Surveillance data for human leishmaniasis indicate the need for a sustainable action plan for its management and control, Greece, 2004 to 2018.

BackgroundThe World Health Organization (WHO) lists human leishmaniasis as a neglected tropical disease; it is not under surveillance at European level.AimWe present surveillance data for visceral (VL) and cutaneous (CL) leishmaniasis for the period 2004 to 2018 in Greece to assess their public health importance.MethodsWe extracted data from the mandatory notification system to analyse separately imported and domestic cases of VL and CL. A case was defined by clinical manifestations compatible with VL or CL and laboratory confirmation.ResultsBetween 2004 and 2018, 881 VL (862 domestic, 19 imported) and 58 CL cases (24 domestic, 34 imported) were recorded. The mean annual notification rate of domestic VL was 0.5 per 100,000 (range: 0.12-1.43/100,000) with a statistically significant increasing trend (p = 0.013). Cases were reported by all regions. The highest notification rate occurred in the age group 0-4 years (1.3/100,000). Overall 24% (164/680) of the cases were immunocompromised and their proportion increased after 2010 (p < 0.001). The mean annual notification rate of domestic CL was 0.05 per 100,000 (range: 0.01-0.19/100,000) with the highest rate in the age group 5-14 years (0.03/100,000). Cases were recorded in six of the 13 regions. Among 34 imported CL cases, 29 were foreign nationals.ConclusionVL is endemic in Greece, with an increasing trend and a considerable burden of severe disease and young children being most affected. CL is rarely reported. A sustainable action plan is needed to reduce the burden of VL and prevent local transmission of CL.

Epidemiology of human West Nile virus infections in the European Union and European Union enlargement countries, 2010 to 2018.

BackgroundWest Nile virus (WNV) circulates in an enzootic cycle involving mosquitoes and birds; humans are accidental hosts.AimWe analysed human WNV infections reported between 2010 and 2018 to the European Centre for Disease Prevention and Control to better understand WNV epidemiology.MethodsWe describe probable and confirmed autochthonous human cases of WNV infection reported by European Union (EU) and EU enlargement countries. Cases with unknown clinical manifestation or with unknown place of infection at NUTS 3 or GAUL 1 level were excluded from analysis.ResultsFrom southern, eastern and western Europe, 3,849 WNV human infections and 379 deaths were reported. Most cases occurred between June and October. Two large outbreaks occurred, in 2010 (n = 391) and in 2018 (n = 1,993). The outbreak in 2018 was larger than in all previous years and the first cases were reported unusually early. The number of newly affected areas (n = 45) was higher in 2018 than in previous years suggesting wider spread of WNV.ConclusionReal-time surveillance of WNV infections is key to ensuring that clinicians and public health authorities receive early warning about the occurrence of cases and potential unusual seasonal patterns. Human cases may appear shortly after first detection of animal cases. Therefore, public health authorities should develop preparedness plans before the occurrence of human or animal WNV infections.

West Nile virus in Europe: after action reviews of preparedness and response to the 2018 transmission season in Italy, Slovenia, Serbia and Greece.

BACKGROUND: After Action Reviews (AAR) with a One Health perspective were performed in Slovenia, Italy, Serbia and Greece following a severe West Nile virus (WNV) transmission season in 2018. A protocol combining traditional techniques and organizational process analysis was developed and then implemented in each country. RESULTS: In 2018, response to the unusually intense transmission season of WNV in Slovenia, Italy, Serbia and Greece took place through routine response mechanisms. None of the four countries declared a national or subnational emergency. We found a very strong consensus on the strengths identified in responding to this event. All countries indicated the availability of One Health Plans for surveillance and response; very high laboratory diagnostic capacity in the human, veterinary and entomology sectors and strong inter-sectoral collaboration with strong commitment of engaged institutions as critical in the management of the event. Finally, countries implementing One Health surveillance for WNV (in terms of early warning and early activation of prevention measures) consistently reported a positive impact on their activities, in particular when combining mosquito and bird surveillance with surveillance of cases in humans and equids. Recurring priority areas for improvement included: increasing knowledge on vector-control measures, ensuring the sustainability of vector monitoring and surveillance, and improving capacity to manage media pressure. CONCLUSIONS: The AARs presented here demonstrate the benefit of cross-sectoral and cross-disciplinary approaches to preparedness for West Nile virus outbreaks in Europe. In the coming years, priorities include fostering and strengthening arrangements that: enable coordinated One Health surveillance and response during WNV transmission seasons; ensure adequate laboratory capacities; strengthen risk communication; and fund longer-term research to address the knowledge gaps identified in this study.

Correction to: West Nile virus in Europe: after action reviews of preparedness and response to the 2018 transmission season in Italy, Slovenia, Serbia and Greece.

An amendment to this paper has been published and can be accessed via the original article.

West Nile virus in humans, Greece, 2018: the largest seasonal number of cases, 9 years after its emergence in the country.

BackgroundHuman cases of West Nile virus (WNV) infection are recorded since 2010 in Greece, with seasonal outbreaks occurring almost annually. Enhanced surveillance has been implemented since 2010, to promptly characterise cases' temporal and geographical distribution and inform authorities for implementation of appropriate measures (mosquito control, health education, blood safety).AimWe describe the epidemiology of WNV human infections in Greece focusing on the 2018 season.MethodsThe National Public Health Organization advised physicians to test all suspect WNV infection cases and refer samples to reference laboratories. Laboratories notified diagnosed cases on a daily basis. Treating physicians, patients, and infected blood donors were interviewed within 48 hours after diagnosis and the probable infection location was identified. Hospitalised cases were followed up until discharge.ResultsA total of 317 autochthonous WNV infection cases were diagnosed in 2018. Among them, 243 cases had neuroinvasive disease (WNND), representing a 23% increase of WNND cases compared with 2010, the previous most intense season. There were 51 deaths. Cases started occurring from week 22, earlier than usual. Both rural and urban areas were affected, with 86 (26% of the total) municipalities belonging to seven (54% of the total) regions recording cases. Two major epicentres were identified in Attica and Central Macedonia regions.ConclusionsThe largest number of human cases of WNV infection ever recorded in Greece occurred in 2018, with a wide geographical distribution, suggesting intense virus circulation. Enhanced surveillance is vital for the early detection of human cases and the prompt implementation of response measures.

Evolutionary dynamics of lineage 2 West Nile virus in Europe, 2004-2018: Phylogeny, selection pressure and phylogeography.

West Nile virus (WNV) is an arbovirus causing neuroinvasive disease to humans and equines. Since 2004, lineage 2 WNV strains have been identified in Europe and have been implicated in severe outbreaks, with that of 2018 exceeding the total number from the previous seven years. The aim of this study was to explore the evolutionary process that shapes the genetic diversity of lineage 2 WNV strains (belonging to the Central European/Hungarian subclade) and reconstruct the origin and transmission routes in Europe, and especially in the Balkans. For this purpose, a high number of whole genome sequences (WGSs) were analyzed, along with newly characterized sequences, including strains from the 2018 WNV transmission season in Greece. Maximum likelihood and Bayesian inference methods were used to perform the phylogenetic and phylodynamic analyses and phylogeographic reconstruction. The majority of the Central European/Hungarian lineage 2 strains are grouped in 2 phylogenetic subgroups (Central/South-West European and Balkan) with bush-like topology. Purifying selection shapes their evolution, however, strong evidence of positive selection was revealed in 7 non-structural protein codons of NS1, NS4B and NS5. Thirty-two amino-acid substitutions were fixed in different phylogenetic subgroups, indicating that random genetic drift is responsible for the majority of evolutionary changes. Virus migration, followed by subsequent local evolution is responsible for continuously evolving strains throughout Europe. In total, 10 virus transitions between discrete geographical locations, involving virus spread from Central Europe to other regions, were highly supported. Three novel, independent introductions from Hungary and Bulgaria were responsible for the 2018 re-emergence of WNV in Northern Greece, indicating that Hungary remains an important ecological niche for the virus and has a central role for the dissemination of novel strains in the Balkans. In Northern Greece, tMRCA estimations indicated that a 1-to 2-year period of silent enzootic transmission precedes spread to dead-end hosts. Reconstruction of WNV population dynamics, from WGS data, revealed epidemic patterns characterized by 3- to 5-year oscillations in Europe. Future studies are necessary to determine the possible driving factors for these fluctuations i.e. avian herd immunity and climatic conditions affecting mosquito and bird populations. Maintaining adequate epidemiological surveillance with emphasis on obtaining WGS data, in areas at risk, is crucial for understanding the epidemiology and transmission patterns of WNV. It can further support integrated programs for risk assessment of virus circulation dynamics, aiming to targeted prevention and response measures for veterinary and public health in Europe.

Emergence of West Nile virus lineage 2 belonging to the Eastern European subclade, Greece.

West Nile virus (WNV) emerged in Greece in 2010 and since then human outbreaks occurred every year except 2015 and 2016. An early start and prolonged WNV transmission season was observed in 2018 with a record number of 316 reported cases and 47 fatalities. The Greek WNV strains detected during 2010-2018 clustered within the central European subclade of lineage 2. A novel WNV genetic variant was detected in August 2018 in one human case in the north-eastern region of Greece, at the land cross-border with Turkey and Bulgaria. The strain belongs to the Eastern European subclade of lineage 2 suggesting a new virus introduction in the country and the continuously changing epidemiology of the disease.

Genetic Spatiotemporal Anatomy of Plasmodium vivax Malaria Episodes in Greece, 2009-2013.

An influx of immigrants is contributing to the reemergence of Plasmodium vivax malaria in Greece; 1 persistent focus of transmission is in Laconia, Pelopónnese. We genotyped archived blood samples from a substantial proportion of malaria cases recorded in Greece in 2009-2013 using 8 microsatellite markers and a PvMSP-3α gene fragment and plotted their spatiotemporal distribution. High parasite genetic diversity with low multiplicity of infection was observed. A subset of genetically identical/related parasites was restricted to 3 areas in migrants and Greek residents, with some persisting over 2 consecutive transmission periods. We identified 2 hitherto unsuspected additional foci of local transmission: Kardhítsa and Attica. Furthermore, this analysis indicates that several cases in migrants initially classified as imported malaria were actually locally acquired. This study shows the potential for P. vivax to reestablish transmission and counsels public health authorities about the need for vigilance to achieve or maintain sustainable malaria elimination.

Crimean-Congo haemorrhagic fever in a Greek worker returning from Bulgaria, June 2018.

We report a tick-borne case of severe Crimean-Congo haemorrhagic fever (CCHF) imported into Greece from Bulgaria. The patient presented severe thrombocytopenia, hemophagocytosis, haemodynamic instability, large haematomas and altered mental status. Supportive treatment and ribavirin were administered. Symptoms started one day after the tick was removed; the patient was discharged from the hospital 26 days after symptom onset. No secondary cases were observed. Phylogenetically the CCHF virus strain belongs to clade Europe 1.

Early start of the West Nile fever transmission season 2018 in Europe.

In Europe, surveillance indicates that the 2018 West Nile fever transmission season started earlier than in previous years and with a steeper increase of locally-acquired human infections. Between 2014 and 2017, European Union/European Economic Area (EU/EEA) and EU enlargement countries notified five to 25 cases in weeks 25 to 31 compared with 168 cases in 2018. Clinicians and public health authorities should be alerted to ensure timely implementation of prevention measures including blood safety measures.

West Nile virus surveillance in Europe: moving towards an integrated animal-human-vector approach.

This article uses the experience of five European countries to review the integrated approaches (human, animal and vector) for surveillance and monitoring of West Nile virus (WNV) at national and European levels. The epidemiological situation of West Nile fever in Europe is heterogeneous. No model of surveillance and monitoring fits all, hence this article merely encourages countries to implement the integrated approach that meets their needs. Integration of surveillance and monitoring activities conducted by the public health authorities, the animal health authorities and the authorities in charge of vector surveillance and control should improve efficiency and save resources by implementing targeted measures. The creation of a formal interagency working group is identified as a crucial step towards integration. Blood safety is a key incentive for public health authorities to allocate sufficient resources for WNV surveillance, while the facts that an effective vaccine is available for horses and that most infected animals remain asymptomatic make the disease a lesser priority for animal health authorities. The examples described here can support other European countries wishing to strengthen their WNV surveillance or preparedness, and also serve as a model for surveillance and monitoring of other (vector-borne) zoonotic infections.

Associations of ABO, D, and Lewis blood groups and HLA Class I and Class II alleles with West Nile virus Lineage 2 disease outcome in Greece, 2010 to 2013.

BACKGROUND: West Nile virus (WNV) infection, commonly asymptomatic, may cause mild West Nile fever (WNF) or potentially fatal neuroinvasive disease (WNND). An outbreak of 262 cases of the new Lineage 2 strain in Greece in 2010 continued with high mortality (17%) in WNND. The objective was to investigate ABO, D, and Lewis blood groups, as well as HLA Class I and Class II alleles, in relation to WNV Lineage 2 disease morbidity. STUDY DESIGN AND METHODS: A cohort of 132 Greek WNV cases in 2010 to 2013 (65% male; mean age 64 years; 41% WNF, 59% WNND) was compared to 51,339 healthy WNV-negative blood donors and 246 healthy subjects. RESULTS: Blood group A was more common in WNV cases (51%) than blood donors (39%) and group O less common (32% vs. 42%). D negativity within group A was higher in WNV than in blood donors (18% vs. 10%, p = 0.044). The frequency of secretors (Lewis(a-b+)) was 60% in WNV and 68% in donors (p = 0.16). HLA alleles C*08, DRB1*O4:O5, and DQB1*O2 occurred significantly less frequently in WNV than controls (p < 0.05 unadjusted for multiple testing) and DRB1*10:O1 more frequently (p = 0.039). CONCLUSION: This first study of symptomatic WNV Lineage 2 suggests A/D negativity as a new risk factor associated with WNV infection and level of morbidity. Further studies are required of the possibility that HLA C*08, DRB1*O4:O5, and DQB1*O2 are protective alleles and DRB1*10:O1 a "susceptible" allele to WNV infection and the role of secretor status in relation to WNV infection.

Environmental parameters as risk factors for human and canine Leishmania infection in Thessaly, Central Greece.

Thessaly, Central Greece, is an endemic area for leishmaniasis with higher incidence rate during the last years. We herein investigated the geographical distribution of human leishmaniasis cases and Leishmania infected dogs in relation to environmental parameters to identify high-risk areas. All the human leishmaniasis cases (n = 82) reported to Hellenic Centre for Disease Control and Prevention from 2007 to 2014 and 85 Leishmania polymerase chain reaction positive dogs were included in this study. To analyse the data geographical information system (GIS) together with the Ecological Niche Model (ENM) were used. The most important findings of the study were: (i) Central plain of Thessaly together with the coast line and the western and eastern lowlands were identified as high-risk geographical areas. (ii) The highest percentage of the high-risk areas was found in low altitude (<200 m above sea level) and in irrigated and cultivated agricultural areas. (iii) A total of 20% of the human settlements was found in high-risk areas. (iv) The maximum temperature of the warmest month contributes the highest per cent to define both environmental niche profiles for humans and dogs. (v) The ENM could be a useful tool for the epidemiological study of leishmaniasis. Spatial analysis may allow the design of entomological studies and identify target population in order to implement preventive measures.

Genetic Structure of Introduced Plasmodium vivax Malaria Isolates in Greece, 2015-2019.

Greece has been malaria-free since 1974, after an intense malaria control program. However, as Greece hosts migrant populations from P. vivax malaria-endemic countries, there is a risk of introducing the disease to specific vulnerable and receptive areas of the country. Knowledge of the genetic diversity of P. vivax populations is essential for understanding the dynamics of malaria disease transmission in a given region. We used nine highly polymorphic markers to genotype 124 P. vivax-infected archived DNA samples from human blood specimens referred to the NMRL from all over Greece throughout 2015-2019. The genotypic variability of the samples studied was noted, as they comprised several unique haplotypes, indicative of the importation of a large number of different P. vivax strains in the country. However, only a few events of local transmission were recorded. Genotyping revealed and confirmed the same clusters as those identified through epidemiological investigation. In only one introduction event was the index case found. No sustained/ongoing malaria transmissions in/between the studied regions or during consecutive years or additional foci of local transmission were observed. Genotyping is an important component in assisting malaria surveillance, as it provides information concerning the patterns of introduction and the effectiveness of implemented malaria control and elimination measures.

Evaluation of underreporting of salmonellosis and shigellosis hospitalised cases in Greece, 2011: results of a capture-recapture study and a hospital registry review.

BACKGROUND: Salmonellosis and shigellosis are mandatorily notifiable diseases in Greece. Underreporting of both diseases has been postulated but there has not been any national study to quantify it. The objective of this study was to: a) estimate underreporting of hospitalised cases at public Greek hospitals in 2011 with a capture-recapture (C-RC) study, b) evaluate the accuracy of this estimation, c) investigate the possible impact of specific factors on notification rates, and d) estimate community incidence of both diseases. METHODS: The mandatory notification system database and the database of the National Reference Laboratory for Salmonella and Shigella (NRLSS) were used in the C-RC study. The estimated total number of cases was compared with the actual number found by using the hospital records of the microbiological laboratories. Underreporting was also estimated by patients' age-group, sex, type of hospital, region and month of notification. Assessment of the community incidence was based on the extrapolation of the hospitalisation rate of the diseases in Europe. RESULTS: The estimated underreporting of salmonellosis and shigellosis cases through the C-RC study was 47.7% and 52.0%, respectively. The reporting rate of salmonellosis significantly varied between the thirteen regions of the country from 8.3% to 95.6% (median: 28.4%). Age and sex were not related to the probability of reporting. The notification rate did not significantly differ between urban and rural areas, however, large university hospitals had a higher underreporting rate than district hospitals (p-value < 0.001). The actual underreporting, based on the hospital records review, was close to the estimated via the C-RC study; 52.8% for salmonellosis and 58.4% for shigellosis. The predicted community incidence of salmonellosis ranged from 312 to 936 and of shigellosis from 35 to 104 cases per 100,000 population. CONCLUSIONS: Underreporting was higher than that reported by other countries and factors associated with underreporting should be further explored. C-RC analysis seems to be a useful tool for the assessment of the underreporting of hospitalised cases. National data on underreporting and under-ascertainment rate are needed for assessing the accuracy of the estimation of the community burden of the diseases.

The 2022 West Nile Virus Season in Greece; A Quite Intense Season.

Since 2010, the West Nile virus (WNV) has been established in Greece. We describe the epidemiology of diagnosed human WNV infections in Greece with a focus on the 2022 season. During the transmission period, clinicians were sending samples from suspected cases for testing. Active laboratory-based surveillance was performed with immediate notification of diagnosed cases. We collected clinical information and interviewed patients on a timely basis to identify their place of exposure. Besides serological and molecular diagnostic methods, next-generation sequencing was also performed. In 2022, 286 cases of WNV infection were diagnosed, including 278 symptomatic cases and 184 (64%) cases with neuroinvasive disease (WNND); 33 patients died. This was the third most intense season concerning the number of WNND cases, following 2018 and 2010. Most (96%) cases were recorded in two regions, in northern and central Greece. The virus strain was a variant of previous years, clustering into the Central European subclade of WNV lineage 2. The 2022 WNV season was quite intense in Greece. The prompt diagnosis and investigation of cases are considered pivotal for the timely response, while the availability of whole genome sequences enables studies on the molecular epidemiology of the disease.

Entomological Surveillance Activities in Regions in Greece: Data on Mosquito Species Abundance and West Nile Virus Detection in Culex pipiens Pools (2019-2020).

Human cases of West Nile virus (WNV) infections have been recorded in Greece since 2010, with seasonal outbreaks (summer-autumn) on an almost annual basis, caused mainly by the WNV lineage 2 strain (Nea Santa-Greece-2010). National Public Health Organization (NPHO) in Greece is annually implementing enhanced surveillance of human WNV infection, in order to promptly identify human cases of WNV infection and monitor distribution in terms of time and place. Entomological surveillance activities were carried out on a national basis in 2019 and 2020, under NPHO coordination and the collaboration of several private subcontractors, along with the Unit of Medical Entomology, Laboratory for Surveillance of Infectious Diseases (LSID). The aim was to monitor mosquito species composition, abundance, and WNV circulation in mosquito pools of Culex pipiens s.l. species. Adult mosquito traps were placed in selected sites; collected samples were morphologically characterized and pooled by date of collection, location, and species types. Female Culex pipiens s.l. pools were tested for WNV and WNV infection rates (MIR and MLE) were estimated. Highest mean number of female Culex pipiens s.l. species was recorded in Central Macedonia both for 2019 and 2020. Six hundred and fifty-nine mosquito pools (147 in 2019 and 512 in 2020) of female Culex pipiens s.l. were examined for WNV presence. The highest MLE was detected in Western Macedonia in 2019 and in Thessaly in 2020. Here, we present data on the mosquito species composition in the studied areas and WNV detection in mosquitoes from areas in Greece where the specific national mosquito surveillance program was implemented, for two years, 2019 and 2020.

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

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.

An outbreak of gastroenteritis linked to seafood consumption in a remote Northern Aegean island, February-March 2010.

INTRODUCTION: Raw seafood consumption has frequently been linked to gastroenteritis and Norovirus is a common cause. In February and March 2010, there was an increase cases of gastroenteritis on the remote island of Agios Efstratios in the Northern Aegean Sea, Greece. A massive increase in seafood consumption associated with a religious festival a few days prior to the outbreak suggested seafood as the vehicle of transmission. METHODS: An outbreak investigation team visited the island in order to document the outbreak and find epidemiological evidence for its source. The whole island was used as a cohort in the retrospective cohort study that was conducted. RESULTS: Sixty-four of the 181 participants reported having had symptoms of gastroenteritis, of which 34 were considered primary cases. People who consumed any raw seafood imported to the island were 21.5 times (95% CI: 8.95-51.8) more likely to develop symptoms of gastroenteritis in the 72 hours following exposure. Consumption of local seafood was not found to be a risk factor. CONCLUSION: Despite the lack of laboratory evidence, all four Kaplan's criteria were met and the outbreak was thought to have been caused by Norovirus. The outbreak investigation demonstrates epidemiological methods for use in a remote setting, where the means for laboratory and environmental investigation may be absent or limited.

Entomological Data and Detection of West Nile Virus in Mosquitoes in Greece (2014-2016), Before Disease Re-Emergence in 2017.

West Nile virus (WNV) cases were seasonally recorded in humans and animals in Greece, from 2010 to 2014, and circulation of the virus was detected in different Regional Units of the country. Small scale entomological surveillance activities were carried out by several regions and regional units in Greece, during 2014-2016, with the participation of subcontractors for the vector control programs aiming to record presence/absence of mosquito species, and monitor and control mosquito populations. Mosquito traps were placed in rural and urban sites; specimens were collected, morphologically characterized, and pooled by date of collection, location, and species types. Mosquito pools containing Culex pipiens, Aedes caspius, and Aedes albopictus were examined for the presence of WNV and positive pools were detected in different areas of the country. Sequencing of a selected number of amplicons revealed WNV lineage 2 partial NS5 gene sequences. In this study, we present data on the mosquito species composition in the areas of study and WNV detection from several parts of Greece, in 6, 11, and 26 mosquito pools corresponding to the years 2014, 2015, and 2016, respectively. A total of 15 WNV human infections were reported to the public health authorities of the country in 2014, whereas no human cases were detected for 2015-2016. Taking into consideration the complex epidemiological profile of WNV and unforeseen changes in its circulation, re-emergence of WNV human cases in Greece was possible and expected, thus rendering surveillance activities imperative.