Molecular Evidence Indicates ThatPhlebotomus major sensu lato(Diptera: Psychodidae) Is the Vector Species of the Recently-Identified Sandfly Fever Sicilian Virus Variant: Sandfly Fever Turkey Virus

Comprehensive Cross-Sectional Evaluation of Human Sandfly-Borne Phlebovirus Exposure in an Endemic Region

Sandfly-borne phleboviruses are endemic in countries around the Mediterranean Basin and pose a significant health threat for populations, with symptoms spanning from febrile diseases to central nervous system involvement. We carried out a comprehensive cross-sectional screening via microneutralization (MN) assays for a quantitative assessment of neutralizing antibodies (NAs) to seven phleboviruses representing three distinct serocomplexes, using samples previously screened via immunofluorescence assays (IFAs) in Turkey, an endemic region with various phleboviruses in circulation. We detected NAs to three phleboviruses: Toscana virus (TOSV), sandfly fever Naples virus (SFNV), and sandfly fever Sicilian virus (SFSV), while assays utilizing Adana virus, Punique virus, Massilia virus, and Zerdali virus remained negative. The most frequently observed virus exposure was due to TOSV, with a total prevalence of 22.6%, followed by SFNV (15.3%) and SFSV (12.1%). For each virus, IFA reactivity was significantly associated with NA detection, and further correlated with NA titers. TOSV and SFSV seroreactivities were co-detected, suggesting exposure to multiple pathogenic viruses presumably due to shared sandfly vectors. In 9.6% of the samples, multiple virus exposure was documented. In conclusion, our findings demonstrate widespread exposure to distinct pathogenic phleboviruses, for which diagnostic testing and serological screening efforts should be directed.

Investigation of Phlebotominae (Diptera: Psychodidae) Fauna, Seasonal Dynamics, and Natural Leishmania spp. Infection in Muğla, Southwest of Turkey

Due to its geographical location, Muğla province is one of the most frequently used places by refugees. Although leishmaniasis have been previously reported in this region, there is a lack of information on the etiological agent and possible vectors. The main objectives of this study were; i) to investigate the sand fly fauna, ii) to reveal the natural Leishmania spp. infection in wild caught sand flies using molecular tools, and iii) to determine the annual seasonal dynamics of the sand flies in Muğla region. Totally, 2093 specimens belonging to 15 species [12 Phlebotomus, three Sergentomyia; 51 unidentified] were collected during the one-year (June 2016- June 2017) period. Of the collected sand flies, 1928 (92.12%) were caught by the Centers for Disease Control (CDC) light traps, while 165 (7.88%) of them were caught by sticky traps. Phlebotomus major sensu lato (s.l.), the potential vector of visceral leishmaniasis (VL) and canine leishmaniasis (CanL) in the Mediterranean and Aegean region, was detected in all sampling locations and found as the dominant taxon (n=1035; 49.45%) of the study area and followed by Phlebotomus tobbi (n=371; 17.72%). During the sampling period, sand fly activity was started in March and peaked in August. Sand fly population size reduced dramatically between mid-September and early October. The number of collected specimens was peaked in August, while there is only one sample collected both in November and March. The majority of the sand flies (78.66%) were collected at an altitude range of 200-400 m. Seventy-two monospecific pools were screened for the presence of Leishmania DNA by real time ITS1 PCR and 24 (nine P. major s.l., eight P. tobbi, two P. papatasi, two S. minuta, one P. alexandri, one P. similis, and one Phlebotomus (Transphlebotomus spp.) of them (33.8%) were found positive (L. infantum, L. tropica, and L. major). To the best of our knowledge, the presence of fifteen sand fly species and their distribution, seasonal dynamics, molecular detection of Leishmania parasites in Muğla province was reported for the first time. The presence of vector species in the study area, appropriate temperature and humidity conditions, long sand fly activity season, and presence of Leishmania parasite suggests that there is a serious risk in the transmission of leishmaniasis in Muğla.

Vector-borne viruses in Turkey: A systematic review and bibliography

Turkey serves as a natural hub for the dissemination of vector-borne viruses and provides many suitable habitats with diverse ecologies for introduction and establishment of new pathogens. This manuscript provides an updated systematic review and meta-analysis of the vector-borne viruses documented in Turkey. Following web-based identification, screening and eligibility evaluation, 291 published reports were reviewed. The publications were categorized and listed as a supplementary bibliography accompanying the manuscript. In brief, Crimean-Congo hemorrhagic fever virus (CCHFV) and West Nile virus (WNV) are currently documented as prominent tick and mosquito-borne viral pathogens in Turkey. CCHFV produces a significant number of infections annually, with severe outcome or death in a portion of cases. WNV gained attention following the clustering of cases in 2010. Exposure and infections with sandfly-borne phleboviruses, such as Toscana virus, are indigenous and widespread. Epidemiology, risk factors, symptomatic infections in susceptible hosts, vectors and reservoirs for these pathogens have been explored in detail. Detection of novel viruses in mosquitoes, sandflies and ticks from several regions is of particular interest, despite scarce information on their epidemiology and pathogenicity in vertebrates. Introduction and emergence of viruses transmitted by invasive Aedes mosquitoes constitute a threat, albeit only imported infections have so far been documented. Detection of Rift valley fever virus exposure is also of concern, due to its detrimental effects on livestock and spillover infections in humans. Vigilance to identify and diagnose probable cases as well as vector surveillance for established and potential pathogens is therefore, imperative.

Revision of the species composition and distribution of Turkish sand flies using DNA barcodes

Background

Currently, knowledge regarding the phlebotomine sand fly (Diptera: Psychodidae) fauna of Turkey is restricted to regions with endemic leishmaniasis. However, rapidly changing environmental and social conditions highlight concerns on the possible future expansion of sand fly-borne diseases in Turkey, promoting risk assessment through biosurveillance activities in non-endemic regions. Traditional morphological approaches are complicated by extensive cryptic speciation in sand flies, thus integrated studies utilizing DNA markers are becoming increasingly important for correct sand fly identification. This study contributes to the knowledge of the sand fly fauna in understudied regions of Turkey, and provides an extensive DNA barcode reference library of expertly identified Turkish sand fly species for the first time.

Methods

Fly sampling was conducted at 101 locations from 29 provinces, covering all three biogeographical regions of Turkey. Specimens were morphologically identified using available keys. Cytochrome c oxidase I (cox1) barcode sequences were analyzed both for morphologically distinct species and those specimens with cryptic identity. A taxon identity tree was obtained using Neighbor Joining (NJ) analysis. Species boundaries among closely related taxa evaluated using ABGD, Maximum Likelihood (ML) and haplotype network analyses. Sand fly richness of all three biogeographical regions were compared using nonparametric species richness estimators.

Results

A total of 729 barcode sequences (including representatives of all previously reported subgenera) were obtained from a total of 9642 sand fly specimens collected in Turkey. Specimens belonging to the same species or species complex clustered together in the NJ tree, regardless of their geographical origin. The species delimitation methods revealed the existence of 33 MOTUs, increasing the previously reported 28 recorded sand fly species by 17.8%. The richest sand fly diversity was determined in Anatolia, followed by the Mediterranean, and then the Black Sea regions of the country.

Conclusions

A comprehensive cox1 reference library is provided for the sand fly species of Turkey, including the proposed novel taxa discovered herein. Our results have epidemiological significance exposing extensive distributions of proven and suspected sand fly vectors in Turkey, including those areas currently regarded as non-endemic for sand fly-borne disease.

Electronic supplementary material

The online version of this article (10.1186/s13071-019-3669-3) contains supplementary material, which is available to authorized users.

Isolation and sequencing of Dashli virus, a novel Sicilian-like virus in sandflies from Iran; genetic and phylogenetic evidence for the creation of one novel species within the Phlebovirus genus in the Phenuiviridae family

Phlebotomine sandflies are vectors of phleboviruses that cause sandfly fever or meningitis with significant implications for public health. Although several strains of these viruses had been isolated in Iran in the late 1970's, there was no recent data about the present situation at the outset of this study. Entomological investigations performed in 2009 and 2011 in Iran collected 4,770 sandflies from 10 different regions. Based on morphological identification, they were sorted into 315 pools according to species, sex, trapping station and date of capture. A phlebovirus, provisionally named Dashli virus (DASHV), was isolated from one pool of Sergentomyia spp, and subsequently DASHV RNA was detected in a second pool of Phlebotomus papatasi. Genetic and phylogenetic analyses based on complete coding genomic sequences indicated that (i) DASHV is most closely related to the Iranian isolates of Sandfly fever Sicilian virus [SFSV], (ii) there is a common ancestor to DASHV, Sandfly fever Sicilian- (SFS) and SFS-like viruses isolated in Italy, India, Turkey, and Cyprus (lineage I), (iii) DASHV is more distantly related with Corfou and Toros viruses (lineage II) although common ancestry is supported with 100% bootstrap, (iii) lineage I can be subdivided into sublineage Ia including all SFSV, SFCV and SFTV except those isolated in Iran which forms sublineage Ib (DASHV). Accordingly, we suggest to approve Sandfly fever Sicilian virus species consisting of the all aforementioned viruses. Owing that most of these viruses have been identified in human patients with febrile illness, DASHV should be considered as a potential human pathogen in Iran.

Phlebotomine sandflies are vectors of phleboviruses that cause sandfly fever or meningitis with significant implications for public health. Although several strains of these viruses had been isolated in Iran in the late 1970's, there was no recent data about the present situation at the outset of this study. Entomological investigations performed in 2009 and 2011 in Iran collected 4,770 sandflies from 10 different regions. A phlebovirus, provisionally named Dashli virus (DASHV), was isolated / detected in two pools. DASHV strain was isolated in cell culture and complete genome sequence was determined. Sequence analysis indicated that (i) DASHV is most closely related to the Iranian isolates of Sandfly fever Sicilian virus [SFSV], a virus that is known to cause self-resolutive incapacitating febrile illness in humans, (ii) there is a common ancestor to DASHV and all other variants of SFSV isolated in Italy, India, Turkey, and Cyprus (lineage I), (iii) DASHV is more distantly related with Corfou and Toros viruses (lineage II) although common ancestry is supported with 100% bootstrap, (iii) lineage I can be subdivided into sublineage Ia including all SFSV strains, whereas Iranian viruses are most closely related and should be individualized as DASHV (sublineage Ib). Although discovered first in the 1940's, SFSV is still listed as "tentative species" by the International Committee for Taxonomy of Viruses. Based on the results described in this study, we propose to approve Sandfly fever Sicilian virus species. Owing that most of these viruses have been identified in human patients with febrile illness, DASHV should be considered as a potential human pathogen in Iran.

Practical Guidelines for Studies on Sandfly-Borne Phleboviruses: Part I: Important Points to Consider Ante Field Work

The purpose of this review is to provide practical information to help researchers intending to perform "from field to laboratory" studies on phleboviruses transmitted by sandflies. This guideline addresses the different steps to be considered starting from the field collection of sandflies to the laboratory techniques aiming at the detection, isolation, and characterization of sandfly-borne phleboviruses. In this guideline article, we address the impact of various types of data for an optimal organization of the field work intending to collect wildlife sandflies for subsequent virology studies. Analysis of different data sets should result in the geographic positioning of the trapping stations. The overall planning, the equipment and tools needed, the manpower to be deployed, and the logistics to be anticipated and set up should be organized according to the objectives of the field study for optimal efficiency.

Novel and emergent sandfly-borne phleboviruses in Asia Minor: a systematic review

Sandfly-transmitted phleboviruses are globally spread agents causing febrile diseases and central nervous system infections. The activity of pathogenic phleboviruses, as well as several novel strains, has been reported from Turkey, a transboundary country connecting Asia, Europe, and Africa with suitable habitats for sandflies. This study overviews all published data on phleboviruses from Turkey and evaluates the impact from the virological, epidemiological, and public health perspectives. A systematic review of Web-based global and local resources was performed. Comparison and phylogenetic analyses of particular phlebovirus sequences were also undertaken. Through the evaluation of 1693 international and regional entries, 31 manuscripts providing data on case reports or outbreaks, serological surveillance, animal infections and exposure, virus characterization, vector surveillance, and/or diagnostics were accessed. Detailed information on 5 novel phleboviruses completely or partially characterized during 2008-2015 as well as on clinical and epidemiological features of major phleboviruses established as human pathogens such as Toscana virus and sandfly fever Sicilian virus has been compiled. The ongoing activity of these agents, as indicated by consistently reported symptomatic cases and confirmed exposure in vertebrates including humans, was noted. The circulation in the Anatolian peninsula of phleboviruses with surprising diversity as well as distinct virus species is documented. Specific phlebovirus strains constitute a public health threat for local populations and travelers and must be considered in the diagnostic workup of clinically compatible cases. Human health impact and epidemiological aspects of certain viruses require further investigation via intensive surveillance.

DNA sequencing confirms PCR-RFLP identification of wild caught Larroussius sand flies from Crete and Cyprus

Many Phlebotomine sand fly species (Diptera, Psychodidae) are vectors of the protozoan parasite Leishmania causing a group of diseases called the leishmaniases. The subgenus Larroussius includes sand fly vectors found in South East Mediterranean Basin responsible for Visceral (VL) and Cutaneous human leishmaniasis (CL). It is important to monitor these medically important insects in order to safely predict possible Leishmania transmission cycles. Leishmania infantum is endemic in the islands of Crete and Cyprus with increasing VL cases in humans and dogs and in Cyprus the newly introduced Leishmania donovani causes both VL and CL in humans. The morphological identification of the females of the subgenus Larroussius often presents difficulties. Morphology and COI PCR - RFLP were used to identify wild caught Larroussius sand flies belonging to Phlebotomus tobbi, P. perfiliewi, and P. neglectus species from Crete and Cyprus. The identification results were further confirmed by sequencing (DNA barcoding) and Bayesian phylogenetic analysis. COI PCR - RFLP, when correctly optimized and with respect to geographical origin, can serve as an initial patterning identification tool when large sand fly numbers need to be identified. It could accurately assign Larroussius females and males to their taxa overcoming the difficulties of morphological identification. Finally, DNA barcoding will contribute to a molecular identification database to be used for in-depth species studies.

Sandfly-Borne Phlebovirus Isolations from Turkey: New Insight into the Sandfly fever Sicilian and Sandfly fever Naples Species

Southern Anatolia in Turkey at the border with Syria, where many refugee camps are settled, is endemic for sandfly-borne leishmaniasis. Sandfly-borne phleboviruses are also known to circulate in this region, although their relevance in terms of medical implications is virtually unknown. Therefore, the specific objectives of our study were firstly to identify isolate and characterise potentially pathogenic phleboviruses in sandflies; secondly to determine the complete genomic sequence of any viruses that we were able to isolate; and thirdly, to further our understanding of the potential medical importance and epidemiological significance of these viruses. To achieve these objectives, we organised field campaigns in 2012 and 2013. Two new phleboviruses (Toros and Zerdali viruses) were isolated and characterized by complete genome sequencing and phylogenetic analyses. Toros virus was genetically most closely related to Corfou virus within the Sandfly fever Sicilian group. Zerdali virus was most closely related to Tehran virus within the Sandfly fever Naples species. Although these new viruses belong to genetic groups that include several human pathogens, it is not yet clear if Toros and Zerdali viruses can infect humans and cause disease such as sandfly fever. Consequently, the availability of these genetically characterized infectious viruses will enable seroprevalence studies to establish their medical importance in this region and to assist the health agencies to develop appropriate and effective disease control strategies.

We provide evidence that sandfly-borne phleboviruses belonging to 3 distinct genetic and phylogenetic groups (Sandfly fever Naples virus [SFNV], Sandfly fever Sicilian virus [SFSV], and Salehabad virus [SALV]) co-circulate in Adana city, in Mediterranean Turkey. While Adana virus was recently described as a new member of the SALV species, Zerdali and Toros viruses are described here as new phleboviruses genetically closely related to SFNV and SFSV, respectively. In this study, isolated and characterised these two new viruses by determining their complete genome sequence and by phylogenetic analysis. This study demonstrates that 3 distinct viruses can co-circulate in the same geographic area and based on their phylogenetic relationships and association with sandflies are likely to be transmitted by these arthropod vectors. Our molecular and phylogenetic data are important for establishing group-specific molecular detection assays in order to further understand of the possible impact of these viruses in animal and human health in this region of Turkey.

Sampling strategies for phlebotomine sand flies (Diptera: Psychodidae) in Europe

The distribution of phlebotomine sand flies is widely reported to be changing in Europe. This can be attributed to either the discovery of sand flies in areas where they were previously overlooked (generally following an outbreak of leishmaniasis or other sand fly-related disease) or to true expansion of their range as a result of climatic or environmental changes. Routine surveillance for phlebotomines in Europe is localized, and often one of the challenges for entomologists working in non-leishmaniasis endemic countries is the lack of knowledge on how to conduct, plan and execute sampling for phlebotomines, or how to adapt on-going sampling strategies for other haematophagous diptera. This review brings together published and unpublished expert knowledge on sampling strategies for European phlebotomines of public health concern in order to provide practical advice on: how to conduct surveys; the collection and interpretation of field data; suitable techniques for the preservation of specimens obtained by different sampling methods; molecular techniques used for species identification; and the pathogens associated with sand flies and their detection methods.

Potential animal reservoirs of Toscana virus and coinfections with Leishmania infantum in Turkey

Toscana virus (TOSV), a sandfly-borne phlebovirus, is an important agent of human meningoencephalitis in the Mediterranean region, for which vertebrates acting as reservoirs have not yet been determined. This study investigates TOSV and Leishmania infections in dogs, cats, sheep, and goats from Adana and Mersin provinces in southeastern Turkey. TOSV neutralizing antibodies were demonstrated in 40.4% of the dog and 4% of the goat samples. TOSV RNA was detected in 9.9% of the 252 samples that mainly comprise dogs (96%). Thus, canine species can be suggested as the candidate reservoirs of TOSV. Partial sequences revealed the activity of TOSV genotypes A and B. In two dogs presenting with symptoms of canine leishmaniasis, infections of TOSV genotype B and Leishmania infantum have been documented, describing the first report of coinfections with these agents.

Isolation, genetic characterization, and seroprevalence of Adana virus, a novel phlebovirus belonging to the Salehabad virus complex, in Turkey

A new phlebovirus, Adana virus, was isolated from a pool of Phlebotomus spp. (Diptera; Psychodidae) in the province of Adana, in the Mediterranean region of Turkey. Genetic analysis based on complete coding of genomic sequences indicated that Adana virus belongs to the Salehabad virus species of the genus Phlebovirus in the family Bunyaviridae. Adana virus is the third virus of the Salehabad virus species for which the complete sequence has been determined. To understand the epidemiology of Adana virus, a seroprevalence study using microneutralization assay was performed to detect the presence of specific antibodies in human and domestic animal sera collected in Adana as well as Mersin province, located 147 km west of Adana. The results demonstrate that the virus is present in both provinces. High seroprevalence rates in goats, sheep, and dogs support intensive exposure to Adana virus in the region, which has not been previously reported for any virus included in the Salehabad serocomplex; however, low seroprevalence rates in humans suggest that Adana virus is not likely to constitute an important public health problem in exposed human populations, but this deserves further studies.

IMPORTANCE

Until recently, in the genus Phlebovirus, the Salehabad virus species consisted of two viruses: Salehabad virus, isolated from sand flies in Iran, and Arbia virus, isolated from sand flies in Italy. Here we present the isolation and complete genome characterization of the Adana virus, which we propose to be included in the Salehabad virus species. To our knowledge, this is the first report of the isolation and complete genome characterization, from sand flies in Turkey, of a Salehabad virus-related phlebovirus with supporting seropositivity in the Mediterranean, Aegean, and Central Anatolia regions, where phleboviruses have been circulating and causing outbreaks. Salehabad species viruses have generally been considered to be a group of viruses with little medical or veterinary interest. This view deserves to be revisited according to our results, which indicate a high animal infection rate of Adana virus and recent evidence of human infection with Adria virus in Greece.

Ongoing activity of Toscana virus genotype A and West Nile virus lineage 1 strains in Turkey: a clinical and field survey

Toscana virus (TOSV), West Nile virus (WNV) and tickborne encephalitis virus (TBEV) are among major viral pathogens causing febrile disease and meningitis/encephalitis. The impact of these viruses was investigated at a referral centre in Ankara Province, Central Anatolia in 2012, where previous reports suggested virus circulation but with scarce information on clinical cases and vector activity. Serum and/or cerebrospinal fluid samples from 94 individuals were evaluated, in addition to field-collected arthropod specimens that included 767 sandflies and 239 mosquitoes. Viral nucleic acids in clinical samples and arthropods were sought via specific and generic nested/real-time PCRs, and antibody responses in clinical samples were investigated via commercial indirect immunofluorescence tests (IIFTs) and virus neutralization. A WNV antigen assay was also employed for mosquitoes. WNV neuroinvasive disease has been identified in a 63-year-old male via RNA detection, and the WNV strain was characterized as lineage 1. TOSV infections were diagnosed in six individuals (6.3%) via RNA or IgM detection. Partial sequences in a 23-year-old female, presented with fever and transient pancytopenia, were characterized as TOSV genotype A. Febrile disease with arthralgia and/or peripheral cranial nerve involvement was noted in cases with TOSV infections. Previous WNV and TOSV exposures have been observed in 5.3% and 2.1% of the subjects, respectively. No confirmed TBEV exposure could be identified. Morphological identification of the field-collected mosquitoes revealed Culex pipiens sensu lato (74.4%), Anopheles maculipennis (20.9%), An. claviger (2.1%) and others. Sandfly species were determined as Phlebotomus papatasi (36.2%), P. halepensis (27.3%), P. major s. l. (19.3%), P. sergenti (8.9%), P. perfiliewi (4.4%), P. simici (2.6%) and others. Viral infections in arthropods could not be demonstrated. TOSV genotype A and WNV lineage 1 activity have been demonstrated as well as serologically proven exposure in patients. Presence of sandfly and mosquito species capable of virus transmission has also been revealed.

The distribution of the Phlebotomus major complex (Diptera: Psychodidae) in Turkey

The taxonomic status and distribution of the morphologically similar members of the Phlebotomus major complex in Turkey are unclear. To examine the utility of traditional morphological characters and molecular markers, sand flies were sampled from 90 localities in eleven different provinces covering a wide geographical range throughout Turkey. The morphometric variability was analysed using multivariate analyses of twelve characters, while mitochondrial cytochrome b (Cyt b) and nuclear elongation factor 1α (EF 1-α) genes were used for molecular discrimination. Three distinct monophyletic lineages were identified based on the phylogenetic analysis of the combined data set of mitochondrial and nuclear gene regions, which were also supported by parsimony haplotype network analysis and AMOVA of Cyt b. The first lineage is restricted to south eastern Turkey and represents the species Phlebotomus syriacus, the second is present mostly in the westernmost and the easternmost localities and represents P. neglectus, and the third member of this complex is distributed across the mid-northern and mid-southern regions. None of the studied morphological characters were found to be sufficient to discriminate between these three members of the P. major s.l. complex; however their presence sympatrically in several localities supports their status as species rather than inter-population variability.

Emergence and co-infections of West Nile virus and Toscana virus in Eastern Thrace, Turkey

The objective of this study was to identify the impact of West Nile virus (WNV) and Toscana virus (TOSV) in febrile diseases of unknown aetiology in Eastern Thrace, Turkey; this study was conducted during August-October 2012, and included 18 clinical cases and 296 blood donors for local serosurveillance. Antibodies were determined via commercial assays and further tested for specificity via neutralization assays (NA). Viral RNAs were sought via specific and/or generic primers. WNV infections were diagnosed in seven patients (38.8%), detected via RNA+IgM in four, RNA in one and IgM and low avidity IgG in two cases. The most common symptom was fever (>38°C), followed by headache, malaise/fatigue, myalgia/arthralgia, muscle stiffness/lower back pain, anorexia, nausea/vomiting, diarrhoea, supraorbital/retrobulbar pain and abdominal pain. Neurological symptoms were noted in one individual. WNV strains in RNA-detectable patients were characterized as lineage 1. TOSV RNA or IgM were identified in two individuals with confirmed WNV infections and in one patient without evidence of WNV exposure. The clinical and laboratory findings in individuals with WNV/TOSV co-infection were comparable to those in WNV-induced disease. The TOSV strain in the patient with detectable viral RNA was characterized as genotype A. In local blood donors, seroreactivity for specific WNV and TOSV immunoglobulins was observed in 1.7% (5/296) and 14.4% (26/180), respectively. These findings indicate the emergence of WNV and TOSV-associated diseases in Eastern Thrace. WNV/TOSV co-infections were documented for the first time.