Recent advances in understanding Crimean-Congo hemorrhagic fever virus

Recent Advances in Crimean-Congo Hemorrhagic Fever Virus Detection, Treatment, and Vaccination: Overview of Current Status and Challenges

Crimean-Congo hemorrhagic fever virus (CCHFV) is a tick-borne virus, and zoonosis, and affects large regions of Asia, Southwestern and Southeastern Europe, and Africa. CCHFV can produce symptoms, including no specific clinical symptoms, mild to severe clinical symptoms, or deadly infections. Virus isolation attempts, antigen-capture enzyme-linked immunosorbent assay (ELISA), and reverse transcription polymerase chain reaction (RT-PCR) are all possible diagnostic tests for CCHFV. Furthermore, an efficient, quick, and cheap technology, including biosensors, must be designed and developed to detect CCHFV. The goal of this article is to offer an overview of modern laboratory tests available as well as other innovative detection methods such as biosensors for CCHFV, as well as the benefits and limits of the assays. Furthermore, confirmed cases of CCHF are managed with symptomatic assistance and general supportive care. This study examined the various treatment modalities, as well as their respective limitations and developments, including immunotherapy and antivirals. Recent biotechnology advancements and the availability of suitable animal models have accelerated the development of CCHF vaccines by a substantial margin. We examined a range of potential vaccines for CCHF in this research, comprising nucleic acid, viral particles, inactivated, and multi-epitope vaccines, as well as the present obstacles and developments in this field. Thus, the purpose of this review is to present a comprehensive summary of the endeavors dedicated to advancing various diagnostic, therapeutic, and preventive strategies for CCHF infection in anticipation of forthcoming hazards.

A Review on Crimean-Congo Hemorrhagic Fever Infections in Tunisia

Crimean-Congo hemorrhagic fever (CCHF) is a zoonotic tick-borne disease, caused by an arbovirus of the genus Orthonairovirus and the family Nairoviridae. Crimean-Congo hemorrhagic fever virus (CCHFV) is widespread in several regions of the world. While the virus is not pathogenic to all susceptible livestock and wild mammals, it can lead to severe hemorrhagic fever in humans. In this review, we compiled published data on CCHFV infections in humans, animals, and ticks in Tunisia. Based on that, we discussed the epidemiology and the distribution patterns of CCHFV infections highlighting the risk factors for this virus in the country. CCHF infection prevalence in humans was estimated to 2.76% (5/181) and 5% (2/38) in Tunisian febrile patients and Tunisian slaughterhouse workers, respectively. Concurrently, seroprevalence in domestic ungulates (sheep, goats, cattle, and dromedaries) ranged from zero to 89.7%, and only one Hyalomma impeltatum tick specimen collected from dromedaries in southern Tunisian was positive for CCHFV by reverse transcriptase-polymerase chain reaction (0.6%; 1/165). As Tunisian studies on CCHFV are geographically scattered and limited due to very small sample sizes, further studies are needed to improve the knowledge on the epidemiology of CCHF in Tunisia.

Approaching the complexity of Crimean-Congo hemorrhagic fever virus serology: A study in swine

Crimean-Congo hemorrhagic fever virus (CCHFV) is a tick-borne zoonotic orthonairovirus of public health concern and widespread geographic distribution. Several animal species are known to seroconvert after infection with CCHFV without showing clinical symptoms. The commercial availability of a multi-species ELISA has led to an increase in recent serosurveillance studies as well as in the range of species reported to be exposed to CCHFV in the field, including wild boar (Sus scrofa). However, development and validation of confirmatory serological tests for swine based on different CCHFV antigens or test principles are hampered by the lack of defined control sera from infected and non-infected animals. For the detection of anti-CCHFV antibodies in swine, we established a swine-specific in-house ELISA using a panel of swine sera from CCHFV-free regions and regions with reported CCHFV circulation. We initially screened more than 700 serum samples from wild boar and domestic pigs and observed a correlation of ≃67% between the commercial and the in-house test. From these sera, we selected a panel of 60 samples that were further analyzed in a newly established indirect immunofluorescence assay (iIFA) and virus neutralization test. ELISA-non-reactive samples tested negative. Interestingly, only a subset of samples reactive in both ELISA and iIFA displayed CCHFV-neutralizing antibodies. The observed partial discrepancy between the tests may be explained by different test sensitivities, antibody cross-reactivities or suggests that the immune response to CCHFV in swine is not necessarily associated with eliciting neutralizing antibodies. Overall, this study highlights that meaningful CCHFV serology in swine, and possibly other species, should involve the performance of multiple tests and careful interpretation of the results.

Epidemiologic Survey of Crimean-Congo Hemorrhagic Fever Virus in Suids, Spain

We conducted a cross-sectional study in wild boar and extensively managed Iberian pig populations in a hotspot area of Crimean-Congo hemorrhagic fever virus (CCHFV) in Spain. We tested for antibodies against CCHFV by using 2 ELISAs in parallel. We assessed the presence of CCHFV RNA by means of reverse transcription quantitative PCR protocol, which detects all genotypes. A total of 113 (21.8%) of 518 suids sampled showed antibodies against CCHFV by ELISA. By species, 106 (39.7%) of 267 wild boars and 7 (2.8%) of 251 Iberian pigs analyzed were seropositive. Of the 231 Iberian pigs and 231 wild boars analyzed, none tested positive for CCHFV RNA. These findings indicate high CCHFV exposure in wild boar populations in endemic areas and confirm the susceptibility of extensively reared pigs to CCHFV, even though they may only play a limited role in the enzootic cycle.

Crimean Congo Hemorrhagic Fever Virus for Clinicians-Virology, Pathogenesis, and Pathology

Crimean-Congo hemorrhagic fever (CCHF), caused by CCHF virus, is a tickborne disease that can cause a range of illness outcomes, from asymptomatic infection to fatal viral hemorrhagic fever; the disease has been described in >30 countries. We conducted a literature review to provide an overview of the virology, pathogenesis, and pathology of CCHF for clinicians. The virus life cycle and molecular interactions are complex and not fully described. Although pathogenesis and immunobiology are not yet fully understood, it is clear that multiple processes contribute to viral entry, replication, and pathological damage. Limited autopsy reports describe multiorgan involvement with extravasation and hemorrhages. Advanced understanding of CCHF virus pathogenesis and immunology will improve patient care and accelerate the development of medical countermeasures for CCHF.

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.

Crimean-Congo Hemorrhagic Fever Virus for Clinicians-Diagnosis, Clinical Management, and Therapeutics

Crimean-Congo hemorrhagic fever virus (CCHFV) is the most geographically widespread tickborne viral infection worldwide and has a fatality rate of up to 62%. Despite its widespread range and high fatality rate, no vaccines or treatments are currently approved by regulatory agencies in the United States or Europe. Supportive treatment remains the standard of care, but the use of antiviral medications developed for other viral infections have been considered. We reviewed published literature to summarize the main aspects of CCHFV infection in humans. We provide an overview of diagnostic testing and management and medical countermeasures, including investigational vaccines and limited therapeutics. CCHFV continues to pose a public health threat because of its wide geographic distribution, potential to spread to new regions, propensity for genetic variability, potential for severe and fatal illness, and limited medical countermeasures for prophylaxis and treatment. Clinicians should become familiar with available diagnostic and management tools for CCHFV infections in humans.

Crimean-Congo Hemorrhagic Fever Virus Diversity and Reassortment, Pakistan, 2017-2020

Sporadic cases and outbreaks of Crimean-Congo hemorrhagic fever (CCHF) have been documented across Pakistan since 1976; however, data regarding the diversity of CCHF virus (CCHFV) in Pakistan is sparse. We whole-genome sequenced 36 CCHFV samples collected from persons infected in Pakistan during 2017-2020. Most CCHF cases were from Rawalpindi (n = 10), followed by Peshawar (n = 7) and Islamabad (n = 4). Phylogenetic analysis revealed the Asia-1 genotype was dominant, but 4 reassorted strains were identified. Strains with reassorted medium gene segments clustered with Asia-2 (n = 2) and Africa-2 (n = 1) genotypes; small segment reassortments clustered with the Asia-2 genotype (n = 2). Reassorted viruses showed close identity with isolates from India, Iran, and Tajikistan, suggesting potential crossborder movement of CCHFV. Improved and continuous human, tick, and animal surveillance is needed to define the diversity of circulating CCHFV strains in Pakistan and prevent transmission.

The impact of volatiles on tick-host interaction and vector competence

Ticks are obligatory hematophagous arachnids, serving as vectors for a wide array of pathogens that can be transmitted to humans or animals. The ability of tick-borne pathogens to maintain within natural reservoirs is intricately influenced by the attractiveness of ticks to their animal hosts, including humans. However, the complex dynamics of tick behavior and host-seeking strategies remain understudied. This review aims to summarize the impact of volatiles or odors on tick behavior and vector competence. Our literature review has identified a selection of compounds, such as 1-octen-3-ol, hexanal, heptanal, nonanal, 6-methyl-5-hepten-2-one, acetone, and octanal, as having the potential to impact both ticks' and mosquitos' behaviors. In addition, carbon dioxide (CO2) is a universal attractant for hematophagous arthropods. Moreover, we have gathered some clues indicating that volatiles emitted by infected animal hosts might play a role in the transmission of tick-borne pathogens. Nonetheless, our understanding of this phenomenon remains largely inadequate, particularly with regarding to whether the tick microbiome or the skin microbiota of the feeding mammals, including humans, can actively modulate tick-host-seeking behavior. Further investigations in this emerging field hold immense promise for the development of innovative strategies aimed at controlling vectors and curtailing the spread of tick-borne diseases.

Single dose, dual antigen RNA vaccines protect against lethal Crimean-Congo haemorrhagic fever virus infection in mice

BACKGROUND

Crimean-Congo Haemorrhagic Fever Virus is a tick-borne bunyavirus prevalent across Asia, Africa, the Middle East, and Europe. The virus causes a non-specific febrile illness which may develop into severe haemorrhagic disease. To date, there are no widely approved therapeutics. Recently, we reported an alphavirus-based replicon RNA vaccine which expresses the CCHFV nucleoprotein (repNP) or glycoprotein precursor (repGPC) and is protective against lethal disease in mice.

METHODS

Here, we evaluated engineered GPC constructs to find the minimal enhancing epitope of repGPC and test two RNA vaccine approaches to express multiple antigens in vivo to optimize protective efficacy of our repRNA.

FINDINGS

Vaccination with repNP and a construct expressing just the Gc antigen (repGc-FL) resulted in equivalent immunogenicity and protective efficacy compared to original repNP + repGPC vaccination. This vaccine was protective when prepared in either of two vaccine approaches, a mixed synthesis reaction producing two RNAs in a single tube and a single RNA expressing two antigens.

INTERPRETATION

Overall, our data illustrate two vaccine approaches to deliver two antigens in a single immunization. Both approaches induced protective immune responses against CCHFV in this model. These approaches support their continued development for this and future vaccine candidates for CCHFV and other vaccines where inclusion of multiple antigens would be optimal.

FUNDING

This work was supported by the Intramural Research Program, NIAID/NIH, HDT Bio and MCDC Grant #MCDC2204-011.

LDLR is an entry receptor for Crimean-Congo hemorrhagic fever virus

Crimean-Congo hemorrhagic fever virus (CCHFV) is the most widespread tick-born zoonotic bunyavirus that causes severe hemorrhagic fever and death in humans. CCHFV enters the cell via clathrin-mediated endocytosis which is dependent on its surface glycoproteins. However, the cellular receptors that are required for CCHFV entry are unknown. Here we show that the low density lipoprotein receptor (LDLR) is an entry receptor for CCHFV. Genetic knockout of LDLR impairs viral infection in various CCHFV-susceptible human, monkey and mouse cells, which is restored upon reconstitution with ectopically-expressed LDLR. Mutagenesis studies indicate that the ligand binding domain (LBD) of LDLR is necessary for CCHFV infection. LDLR binds directly to CCHFV glycoprotein Gc with high affinity, which supports virus attachment and internalization into host cells. Consistently, a soluble sLDLR-Fc fusion protein or anti-LDLR blocking antibodies impair CCHFV infection into various susceptible cells. Furthermore, genetic knockout of LDLR or administration of an LDLR blocking antibody significantly reduces viral loads, pathological effects and death following CCHFV infection in mice. Our findings suggest that LDLR is an entry receptor for CCHFV and pharmacological targeting of LDLR may provide a strategy to prevent and treat Crimean-Congo hemorrhagic fever.

Medically Significant Vector-Borne Viral Diseases in Iran

Vector-borne viral diseases (VBVDs) continue to pose a considerable public health risk to animals and humans globally. Vectors have integral roles in autochthonous circulation and dissemination of VBVDs worldwide. The interplay of agricultural activities, population expansion, urbanization, host/pathogen evolution, and climate change, all contribute to the continual flux in shaping the epidemiology of VBVDs. In recent decades, VBVDs, once endemic to particular countries, have expanded into new regions such as Iran and its neighbors, increasing the risk of outbreaks and other public health concerns. Both Iran and its neighboring countries are known to host a number of VBVDs that are endemic to these countries or newly circulating. The proximity of Iran to countries hosting regional diseases, along with increased global socioeconomic activities, e.g., international trade and travel, potentially increases the risk for introduction of new VBVDs into Iran. In this review, we examined the epidemiology of numerous VBVDs circulating in Iran, such as Chikungunya virus, Dengue virus, Sindbis virus, West Nile virus, Crimean-Congo hemorrhagic fever virus, Sandfly-borne phleboviruses, and Hantavirus, in relation to their vectors, specifically mosquitoes, ticks, sandflies, and rodents. In addition, we discussed the interplay of factors, e.g., urbanization and climate change on VBVD dissemination patterns and the consequent public health risks in Iran, highlighting the importance of a One Health approach to further surveil and to evolve mitigation strategies.

Favipiravir and Ribavirin protect immunocompetent mice from lethal CCHFV infection

Crimean-Congo hemorrhagic fever virus (CCHFV) causes Crimean-Congo hemorrhagic fever (CCHF) in humans with high morbidity and mortality. Currently, there is neither an approved antiviral drug nor a vaccine against CCHFV. In this study, we describe a lethal model of CCHFV infection using a mouse-adapted strain of CCHFV (MA-CCHFV) in adult wild-type male mice. Infected mice developed high viral loads, tissue pathology, and inflammatory immune responses before ultimately succumbing to the infection. We used the model to evaluate the protective efficacy of nucleoside analogs monulpiravir, favipiravir, ribavirin, the antibiotic tigecycline and the corticosteroids dexamethasone and methylprednisolone against lethal CCHFV infection. Tigecycline, monulpiravir and the corticosteroids failed to protect mice from lethal MA-CCHFV infection. In contrast, favipiravir and ribavirin protected animals from clinical disease and death even when treatment was delayed. Despite demonstrating uniform protection, CCHFV RNA persisted in survivors treated with favipiravir and ribavirin. Nevertheless, the study demonstrated the anti-CCHFV efficacy of favipiravir and ribavirin in a model with intact innate immunity and establishes this model for continued development of CCHFV countermeasures.

Emerging Pathogenic Viral Infections of the Eye

Global health security threats and the public health impact resulting from emerging infectious diseases including the ongoing COVID-19 pandemic and recent Ebola virus disease outbreaks continuously emphasize the need for a comprehensive approach to preparedness, management of disease outbreaks, and health sequelae associated with emergent pathogens. A spectrum of associated ophthalmic manifestations, along with the potential persistence of emerging viral pathogens in ocular tissues, highlight the importance of an ophthalmic approach to contributing to efforts in the response to public health emergencies from disease outbreaks. This article summarizes the ophthalmic and systemic findings, epidemiology, and therapeutics for emerging viral pathogens identified by the World Health Organization as high-priority pathogens with epidemic potential.

Evaluation of the immunogenicity of a Crimean-Congo hemorrhagic fever virus vaccine candidate in mice developed based on a baculovirus Zera nanoparticle delivery system

Crimean-Congo hemorrhagic fever (CCHF) is a zoonotic disease caused by Crimean-Congo hemorrhagic fever virus (CCHFV), which can cause severe clinical disease and even death in humans. In recent years, the disease has spread to a wider area, posing a major public health threat to China as well as the Middle East, Europe and Africa, and there is no safe and effective vaccine to prevent the disease. Recently, it has been shown that using the Zera fusion to target proteins can enhance immunogenicity and improve the potential for developing viral vaccines. Based on this finding, in this study, two vaccine candidates, Zera-Gn and Zera-Np, were prepared using an insect baculovirus system expressing CCHFV glycoprotein (Gn) and nucleocapsid protein (Np) fused with Zera tags, and evaluated for immunogenicity in BALB/c mice. The obtainedresults showed that both Zera-Gn and Zera-Np recombinant nanoparticles were successfully expressed, and Zera-Gn had good induction of humoral and cellular immunity in mice, and its immunogenicity was significantly higher than that of Zera-Np. The results indicated that Zera-Gn self-assembled nanoparticles prepared by fusing Zera tags with CCHFV spike-in protein Gn have the potential to be a candidate vaccine for CCHF, and this study provides a reference for the development of Zera self-assembled nanoparticle vaccine for CCHF.

Latest Advances in Arbovirus Diagnostics

Arboviruses are a diverse family of vector-borne pathogens that include members of the Flaviviridae, Togaviridae, Phenuviridae, Peribunyaviridae, Reoviridae, Asfarviridae, Rhabdoviridae, Orthomyxoviridae and Poxviridae families. It is thought that new world arboviruses such as yellow fever virus emerged in the 16th century due to the slave trade from Africa to America. Severe disease-causing viruses in humans include Japanese encephalitis virus (JEV), yellow fever virus (YFV), dengue virus (DENV), West Nile virus (WNV), Zika virus (ZIKV), Crimean-Congo hemorrhagic fever virus (CCHFV), severe fever with thrombocytopenia syndrome virus (SFTSV) and Rift Valley fever virus (RVFV). Numerous methods have been developed to detect the presence of these pathogens in clinical samples, including enzyme-linked immunosorbent assays (ELISAs), lateral flow assays (LFAs) and reverse transcriptase-polymerase chain reaction (RT-PCR). Most of these assays are performed in centralized laboratories due to the need for specialized equipment, such as PCR thermal cyclers and dedicated infrastructure. More recently, molecular methods have been developed which can be performed at a constant temperature, termed isothermal amplification, negating the need for expensive thermal cycling equipment. In most cases, isothermal amplification can now be carried out in as little as 5-20 min. These methods can potentially be used as inexpensive point of care (POC) tests and in-field deployable applications, thus decentralizing the molecular diagnosis of arboviral disease. This review focuses on the latest developments in isothermal amplification technology and detection techniques that have been applied to arboviral diagnostics and highlights future applications of these new technologies.

Transcriptome profiling highlights regulated biological processes and type III interferon antiviral responses upon Crimean-Congo hemorrhagic fever virus infection

Crimean-Congo hemorrhagic fever virus (CCHFV) is a biosafety level-4 (BSL-4) pathogen that causes Crimean-Congo hemorrhagic fever (CCHF) characterized by hemorrhagic manifestation, multiple organ failure and high mortality rate, posing great threat to public health. Despite the recently increasing research efforts on CCHFV, host cell responses associated with CCHFV infection remain to be further characterized. Here, to better understand the cellular response to CCHFV infection, we performed a transcriptomic analysis in human kidney HEK293 ​cells by high-throughput RNA sequencing (RNA-seq) technology. In total, 496 differentially expressed genes (DEGs), including 361 up-regulated and 135 down-regulated genes, were identified in CCHFV-infected cells. These regulated genes were mainly involved in host processes including defense response to virus, response to stress, regulation of viral process, immune response, metabolism, stimulus, apoptosis and protein catabolic process. Therein, a significant up-regulation of type III interferon (IFN) signaling pathway as well as endoplasmic reticulum (ER) stress response was especially remarkable. Subsequently, representative DEGs from these processes were well validated by RT-qPCR, confirming the RNA-seq results and the typical regulation of IFN responses and ER stress by CCHFV. Furthermore, we demonstrate that not only type I but also type III IFNs (even at low dosages) have substantial anti-CCHFV activities. Collectively, the data may provide new and comprehensive insights into the virus-host interactions and particularly highlights the potential role of type III IFNs in restricting CCHFV, which may help inform further mechanistic delineation of the viral infection and development of anti-CCHFV strategies.

Evaluation of Nucleoprotein-Based Enzyme-Linked Immunosorbent Assay for Serodiagnosis of Acute Crimean-Congo Hemorrhagic Fever Virus Infections in a Turkish Population

Background: Crimean-Congo hemorrhagic fever virus (CCHFV) causes a highly contagious tick-borne disease with high case-fatality rates in humans. It is circulating not only in many Asian and African countries, but also spreading to and within Europe. To cope better with future outbreaks of Crimean-Congo hemorrhagic fever (CCHF), the WHO has prioritized the need for the development and validation of CCHF diagnostics, including serological assays. In this study, we evaluated the performance of the new EUROIMMUN anti-CCHFV IgM and IgG enzyme-linked immunosorbent assays (ELISAs). Materials and Methods: Both ELISAs were compared to the Vector-Best VectoCrimean-CHF-IgM and -IgG ELISAs using the EUROIMMUN CCHFV Mosaic 2 IgM and IgG indirect immunofluorescence assays (IFA) as reference. Forty-nine acute-phase serum samples from patients with CCHFV infection confirmed by reverse transcription-polymerase chain reaction (RT-PCR) and/or anti-CCHFV IgM IFA positivity were used to determine assay sensitivity. The assessment of specificity was based on sera from 30 control patients, 30 healthy blood donors, and 29 patients with hantavirus or sandfly fever virus infections. All samples originated from Turkey. Results: Sensitivity of the EUROIMMUN ELISAs (IgM 98.0%, IgG 47.1%) exceeded that of the Vector-Best ELISAs (IgM 95.9%, IgG 35.3%). Specificity of the EUROIMMUN ELISA IgM (86.4%) was slightly higher compared with the Vector-Best ELISA IgM (84.7%), while specificity for IgG was 100% for both assays. Qualitative agreement between the EUROIMMUN and Vector-Best ELISAs was substantial for detecting anti-CCHFV IgM (84.1%, ĸ = 0.673) and IgG (94.9%, ĸ = 0.791), whereas the quantitative results indicated a very strong positive correlation (IgM: r = 0.868, IgG: r = 0.913). Conclusion: The new EUROIMMUN anti-CCHFV ELISAs are standardized and easy-to-use tools that reliably support the identification of acute CCHF cases, and thus suitable for laboratories involved in on-site outbreak support.

First serological evidence of Crimean-Congo haemorrhagic fever virus in transhumant bovines in Italy

Crimean-Congo haemorrhagic fever (CCHF) is an emerging tick-borne disease caused by the arbovirus Crimean-Congo haemorrhagic fever virus (CCHFV; family Nairoviridae). Given the public health impact, CCHF is considered a priority disease for the European Union. This study describes the first detection of anti-CCHFV antibodies in transhumant bovines in Italy. Sera from 794 cattle collected across Basilicata region (Southern Italy) were screened using a commercial ELISA kit. The animal-level and herd-level seroprevalences detected were 1.89% [95%CI: 1.12-3.1] and 29.63% [95%CI: 15.68-48.65], respectively. Results of the χ² test for trend show that the exposure to CCHFV was significantly associated with increasing age, with the odds 5 times higher in 11-22-year old cattle than 1-4-year old cattle. The detection of antibodies against CCHFV in indigenous cattle indicates that the infection occurred in the study area and may warrant further consideration. Additionally, no significant spatial clustering of CCHF infection was detected, supporting the hypothesis that the disease is widespread in the region. Further studies at larger scale are needed to identify the areas at higher risk of zoonotic infection. A One Health approach should be implemented to better understand the disease risk and dynamics in the country, which effectively address the related public health threat.

Widespread exposure to Crimean-Congo haemorrhagic fever in Uganda might be driven by transmission from Rhipicephalus ticks: Evidence from cross-sectional and modelling studies

BACKGROUND

Crimean-Congo haemorrhagic fever (CCHF) is a widespread tick-borne viral infection, present across Africa and Eurasia, which might pose a cryptic public health problem in Uganda. We aimed to understand the magnitude and distribution of CCHF risk in humans, livestock and ticks across Uganda by synthesising epidemiological (cross-sectional) and ecological (modelling) studies.

METHODS

We conducted a cross-sectional study at three urban abattoirs receiving cattle from across Uganda. We sampled humans (n = 478), livestock (n = 419) and ticks (n = 1065) and used commercially-available kits to detect human and livestock CCHF virus (CCHFV) antibodies and antigen in tick pools. We developed boosted regression tree models to evaluate the correlates and geographical distribution of expected tick and wildlife hosts, and of human CCHF exposures, drawing on continent-wide data.

FINDINGS

The cross-sectional study found CCHFV IgG/IgM seroprevalence in humans of 10·3% (7·8-13·3), with antibody detection positively associated with reported history of tick bite (age-adjusted odds ratio = 2·09 (1·09-3·98)). Cattle had a seroprevalence of 69·7% (65·1-73·4). Only one Hyalomma tick (CCHFV-negative) was found. However, CCHFV antigen was detected in Rhipicephalus (5·9% of 304 pools) and Amblyomma (2·9% of 34 pools) species. Modelling predicted high human CCHF risk across much of Uganda, low environmental suitability for Hyalomma, and high suitability for Rhipicephalus and Amblyomma.

INTERPRETATION

Our epidemiological and ecological studies provide complementary evidence that CCHF exposure risk is widespread across Uganda. We challenge the idea that Hyalomma ticks are consistently the principal reservoir and vector for CCHFV, and postulate that Rhipicephalus might be important for CCHFV transmission in Uganda, due to high frequency of infected ticks and predicted environmental suitability.

FUNDING

UCL Global Challenges Research Fund (GCRF) and Pan-African Network on Emerging and Re-Emerging Infections (PANDORA-ID-NET) funded by the European and Developing Countries Clinical Trials Partnership (EDCTP) under the EU Horizon 2020 Framework Programme for Research and Innovation.

Replicating RNA vaccination elicits an unexpected immune response that efficiently protects mice against lethal Crimean-Congo hemorrhagic fever virus challenge

Background

Crimean-Congo hemorrhagic fever virus is the cause of a severe hemorrhagic fever with cases reported throughout a wide-geographic region. Spread by the bite of infected ticks, contact with infected livestock or in the health care setting, disease begins as a non-specific febrile illness that can rapidly progress to hemorrhagic manifestations. Currently, there are no approved vaccines and antivirals such as ribavirin have unclear efficacy. Thus treatment is mostly limited to supportive care.

Methods

In this report we evaluated an alphavirus-based replicon RNA vaccine expressing either the CCHFV nucleoprotein or glycoprotein precursor in a stringent, heterologous lethal challenge mouse model.

Findings

Vaccination with the RNA expressing the nucleoprotein alone could confer complete protection against clinical disease, but vaccination with a combination of both the nucleoprotein and glycoprotein precursor afforded robust protection against disease and viral replication. Protection from lethal challenge required as little as a single immunization with 100ng of RNA. Unexpectedly, analysis of the immune responses elicited by the vaccine components showed that vaccination resulted in antibodies against the internal viral nucleoprotein and cellular immunity against the virion-exposed glycoproteins.

Interpretation

Cumulatively this vaccine conferred robust protection against Crimean-Congo hemorrhagic fever virus and supports continued development of this vaccine candidate.

Funding

This research was supported by the Intramural Research Program of the NIAID/NIH and HDT Bio.

The Prevalence and Genetic Variants of the CCHF Virus Circulating among Ticks in the Southern Regions of Kazakhstan

Crimean–Congo hemorrhagic fever (CCHF) disease cases are registered annually in endemic regions of Kazakhstan. To study the prevalence of various Crimean–Congo hemorrhagic fever virus (CCHFV) genotypes, a total of 694 ticks were collected from southern regions of Kazakhstan in 2021. Hyalomma marginatum (n = 323) (46.5%), Hyalomma anatolicum (n = 138) (19.9%), Hyalomma asiaticum (n = 126) (18.2%), Hyalomma scupense (n = 80) (11.5%) and Ixodes ricinus (n = 27) (3.9%) were collected using the standardized flagging technique from the environment. All the tick samples were analyzed for the presence of CCHFV RNA by RT-PCR. The CCHF-positive samples were found within three Hyalomma asiaticum and one Ixodes ricinus tick sample. For the first time in Kazakhstan, infection of the Ixodes ricinus tick with CCHFV was detected. The results of sequencing and analysis of the S-gene fragment showed that the Asia 1 and Asia 2 CCHF genotypes circulate in the southern regions of Kazakhstan. Viruses isolated in the Zhambyl and Turkestan regions are assigned to the Asia-2 genotype, whereas the virus isolated in the Kyzylorda region to the Asia-1 genotype.

Crimean-Congo hemorrhagic fever virus circulating among sheep of Portugal: a nationwide serosurvey assessment

Crimean-Congo hemorrhagic fever virus (CCHFV) is a widespread zoonotic pathogen that can cause mild to severe hemorrhagic disease in humans. CCHFV may be transmitted through direct contact with tissue or blood of viremic animals; however, the primary transmission route is through infected tick bites. CCHFV RNA has been detected in ticks feeding on domestic and wild animals in western Spain, suggesting an established circulation of CCHFV in Western Europe. Ruminants have been recognized as important CCHFV reservoirs and have been linked to human cases in endemic regions. Given the emergence of CCHF in neighboring Spain, and a report of two CCHFV seropositive humans in southern Portugal in 1985, we investigated the potential circulation of this virus in the country by performing a nationwide anti-CCHFV IgG serosurvey in sentinel sheep of Portugal. Sera (n = 459) randomly selected from widely distributed farms (n = 20) of Portugal were tested using a commercial double-antigen enzyme-linked immunosorbent assay, yielding an overall seroprevalence of 0.4% (95% confidence interval [CI] 0.04-1.56%). Positive sheep were from the southern region of Portugal (Alentejo region), which raise the seroprevalence of this region to 0.74% (95% CI 0.09-2.66%). This is the first study reporting the presence of CCHFV antibodies in sheep of Portugal, thus suggesting a geographical expansion of CCHFV to this country. It seems likely that CCHFV may exist focally in southern Portugal.

Molecular docking and dynamics simulation analysis of nucleoprotein from the Crimea-Congo hemorrhagic fever virus strain Baghdad-12 with FDA approved drugs

Crimea-Congo hemorrhagic fever virus is considered a potential public health threat due to the high case fatality ratio of the disease hemorrhagic phase and absence of approved vaccines or antiviral agents. Therefore, it is of interest to screen FDA approved drugs against the nucleoprotein crystal of Crimea-Congo hemorrhagic fever virus strain Baghdad-12 by using molecular docking and dynamics simulation. Hence, we report that the beta receptor blocker Nebivolol and the antihistamine Loratadine may bind to RNA binding region on nucleoprotein for further consideration in drug design and development.

In silico design and analyses of a multi-epitope vaccine against Crimean-Congo hemorrhagic fever virus through reverse vaccinology and immunoinformatics approaches

Crimean Congo Hemorrhagic Fever virus (CCHFV) is a deadly human pathogen that causes an emerging zoonotic disease with a broad geographic spread, especially in Africa, Asia, and Europe, and the second most common viral hemorrhagic fever and widely transmitted tick-borne viral disease. Following infection, the patients are presented with a variety of clinical manifestations and a fatality rate of 40%. Despite the high fatality rate, there are unmet clinical interventions, as no antiviral drugs or vaccines for CCHF have been approved. Immunoinformatics pipeline and reverse vaccinology were used in this study to design a multi-epitope vaccine that may elicit a protective humoral and cellular immune response against Crimean-Congo hemorrhagic fever virus infection. Three essential virulent and antigenic proteins (S, M, and L) were used to predict seven CTL and 18 HTL epitopes that were non-allergenic, antigenic, IFN-γ inducing, and non-toxic. The epitopes were connected using linkers and 50S ribosomal protein L7/L12 was used as an adjuvant and raised a multi-epitope vaccine (MEV) that is 567 amino acids long. Molecular docking and simulation of the predicted 3D structure of the MEV with the toll-like (TLR2, TLR3, and TLR4) receptors and major histocompatibility complex (MCH-I and MCH-II) indicate high interactions and stability of the complexes, MM-GBSA free binding energy calculation revealed a favourable protein-protein complex. Maximum MEV expression was achieved with a CAI value of 0.98 through in silico cloning in the Drosophila melanogaster host. According to the immune simulation, IgG1, T-helper cells, T-cytotoxic cells, INF-γ, and IL-2 were predicted to be significantly elevated. These robust computational analyses demonstrated that the proposed MEV is effective in preventing CCHFV infections. However, it is still necessary to conduct both in vitro and in vivo experiments to validate the potential of the vaccine.

Current and Future Molecular Diagnostics of Tick-Borne Diseases in Cattle

Ticks and tick-borne diseases such as babesiosis, anaplasmosis, ehrlichiosis, Lyme disease, Crimean Congo hemorrhagic fever, and Rocky Mountain spotted fever pose a significant threat to animal and human health. Tick-borne diseases cause billions of dollars of losses to livestock farmers annually. These losses are partially attributed to the lack of sensitive, robust, cost effective and efficient diagnostic approaches that could detect the infectious pathogen at the early stages of illness. The modern nucleic acid-based multiplex diagnostic approaches have been developed in human medicine but are still absent in veterinary medicine. These powerful assays can screen 384 patient samples at one time, simultaneously detect numerous infectious pathogens in each test sample and provide the diagnostic answer in a few hours. Development, commercialization, and wide use of such high throughput multiplex molecular assays in the cattle tick-borne disease surveillance will help in early detection and control of infectious pathogens in the animal reservoir before community spread and spillover to humans. Such approaches in veterinary medicine will save animal life, prevent billions of dollars of economic loss to cattle herders and reduce unwanted stress to both human and animal health care systems. This literature review provides recent updates on molecular diagnostics of tick-borne pathogens and discusses the importance of modern nucleic acid high throughput multiplex diagnostic approaches in the prevention of tick-borne infection to livestock.

Ticks and prevalence of tick-borne pathogens from domestic animals in Ghana

Background

Ticks are important vectors of various pathogenic protozoa, bacteria and viruses that cause serious and life-threatening illnesses in humans and animals worldwide. Estimating tick-borne pathogen prevalence in tick populations is necessary to delineate how geographical differences, environmental variability and host factors influence pathogen prevalence and transmission. This study identified ticks and tick-borne pathogens in samples collected from June 2016 to December 2017 at seven sites within the Coastal, Sudan and Guinea savanna ecological zones of Ghana.

Methods

A total of 2016 ticks were collected from domestic animals including cattle, goats and dogs. Ticks were morphologically identified and analysed for pathogens such as Crimean-Congo haemorrhagic fever virus (CCHFV), Alkhurma haemorrhagic fever virus (AHFV), Rickettsia spp. and Coxiella burnetii using polymerase chain reaction assays (PCR) and sequence analysis.

Results

Seven species were identified, with Amblyomma variegatum (60%) most frequently found, followed by Rhipicephalus sanguineus sensu lato (21%), Rhipicephalus spp. (9%), Hyalomma truncatum (6%), Hyalomma rufipes (3%), Rhipicephalus evertsi (1%) and Rhipicephalus (Boophilus) sp. (0.1%). Out of 912 pools of ticks tested, Rickettsia spp. and Coxiella burnetii DNA was found in 45.6% and 16.7% of pools, respectively, whereas no CCHFV or AHFV RNA were detected. Co-infection of bacterial DNA was identified in 9.6% of tick pools, with no statistical difference among the ecozones studied.

Conclusions

Based on these data, humans and animals in these ecological zones are likely at the highest risk of exposure to rickettsiosis, since ticks infected with Rickettsia spp. displayed the highest rates of infection and co-infection with C. burnetii, compared to other tick-borne pathogens in Ghana.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s13071-022-05208-8.

Seroprevalence and Risk Factors of Crimean-Congo Hemorrhagic Fever in Cattle of Smallholder Farmers in Central Malawi

Crimean-Congo hemorrhagic fever virus (CCHFV) is endemic in Africa, Asia, and Eastern Europe where it circulates among animals and ticks causing sporadic outbreaks in humans. Although CCHF is endemic in sub-Saharan Africa, epidemiological information is lacking in many countries, including Malawi. To assess the risk of CCHF in Malawi, we conducted an epidemiological study in cattle reared by smallholder livestock farmers in central Malawi. A cross-sectional study was conducted in April 2020 involving seven districts, four from Kasungu and three from Lilongwe Agriculture Development Divisions. A structured questionnaire was administered to farmers to obtain demographic, animal management, and ecological risk factors data. Sera were collected from randomly selected cattle and screened for CCHF virus (CCHFV) specific antibodies using a commercial ELISA kit. Ticks were collected from cattle and classified morphologically to species level. An overall CCHFV seropositivity rate of 46.9% (n = 416; 95% CI: 42.0–51.8%) was observed. The seropositivity was significantly associated with the age of cattle (p < 0.001), sex (p < 0.001), presence of ticks in herds (p = 0.01), district (p = 0.025), and type of grazing lands (p = 0.013). Five species of ticks were identified, including Hyalomma truncatum, a known vector of CCHFV. Ticks of the species Hyalomma truncatum were not detected in two districts with the highest seroprevalence for CCHF and vector competency must be further explored in the study area. To our knowledge, this is the first report of serologic evidence of the presence of CCHV among smallholder cattle in central Malawi. This study emphasizes the need for continued monitoring of CCHFV infection among livestock, ticks, and humans for the development of data-based risk mitigation strategies.

Clinical profile and outcome of patients with Crimean Congo haemorrhagic fever: a hospital based observational study from Rajasthan, India

BACKGROUND

Crimean Congo haemorrhagic fever (CCHF) is an emerging zoonotic infection with high mortality. Nosocomial spread is described secondary to body fluid contact.

METHODS

Patients meeting the case definition for viral haemorrhagic fever (VHF) from August to November 2019 were tested for CCHF after ruling out dengue, malaria, scrub typhus and leptospirosis in a tertiary teaching hospital in western Rajasthan, India. Diagnosis was confirmed using both quantitative reverse transcription polymerase chain reaction and immunoglobulin M/immunoglobulin G enzyme-linked immunosorbent assay for all patients. All hospital contacts were line listed and tested and symptomatic high-risk contacts received ribavirin post-exposure prophylaxis. Cohorting, personal protective equipment use and hand washing were employed to prevent nosocomial spread.

RESULTS

Four patients tested positive for CCHF. We encountered uncommon initial presentations involving motor weakness and supraventricular tachycardia. Elevated serum lactate dehydrogenase and creatinine kinase were useful in clinical diagnosis. Only one patient survived despite ribavirin therapy. There was zero nosocomial transmission. A partial segment of nucleocapsid of amplified CCHF virus was 99.62% identical to the Afghanistan and Oman strains.

CONCLUSIONS

The distribution of CCHF appears to be expanding, with CCHF emerging as endemic in Rajasthan, India. In this setting of high mortality, hand washing and PPE use prevented nosocomial transmission.

First Serological Evidence of Crimean-Congo Hemorrhagic Fever Virus and Rift Valley Fever Virus in Ruminants in Tunisia

Crimean-Congo hemorrhagic fever virus (CCHFV, Nairoviridae family) and Rift Valley fever virus (RVFV, Phenuiviridae family) are zoonotic vector-borne pathogens with clinical relevance worldwide. Our study aimed to determine seroprevalences of these viruses and potential risk factors among livestock (cattle, sheep, and goats) in Tunisia. Sera were tested for antibodies against CCHFV (n = 879) and RVFV (n = 699) using various enzyme-linked immunosorbent assays (ELISAs) and indirect immunofluorescence assays (IIFA). The overall seroprevalence of IgG antibodies was 8.6% (76/879) and 2.3% (16/699) against CCHFV and RVFV, respectively. For CCHF seropositivity bioclimatic zones and breed were potential risk factors for the three tested animal species; while the season was associated with cattle and sheep seropositivity, tick infestation was associated with cattle and goats seropositivity and age as a risk factor was only associated with cattle seropositivity. Age and season were significantly associated with RVFV seropositivity in sheep. Our results confirm the circulation of CCHFV and RVFV in Tunisia and identified the principal risk factors in ruminants. This knowledge could help to mitigate the risk of ruminant infections and subsequently also human infections.

Development of a Novel Multi-Epitope Vaccine Against Crimean-Congo Hemorrhagic Fever Virus: An Integrated Reverse Vaccinology, Vaccine Informatics and Biophysics Approach

Crimean-Congo hemorrhagic fever (CCHF) is a highly severe and virulent viral disease of zoonotic origin, caused by a tick-born CCHF virus (CCHFV). The virus is endemic in many countries and has a mortality rate between 10% and 40%. As there is no licensed vaccine or therapeutic options available to treat CCHF, the present study was designed to focus on application of modern computational approaches to propose a multi-epitope vaccine (MEV) expressing antigenic determinants prioritized from the CCHFV genome. Integrated computational analyses revealed the presence of 9 immunodominant epitopes from Nucleoprotein (N), RNA dependent RNA polymerase (RdRp), Glycoprotein N (Gn/G2), and Glycoprotein C (Gc/G1). Together these epitopes were observed to cover 99.74% of the world populations. The epitopes demonstrated excellent binding affinity for the B- and T-cell reference set of alleles, the high antigenic potential, non-allergenic nature, excellent solubility, zero percent toxicity and interferon-gamma induction potential. The epitopes were engineered into an MEV through suitable linkers and adjuvating with an appropriate adjuvant molecule. The recombinant vaccine sequence revealed all favorable physicochemical properties allowing the ease of experimental analysis in vivo and in vitro. The vaccine 3D structure was established ab initio. Furthermore, the vaccine displayed excellent binding affinity for critical innate immune receptors: TLR2 (-14.33 kcal/mol) and TLR3 (-6.95 kcal/mol). Vaccine binding with these receptors was dynamically analyzed in terms of complex stability and interaction energetics. Finally, we speculate the vaccine sequence reported here has excellent potential to evoke protective and specific immune responses subject to evaluation of downstream experimental analysis.

Monitoring Symptoms of Infectious Diseases: Perspectives for Printed Wearable Sensors

Infectious diseases possess a serious threat to the world's population, economies, and healthcare systems. In this review, we cover the infectious diseases that are most likely to cause a pandemic according to the WHO (World Health Organization). The list includes COVID-19, Crimean-Congo Hemorrhagic Fever (CCHF), Ebola Virus Disease (EBOV), Marburg Virus Disease (MARV), Lassa Hemorrhagic Fever (LHF), Middle East Respiratory Syndrome (MERS), Severe Acute Respiratory Syndrome (SARS), Nipah Virus diseases (NiV), and Rift Valley fever (RVF). This review also investigates research trends in infectious diseases by analyzing published research history on each disease from 2000-2020 in PubMed. A comprehensive review of sensor printing methods including flexographic printing, gravure printing, inkjet printing, and screen printing is conducted to provide guidelines for the best method depending on the printing scale, resolution, design modification ability, and other requirements. Printed sensors for respiratory rate, heart rate, oxygen saturation, body temperature, and blood pressure are reviewed for the possibility of being used for disease symptom monitoring. Printed wearable sensors are of great potential for continuous monitoring of vital signs in patients and the quarantined as tools for epidemiological screening.

Imported Hyalomma ticks in the Netherlands 2018-2020

BACKGROUND

Ticks of the genus Hyalomma, which are vectors for several tick-borne diseases, are occasionally found in areas outside their endemic range including northern parts of Europe. The objective of this study was to analyse adult Hyalomma ticks that were recently found in the Netherlands.

METHODS

Hyalomma ticks were morphologically identified. Cluster analysis, based upon sequence data (cox1 barcoding) for molecular identification, and pathogen detection were performed. Additionally, a cross-sectional survey of horses was conducted to actively search for Hyalomma ticks in summer 2019. Analysis of temperature was done to assess the possibility of (i) introduced engorged nymphs moulting to adults and (ii) establishment of populations in the Netherlands.

RESULTS

Seventeen adult Hyalomma ticks (one in 2018, eleven in 2019, five in 2020) were found by citizens and reported. Fifteen ticks were detected on horses and two on humans. Twelve were identified as H. marginatum, one as H. rufipes and four, of which only photographic images were available, as Hyalomma sp. No Crimean-Congo haemorrhagic fever virus or Babesia/Theileria parasites were detected. One adult tick tested positive for Rickettsia aeschlimannii. In the cross-sectional horse survey, no Hyalomma ticks were found. Analysis of temperatures showed that engorged nymphs arriving on migratory birds in spring were able to moult to adults in 2019 and 2020, and that cumulative daily temperatures in the Netherlands were lower than in areas with established H. marginatum populations.

CONCLUSIONS

Our results show that Hyalomma ticks are regularly introduced in the Netherlands as nymphs. Under the Dutch weather conditions, these nymphs are able to develop to the adult stage, which can be sighted by vigilant citizens. Only one human pathogen, Rickettsia aeschlimannii, was found in one of the ticks. The risk of introduction of tick-borne diseases via Hyalomma ticks on migratory birds is considered to be low. Establishment of permanent Hyalomma populations is considered unlikely under the current Dutch climatic conditions.

Crimean-Congo Hemorrhagic Fever Virus (CCHFV): A Silent but Widespread Threat

Purpose of Review

This review is aimed at highlighting recent research and articles on the complicated relationship between virus, vector, and host and how biosurveillance at each level informs disease spread and risk.

Recent Findings

While human cases of CCHFV and tick identification in non-endemic areas in 2019–2020 were reported to sites such as ProMed, there is a gap in recent published literature on these and broader CCHFV surveillance efforts from the late 2010s.

Summary

A review of the complex aspects of CCHFV maintenance in the environment coupled with high fatality rate and lack of vaccines and therapeutics warrants the need for a One-Health approach toward detection and increased biosurveillance programs for CCHFV.

Neurologic Manifestations of the World Health Organization's List of Pandemic and Epidemic Diseases

The World Health Organization (WHO) monitors the spread of diseases globally and maintains a list of diseases with epidemic or pandemic potential. Currently listed diseases include Chikungunya, cholera, Crimean-Congo hemorrhagic fever, Ebola virus disease, Hendra virus infection, influenza, Lassa fever, Marburg virus disease, Neisseria meningitis, MERS-CoV, monkeypox, Nipah virus infection, novel coronavirus (COVID-19), plague, Rift Valley fever, SARS, smallpox, tularemia, yellow fever, and Zika virus disease. The associated pathogens are increasingly important on the global stage. The majority of these diseases have neurological manifestations. Those with less frequent neurological manifestations may also have important consequences. This is highlighted now in particular through the ongoing COVID-19 pandemic and reinforces that pathogens with the potential to spread rapidly and widely, in spite of concerted global efforts, may affect the nervous system. We searched the scientific literature, dating from 1934 to August 2020, to compile data on the cause, epidemiology, clinical presentation, neuroimaging features, and treatment of each of the diseases of epidemic or pandemic potential as viewed through a neurologist's lens. We included articles with an abstract or full text in English in this topical and scoping review. Diseases with epidemic and pandemic potential can be spread directly from human to human, animal to human, via mosquitoes or other insects, or via environmental contamination. Manifestations include central neurologic conditions (meningitis, encephalitis, intraparenchymal hemorrhage, seizures), peripheral and cranial nerve syndromes (sensory neuropathy, sensorineural hearing loss, ophthalmoplegia), post-infectious syndromes (acute inflammatory polyneuropathy), and congenital syndromes (fetal microcephaly), among others. Some diseases have not been well-characterized from a neurological standpoint, but all have at least scattered case reports of neurological features. Some of the diseases have curative treatments available while in other cases, supportive care remains the only management option. Regardless of the pathogen, prompt, and aggressive measures to control the spread of these agents are the most important factors in lowering the overall morbidity and mortality they can cause.

Widespread Detection of Multiple Strains of Crimean-Congo Hemorrhagic Fever Virus in Ticks, Spain

Human cases of Crimean-Congo hemorrhagic fever (CCHF) were first detected in Spain in 2016. National human and animal health authorities organized a large, multidisciplinary study focusing on ticks as sentinels to determine the nationwide distribution of ticks with CCHF virus. Ticks were collected from animals and vegetation, samples pooled (12,584 ticks; 4,556 pools), and molecular methods used to look for the virus. We detected the virus in 135 pools from most of the regions studied, indicating that it is widespread in Spain. We found sequences of CCHF virus genotypes I, III, and IV in the tick species collected, most commonly in Hyalomma lusitanicum, suggesting this tick has a prominent role in the virus’s natural cycle. The red deer (Cervus elaphus) was the host that most frequently yielded positive ticks. Our study highlights the need for larger studies in Spain to ascertain the complete risk to public health.

Efficacy of therapeutic plasma exchange in patients with Crimean-Congo hemorrhagic fever

OBJECTIVE

To examine the efficacy of therapeutic plasma exchange (TPE) in patients critically ill with Crimean-Congo hemorrhagic fever (CCHF).

METHODS

Patients with CCHF received supportive treatment (ST) or TPE. After laboratory and clinical evaluations, the patients were divided into mild, moderate, and severe CCHF groups according to the severity score index (SSI). To assess the efficacy of TPE, the incubation period, time of admission to hospital, hospitalization duration, mortality rate and times to recovery of the platelet count and aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels were compared between patients receiving ST and TPE.

RESULT

A total of 119 confirmed CCHF cases was analyzed. The median SSIs were 7 in the TPE group and 5 in the ST group. The SSI stages, median incubation times and admission times were similar in the two groups. However, the duration of hospitalization was longer in the TPE group. The overall mortality rates were 9% (3 of 33 patients) in the TPE group and 16% (5 of 31 patients) in the ST group; the difference was significant. The platelet count recovered after a median of 6 (4-7) days in the ST group.

CONCLUSION

The mortality rate was lower in the TPE group than in the ST group, but the duration of hospitalization and the time to platelet recovery were longer in the TPE group than in the ST group. TPE did not contribute significantly to the prognosis of patients with intermediate-severity CCHF. However, TPE might be efficacious in patients with severe CCHF.

Treatment of Crimean-Congo Haemorrhagic Fever by Favipiravir in a Patient with Novel Coronavirus Co-Infection

Introduction

Crimean-Congo haemorrhagic fever (CCHF) is a lethal zoonotic disease caused by an RNA virus that is a member of the Nairovirus genus in the Bunyaviridae family from the arbovirus group. CCHF is transmitted by Hyalomma ticks through direct contact with the blood and other bodily fluids of patients or infected animals.

Case description

A 65-year-old man was admitted to the emergency unit with dry cough, myalgia and fever. He was treated with favipiravir. He had disseminated intravascular coagulopathy with thrombocytopenia in the setting of COVID-19 infection. He tested positive for both COVID-19 and CCHF. By the end of the fifth day of treatment, his laboratory parameters and clinical symptoms had normalized.

Conclusion

Favipiravir is currently on the market for treating COVID-19 infection worldwide. It has also been used to treat CCHF in laboratory animals. To the best of our knowledge this is the first report of CCHF successfully treated with favipiravir, which could be a key drug for treating human CCHF.

LEARNING POINTS

Clinicians should be alert for concomitant viral infections such as Crimean-Congo haemorrhagic fever, which share similar clinical and laboratory findings to COVID-19.The effectiveness of favipiravir for viral infections other than influenza and COVID-19, such as Crimean-Congo haemorrhagic fever, should be elucidated.

Evaluation of the cell culture based and the mouse brain derived inactivated vaccines against Crimean-Congo hemorrhagic fever virus in transiently immune-suppressed (IS) mouse model

Crimean-Congo hemorrhagic fever virus (CCHFV) is a tick-borne virus in the Nairoviridae family within the Bunyavirales order of viruses. Crimean-Congo hemorrhagic fever (CCHF) is the most widespread among tick-borne human viral diseases. It is endemic in many areas of Africa, Asia, the Middle East, in the Balkans, Russia and countries of the former Soviet Union. The confirmed CCHF cases were seen in Spain in 2016 to signify expansion of the virus into new geographical areas. CCHFV causes a viral human disease characterized by sudden onset of fever, headache, abdominal pain, nausea, hypotension, hemorrhage, and hepatic dysfunction with fatality rates up to 30%. Currently, there are no spesific treatments or licensed vaccines available for CCHFV. The absence of a susceptible animal model for CCHFV infection was severely hindered work on the development of vaccines. However, several animal models of CCHFV infection have been recently developed and used to assess vaccine efficacy. In this study, we have used the transiently immune-suppressed (IS) mouse model that MAb-5A3 was used to block IFN-I signaling in immune intact, wild-type mice at the time of CCHFV infection to evaluate the immune response and efficacy of the cell culture based and the mouse brain derived inactivated vaccines against CCHFV. Both vaccine preparations have provided complete protection but the cell culture based vaccine more effectively induced to CCFHV spesific antibodies and T cell responses. This is the first comparison of the cell culture based and the mouse brain derived vaccines for assessing the protective efficacy and the immunogenicity in the IS mouse CCHFV model.

Strategies for Assessing Arbovirus Genetic Variability in Vectors and/or Mammals

Animal arboviruses replicate in their invertebrate vectors and vertebrate hosts. They use several strategies to ensure replication/transmission. Their high mutation rates and propensity to generate recombinants and/or genome segment reassortments help them adapt to new hosts/emerge in new geographical areas. Studying arbovirus genetic variability has been used to identify indicators which predict their potential to adapt to new hosts and/or emergence and in particular quasi-species. Multiple studies conducted with insect-borne viruses laid the foundations for the "trade-off" hypothesis (alternation of host transmission cycle constrains arbovirus evolution). It was extrapolated to tick-borne viruses, where too few studies have been conducted, even though humans faced emergence of numerous tick-borne virus during the last decades. There is a paucity of information regarding genetic variability of these viruses. In addition, insects and ticks do not have similar lifecycles/lifestyles. Indeed, tick-borne viruses are longer associated with their vectors due to tick lifespan. The objectives of this review are: (i) to describe the state of the art for all strategies developed to study genetic variability of insect-borne viruses both in vitro and in vivo and potential applications to tick-borne viruses; and (ii) to highlight the specificities of arboviruses and vectors as a complex and diverse system.

The emerging tick-borne Crimean-Congo haemorrhagic fever virus: A narrative review

Crimean-Congo Haemorrhagic Fever (CCHF) is an increasingly relevant viral zoonosis caused by the negative-sense single-stranded (ss) RNA Crimean-Congo Haemorrhagic Fever Orthonairovirus (CCHFV) (Nairoviridae family, Bunyavirales order). The viral genome is divided into three segments (L-M-S) of distinct size and functions. The infection is generally mediated by a tick vector, in particular belonging to the Hyalomma genus, and the transmission follows a tick-vertebrate-tick ecologic cycle, with asymptomatic infected animals functioning as reservoirs and amplifiers for CCHFV. Human hosts could be infected primarily through infected ticks or by contact with infected hosts or their body fluids and tissues, also in a nosocomial way and in occupational contexts. Infected symptomatic patients generally manifest a nonspecific illness, which progresses across four stages, with possibly lethal outcomes. Disease outbreaks show a widespread geographic diffusion and a highly variable mortality rate, dramatically peaking in untreated patients. The lack of an adequate animal model and the elevated virus biological risk (only manageable under biosafety level 4 conditions) represent strongly limiting factors for a better characterization of the disease and for the development of specific therapies and vaccines. The present review discusses updated information on CCHFV-related disease, including details about the virus (taxonomy, structure, life cycle, transmission modalities) and considering CCHF pathogenesis, epidemiology and current strategies (diagnostic, therapeutic and preventive).

Detection of new Crimean-Congo haemorrhagic fever virus genotypes in ticks feeding on deer and wild boar, Spain

Crimean-Congo haemorrhagic fever virus (CCHFV) is the causative agent of the severe tick-borne, often fatal, zoonotic Crimean-Congo haemorrhagic fever (CCHF), 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. Given the emergence of CCHF and the role of ticks in pathogen maintenance and transmission, we investigated the presence and genotype identity of the virus in tick species parasitizing abundant wild host species in south-western Spain. A total of 613 adult ticks were collected from hunter-harvested wild ungulates in twenty locations throughout south-western Spain. Ticks were identified, nucleic acids were extracted, RNA was analysed by a nested RT-PCR targeting CCHFV S segment, and the amplicons were sequenced. According to the 212-bp sequence amplified, the presence of CCHFV human genotype Europe V was detected in Hyalomma lusitanicum and Dermacentor marginatus ticks collected from red deer, fallow deer and Eurasian wild boar in different locations from south-western Spain. Genotype Africa IV was also detected in a H. lusitanicum tick collected from a red deer. The detection of CCHFV in different tick species collected from various wild hosts and localities provided strong evidence of widespread CCHFV presence in the region, suggesting that the circulation of the virus 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.

Personal protective equipment for viral hemorrhagic fevers

PURPOSE OF REVIEW

Viral hemorrhagic fevers (VHF) encompass many organisms that have caused sporadic outbreaks with high case fatality rates. This article reviews VHF with reported human-to-human transmission and describes updates about personal protective equipment (PPE) for healthcare personnel (HCP) and others. We summarize existing information about appropriate PPE use, training, and compliance for care of VHF patients in endemic and nonendemic countries, as well as addresses the challenges HCP experience when using PPE.

RECENT FINDINGS

PPE is essential in protecting HCP from exposure to disease-causing pathogens. Recent evidence shows that anyone involved in care, management, and transport of certain VHF patients must use elements of PPE as part of appropriate infection prevention and control (IPC) practices. Strict adherence to standard precautions has effectively interrupted human-to-human transmission of a number of VHF. However, unclear protocols, inconsistent training, climate challenges, and cultural sensitivities impede proper PPE use. Appropriate PPE use can drastically reduce the risk of HCP exposure to VHF.

SUMMARY

Infections caused by certain VHFs can be highly pathogenic and associated with significant morbidity and mortality. Though it is well documented that use of PPE and good IPC practices are critical to reducing transmission, little conclusive evidence exists about the ideal PPE ensemble or components. Concerns with comfort, compliance, training, and usability may impede proper PPE use. Basic PPE elements, used appropriately as part of stringent IPC, must always form the foundation of care for HCP-treating patients with VHF. More research is required to identify the ideal PPE ensemble for caring for VHF patients in various settings.

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.