Hyalomma marginatum is a prominent tick vector responsible for transmitting various pathogens, including the Crimean-Congo hemorrhagic fever virus (CCHFV), across Europe. This systematic review consolidates findings from 144 publications regarding the geographical distribution of H. marginatum and its associated pathogens. Significant populations have been identified primarily in Southern Europe and Balkan Peninsula, indicating a concerning trend. Additionally, climate change and migratory bird movements may facilitate its further dispersal, potentially leading to the establishment of H. marginatum in transalpine regions. Consequently, robust monitoring and surveillance strategies are essential to mitigate the public health and livestock threats posed by Hyalomma-borne diseases. Raising awareness and implementing preventive measures will be crucial in addressing the challenges associated with this tick vector.

• Keywords
• Crimean–Congo hemorrhagic fever virus, Hyalomma marginatum, Rickettsia, migratory birds, surveillance, tick distribution,
• MeSH
• Arachnid Vectors * virology   physiology   MeSH
• Ixodidae * virology   physiology   MeSH
• Animal Distribution MeSH
• Animals MeSH
• Check Tag
• Animals MeSH
• Publication type
• Journal Article MeSH
• Review MeSH
• Systematic Review MeSH
• Geographicals
• Europe epidemiology   MeSH

Crimean-Congo haemorrhagic fever virus (CCHFV) poses a significant public health threat due to its potential for causing severe disease in humans and its wide geographic distribution. The virus, primarily transmitted by Hyalomma ticks, is prevalent across Africa, Asia, Europe, and the Middle East. Understanding the virus's spread among tick populations is crucial for assessing its transmission dynamics. Vertebrates play a key role in CCHF epidemiology by supporting tick populations and acting as virus carriers during viremia. Livestock, such as cattle, sheep, and goats, amplify the virus and increase tick numbers, posing zoonotic risks. Wildlife, while asymptomatic, can serve as reservoirs. Birds generally do not show signs of the virus but can introduce infected ticks to new regions. This review compiles information on CCHFV's tick vectors and vertebrate hosts, emphasizing their roles in the virus's transmission dynamics. Understanding these dynamics is essential for developing effective control and prevention strategies.

• Keywords
• Crimean-Congo haemorrhagic fever virus, livestock, ticks, wildlife, zoonotic disease,
• Publication type
• Journal Article MeSH
• Review MeSH

Crimean-Congo haemorrhagic fever (CCHF) is the most widely distributed tick-borne viral disease in humans and is caused by the Crimean-Congo haemorrhagic fever virus (CCHFV). The virus has a broader distribution, expanding from western China and South Asia to the Middle East, southeast Europe, and Africa. The historical known distribution of the CCHFV vector Hyalomma marginatum in Europe includes most of the Mediterranean and the Balkan countries, Ukraine, and southern Russia. Further expansion of its potential distribution may have occurred in and out of the Mediterranean region. This study updated the distributional map of the principal vector of CCHFV, H. marginatum, in the Old World using an ecological niche modeling approach based on occurrence records from the Global Biodiversity Information Facility (GBIF) and a set of covariates. The model predicted higher suitability of H. marginatum occurrences in diverse regions of Africa and Asia. Furthermore, the model estimated the environmental suitability of H. marginatum across Europe. On a continental scale, the model anticipated a widespread potential distribution encompassing the southern, western, central, and eastern parts of Europe, reaching as far north as the southern regions of Scandinavian countries. The distribution of H. marginatum also covered countries across Central Europe where the species is not autochthonous. All models were statistically robust and performed better than random expectations (p < 0.001). Based on the model results, climatic conditions could hamper the successful overwintering of H. marginatum and their survival as adults in many regions of the Old World. Regular updates of the models are still required to continually assess the areas at risk using up-to-date occurrence and climatic data in present-day and future conditions.

• MeSH
• Hemorrhagic Fever, Crimean * epidemiology   MeSH
• Ixodidae * MeSH
• Humans MeSH
• Tick-Borne Diseases * MeSH
• Hemorrhagic Fever Virus, Crimean-Congo * MeSH
• Animals MeSH
• Check Tag
• Humans MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Geographicals
• Europe epidemiology   MeSH

BACKGROUND: Ixodes ricinus is an important vector of several pathogens, primarily in Europe. Recently, Ixodes inopinatus was described from Spain, Portugal, and North Africa and then reported from several European countries. In this study, a multiplex polymerase chain reaction (PCR) was developed to distinguish I. ricinus from I. inopinatus and used in the surveillance of I. inopinatus in Algeria (ALG) and three regions in the Czech Republic (CZ). METHODS: A multiplex PCR on TROSPA and sequencing of several mitochondrial (16S rDNA, COI) and nuclear markers (TROSPA, ITS2, calreticulin) were used to differentiate these two species and for a subsequent phylogenetic analysis. RESULTS: Sequencing of TROSPA, COI, and ITS2 separated these two species into two subclades, while 16S rDNA and calreticulin could not distinguish I. ricinus from I. inopinatus. Interestingly, 23 nucleotide positions in the TROSPA gene had consistently double peaks in a subset of ticks from CZ. Cloning of these PCR products led to a clear separation of I. ricinus and I. inopinatus indicating hybridization and introgression between these two tick taxa. Based on a multiplex PCR of TROSPA and analysis of sequences of TROSPA, COI, and ITS2, the majority of ticks in CZ were I. ricinus, no I. inopinatus ticks were found, and 10 specimens showed signs of hybridization. In contrast, most ticks in ALG were I. inopinatus, four ticks were I. ricinus, and no signs of hybridization and introgression were detected. CONCLUSIONS: We developed a multiplex PCR method based on the TROSPA gene to differentiate I. ricinus and I. inopinatus. We demonstrate the lack of evidence for the presence of I. inopinatus in Central Europe and propose that previous studies be re-examined. Mitochondrial markers are not suitable for distinguishing I. inopinatus from I. ricinus. Furthermore, our data indicate that I. inopinatus and I. ricinus can hybridize, and the hybrids can survive in Europe.

• Keywords
• 16S rDNA, Algeria, COI, Czech Republic, ITS2, Ixodes inopinatus, Ixodes ricinus, TROSPA, Tick,
• MeSH
• Phylogeny MeSH
• Ixodes * MeSH
• Multiplex Polymerase Chain Reaction MeSH
• DNA, Ribosomal genetics   MeSH
• Animals MeSH
• Check Tag
• Animals MeSH
• Publication type
• Journal Article MeSH
• Geographicals
• Europe MeSH
• Names of Substances
• DNA, Ribosomal MeSH