Circulation Of Crimean-Congo Hemorrhagic Fever Virus Research Articles

Risk factors associated with Crimean-Congo hemorrhagic fever virus circulation among human, livestock and ticks in Mauritania through a one health retrospective study

BackgroundCrimean Congo hemorrhagic fever (CCHF) is endemic in Southern Mauritania where recurrent outbreaks have been constantly observed since the 1980’s. The present study is the first to assess CCHFV antibodies and RNA in humans.MethodsA retrospective study was conducted using 263 humans and 1380 domestic animals serum samples, and 282 tick specimens of Hyalomma genus collected from 54 settings in 12 provinces across Mauritania. Antibodies targeting CCHF viral nucleoprotein were detected in animal and human sera using double-antigen ELISA. CCHFV specific RNA was detected in human and animal sera as well as tick supernatants using a CCHFV real time RT-PCR kit. Individual characteristics of sampled hosts were collected at the same time and data were geo-referenced. Satellite data of several environmental and climatic factors, were downloaded from publicly available datasets, and combined with data on livestock mobility, animal and human density, road accessibility and individual characteristics to identify possible risk factors for CCHFV spatial distribution. To this end, multivariate logistic models were developed for each host category (human, small and large ruminants).ResultsThe overall CCHFV antibody prevalence was 11.8% [95% CI: 8.4–16.3] in humans (17.9% in 2020 and 5.4% in 2021; p = 0.0017) and 33.1% (95% CI: 30.1–36.3) in livestock. CCHFV-specific antibodies were detected in 91 (18.1%) out of 502 sheep, 43 (9.0%) out of 477 goats, 144 (90.5%) out of 161 dromedaries and 179 (74.6%) out of 240 cattle. CCHFV RNA was detected in only 2 (0.7%) sera out of 263 animals herders samples from Hodh El Gharbi province and in 32 (11.3%) out of 282 Hyalomma ticks. In humans as well as in animals, seropositivity was not associated with sex or age groups. The multivariate analysis determined the role of different environmental, climatic and anthropic factors in the spatial distribution of the disease with animal mobility and age being identified as risk factors.ConclusionResults of the present study demonstrate the potential risk of CCHF for human population in Mauritania primarily those living in rural areas in close vicinity with animals. Future studies should prioritize an integrative human and veterinary approach for better understanding and managing Crimean-Congo hemorrhagic fever.

Crimean-Congo hemorrhagic fever: a growing threat to Europe

Tick-borne infectious diseases are increasing, driven by geographic expansion of ticks. Crimean-Congo hemorrhagic fever virus (CCHFV) is a tick-borne virus of the family Nairoviridae that poses serious threat to public health. CCHFV can cause severe forms of hemorrhagic fever with high case fatality rates (CFR) (10-40%) and can be transmitted from human to human. Until a few years ago, no cases of CCHF had been reported in western Europe. However, high seropositivity rates in wildlife and detection of multiple strains of CCHFV in ticks in Spain suggest that CCHFV enzootic cycle has been established in some areas of southwestern Europe. As far as CCHFV-associated morbidity and mortality are concerned, there are no approved therapeutic options or US/EU licensed vaccines for treatment. Here we discuss some eco-epidemiological aspects as well as public health and socio-economic impacts associated with CCHFV circulation and outbreaks. We also emphasize that it has become essential to identify key inter-species transmission processes of this group of pathogens, to understand basic molecular mechanisms of their replication, and to define their pathogenic potentials.

Serological data suggest the spread of Crimean-Congo hemorrhagic fever virus in domestic animals in Kosovo - a short communication

Crimean-Congo hemorrhagic fever virus (CCHFV) is a tick-borne virus that causes silent infections of livestock animals and severe illness in humans. Circulation of CCHFV among animals within a geographic region can be detected by the presence of antibodies to the virus. In Kosovo, human cases have occurred most frequently in the Malisheve region, but have not been seen in Vushtrri. The study was carried out in 2018 in Malisheve and Vushtrri to determine the prevalence of antibodies to CCHFV in domestic animals in Malisheve and Vushtrri, and if there is evidence that the virus is becoming more widely distributed within Kosovo. Blood samples were collected from 385 animals (285 cattle, 87 sheep and 13 goats), from 33 locations and 58 farms in total. Sera were tested using enzymelinked immunosorbent assay (ELISA) for anti-CCHFV antibodies (IgM/IgG). The seroprevalence of antibodies in Malisheve was 24.7% (59 out of 239) (CI 19.65-30.52), while in Vushtrri the seroprevalence of antibodies was 4.8% (7 out of 146) (CI 2.34-9.57). This is the first record of seropositive livestock in the Vushtrri region, suggesting that the virus is spreading in Kosovo through the movement of infected animals. Public health and veterinary state institutions should therefore start an integrated surveillance program with a concept of “One Health”, to control and prevent the spread of the virus.

Ticks on the Run: A Mathematical Model of Crimean-Congo Haemorrhagic Fever (CCHF)-Key Factors for Transmission.

Crimean-Congo haemorrhagic fever (CCHF) is a zoonotic disease caused by the Crimean-Congo hemorrhagic fever virus (CCHFV). Ticks of the genus Hyalomma are the main vectors and represent a reservoir for the virus. CCHF is maintained in nature in an endemic vertebrate-tick-vertebrate cycle. The disease is prevalent in wide geographical areas including Asia, Africa, South-Eastern Europe and the Middle East. It is of great importance for the public health given its occasionally high case/fatality ratio of CCHFV in humans. Climate change and the detection of possible CCHFV vectors in Central Europe suggest that the establishment of the transmission in Central Europe may be possible in future. We have developed a compartment-based nonlinear Ordinary Differential Equation (ODE) system to model the disease transmission cycle including blood sucking ticks, livestock and human. Sensitivity analysis of the basic reproduction number R0 shows that decreasing the tick survival time is an efficient method to control the disease. The model supports us in understanding the influence of different model parameters on the spread of CCHFV. Tick-to-tick transmission through co-feeding and the CCHFV circulation through transstadial and transovarial transmission are important factors to sustain the disease cycle. The proposed model dynamics are calibrated through an empirical multi-country analysis and multidimensional plot reveals that the disease-parameter sets of different countries burdened with CCHF are different. This information may help decision makers to select efficient control strategies.

Detection of New Crimean-Congo Hemorrhagic Fever Virus Genotypes in Ticks Feeding on Deer and Wild Boar, Spain

Background: Crimean-Congo hemorrhagic fever virus (CCHFV) is the causative agent of the severe tick-borne, which is widely distributed worldwide. The CCHFV transmission to humans occurs through tick bite, crushing of engorged ticks, or contact with infected host blood. Previously, CCHFV genotype Africa III was reported in Spain. Methods: A total of 613 ticks, including Hyalomma lusitanicum and Dermacentor marginatus, were collected from hunter-harvested wild ungulates in twenty locations throughout southwestern Spain. Tick RNA was analyzed by a nested RT-PCR targeting CCHFV S segment and the amplicons were sequenced. Findings: The study reports the presence of CCHFV human genotype Europe V in both tick species collected from red deer (Cervus elaphus), fallow deer (Dama dama), and Eurasian wild boar (Sus scrofa). Viral RNA was detected in 129 of the analyzed ticks. Most of the CCHFV S segment sequences showed 99-100% identity to reported sequences of human isolates from Russia and Iran belonging to genotype Europe V. Interpretation: The detection of CCHFV in different tick species collected from various wild host species and localities provided strong evidence of widespread CCHFV presence in the region, suggesting that CCHFV circulation in Spain requires more attention. Additionally, the identification of the CCHFV genotype Europe V in ticks suggested that its introduction in Spain was probably from Eastern Europe. Funding: This study was partially supported by MINECO Plan Nacional grant CGL2017-89866-R and EU-FEDER. Declaration of Interest: The authors declare no commercial or financial conflict of interest. Ethical Approval: Tick sampling were collected according to hunting disease surveillance schemes and in the framework of Spanish and EU laws for notifiable disease surveillance. Therefore, no Animal Ethics Committee approval was required for the collection of ticks from hunter harvested wild ungulates.

Evidence of Crimean-Congo Haemorrhagic Fever Virus Occurrence in Ixodi¬dae Ticks of Armenia

Crimean-Congo hemorrhagic fever (CCHF) causes serious health problems in humans. Though ticks of the genera Hyalomma play a significant role in the CCHF virus transmission it was also found in 31 other tick species. Totally, 1412 ticks from 8 remote sites in Armenia during 2016 were sampled, pooled (3-5 ticks per pool) and tested for the presence of CCHFV antigen using ELISA test. From 359 tick pools, 132 were CCHF virus antigen-positive. From 6 tick species, four species (Rhipicephalus sanguineus, R. annulatus, R. bursa, Hyalomma marginatum) were positive for the virus antigen and R. sanguineus was the most prevalent (37.9%). Dermacentor marginatus and Ixodes ricinus revealed no positive pools, but both revealed delectable but very low virus antigen titers. The highest infection rate (50%) was observed in R. sanguineus, whereas H. marginatus rate of infection was 1 out of 17 pools. For the first time in the last four decades CCHF virus antigen was detected in Ixodid ticks of Armenia. This finding substantiates the role of R. sanguineus in the disease epidemiology; however, the role of H. marginatum in the CCHF virus circulation in the country could not be excluded.

Molecular detection of Crimean-Congo hemorrhagic fever virus in ticks, Greece, 2012-2014.

Crimean-Congo hemorrhagic fever virus (CCHFV) is transmitted to humans mainly through the bite of infected ticks. In Greece, only one clinical case has been observed, in 2008, but the seroprevalence in humans is relatively high (4.2%). To have a first insight into the circulation of CCHFV in Greece, 2000 ticks collected from livestock during 2012-2014 were tested. CCHFV was detected in 36 of the 1290 (2.8%) tick pools (1-5 ticks per pool). Two genetic lineages were identified: Europe 1 and Europe 2. Most Europe 1 sequences were obtained from Rhipicephalus sanguineus sensu lato ticks, while most Europe 2 sequences were recovered from Rhipicephalus bursa ticks. The number of collected Hyalomma marginatum ticks (the principal vector of CCHFV) was low (0.5% of ticks) and all were CCHFV negative. Since it is not known how efficient ticks of the Rhipicephalus genus are as vectors of the virus, laboratory studies will be required to explore the role of Rhipicephalus spp. ticks in CCHFV maintenance and transmission.

Country-wide seroprevalence studies on Crimean-Congo hemorrhagic fever and hantavirus infections in general population of Bulgaria.

Crimean-Congo hemorrhagic fever (CCHF) and hantavirus infections are the two viral hemorrhagic fevers spread in Europe. To test actual circulation of CCHF virus (CCHFV) and hantaviruses in Bulgaria, we conducted country-wide seroepidemiological studies. Serum samples were collected prospectively from 1500 residents of all 28 districts in Bulgaria. CCHFV seroprevalence of 3.7% was revealed. Anamnesis for tick bites, contact with livestock, age over 40 years and residency in Haskovo district were found as risk factors. The highest CCHFV seroprevalence was observed in the known endemic districts in southeastern Bulgaria: Haskovo (28%) and Yambol (12%). Reactive samples were found in residents of 20 of the 28 districts in Bulgaria. In comparison with the previous studies, the data presented indicate that CCHFV increased substantially its circulation in the endemic regions and was introduced in many new areas. Hantavirus seroprevalence was based on results of the immunoblot and estimated as 3.1%. Surprisingly, contrary to all available data, Puumala virus seroprevalence rate was 2.3% versus 0.8% of Dobrava-Belgrade virus. Evidence for hantavirus IgG seropositivity was found in residents of 23 of the 28 districts in the country. The first hantavirus seroprevalence study in Bulgaria showed that Puumala virus is probably more wide-spread in the country than Dobrava-Belgrade virus.