Publications by authors named "Katerina Tsioka"

17 Publications

  • Page 1 of 1

West Nile fever upsurge in a Greek regional unit, 2020.

Acta Trop 2021 Sep 12;221:106010. Epub 2021 Jun 12.

Ecodevelopment SA, Thessaloniki, Greece.

During the 2020 West Nile virus (WNV) transmission season, Greece was the most affected EU Member State. More than one third of human cases occurred in Serres regional unit in northern Greece, which is characterized by the presence of a major wetland (Kerkini lake and Strimon river). A total of 2809 Culex pipiens mosquitoes collected in Serres were grouped into 70 pools and tested for WNV. Ten (14.3%) pools were found positive, and all WNV sequences belonged to the Central European subclade of WNV lineage 2. The first human case occurred in a village nearby the lake, and all following cases occurred across the connected river and its tributaries. Similar distribution presented the sites where WNV-positive mosquitoes were detected. The number of Culex spp. mosquitoes per trap per night was higher in 2020 than in previous years (2017-2019). The spatial and temporal distribution of human cases and WNV-positive mosquitoes in 2020 in Serres regional unit suggest that the upsurge of the virus circulation was probably related with factors that affected the ecosystem of the wetland.
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http://dx.doi.org/10.1016/j.actatropica.2021.106010DOI Listing
September 2021

Recommendations for the introduction of metagenomic next-generation sequencing in clinical virology, part II: bioinformatic analysis and reporting.

J Clin Virol 2021 May 26;138:104812. Epub 2021 Mar 26.

Virology Laboratory, Genomics and Health Area, Centre for Public Health Research (FISABIO-Public Health), Valencia, Spain; Department of Microbiology, Medical School, University of Valencia, Spain; CIBERESP, Instituto de Salud Carlos III, Madrid, Spain. Electronic address:

Metagenomic next-generation sequencing (mNGS) is an untargeted technique for determination of microbial DNA/RNA sequences in a variety of sample types from patients with infectious syndromes. mNGS is still in its early stages of broader translation into clinical applications. To further support the development, implementation, optimization and standardization of mNGS procedures for virus diagnostics, the European Society for Clinical Virology (ESCV) Network on Next-Generation Sequencing (ENNGS) has been established. The aim of ENNGS is to bring together professionals involved in mNGS for viral diagnostics to share methodologies and experiences, and to develop application guidelines. Following the ENNGS publication Recommendations for the introduction of mNGS in clinical virology, part I: wet lab procedure in this journal, the current manuscript aims to provide practical recommendations for the bioinformatic analysis of mNGS data and reporting of results to clinicians.
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http://dx.doi.org/10.1016/j.jcv.2021.104812DOI Listing
May 2021

Spread of NDM-producing Klebsiella pneumoniae in a tertiary Greek hospital.

Acta Microbiol Immunol Hung 2021 Mar 3. Epub 2021 Mar 3.

2Department of Microbiology, Medical School, Aristotle University of Thessaloniki, Thessaloniki, Greece.

Bacterial carbapenem resistance, especially when mediated by transferable carbapenemases, is of important public health concern. An increased number of metallo-β-lactamase (MBL)-producing Klebsiella pneumoniae strains isolated in a tertiary hospital in Thessaloniki, Greece, called for further genetic investigation.The study included 29 non-repetitive carbapenem resistant K. pneumoniae isolates phenotypically characterized as MBL-producers collected in a tertiary hospital in Greece. The isolates were screened for the detection of carbapenemase genes (K. pneumoniae carbapenemase (blaKPC), Verona-integron-encoded MBL-1 (blaVIM-1), imipenemase (blaIMP), oxacillinase-48 (blaOXA-48) and New Delhi MBL (blaNDM)). The genetic relationship of the isolates was determined by Random Amplified Polymorphic DNA (RAPD) analysis. The whole genome sequences (WGS) from two NDM-positive K. pneumoniae isolates were further characterized.The presence of New Delhi MBL (blaNDM) gene was confirmed in all K. pneumoniae isolates, while blaKPC and blaVIM-1 genes were co-detected in one and two isolates, respectively. The RAPD analysis showed that the isolates were clustered into two groups. The whole genome sequence analysis of two K. pneumoniae isolates revealed that they belonged to the sequence type 11, they carried the blaNDM-1 gene, and exhibited differences in the number and type of the plasmids and the resistant genes.All MBL-producing K. pneumoniae isolates of the study harbored a blaNDM gene, while WGS analysis revealed genetic diversity in resistance genes. Continuous surveillance is needed to detect the emergence of new clones in a hospital setting, while application of antimicrobial stewardship is the only way to reduce the spread of multi-resistant bacteria.
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http://dx.doi.org/10.1556/030.2021.01400DOI Listing
March 2021

Application of 16S rRNA next generation sequencing in ticks in Greece.

Heliyon 2020 Jul 28;6(7):e04542. Epub 2020 Jul 28.

Clinic of Farm Animals, Faculty of Veterinary Medicine, Aristotle University of Thessaloniki, Greece.

Tick-borne bacteria pose a significant threat to human and veterinary public health. Greece is a Mediterranean country with rich tick fauna and the most commonly detected tick-borne bacterial pathogens are members of the and species. The variable V2-V4 and V6-V9 regions of 16S rRNA gene of seven ticks belonging to four genera representative in Greece () were analysed using multiple primer pairs by next generation sequencing (NGS). Nine bacterial phyla corresponding to 95 families, 116 genera and 172 species were identified. Proteobacteria was the predominant phylum in five of the seven ticks, followed by Actinobacteria, which predominated in two ticks. The tick-borne bacteria included and species, while " Midichloria mitochondrii" were detected in high abundance in ticks and less in ; -like endosymbionts were detected in , , and less in ticks. Co-infections with and were also observed. 16S rRNA NGS is a powerful tool to investigate the tick bacteriome and can improve the strategies for prevention and control of tick-borne diseases.
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http://dx.doi.org/10.1016/j.heliyon.2020.e04542DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7393430PMC
July 2020

West Nile virus lineage 2 in Culex mosquitoes in Thessaly, Greece, 2019.

Acta Trop 2020 May 15;208:105514. Epub 2020 May 15.

EcoDevelopment SA, Thessaloniki, Greece.

West Nile virus is a flavivirus transmitted to humans mainly by mosquito bites. Outbreaks are observed in several European countries, and Greece is one of the most affected countries during the recent years. Thessaly was one of the most affected regions in Greece in 2019. A total of 3,025 Culex spp. mosquitoes collected in Thessaly were grouped into 47 pools and tested for West Nile virus (WNV). Eight (17%) pools were found positive. Whole genome sequences were obtained from two positive pools. Phylogenetic analysis showed that the causative strain was an evolutionary variant of the strains circulating in 2018 belonging to the Balkan subgroup of the Central European subclade of WNV lineage 2.
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http://dx.doi.org/10.1016/j.actatropica.2020.105514DOI Listing
May 2020

Detection of flaviviruses and alphaviruses in mosquitoes in Central Macedonia, Greece, 2018.

Acta Trop 2020 Feb 20;202:105278. Epub 2019 Nov 20.

EcoDevelopment SA, Thessaloniki, Greece.

Culex mosquitoes are vectors of several flaviviruses and alphaviruses posing a potential risk to public and veterinary health. In order to gain an insight into the flaviviruses and alphaviruses circulating in the five regional units of Central Macedonia in northern Greece, 17,470 female Culex spp. mosquitoes collected during 2018 were tested for these viruses. Among 229 mosquito pools, West Nile virus (WNV) was detected in 10 (4.4%) pools, while insect-specific flavi- and alphaviruses were detected in 2 (0.9%) and 8 (3.5%) pools, respectively. WNV minimum infection rate (MIR) was 0.57. The highest MIR was identified in Thessaloniki regional unit, where several human cases of WNV infection occurred in 2018. All ten WNV sequences cluster into the Central European subclade of lineage 2. It is of note that the first WNV-positive mosquito pool was detected two weeks prior the report of the first human case in the area, suggesting that testing of mosquitoes could serve as early warning system.
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http://dx.doi.org/10.1016/j.actatropica.2019.105278DOI Listing
February 2020

Molecular epidemiology of Dobrava-Belgrade virus in Greece.

Infect Genet Evol 2018 10 7;64:9-12. Epub 2018 Jun 7.

Department of Microbiology, Medical School, Aristotle University of Thessaloniki, Thessaloniki, Greece. Electronic address:

In order to gain an insight into the genetic relatedness of the Dobrava-Belgrade virus (DOBV) in Greece, a phylogenetic analysis was performed based on all currently available DOBV sequences obtained from hospitalized cases with hemorrhagic fever with renal syndrome (HFRS). Most cases occurred in northwestern and north central part of the country. Two sequence datasets consisted of 41 S and 12 M partial DOBV RNA segment sequences were analyzed. All DOBV strains belong to Dobrava genotype which is associated with the rodent Apodemus flavicollis. In both phylogenetic trees (S and M segments), two main clusters of Greek strains could be distinguished. Phylogenetic analysis showed a spatial rather than temporal relation of the strains, since their genetic clustering was highly associated with the geographic distribution of the cases. Besides previous characterized endemic foci, novel ones have been identified, expanding our knowledge on the epidemiology of HFRS in Greece.
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http://dx.doi.org/10.1016/j.meegid.2018.06.007DOI Listing
October 2018

Isolation and whole-genome sequencing of a Crimean-Congo hemorrhagic fever virus strain, Greece.

Ticks Tick Borne Dis 2018 05 1;9(4):788-791. Epub 2018 Mar 1.

Clinic of Farm Animals, Faculty of Veterinary Medicine, Aristotle University of Thessaloniki, Greece.

Crimean-Congo hemorrhagic fever virus (CCHFV) was isolated from a pool of two adult Rhipicephalus bursa ticks removed from a goat in 2015 in Greece. The strain clusters into lineage Europe 2 representing the second available whole-genome sequenced isolate of this lineage. CCHFV IgG antibodies were detected in 8 of 19 goats of the farm. Currently CCHFV is not associated with disease in mammals other than humans. Studies in animal models are needed to investigate the pathogenicity level of lineage Europe 2 and compare it with that of other lineages.
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http://dx.doi.org/10.1016/j.ttbdis.2018.02.024DOI Listing
May 2018

Molecular detection of Crimean-Congo hemorrhagic fever virus in ticks, Greece, 2012-2014.

Parasitol Res 2017 Nov 17;116(11):3057-3063. Epub 2017 Sep 17.

Veterinary Research Institute, HAO-Demeter, NAGREF Campus, Thessaloniki, Greece.

Crimean-Congo hemorrhagic fever virus (CCHFV) is transmitted to humans mainly through the bite of infected ticks. In Greece, only one clinical case has been observed, in 2008, but the seroprevalence in humans is relatively high (4.2%). To have a first insight into the circulation of CCHFV in Greece, 2000 ticks collected from livestock during 2012-2014 were tested. CCHFV was detected in 36 of the 1290 (2.8%) tick pools (1-5 ticks per pool). Two genetic lineages were identified: Europe 1 and Europe 2. Most Europe 1 sequences were obtained from Rhipicephalus sanguineus sensu lato ticks, while most Europe 2 sequences were recovered from Rhipicephalus bursa ticks. The number of collected Hyalomma marginatum ticks (the principal vector of CCHFV) was low (0.5% of ticks) and all were CCHFV negative. Since it is not known how efficient ticks of the Rhipicephalus genus are as vectors of the virus, laboratory studies will be required to explore the role of Rhipicephalus spp. ticks in CCHFV maintenance and transmission.
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http://dx.doi.org/10.1007/s00436-017-5616-6DOI Listing
November 2017

Crimean-Congo hemorrhagic fever virus in ticks collected from livestock in Albania.

Infect Genet Evol 2017 10 19;54:496-500. Epub 2017 Aug 19.

Department of Control of Infectious Diseases, Institute of Public Health, Tirana, Albania.

Albania is a Balkan country endemic for Crimean-Congo hemorrhagic fever (CCHF). It was shown previously that CCHF virus (CCHFV) sequences from Albanian patients cluster into Europe 1 clade. Aim of the present study was to test for CCHFV ticks collected in several regions of Albania, and to determine the genetic lineage(s) of the CCHFV strains in relation with their geographic distribution. A total of 726 ticks (366 Hyalomma marginatum, 349 Rhipicephalus bursa and 11 Rhipicephalus sanguineus) collected from livestock during 2007-2014 were included in the study. Thirty of 215 (13.9%) tick pools were positive for CCHFV. Lineage Europe 1 was detected in H. marginatum ticks collected in the endemic region of Albania, while lineage Europe 2 was detected mainly in R. bursa ticks in various regions of the country. Both genetic lineages were detected in the CCHF endemic area (northeastern Albania), while only Europe 2 lineage was detected in the south of the country. A higher genetic diversity was seen among Europe 2 than Europe 1 Albanian sequences (mean distance 3.7% versus 1%), suggesting a longer evolution of AP92-like strains (Europe 2) in their tick hosts. The present study shows that besides CCHFV lineage Europe 1, lineage Europe 2 is also present in Albania. Combined with results from recent studies, it is concluded that lineage Europe 2 is widely spread in the Balkans and Turkey, and is associated mainly with R. bursa ticks (at least in this region). Its pathogenicity and impact to the public health remain to be elucidated.
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http://dx.doi.org/10.1016/j.meegid.2017.08.017DOI Listing
October 2017

Crimean-Congo Hemorrhagic Fever: Tick-Host-Virus Interactions.

Front Cell Infect Microbiol 2017 26;7:213. Epub 2017 May 26.

Department of Clinical Microbiology, Institute for Laboratory Medicine, Karolinska InstituteStockholm, Sweden.

Crimean-Congo hemorrhagic fever virus (CCHFV) is transmitted to humans by bite of infected ticks or by direct contact with blood or tissues of viremic patients or animals. It causes to humans a severe disease with fatality up to 30%. The current knowledge about the vector-host-CCHFV interactions is very limited due to the high-level containment required for CCHFV studies. Among ticks, spp. are considered the most competent virus vectors. CCHFV evades the tick immune response, and following its replication in the lining of the tick's midgut, it is disseminated by the hemolymph in the salivary glands and reproductive organs. The introduction of salivary gland secretions into the host cells is the major route via which CCHFV enters the host. Following an initial amplification at the site of inoculation, the virus is spread to the target organs. Apoptosis is induced via both intrinsic and extrinsic pathways. Genetic factors and immune status of the host may affect the release of cytokines which play a major role in disease progression and outcome. It is expected that the use of new technology of metabolomics, transcriptomics and proteomics will lead to improved understanding of CCHFV-host interactions and identify potential targets for blocking the CCHFV transmission.
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http://dx.doi.org/10.3389/fcimb.2017.00213DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5445422PMC
January 2018

Novel phlebovirus detected in Haemaphysalis parva ticks in a Greek island.

Ticks Tick Borne Dis 2017 01 29;8(1):157-160. Epub 2016 Oct 29.

Veterinary Research Institute, National Agricultural Research Foundation, NAGREF Campus, PO Box 60272, Thermi, 57001 Thessaloniki, Greece.

During the last decade the number of novel tick-borne phleboviruses has increased rapidly, especially after the identification of severe fever with thrombocytopenia syndrome and Heartland viruses which can cause severe disease in humans. A novel virus, Antigone virus was recently detected in ticks collected from the mainland of Greece. The aim of the present study was to investigate the presence of tick-borne phleboviruses in an island in Greece. During November 2015, 31 ticks were collected from sheep in Lesvos island. Phleboviral RNA was detected in 12/22 adult Haemaphysalis parva ticks. The virus was provisionally named Lesvos virus after the name of the island. Phylogenetic analysis of a 1108-bp L RNA fragment revealed that the Lesvos virus sequences cluster together with Dabieshan and Yongjia tick viruses detected in China in H. longicornis and H. hystricis ticks, respectively. Further studies are needed to investigate its exact distribution, epidemiology and virulence. It is expected that the research studies on tick biology and pathogen-tick-host interactions will allow a better understanding of the virus life cycle and the elucidation of the possible role of the novel tick-borne phleboviruses in public health.
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http://dx.doi.org/10.1016/j.ttbdis.2016.10.012DOI Listing
January 2017

Bacterial pathogens and endosymbionts in ticks.

Ticks Tick Borne Dis 2017 01 23;8(1):31-35. Epub 2016 Sep 23.

Clinic of Farm Animals, Faculty of Veterinary Medicine, Aristotle University of Thessaloniki, Greece.

Ticks collected from goats in northern Greece were tested for the presence of tick-borne bacteria. Among adult ticks, 37 (57.8%) were Rhipicephalus bursa, 11 (17.2%) Dermacentor marginatus, 10 (15.6%) Ixodes ricinus, 3 (4.7%) Rhipicephalus sanguineus sensu lato and 2 (3.1%) Haemaphysalis parva; one (1.6%) Rhipicephalus spp. tick was nymph. Rickettsia monacensis, Rickettsia massilae, Anaplasma phagocytophilum and Anaplasma platys were detected in I. ricinus and Rh. bursa ticks. A variety of Coxiella-like endosymbionts were detected in all tick genera tested, forming distinct clades from Coxiella burnetii in the phylogenetic tree based on the 16S rRNA gene. An additional endosymbiont, Candidatus Midichloria mitochondrii, was detected in most of the I. ricinus ticks. Surveillance for human pathogens in ticks provides knowledge helpful for the public health, while further studies are needed to determine the role of endosymbionts in tick physiology, vector competence and probably in public health.
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http://dx.doi.org/10.1016/j.ttbdis.2016.09.011DOI Listing
January 2017

Novel phleboviruses detected in ticks, Greece.

Ticks Tick Borne Dis 2016 07 24;7(5):690-693. Epub 2016 Feb 24.

Veterinary Research Institute, National Agricultural Research Foundation, NAGREF Campus, PO Box 60272, Thermi, Thessaloniki 57001, Greece.

Since 2009, when severe fever with thrombocytopenia syndrome virus and Heartland virus have been identified and associated with disease in humans, the interest on tick-borne phleboviruses is increasing rapidly. The aim of the present study was to investigate the presence of tick-borne phleboviruses in Greece and compare them with respective ones detected worldwide. Ticks collected from goats and sheep in 60 sites of 13 regional units of Greece were grouped in pools (1-3 ticks per pool) and tested for the presence of phleboviral RNA. Six of 210 pools were positive; they consisted of Rhipicephalus sanguineus ticks collected from sheep in 3 regional units of Greece: Pella (2/30, 6.7%), Imathia (2/21, 9.5%), and Ioannina (2/28, 7.1%). The overall tick minimum infection rate was 2.1%. The sequences of the Greek phlebovirus (provisionally named Antigone virus) form a distinct clade in the tick-borne phleboviruses, differing by >40% from the currently known phleboviruses. Any probable implication of these viruses to public health remains to be elucidated.
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http://dx.doi.org/10.1016/j.ttbdis.2016.02.017DOI Listing
July 2016

Detection of West Nile virus and insect-specific flavivirus RNA in Culex mosquitoes, central Macedonia, Greece.

Trans R Soc Trop Med Hyg 2014 Sep 17;108(9):555-9. Epub 2014 Jul 17.

EcoDevelopment SA, Thessaloniki, Greece.

Background: West Nile virus (WNV) emerged in central Macedonia, northern Greece, in 2010. The aim of the study was to test Culex mosquitoes for genetic detection of WNV and other flaviviruses, and to check whether the detection of WNV in mosquitoes was correlated with the occurrence of human WNV cases.

Methods: During 2013, 25 780 Culex spp. mosquitoes were collected from central Macedonia, grouped into 295 pools, according to collection site and date, and tested for the presence of flavivirus RNA.

Results: Thirteen (4.4%) pools were flavivirus-positive. WNV lineage 2 was detected in nine (3.1%) pools, and insect-specific flaviviruses (ISFV) in four (1.4%). Three ISFV nucleotide sequences were 98% identical to Culex theileri flavivirus, previously detected in the Iberian peninsula, while the fourth sequence differed by >25% from all known flaviviruses. In most units of central Macedonia WNV detection in mosquitoes preceded the occurrence of human cases by approximately one month.

Conclusions: Detection of WNV lineage 2 in mosquitoes for a fourth consecutive year suggests that the virus is established in Greece. Entomological surveillance provides an early warning system for the circulation of the virus. The detection of Culex theileri flavivirus extends the known range of this virus.
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http://dx.doi.org/10.1093/trstmh/tru100DOI Listing
September 2014

A novel AP92-like Crimean-Congo hemorrhagic fever virus strain, Greece.

Ticks Tick Borne Dis 2014 Sep 18;5(5):590-3. Epub 2014 Jun 18.

Argos Orestiko Health Center, 52200 Argos Orestiko, Kastoria, Greece.

Ticks were collected from various regions of northern Greece and tested for the presence of Crimean-Congo hemorrhagic fever virus (CCHFV) RNA. Human and animal sera were collected in the regions where CCHFV-positive ticks were detected, and they were tested for the presence of IgG antibodies against the virus. A CCHFV strain was detected in Rhipicephalus bursa ticks collected from sheep in Kastoria regional unit, differing by 9.7% at the nucleotide level from the AP92 strain, which was isolated in 1975 in another region of Greece. Up to date, CCHF cases have not been reported in these regions. The human seroprevalence in the area was estimated at 6%, while IgG-positive sheep was detected in two of the four neighboring farms tested. The circulation of this specific CCHFV lineage in Greece, especially in a region where the seroprevalence is high, together with the lack of human CCHF cases, suggests a probable antigenic, but non- or low-pathogenic character of this lineage. Further studies on these strains will increase our knowledge about the role of AP92-like strains in the CCHF epidemiology, which might be useful for drug and vaccine design.
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http://dx.doi.org/10.1016/j.ttbdis.2014.04.008DOI Listing
September 2014

Development time of IgG antibodies to West Nile virus.

Arch Virol 2011 Sep 11;156(9):1661-3. Epub 2011 May 11.

1st Department of Microbiology, Medical School, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece.

Following an outbreak of West Nile virus (WNV) infections in Greece during summer/autumn 2010, a study was conducted to investigate the patterns of WNV IgG reactivity in 255 patients with respect to the day of illness and the type of clinical syndrome. IgG antibodies were detectable after a mean of 8.1 ± 4.9 and 12.6 ± 11.3 days after onset of illness in neuroinvasive and non-neuroinvasive cases, respectively (p < 0.001), suggesting that a delay in the development of WNV IgG antibodies is seen in non-neuroinvasive cases.
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http://dx.doi.org/10.1007/s00705-011-1014-zDOI Listing
September 2011
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