been intensified. However, clinicians and clinical microbiology laboratories play an important role in the early detection of disease, the identification of the putative agent, and notification of the appropriate authorities. To be effective in this role, laboratories must be specially prepared to handle viral agents safely, and need, among other things, the appropriate rapid and sensitive diagnostic tests. In 1998 the European Network for Diagnostics of 'Imported' Viral Diseases (ENIVD) was established. ENIVD presently comprises, as permanent members, 44 expert laboratories in 21 European Union (EU) member states and 4 non-EU countries and is one of the networks on infectious diseases funded by the European Commission. ENIVD fulfils many of the important tasks required for the surveillance and control of imported, rare and emerging viral infections such as the exchange of expertise and the organisation of external quality assurance (EQA) programmes, both of which are needed to improve diagnostics. Here, we summarise the data generated by recent EQA activities focussed on the diagnostics of infections with hantavirus, dengue virus, filovirus, Lassa virus, orthopox virus and the SARS-coronavirus (SARS-CoV). These were carried out between 1999 and 2004 and involved 93 laboratories from 41 countries, including laboratories from additional countries outside of Europe. Particularly the EU-candidate countries and Eastern neighbouring countries will be invited to join the network in the near future. A public website is available at http://www.enivd.de.

Several human diseases in Europe are caused by viruses transmitted by tick bite. These viruses belong to the genus Flavivirus, and include tick-borne encephalitis virus, Omsk haemorrhagic fever virus, louping ill virus, Powassan virus, Nairovirus (Crimean-Congo haemorrhagic fever virus) and Coltivirus (Eyach virus). All of these viruses cause more or less severe neurological diseases, and some are also responsible for haemorrhagic fever. The epidemiology, clinical picture and methods for diagnosis are detailed in this review. Most of these viral pathogens are classified as Biosafety Level 3 or 4 agents, and therefore some of them have been classified in Categories A-C of potential bioterrorism agents by the Centers for Disease Control and Prevention. Their ability to cause severe disease in man means that these viruses, as well as any clinical samples suspected of containing them, must be handled with specific and stringent precautions.

We have conducted an international quality assurance study of filovirus, Lassa virus, and orthopox virus PCR with 24 participants. Of the participating laboratories, 45.8 and 66.7% detected virus in all plasma samples, which contained > or = 5,000 and > or = 100,000 copies per ml, respectively. Sensitivity levels were not significantly different between viruses. False-negative results were attributable to a lack of sensitivity.