A story of viral co-infection, co-transmission and co-feeding in ticks: how to compute an invasion reproduction number.

With a single circulating vector-borne virus, the basic reproduction number incorporates contributions from tick-to-tick (co-feeding), tick-to-host and host-to-tick transmission routes. With two different circulating vector-borne viral strains, resident and invasive, and under the assumption that co-feeding is the only transmission route in a tick population, the invasion reproduction number depends on whether the model system of ordinary differential equations possesses the property of neutrality. We show that a simple model, with two populations of ticks infected with one strain, resident or invasive, and one population of co-infected ticks, does not have Alizon's neutrality property. We present model alternatives that are capable of representing the invasion potential of a novel strain by including populations of ticks dually infected with the same strain. The invasion reproduction number is analysed with the next-generation method and via numerical simulations.

Third International Conference on Crimean-Congo Hemorrhagic Fever in Thessaloniki, Greece, September 19-21, 2023.

The Third International Conference on Crimean-Congo Hemorrhagic Fever (CCHF) was held in Thessaloniki, Greece, September 19-21, 2023, bringing together a diverse group of international partners, including public health professionals, clinicians, ecologists, epidemiologists, immunologists, and virologists. The conference was attended by 118 participants representing 24 countries and the World Health Organization (WHO). Meeting sessions covered the epidemiology of CCHF in humans; Crimean-Congo hemorrhagic fever virus (CCHFV) in ticks; wild and domestic animal hosts; molecular virology; pathogenesis and animal models; immune response related to therapeutics; and CCHF prevention in humans. The concluding session focused on recent WHO recommendations regarding disease prevention, control strategies, and innovations against CCHFV outbreaks. This meeting report summarizes lectures by the invited speakers and highlights advances in the field.

Dermacentor reticulatus - a tick on its way from glacial refugia to a panmictic Eurasian population.

The ornate dog tick (Dermacentor reticulatus) shows a recently expanding geographic distribution. Knowledge on its intraspecific variability, population structure, rate of genetic diversity and divergence, including its evolution and geographic distribution, is crucial to understand its dispersal capacity. All such information would help to evaluate the potential risk of future spread of associated pathogens of medical and veterinary concern. A set of 865 D. reticulatus ticks was collected from 65 localities across 21 countries, from Portugal in the west to Kazakhstan and southern Russia in the east. Cluster analyses of 16 microsatellite loci were combined with nuclear (ITS2, 18S) and mitochondrial (12S, 16S, COI) sequence data to uncover the ticks' population structures and geographical patterns. Approximate Bayesian computation was applied to model evolutionary relationships among the found clusters. Low variability and a weak phylogenetic signal showing an east-west cline were detected both for mitochondrial and nuclear sequence markers. Microsatellite analyses revealed three genetic clusters, where the eastern and western cluster gradient was supplemented by a third, northern cluster. Alternative scenarios could explain such a tripartite population structure by independent formation of clusters in separate refugia, limited gene flow connected with isolation by distance causing a "bipolar pattern", and the northern cluster deriving from admixture between the eastern and western populations. The best supported demographic scenario of this tick species indicates that the northern cluster derived from admixture between the eastern and western populations 441 (median) to 224 (mode) generations ago, suggesting a possible link with the end of the Little Ice Age in Europe.

Molecular Epidemiology of Babesia and Theileria Species in Sheep in Kars Region of Turkey

Objective: This study aimed to evaluate Babesia and Theileria species and vector ticks in sheep in the Eastern Anatolia Region of Turkey. Methods: Blood samples were collected from 960 sheep, and ticks were collected from the same animals between January and December 2017. The reverse line blotting (RLB) method was used to analyze Babesia and Theileria piroplasm DNAs. Ticks and tick egg clusters were evaluated in terms of Babesia and Theileria species using the RLB technique. Results: Microscopically, 3.96% (38/960) of Theileria spp. piroplasm forms were identified; however, no Babesia spp. piroplasm forms were identified. The distribution of Babesia and Theileria spp. by RLB was 35.52% (341/960). The species identified included Theileria ovis (24.79%, 238/960), Theileria sp. (6.15%, 59/960), Theileria sp. OT3 (4.27%, 41/960), and Babesia ovis (0.31%, 3/960). Tick infestation was found in 17.5% (168/960) of the sheep. Dermacentor marginatus (66.31%), Haemaphysalis parva (32.73%), Hae. punctata (0.21%), Rhipicephalus bursa (0.53%), and Hyalomma marginatum (0.11%) were identified in the infected sheep. No pathogenic species were found in the analysis of egg clusters or tick carcasses according to the RLB method. Conclusion: Theileria ovis is the theileriosis agent in sheep in the study region. Species commonly detected in tick-infested sheep were D. marginatus and Hae. parva.

Monthly infestation characteristics of ticks on cattle in Thrace, a Crimean Congo hemorrhagic fever-endemic area of Turkey.

The first etiologically confirmed cases of Crimean-Congo hemorrhagic fever (CCHF) in humans were detected in Turkey in 2002. Since then, thousands of cases have been reported from different parts of the country. Hyalomma (Hy.) marginatum is considered the main vector tick of CCHFe in Turkey, and the primary infection route for humans is known to be the tick bite. This study was carried out between January 2013 and December 2014 in Thrace, Turkey, to determine monthly prevalence and intensity of tick infestation in cattle and, ultimately, to predict the related risk of human exposure to ticks and tick-borne diseases. During the study, 1,701 cattle in 24 villages were screened for ticks; 24,012 adult ticks, 1,887 nymphs, and 766 larvae were encountered on 1,228 of these cattle. On the 1,318 cattle that routinely grazed in the daytime, Hy. marginatum was the most predominant species, with an infestation prevalence of 73.6% and an average tick intensity of 16.1 on the infested cattle. In order of prevalence (%) in the grazing cattle, Hy. marginatum was followed by Rhipicephalus (R.) bursa (32.7%), R. turanicus (%29.5), Ixodes (I.) ricinus (15.1%), Haemaphysalis (Ha.) parva (10.4%), Ha. inermis (10%), Ha. punctata (6.5%), and Dermacentor (D.) marginatus (2.3%). The obtained data were discussed in terms of the infestation characteristics of the observed tick species, the drivers that may affect these characteristics, and the features of possible relationship between Hy. marginatum infestation in the cattle and CCHF cases among humans in the area.

Monthly dynamics of the cold-adapted one-host biological north form of Hyalomma scupense under the influence of the warm summer subtype of the Mediterranean climate in Turkey.

The one-host biological north form / ecotype of Hyalomma scupense Schulze, 1919 (Acari, Ixodidae) is reported for the first time in Turkey herein. Following the first detection of the tick, a longitudinal field study was carried out to fill gaps in the data concerning its biological features. This study also aimed to determine how the monthly activation dynamics of this relatively cold climate-adapted species is characterized under the influence of the warm summer subtype of the Mediterranean climate. During this study, which was carried out on a monthly basis in 2014, H. scupense was found on cattle from 5 out of 18 villages screened in Thrace (the European part of Turkey). The field study revealed that i) this north ecotype of H. scupense exhibits winter one-host behavior beginning in October (with larval stages) and ending in April (with engorged adults); ii) engorged females detach from the cattle, drop on the floors of barns during night and accumulate on piled bedding contaminated with slurry manure; iii) in the late spring, engorged females lay eggs, and larvae hatch in the same area; and iv) larvae become active in autumn as the weather grows cooler. The results indicated that although one-host H. scupense is known to be distinctly adapted to cold conditions, it can also be effectively established in relatively temperate regions and complete its life cycle with some modifications in the timing of its monthly activation dynamics.

Rediscovery and first genetic description of some poorly known tick species: Haemaphysalis kopetdaghica Kerbabaev, 1962 and Dermacentor raskemensis Pomerantzev, 1946.

This study aimed to provide novel information for some poorly known/rare tick species collected from wild goats (Capra aegagrus) in the mountains of Eastern Anatolia, Turkey and to expand upon the available genetic data. The collected ticks were morphologically identified as Haemaphysalis kopetdaghica (all active stages, n = 140), Dermacentor raskemensis (adults, n = 7), Ixodes gibbosus (adults, n = 15), Rhipicephalus kohlsi (female, n = 1), and R. bursa (nymphs, n = 2). A total of 32 engorged ticks (6 larvae, 6 nymphs, and 20 females) collected were allowed to molt to the next stage or for egg laying and larval hatching, respectively. In addition, one R. kohlsi female (previously confirmed by SEM microscopy) collected from a wild goat in the neighboring province of Erzurum was included in this study for further genetic comparison. The partial mitochondrial 16S rDNA and cytochrome c oxidase subunit 1 (barcoding regions) genes of each tick species were sequenced. All DNA samples obtained from the ticks were checked by PCR for the presence of Anaplasma spp., Babesia spp., Borrelia burgdorferi sensu lato, spotted fever group rickettsiae, and Theileria spp., but were found to be negative. Phylogenetic analyses of the 16S rDNA and cox1 genes were performed using the ML method to determine their genetic relationship with related ticks. As a result, this study has: i) rediscovered and provided two new tick records (H. kopetdaghica and D. raskemensis) for Turkey, ii) provided the first genetic data for H. kopetdaghica and D. raskemensis and revealed their phylogenetic relationships, iii) characterized the cox1 region of I. gibbosus for the first time, and iv) revealed significant genetic diversity between R. kohlsi from Anatolia and R. kohlsi from Oman, suggesting that R. kohlsi could include a cryptic species.

High prevalence and different genotypes of Crimean-Congo hemorrhagic fever virus genome in questing unfed adult Hyalomma marginatum in Thrace, Turkey.

Crimean-Congo hemorrhagic fever (CCHF) is a tick-borne viral disease in the old continents, in many countries south of the 50 °North Parallel. The agent is known to be the most prevalent and major cause of severe and fatal human hemorrhagic diseases among the tick-borne viruses, and is the second most widespread of all medically critical arboviruses following dengue. Members of the Hyalomma genus are mainly involved in the natural transmission of the CCHF virus (CCHFV); of those, H. marginatum is known to be the primary vector of the disease in the Western Palaearctic. In general, epidemiological studies have been based on serological detections in the hosts and/or virus screening of ticks collected from the hosts. To the best of our knowledge, only a few studies have been carried out to screen the virus in unfed, questing field ticks. Nevertheless, detection of the virus in questing ticks is known to be a crucial parameter to determine the possible vector roles of the ticks and to understand the ecological dynamics of related diseases. In this study, 200 (75 males,125 females) questing H. marginatum adults collected from the field in nine villages in Thrace, located in the European part of Turkey, were screened individually for CCHFV using nested PCR. As a result, 103 (51.5 %) ticks were determined as positive with various strains of CCHFV. High positivity in questing vectors in a region where a significantly lower number of human cases have been encountered suggests that there should be some region-specific drivers that are effective in the natural dynamics of the disease. Detailed etiological and epidemiological studies are needed to reveal the possible reason for this unexpected discrepancy.

Potential Mosquito Vectors of Dirofilaria immitis and Dirofilaira repens (Spirurida: Onchocercidae) in Aras Valley, Turkey.

Dirofilaria immitis (Leidy, 1856) and Dirofilaria repens (Railliet & Henry, 1911) are mosquito-borne filarial nematodes that primarily affect dogs, causing heartworm disease and subcutaneous dirofilariosis. The canine heartworm is reported in different provinces in Turkey. However, studies about the transmitting mosquito species are limited. Hence, this study aimed to investigate potential vectors of D. immitis and D. repens in Aras Valley, Turkey. In total, 17,995 female mosquitoes were collected from eight villages during three mosquito seasons (2012-2014) in Aras Valley, located in north-eastern Turkey. A total of 1,054 DNA pools (527 abdomen and 527 head-thorax) were tested with Dirofilaria primers by multiplex-polymerase chain reaction (PCR). Aedes caspius was the most abundant species in collection sites with 90%; this was followed by Culex theileri Theobald, 1903 (Diptera: Culicidae) (7.31%), Anopheles maculipennis Meigen 1818 (Diptera: Culicidae) (1.28%), Culex pipiens Linnaeus, 1758 (Diptera: Culicidae) (0.43%), (Anopheles) hyrcanus (Pallas, 1771) (Diptera: Culicidae) (0.37%), Aedes vexans (Meigen, 1830) (Diptera: Culicidae) (0.25%), and Culiseta annulata Schrank, 1776 (Diptera:Culicidae) (0.02%). Dirofilaria immitis and D. repens were detected in mosquito pools from five villages. The total Dirofilaria spp. estimated infection rate was 1.33%. The highest estimated infection rate was found in Ae. vexans (6.66%) and the lowest was in Ae. caspius (1.26%). The results show that An. maculipennis sl, Ae. caspius, Ae. vexans, Cx. theileri and Cx. pipiens are potential vectors of D. immitis and D. repens with DNA in head-thorax pools; An. hyrcanus is also a likely vector, but Dirofilaria DNA was found only in abdomen pools for the study area. This study revealed new potential vector species for D. immitis. Mosquitoes with natural infections of D. repens were reported for the first time in Turkey.

Correction to: The tree that hides the forest: cryptic diversity and phylogenetic relationships in the Palaearctic vector Obsoletus/Scoticus complex (Diptera: Ceratopogonidae) at the European level.

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

The tree that hides the forest: cryptic diversity and phylogenetic relationships in the Palaearctic vector Obsoletus/Scoticus Complex (Diptera: Ceratopogonidae) at the European level.

BACKGROUND: Culicoides obsoletus is an abundant and widely distributed Holarctic biting midge species, involved in the transmission of bluetongue virus (BTV) and Schmallenberg virus (SBV) to wild and domestic ruminants. Females of this vector species are often reported jointly with two morphologically very close species, C. scoticus and C. montanus, forming the Obsoletus/Scoticus Complex. Recently, cryptic diversity within C. obsoletus was reported in geographically distant sites. Clear delineation of species and characterization of genetic variability is mandatory to revise their taxonomic status and assess the vector role of each taxonomic entity. Our objectives were to characterize and map the cryptic diversity within the Obsoletus/Scoticus Complex. METHODS: Portion of the cox1 mitochondrial gene of 3763 individuals belonging to the Obsoletus/Scoticus Complex was sequenced. Populations from 20 countries along a Palaearctic Mediterranean transect covering Scandinavia to Canary islands (North to South) and Canary islands to Turkey (West to East) were included. Genetic diversity based on cox1 barcoding was supported by 16S rDNA mitochondrial gene sequences and a gene coding for ribosomal 28S rDNA. Species delimitation using a multi-marker methodology was used to revise the current taxonomic scheme of the Obsoletus/Scoticus Complex. RESULTS: Our analysis showed the existence of three phylogenetic clades (C. obsoletus clade O2, C. obsoletus clade dark and one not yet named and identified) within C. obsoletus. These analyses also revealed two intra-specific clades within C. scoticus and raised questions about the taxonomic status of C. montanus. CONCLUSIONS: To our knowledge, our study provides the first genetic characterization of the Obsoletus/Scoticus Complex on a large geographical scale and allows a revision of the current taxonomic classification for an important group of vector species of livestock viruses in the Palaearctic region.

Dynamic Modeling of Crimean Congo Hemorrhagic Fever Virus (CCHFV) Spread to Test Control Strategies.

Crimean Congo hemorrhagic fever is a zoonotic disease which has emerged or re-emerged recently in Eastern Europe and Turkey. The causative agent is a virus, mainly transmitted by ticks of the species Hyalomma marginatum (Koch, 1844, Ixodida, Amblyommidae). To test potential scenarios for the control of pathogen spread, a dynamic mechanistic model has been developed that takes into account the major processes involved in tick population dynamics and pathogen spread. The tick population dynamics model represents both abiotic (meteorological variables) and biotic (hare and cattle densities) factors in the determination of processes (development, host finding, and mortality). The infection model consists of an SIRS model for the host part whereas a lifelong infectiousness was considered for ticks. The model was first applied to a zone in Central Anatolia (Turkey). Simulated dynamics represent the average reported level of infection in vectors and hosts. A sensitivity analysis to parameter value has been carried out and highlighted the role of transstadial transmission as well as acquisition of the pathogen by immature stages. Applying the model to different sites of Turkey shows different patterns in the dynamics of acarological risk (number of infectious questing adults). This model was thereafter used to test control strategies. Simulation results indicate that acaricide treatments and decrease in hare density could have valuable effects when combined, either on the acarological risk or on the prevalence in cattle. The kind of model we have developed provides insight into the ability of different strategies to prevent and control disease spread.

A novel double-antigen sandwich ELISA for the species-independent detection of Crimean-Congo hemorrhagic fever virus-specific antibodies.

Crimean-Congo hemorrhagic fever (CCHF) is a tick-borne disease in humans caused by the CCHF virus (CCHFV). The detection of anti-CCHFV antibodies in animals is used to reveal infection risk areas. Therefore a simple, quick and reliable multispecies assay for the detection of CCHFV-specific antibodies is needed. This work presents the development and validation of a novel CCHF double-antigen ELISA for the detection of anti-CCHFV nucleoprotein antibodies. The test requires 30 µl of serum, and results are obtained within 90 min. As the ELISA is based on recombinant N-protein of the IbAr10200 virus, it can be run under standard biosafety conditions. For assay validation, sera from 95 cattle and 176 small ruminants from CCHF-endemic regions (origin: Albania, Cameroon, Kosovo, Former Yugoslav Republic of Macedonia, Mauritania, Pakistan, Turkey) served as a positive reference serum panel. The CCHF antibody status of the positive reference samples had been previously confirmed by two serological assays (species-adapted VectorBest ELISA and Euroimmun IFA). CCHFV strains belonging to three different clades are known to circulate in the countries where the positive samples originated. Sera from 402 cattle and 804 small ruminants from Germany and France served as the negative serum panel, as both countries are considered outside of the CCHFV endemic zone. Sera from monkeys, camels, rats, ferrets, raccoon dogs, raccoons, foxes, hares, pigs and humans were also tested, to determine the suitability of this novel ELISA for these species. All negative reference sera were confirmed by the CCHF double-antigen ELISA, indicating a specificity of 100%. 268 of 271 positive reference sera tested positive for CCHFV-specific antibodies, 8sensitivity of 99%9. Further analysis are needed to ensure a recognition of the IbAr10200 nucleoprotein by antibodies directed against all known CCHFV clades. This is planned to be realized with sera from other regions covering the three missing clades.

Otoacariasis: demographic and clinical outcomes of patients with ticks in the ear canal / Otoacaríase: desfechos demográficos e clínicos de pacientes com carrapatos no conduto auditivo externo

ABSTRACT INTRODUCTION: Otoacariasis, the attachment of ticks and mites within the ear canal is a common phenomenon especially in rural areas. OBJECTIVE: To determine the clinical and demographic features of cases with detected ticks in the ear canal, which is a common health problem, and identify tick species. METHODS: Data of patients who had otoacariasis were collected. We also investigated all ticks at the Veterinary Department of Kafkas University. RESULTS: We present the data of patients with otoacariasis. All ticks were identified as otobius. Otobius ticks were found not related with any complications. CONCLUSION: It is very important to detect ticks in the ear canal as they act as vector of some diseases. Identifying species of ticks may help clinicians to prevent further complications associated with vector-borne diseases.

Resumo Introdução: A otoacaríase, fixação de carrapatos duros e moles no interior do conduto auditivo, é fenômeno comum, especialmente em áreas rurais. Objetivo: Determinar as características clínicas e demográficas de casos de carrapatos detectados no conduto auditivo externo, um problema de saúde frequente, e identificar as espécies do ácaro. Método: Coletaram-se dados dos pacientes com otoacaríase, e todos os carrapatos foram investigados no Departamento de Veterinária da Universidade Kafkas. Resultados: Os dados de pacientes com otoacaríase são apresentados. Todos os carrapatos foram identificados como pertencentes ao gênero Otobius e constatou-se não haver relação entre os carrapatos e qualquer tipo de complicação. Conclusão: É muito importante detectar carrapatos no conduto auditivo externo, pois esses ácaros funcionam como vetores para algumas doenças. A identificação da espécie do ácaro pode ajudar o clínico a prevenir complicações associadas às doenças transmitidas por esse vetor.

Crimean-Congo Hemorrhagic Fever Virus in Bulgaria and Turkey.

Infections of humans with the tick-borne Crimean-Congo hemorrhagic fever virus (CCHFV) can cause a severe hemorrhagic fever with case fatality rates of up to 80%. Most humans are infected by tick bite, crushing infected ticks by hand or by unprotected contact with blood of viremic mammals. Next to the notified human CCHF cases, the real distribution and the situation in animals in Southeastern Europe are nearly unknown. Since domestic ruminants play a crucial role in the life cycle of the vector ticks and the transmission and amplification of the virus, the antibody prevalence in those animals is a good indicator for the presence of CCHFV in a region. Therefore, the prevalence of CCHFV-specific antibodies was investigated in domestic ruminants of different regions of Bulgaria and Turkey. Sera of 1165 ruminants were tested and a prevalence of up to 90% was identified. The overall prevalence for Bulgaria was 26% and for Turkey 57%. The results highlight the risk of human infections in those regions and the importance of the investigation of the prevalence in animals for identification of risk areas. This article provides a unique overview about published CCHFV antibody prevalence in animals in comparison to human incidences in different areas of Bulgaria and Turkey. Although it will help to complete the understanding of the CCHFV situation in these countries, it also demonstrates the lack of unpublished and published data even in these highly endemic areas.

Otoacariasis: demographic and clinical outcomes of patients with ticks in the ear canal.

INTRODUCTION: Otoacariasis, the attachment of ticks and mites within the ear canal is a common phenomenon especially in rural areas. OBJECTIVE: To determine the clinical and demographic features of cases with detected ticks in the ear canal, which is a common health problem, and identify tick species. METHODS: Data of patients who had otoacariasis were collected. We also investigated all ticks at the Veterinary Department of Kafkas University. RESULTS: We present the data of patients with otoacariasis. All ticks were identified as otobius. Otobius ticks were found not related with any complications. CONCLUSION: It is very important to detect ticks in the ear canal as they act as vector of some diseases. Identifying species of ticks may help clinicians to prevent further complications associated with vector-borne diseases.

External morphological anomalies in ixodid ticks from Thrace, Turkey.

Of 18,667 ticks examined, 33 specimens from species identified as Haemaphysalis parva, Hyalomma marginatum, Hy. scupense, Rhipicephalus bursa and Rh. turanicus were found to have external morphological anomalies. Anomalous Ha. parva, Hy. scupence and Rh. turanicus were reported in this study for the first time. General anomalies manifested as asymmetry and deformations of the idiosoma, whereas local anomalies occurred in legs, exoskeleton, spiracular, adanal, subanal and accessory plates, mouthparts and capitulum. With this study describing a gynandromorphic Hy. marginatum, the number of gynandromorphic tick cases has been raised to two in Turkey.

Circulation of Crimean-Congo Hemorrhagic Fever Virus in the former Yugoslav Republic of Macedonia revealed by screening of cattle sera using a novel enzyme-linked immunosorbent assay.

BACKGROUND: There are only few assays available for the detection of Crimean-Congo Hemorrhagic Fever Virus (CCHFV)-specific antibodies in animals, and data about diagnostic sensitivity and specificity are incompletely documented for most of these tests. This is unfortunate since CCHFV antibodies in animals can be used as indicator for virus circulation in a geographic area and therewith potential risk of human exposure. This paper therefore reports on a novel ELISA for the detection of CCHFV-specific antibodies in cattle and on its application for testing ruminant sera from the Former Yugoslav Republic of Macedonia. PRINCIPAL FINDINGS: A highly sensitive and specific ELISA was developed to detect CCHFV-specific IgG antibodies in cattle. The assay was validated by using 503 negative serum samples from a country where CCHFV has never been detected until now, and by using 54 positive serum samples. The positive sera were verified by using two commercially available assays (for testing human serum) which we have adapted for use in animals. The sensitivity of the novel ELISA was 98% and its specificity 99%. The presence of Hyalomma ticks was demonstrated in the Former Yugoslav Republic of Macedonia and depending on the region antibody prevalence rates up to 80% were detected in the cattle population. CONCLUSION: This article describes a fully validated, highly sensitive and specific ELISA for the detection of CCHFV-specific IgG antibodies in cattle. Using this assay, CCHFV-specific antibodies were detected for the first time in cattle in the Former Yugoslav Republic of Macedonia, giving evidence for an active circulation of this virus in the country. Supporting this conclusion, the occurrence of the main vector of CCHFV was demonstrated in the present work for the first time in Former Yugoslav Republic of Macedonia.

Molecular evidence for trans-stadial and transovarial transmission of Babesia occultans in Hyalomma marginatum and Rhipicephalus turanicus in Turkey.

A total of 1064 adult ticks identified as Hyalomma marginatum (n=965), Rhipicephalus turanicus (n=86), Haemaphysalis inermis (n=9) and Rhipicephalus bursa (n=4) along with 20 egg masses derived from H. marginatum (n=18) and R. bursa were screened for Babesia occultans. The ticks were combined into 328 pools and infection rates were calculated as the maximum likelihood estimation (MLE) with 95% confidence intervals (CI). Of these pools, 23 (7%) were positive for B. occultans, and the overall MLE was calculated as 2.27% (CI 1.48-3.35). Infection prevalence in tick species was 7.09% for H. marginatum (22/310, MLE 2.41, CI 1.55-3.59) and 7.14% for R. turanicus (1/14, MLE 1.11, CI 0.07-5.18). None of H. inermis and R. bursa was infected with the parasite. Host-seeking H. marginatum females displayed an infection prevalence of 1.68% (2/119, MLE 0.63, CI 0.11-2.06), while no parasite DNA was detected in the males. The prevalence of infection in feeding H. marginatum varied, ranging from 27.27% (9/33, MLE 4.61, CI 2.26-8.52) in males to 25.92% (7/27, MLE 8.22, CI 3.72-15.75) in females. Of the egg masses examined, 4 (22.22%) of H. marginatum and 1 (50%) of R. turanicus were infected with B. occultans. To the best of our knowledge, this is the first time that B. occultans has been detected in R. turanicus.

Unraveling the ecological complexities of tick-associated Crimean-Congo hemorrhagic fever virus transmission: a gap analysis for the western Palearctic.

This review aims to summarize the current knowledge of the eco-epidemiology of Crimean-Congo hemorrhagic fever (CCHF) virus transmission reviewing the most recent scientific advances in the last few decades of epidemic and non-epidemic ("silent") periods. We explicitly aim to highlight the dynamics of transmission that are still largely unknown. Recent knowledge gathered from research in Africa and Europe explains the very focal nature of the virus, and indicates that research on the ecology of the virus in the inter-epidemic periods of the disease has not yet been addressed. Hyalomma spp. ticks have been incriminated in the transmission of the virus under field conditions, but the role of other ticks found infected in nature remains to be tested under experimental conditions. Published evidence suggests that the increase in human cases reported in the Balkans, Turkey, and Russia is perhaps less due to the effect of changes in climate, but rather result from the impact of yet unexplored mechanisms of amplification that might be supported by wild animal hosts. Assessment of the available data suggests that epidemics in Eastern Europe are not the result of a spreading viral wave, but more likely are due to a combination of factors, such as habitat abandonment, landscape fragmentation, and proliferation of wildlife hosts that have exacerbated prevalence rates in tick vectors. There is an urgent need to empirically demonstrate these assumptions as well as the role of birds in introducing infected ticks, and also to evaluate the potential for survival of introduced ticks. Either a replacement of the pathogenic virus in the western Mediterranean or a lack of westward dissemination of infected tick populations may explain the absence of the virus in Western Europe.