Looking Beyond the Lens of Crimean-Congo Hemorrhagic Fever in Africa.

Crimean-Congo hemorrhagic fever (CCHF) is a lethal viral disease that has severe public health effects throughout Africa and a case fatality rate of 10%-40%. CCHF virus was first discovered in Crimea in 1944 and has since caused a substantial disease burden in Africa. The shortage of diagnostic tools, ineffective tick control efforts, slow adoption of preventive measures, and cultural hurdles to public education are among the problems associated with continued CCHF virus transmission. Progress in preventing virus spread is also hampered by the dearth of effective serodiagnostic testing for animals and absence of precise surveillance protocols. Intergovernmental coordination, creation of regional reference laboratories, multiinstitutional public education partnerships, investments in healthcare infrastructure, vaccine development, and a One Health approach are strategic methods for solving prevention challenges. Coordinated efforts and financial commitments are needed to combat Crimean-Congo hemorrhagic fever and improve all-around readiness for newly developing infectious illnesses in Africa.

Crimean-Congo Hemorrhagic Fever Virus for Clinicians-Epidemiology, Clinical Manifestations, and Prevention.

Crimean-Congo hemorrhagic fever (CCHF) is a tickborne infection that can range from asymptomatic to fatal and has been described in >30 countries. Early identification and isolation of patients with suspected or confirmed CCHF and the use of appropriate prevention and control measures are essential for preventing human-to-human transmission. Here, we provide an overview of the epidemiology, clinical features, and prevention and control of CCHF. CCHF poses a continued public health threat given its wide geographic distribution, potential to spread to new regions, propensity for genetic variability, and potential for severe and fatal illness, in addition to the limited medical countermeasures for prophylaxis and treatment. A high index of suspicion, comprehensive travel and epidemiologic history, and clinical evaluation are essential for prompt diagnosis. Infection control measures can be effective in reducing the risk for transmission but require correct and consistent application.

Clinical and Molecular Epidemiology of Crimean-Congo Hemorrhagic Fever in Humans in Uganda, 2013-2019.

Crimean-Congo Hemorrhagic Fever (CCHF) is endemic in Uganda, yet its epidemiology remains largely uncharacterized. To better understand its occurrence within Uganda, case reports of patients hospitalized with CCHF between 2013 and 2019 were reviewed. Further, genome sequences of CCHF-positive RNA obtained during this period were determined for phylogenetic comparisons. We found that a total of 32 cases (75% males; CFR, 31.2%), aged between 9 to 68 years, were reported during the study period. Most cases were detected during July to December of each outbreak year (81.2%; P < 0.01) and were located along the "cattle corridor" (68.7%, P = 0.03). The most common presenting symptoms were fever (93.8%), hemorrhage (81.3%), headache (78.1%), fatigue (68.8%), vomiting (68.8%), and myalgia (65.6%). In five patients for whom hematological data were available, varied abnormalities were observed including thrombocytopenia, leukopenia, anemia, lymphopenia, lymphocytosis, polycythemia, and microcytosis. About 56.3% (P = 0.47) of patients reported tick bites or exposure to livestock as their potential source of infection. Person-to-person transmission was suspected for two cases. Using unbiased metagenomics, we found that the viral S- and L- segments have remained conserved in Africa 2 clade since the 1950s. In contrast, the M segment split into two geographically interspersed clades; one that belongs to Africa 2 and another that is ancestral to Africa 1 and 2. Overall, this data summarizes information on the history and clinical presentation of human CCHF in Uganda. Importantly, it identifies vulnerable populations as well as temporal and geographic regions in Uganda where surveillance and control interventions could be focused.

Crimean-Congo Hemorrhagic Fever Virus: Current Advances and Future Prospects of Antiviral Strategies.

Crimean-Congo hemorrhagic fever virus (CCHFV) is a widespread, tick-borne pathogen that causes Crimean-Congo hemorrhagic fever (CCHF) with high morbidity and mortality. CCHFV is transmitted to humans through tick bites or direct contact with patients or infected animals with viremia. Currently, climate change and globalization have increased the transmission risk of this biosafety level (BSL)-4 virus. The treatment options of CCHFV infection remain limited and there is no FDA-approved vaccine or specific antivirals, which urges the identification of potential therapeutic targets and the design of CCHF therapies with greater effort. In this article, we discuss the current progress and some future directions in the development of antiviral strategies against CCHFV.

An integrated overview of the bacterial flora composition of Hyalomma anatolicum, the main vector of CCHF.

The microbial flora associated with Hyalomma anatolicum ticks was investigated using culture-dependent (CD) and independent (next generation sequencing, NGS) methods. The bacterial profiles of different organs, development stages, sexes, and of host cattle skins were analyzed using the CD method. The egg and female gut microbiota were investigated using NGS. Fourteen distinct bacterial strains were identified using the CD method, of which Bacillus subtilis predominated in eggs, larval guts and in adult female and male guts, suggesting probable transovarial transmission. Bacillus velezensis and B. subtilis were identified in cattle skin and tick samples, suggesting that skin is the origin of tick bacteria. H.anatolicum males harbour lower bacterial diversity and composition than females. The NGS analysis revealed five different bacterial phyla across all samples, Proteobacteria contributing to >95% of the bacteria. In all, 56611sequences were generated representing 6,023 OTUs per female gut and 421 OTUs per egg. Francisellaceae family and Francisella make up the vast majority of the OTUs. Our findings are consistent with interference between Francisella and Rickettsia. The CD method identified bacteria, such B. subtilis that are candidates for vector control intervention approaches such paratransgenesis whereas NGS revealed high Francisella spp. prevalence, indicating that integrated methods are more accurate to characterize microbial community and diversity.

Complete mitochondrial genome characterization and phylogenetic analyses of the main vector of Crimean-Congo haemorrhagic fever virus: Hyalomma marginatum Koch, 1844.

The Mediterranean tick, Hyalomma marginatum, is the most important vector of Crimean-Congo haemorrhagic fever virus and several pathogens that cause animal and human diseases and economic losses to livestock production. Given the medical and veterinary importance of this tick species, we sequenced and characterized its mitochondrial genome (mitogenome) for the first time. We designed two new primer sets and combined long-range PCR with next generation sequencing to generate complete mitogenomes with deep coverage from 10 H. marginatum adults. The mitogenomes contained 13 protein-coding genes (PCGs), 22 transfer RNAs (tRNAs), two ribosomal subunits, two control regions, and three tick-box motifs. The nucleotide composition of the H. marginatum mitogenomes were A+T biased (79.76%) and exhibited negative AT- and GC- skews across most PCGs. All PCGs were initiated by ATK codons and two truncated termination codons were seen in the COX2 and COX3 genes. All tRNAs exhibited typical cloverleaf structures, except for tRNACys and tRNASer1. A total of 62 polymorphic sites defined ten unique haplotypes. Phylogenetic analyses based on the 13 PCGs of 56 tick species revealed that four Hyalomma species (H. marginatum, H. asiaticum, H. rufipes, and H. truncatum) formed a monophyletic clade with strong support. The results of this study provide a comprehensive resource for further studies on the systematics, population genetics, molecular epidemiology, and evolution of ticks.

Update on prevalence and distribution pattern of tick-borne diseases among humans in India: a review.

In the present scenario, tick-borne diseases (TBDs) are well known for their negative impacts on humans as well as animal health in India. The reason lies in their increased incidences due to global warming, environmental and ecological changes, and availability of suitable habitats. On a global basis, they are now considered a serious threat to human as well as livestock health. The major tick-borne diseases in India include Kyasanur forest disease (KFD), Crimean-congo hemorrhagic fever (CCHF), Lyme disease (LD), Q fever (also known as coxiellosis), and Rickettsial infections. In recent years, other tick-borne diseases such as Babesiosis, Ganjam virus (GANV), and Bhanja virus (BHAV) infections have also been reported in India. The purpose of this paper is to review the history and the current state of knowledge of tick-borne diseases in the country. The conclusion of this review is extending the requirement of greater efforts in research and government management for the diagnosis and treatment and as well as prevention of these diseases so that tick-borne disease burden should be minimizing in India.

The Integration of Human and Veterinary Studies for Better Understanding and Management of Crimean-Congo Haemorrhagic Fever.

Outbreaks that occur as a result of zoonotic spillover from an animal reservoir continue to highlight the importance of studying the disease interface between species. One Health approaches recognise the interdependence of human and animal health and the environmental interplay. Improving the understanding and prevention of zoonotic diseases may be achieved through greater consideration of these relationships, potentially leading to better health outcomes across species. In this review, special emphasis is given on the emerging and outbreak pathogen Crimean-Congo Haemorrhagic Fever virus (CCHFV) that can cause severe disease in humans. We discuss the efforts undertaken to better understand CCHF and the importance of integrating veterinary and human research for this pathogen. Furthermore, we consider the use of closely related nairoviruses to model human disease caused by CCHFV. We discuss intervention approaches with potential application for managing CCHFV spread, and how this concept may benefit both animal and human health.

Knowledge, attitude and perceptions about Crimean Congo Haemorrhagic Fever (CCHF) among occupationally high-risk healthcare professionals of Pakistan.

BACKGROUND: Crimean Congo Haemorrhagic Fever (CCHF), a tropically neglected infectious disease caused by Nairovirus, is endemic in low middle-income countries like Pakistan. Emergency health care professionals (HCPs) are at risk of contracting nosocomial transmission of CCHF. We, therefore, aim to analyze the knowledge, attitudes, and perceptions (KAP) of at-risk physicians, nurses, and pharmacists in Pakistan and the factors associated with good KAP. METHOD: A validated questionnaire (Cronbach's alpha 0.71) was used to collect data from HCPs in two CCHF endemic metropolitan cities of Pakistan by employing a cross-sectional study design. For data analysis percentages, chi-square test and Spearman correlation were applied by using SPSS version 22. RESULTS: Of the 478 participants, 56% (n = 268) were physicians, 37.4% (n = 179) were nurses, and 6.5% (n = 31) were pharmacists. The proportion of HCPs with good knowledge, attitude, and perception scores was 54.3%, 81, and 69%, respectively. Being a physician, having more work experience, having a higher age, working in tertiary care settings, were key factors for higher knowledge (p < 0.001). The correlation coefficient showed significant positive correlation between attitude- perception (r = 0.560, p < 0.001). CONCLUSION: We have observed average knowledge of HCPs. Therefore, we recommend time to time education campaigns and workshops in highly endemic CCHF regions to be launched by health ministries and HCPs, in particular nurses, encouraged to follow authentic academic sources of information to prevent nosocomial transmission.

Differential Growth Characteristics of Crimean-Congo Hemorrhagic Fever Virus in Kidney Cells of Human and Bovine Origin.

Crimean-Congo hemorrhagic fever virus (CCHFV) causes a lethal tick-borne zoonotic disease with severe clinical manifestation in humans but does not produce symptomatic disease in wild or domestic animals. The factors contributing to differential outcomes of infection between species are not yet understood. Since CCHFV is known to have tropism to kidney tissue and cattle play an important role as an amplifying host for CCHFV, in this study, we assessed in vitro cell susceptibility to CCHFV infection in immortalized and primary kidney and adrenal gland cell lines of human and bovine origin. Based on our indirect fluorescent focus assay (IFFA), we suggest a cell-to-cell CCHF viral spread process in bovine kidney cells but not in human cells. Over the course of seven days post-infection (dpi), infected bovine kidney cells are found in restricted islet-like areas. In contrast, three dpi infected human kidney or adrenal cells were noted in areas distant from one another yet progressed to up to 100% infection of the monolayer. Pronounced CCHFV replication, measured by quantitative real-time RT-PCR (qRT-PCR) of both intra- and extracellular viral RNA, was documented only in human kidney cells, supporting restrictive infection in cells of bovine origin. To further investigate the differences, lactate dehydrogenase activity and cytopathic effects were measured at different time points in all mentioned cells. In vitro assays indicated that CCHFV infection affects human and bovine kidney cells differently, where human cell lines seem to be markedly permissive. This is the initial reporting of CCHFV susceptibility and replication patterns in bovine cells and the first report to compare human and animal cell permissiveness in vitro. Further investigations will help to understand the impact of different cell types of various origins on the virus-host interaction.

Detection of African genotype in Hyalomma tick pools during Crimean Congo hemorrhagic fever outbreak, Rajasthan, India, 2019.

Crimean Congo hemorrhagic fever (CCHF) is a zoonotic viral disease presenting with fever and hemorrhagic manifestations in humans. After several outbreaks of CCHF being reported from Gujarat since 2011 till 2019 and from Rajasthan in 2014 and 2015, the present study reports the CCHF outbreak which was recorded from five human cases in three districts Jodhpur, Jaisalmer, and Sirohi of Rajasthan state since August 2019 till November 2019. A high percent of positivity was recorded in livestock animal samples for the CCHFV IgG antibody. CCHF virus (CCHFV) positive human blood samples and Hyalomma tick pool samples were sequenced using next-generation sequencing method. Two different M segment genotypes, encoding glycoprotein precursor, were identified from tick pools in the study: first from Asian and second from African lineage. The L gene (polymerase) and the S gene (nucleocapsid) clustered in the Asian lineage. The present study illustrates the existence of two different CCHFV lineages being circulating within the Hyalomma tick pools in the Rajasthan state, India. We also observed 3.56% amino acid changes between the death and the survived case of CCHFV in the M gene. This report also sets an alarm to enhance human, tick and livestock surveillance in other districts of Rajasthan and nearby states of India. Biosafety measures, barrier nursing along with the availability of personal protective equipment and ribavirin drug will always be a mainstay in preventing nosocomial infection for proper case management.

Crimean-Congo hemorrhagic fever virus in tortoises and Hyalomma aegyptium ticks in East Thrace, Turkey: potential of a cryptic transmission cycle.

BACKGROUND: Recent reports have demonstrated the presence of Crimean-Congo hemorrhagic fever virus (CCHFV) genomic material in Hyalomma aegyptium ticks feeding primarily on tortoises belonging to the genus Testudo. This raises the question if these ticks and their hosts play a role in the natural transmission dynamics of CCHFV. However, the studies are limited, and assessing the relevance of H. aegyptium in perpetuating the virus in nature, and a potential spillover to humans remains unknown. This study aimed to detect CCHFV in H. aegyptium ticks and their tortoise hosts in the East Thrace region of Turkey, where H. aegyptium is the most common human-biting tick and where a high density of tortoises of the genus Testudo can be found. METHODS: During the study period, 21 blood samples from different tortoises (2 T. hermanni and 19 T. graeca), 106 tick pools (containing 448 males, 152 females, 93 nymphs and 60 larvae) collected from 65 tortoises (5 T. hermanni and 60 T. graeca), 38 adult unfed questing ticks (25 males and 13 females, screened individually) and 14 pools (containing 8 nymphs and 266 larvae) of immature unfed questing ticks collected from the ground were screened for CCHFV genome by nested PCR and partial genomes sequenced. RESULTS: As a result of the screening of these 179 samples, 17 (9.5%) were detected as positive as follows: 2 of 21 blood samples (9.52%), 13 (containing 18 nymphs in 3 pools, and 52 males and 8 females in 10 pools) of 106 tick pools from tortoises (12.26%), and 2 of 38 adult questing ticks (5.26%). No positive result was determined in 14 pools of immature questing ticks. CONCLUSIONS: Previous studies have shown that reptiles can participate in the transmission of arthropod-borne viruses, but they may contribute to different aspects of the disease ecology and evolution of tick-borne viral pathogens. Our results indicate the presence of CCHFV in questing and feeding H. aegyptium ticks as well as tortoise hosts. This may indicate that CCHFV circulates in a cryptic transmission cycle in addition to the primary transmission cycle that could play a role in the natural dynamic of the virus and the transmission to humans.

Modeling tick vaccines: a key tool to improve protection efficacy.

Introduction: The development of more effective vaccines for the control of tick infestations and pathogen transmission is essential for prevention and control of tick-borne diseases worldwide. Recently, the application of omics technologies has advanced the identification of tick protective antigens. However, other factors such as vaccine formulation and implementation need to be addressed, and tick vaccine modeling will contribute to improve the efficacy of vaccination strategies.Areas covered: In this review, we summarized current information on tick vaccine correlates of protection and modeling, and proposed new approaches to improve vaccine evaluation and implementation using as a proof-of-concept the Hyalomma marginatum-Crimean-Congo hemorrhagic fever virus model due to its high mortality rate and potentially growing impact on human health.Expert opinion: Vaccines are required as an effective and environmentally sound intervention for the control of tick-borne diseases affecting human and animal health worldwide. Despite recent advances in the identification of candidate tick protective antigens, research on vaccine formulation and implementation need to be addressed to improve tick vaccine control efficacy. As shown here, modeling of the vaccination strategies against ticks and transmitted pathogens will contribute to vaccine development by guiding the selection of appropriate antigen combinations, target hosts, and vaccination time schedule.

Seroepidemiological Investigation of Crimean-Congo Hemorrhagic Fever Virus in Sheep and Camels of Inner Mongolia of China.

Crimean-Congo hemorrhagic fever (CCHF) is a highly lethal infectious disease in humans caused by tick-borne Crimean-Congo hemorrhagic fever virus (CCHFV). To determine the potential risk of CCHF in the pastoral area of Northwestern China, the presence of antibody to CCHFV in the sera of two most common tick hosts, sheep and camels, in Inner Mongolia of China was evaluated. The purified recombinant nucleocapsid protein (NP) of CCHFV was prepared from a prokaryotic vector expressing the NP encoding gene, which was employed as the antigen to probe antibody against CCHFV in tick vectors using an immunoblotting assay. In total, 58.3% (35/60) and 54% (12/22) of camels were positive of antibody to CCHFV in sera at Alxa Youqi County and Ulan Hudu Gacha Village of Inner Mongolia Province, respectively. However, only 6.7% (2/30) of sera of sheep were determined positive in antibody to CCHFV in the Wulan Hudug check area in this study. Consequently, these results indicate that 54-58.3% camels were infected by CCHFV after exposure to tick bites in Inner Mongolia, which was significantly higher than 6.7% of infection in the sheep in this area, suggesting there is a certain relationship between the serological reactivity and exposure time to ticks, range of activity, living behaviors, and breeding time. Further intensive surveillance of livestock and exposed population is required to better understand the spread of CCHFV in this area.

Molecular discrimination of Hyalomma tick species serving as reservoirs and vectors for Crimean-Congo hemorrhagic fever virus in sub-Saharan Africa.

The species identification of tick vectors of Crimean-Congo hemorrhagic fever virus (CCHFV), especially Hyalomma (H.) species, is a prerequisite to understand the eco-epidemiology of this disease and to reveal vector and virus reservoir species. However, the morphologic species discrimination can be difficult for damaged or blood-fed ticks and in case of species intercrosses. Therefore, we used matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) and restriction fragment length polymorphism (RFLP) analysis to distinguish the most common Hyalomma species from sub-Saharan Africa (H. truncatum, H. rufipes and H. dromedarii). Within the last years, MALDI-TOF MS analysis based on tick leg proteins has been shown to be a reliable method to distinguish several tick species. For this purpose, a reference spectral library of several European, American and African tick species was established. In this study, six different Hyalomma species were tested, all of which were all clearly distinguishable by mass spectrometric analyses. Moreover, MALDI TOF- MS was able to confirm morphologic findings where sequencing provided ambiguous results. In addition, a polymerase chain reaction (PCR) based on the CO1 gene amplification of ticks has been developed for the unequivocal species identification by amplicon sequencing and specific restriction endonuclease cleavage pattern analysis. RFLP proved to be a feasible auxiliary discrimination tool for selected Hyalomma species when access to sequencing methods is not available, as for instance during field studies.

Ixodid tick species and two tick-borne pathogens in three areas in the Sudan.

Ticks are important parasites from economic and public health points of view because of their ability to reduce farm animals' productivity and transmit zoonotic diseases. We conducted this cross-sectional study between January and March 2016 and between March and April 2017 to identify tick species in West Darfur, Al-Jazeera, and the River Nile states in the Sudan and to investigate whether these ticks carry Rickettsia spp. and Crimean-Congo hemorrhagic fever (CCHF) virus. In total, 1593 ticks were collected from 207 animals and identified based on morphology or 16S rRNA gene and tested for Rickettsia spp. and CCHF virus either individually or as pools containing 2 to 10 pooled ticks using molecular methods. Overall, 14 tick species belonging to three genera, namely Amblyomma, Hyalomma, and Rhipicephalus, were identified. Hyalomma anatolicum and Rhipicephalus evertsi evertsi were the most frequent ticks. A total of 561 tests comprised of individual or pooled ticks were conducted and 13.7% (77/561) were positive for Rickettsia spp. which were mostly Rickettsia aeschlimannii and R. africae. The highest positivity was noticed among H. rufipes collected from cattle and camels in West Darfur. However, none of the screened Hyalomma ticks harbored CCHF viral RNA. These findings suggest that there might be a risk of zoonotic transmission of Rickettsia spp. by ticks but zoonotic transmission of CCHF virus is apparently doubtful. An in-depth and a country-wide epidemiological study is needed to better understand the dynamic of Rickettsia spp. and CCHF virus in the Sudan.

A prospective prediction tool for understanding Crimean-Congo haemorrhagic fever dynamics in Turkey.

OBJECTIVES: We aimed to develop a prospective prediction tool on Crimean-Congo haemorrhagic fever (CCHF) to identify geographic regions at risk. The tool could support public health decision-makers in implementation of an effective control strategy in a timely manner. METHODS: We used monthly surveillance data between 2004 and 2015 to predict case counts between 2016 and 2017 prospectively. The Turkish nationwide surveillance data set collected by the Ministry of Health contained 10 411 confirmed CCHF cases. We collected potential explanatory covariates about climate, land use, and animal and human populations at risk to capture spatiotemporal transmission dynamics. We developed a structured Gaussian process algorithm and prospectively tested this tool predicting the future year's cases given past years' cases. RESULTS: We predicted the annual cases in 2016 and 2017 as 438 and 341, whereas the observed cases were 432 and 343, respectively. Pearson's correlation coefficient and normalized root mean squared error values for 2016 and 2017 predictions were (0.83; 0.58) and (0.87; 0.52), respectively. The most important covariates were found to be the number of settlements with fewer than 25 000 inhabitants, latitude, longitude and potential evapotranspiration (evaporation and transpiration). CONCLUSIONS: Main driving factors of CCHF dynamics were human population at risk in rural areas, geographical dependency and climate effect on ticks. Our model was able to prospectively predict the numbers of CCHF cases. Our proof-of-concept study also provided insight for understanding possible mechanisms of infectious diseases and found important directions for practice and policy to combat against emerging infectious diseases.

Nosocomial infections caused by Crimean-Congo haemorrhagic fever virus.

Crimean-Congo haemorrhagic fever (CCHF) is an acute febrile illness, often accompanied by haemorrhagic manifestations, with a high case fatality rate (CFR). The causative agent is CCHF virus (CCHFV), and is transmitted to humans mainly through tick bites or exposure to blood or tissues of viraemic patients or livestock. Human-to-human transmission usually occurs in hospital settings, and healthcare workers (HCWs) are mainly affected. A review on nosocomial CCHFV infections was performed to elucidate the routes and circumstances of CCHFV transmission in hospital settings. From 1953 to 2016, 158 published cases of CCHFV nosocomial infection in 20 countries in Africa, Asia and Europe were found. Almost all cases were symptomatic (92.4%), with an overall CFR of 32.4%. The majority of cases occurred in hospital clinics (92.0%) and 10 cases (8.0%) occurred in laboratories. Most cases occurred among HCWs (86.1%), followed by visitors (12.7%) and hospitalized patients (1.3%). Nursing staff (44.9%) and doctors (32.3%) were the most affected HCWs, followed by laboratory staff (6.3%). The primary transmission route was percutaneous contact (34.3%). Cutaneous contact accounted for 22.2% of cases, followed by exposure to aerosols (proximity) (18.2%), indirect contact (17.2%) and exposure to patient environment (8.1%). CCHFV can cause nosocomial infections with a high CFR. During the care and treatment of patients with CCHF, standard contact precautions, barrier precautions and airborne preventive measures should be applied. In order to improve patient safety and reduce healthcare-associated CCHFV exposure, there is a need for guidelines and education for HCWs to ensure that CCHF is appropriately included in differential diagnoses; this will enable early diagnosis and implementation of infection prevention measures.

Mapping the environmental suitability of etiological agent and tick vectors of Crimean-Congo hemorrhagic fever.

Crimean-Congo hemorrhagic fever (CCHF) is one of the most important public health threats in many regions across Africa, Europe, and Asia. This study used ecological niche modeling analyses to map the environmental suitability of both CCHF virus (CCHFV), and its tick vectors (Amblyomma variegatum, Dermacentor marginatus, Hyalomma marginatum, Hyalomma rufipes, Hyalomma truncatum, Rhipicephalus appendiculatus, and Rhipicephalus evertsi evertsi) in the Old World countries. The CCHFV was anticipated to occur with high environmental suitability across southern and central Europe, northwestern Africa, central Asia, and western Mediterranean region. Ecological niche models of tick vectors anticipated diverse patterns based on the tick species in question; D. marginatus and H. marginatum showed high environmental suitability in southern and central Europe, and North Africa. The remaining vector species were anticipated to occur in Africa. All models were statistically robust and performed better than random (P < 0.001). Finally, we tested the niche similarities between CCHFV and diverse tick vectors and could not reject the null hypotheses of niche similarity in all vector-virus combinations (P > 0.05) except the combinations of CCHFV with A. variegatum, R. evertsi evertsi and R. appendiculatus (P < 0.05).