Crimean-Congo Hemorrhagic Fever: Prevention and Control Limitations in a Resource-Poor Country

Crimean-Congo Hemorrhagic Fever Survivors Elicit Protective Non-Neutralizing Antibodies that Target 11 Overlapping Regions on Viral Glycoprotein GP38

Crimean-Congo hemorrhagic fever virus can cause lethal disease in humans yet there are no approved medical countermeasures. Viral glycoprotein GP38, unique to Nairoviridae, is a target of protective antibodies, but extensive mapping of the human antibody response to GP38 has not been previously performed. Here, we isolated 188 GP38-specific antibodies from human survivors of infection. Competition experiments showed that these antibodies bind across five distinct antigenic sites, encompassing eleven overlapping regions. Additionally, we reveal structures of GP38 bound with nine of these antibodies targeting different antigenic sites. Although GP38-specific antibodies were non-neutralizing, several antibodies were found to have protection equal to or better than murine antibody 13G8 in two highly stringent rodent models of infection. Together, these data expand our understanding regarding this important viral protein and inform the development of broadly effective CCHFV antibody therapeutics.

Crimean-Congo hemorrhagic fever outbreak in Pakistan, 2022: A warning bell amidst unprecedented floods and COVID 19 pandemic

Crimean-Congo hemorrhagic fever (CCHF) is an infection caused by a tick-borne virus (genus: Nairovirus, family: Bunyaviridae). The most important vector for CCHF is the ixodid tick. Along with tick bite, direct contact with the virus-affected animal is responsible for its spread. Pakistan witnessed its first case of CCHF in 1976 and has been a major victim of CCHF for years, but spikes in cases are seen after Eid-ul-Adha, an Islamic festival involving the sacrifice of cattle. The disease, in particular, is common among butchers, veterinarians, and livestock workers. From the start of this year till June 22, 2022, a total of four cases have been reported across the country. Pakistan faces major challenges in combating CCHF every year due to its specific geographical position and a majority of the population being involved with animal husbandry. There is no approved vaccine for its prevention. All these factors contribute to the burden on the already weakened healthcare system of Pakistan. Strict actions should be taken to contain the spread of the disease. The need of the hour is to engage the general population, raise awareness, and develop policies to ensure disease surveillance. This should be accompanied by fostering collaboration among animal and human health departments for efficient communication and early intervention. The focus should be on medical research to find an efficacious treatment and prophylaxis for the CCHF virus, which will be the cornerstone of future CCHF prevention and control strategies.

Knowledge, attitudes, and practices regarding Crimean-Congo hemorrhagic fever among general people: A cross-sectional study in Pakistan

Background

Crimean-Congo hemorrhagic fever (CCHF) continues to pose a serious threat to the fragile healthcare system of Pakistan with a continuous increase of morbidity and mortality. The present study aimed to assess the knowledge, attitudes, and practices regarding CCHF among general people who resided in Pakistan.

Methods

An online cross-sectional survey design was applied, and a convenience sampling technique was used to recruit 1039 adult people from Pakistan. Data were collected from September 08 to October 12, 2021. The questionnaire consisted of a total of 32 questions in four parts assessing socio-demographics, as well as knowledge, attitudes, and practices regarding CCHF. All statistical analyses were performed using the Statistical Package for the Social Sciences (SPSS), and logistic regression analyses were performed to determine the factors associated with good knowledge, positive attitudes, and good practices.

Results

Alarmingly, 51.5% of participants heard about CCHF infection before administering the survey. Among these, 20.2%, 33.3%, and 48.2% of the study participants had demonstrated good knowledge, positive attitudes, and good practices, respectively. Binary logistic regression analysis revealed that education and income status had a significant impact on knowledge and attitudes (p<0.05). Similarly, the mean attitude scores differed significantly by age, education, and income status (p<0.05).

Conclusions

The findings reflected inadequate levels of knowledge, attitudes, and practices regarding CCHF among general people in Pakistan which may regard as lower than expected. As CCHF is a highly contagious disease, it’s urgent to initiate a comprehensive approach to handle the situation before it spreads further in Pakistan.

Protective neutralizing antibodies from human survivors of Crimean-Congo hemorrhagic fever

Crimean-Congo hemorrhagic fever virus (CCHFV) is a World Health Organization priority pathogen. CCHFV infections cause a highly lethal hemorrhagic fever for which specific treatments and vaccines are urgently needed. Here, we characterize the human immune response to natural CCHFV infection to identify potent neutralizing monoclonal antibodies (nAbs) targeting the viral glycoprotein. Competition experiments showed that these nAbs bind six distinct antigenic sites in the Gc subunit. These sites were further delineated through mutagenesis and mapped onto a prefusion model of Gc. Pairwise screening identified combinations of non-competing nAbs that afford synergistic neutralization. Further enhancements in neutralization breadth and potency were attained by physically linking variable domains of synergistic nAb pairs through bispecific antibody (bsAb) engineering. Although multiple nAbs protected mice from lethal CCHFV challenge in pre- or post-exposure prophylactic settings, only a single bsAb, DVD-121-801, afforded therapeutic protection. DVD-121-801 is a promising candidate suitable for clinical development as a CCHFV therapeutic.

Prevalence and phylogenetic analysis of Crimean-Congo hemorrhagic fever virus in ticks collected from Punjab province of Pakistan

Crimean-Congo hemorrhagic fever (CCHF) is a tick-borne zoonotic disease of human that caused by CCHF virus. To study the epidemiological distribution of CCHFV, 2183 tick samples were collected from sheep, goats, cattle and buffalo of different livestock farms of ten districts of Punjab province of Pakistan. Detection of CCHFV was done using enzyme link immunosorbent assay (ELISA) after proper identification of tick samples. The partial S-segment of CCHFV from ELISA positive tick samples was amplified by PCR and sequenced to determine the genotype of CCHFV. Out of2183 collected tick samples, 1913 ticks belonged to 5 species of genus Hyalomma as H. antolicum (48%), H. marginatum (30.2%), H. rufipes (10.82%), H. impressum (5.43%) and H. dromedarii (5.27%). While 270 ticks belonged to 3 species of genus Rhipicephalus as R. microplus (44.8%), R. sanguineus (32.22%) and R. turanicus (24.8%). The overall antigenic prevalence of CCHFV was found to be 12.13% in collected tick samples and 21 tick pools were sequenced for partial S-segment of CCHFV. All of the 21 tick pools were clustered in genotype IV (Asia-1). The highest prevalence of CCHFV was found in district Chakwal (24.13%) followed by Mianwali (23.68%), Rawalpindi (23.07%), Attock (20.0%), Rajanpur (10.52%) and Lahore (8.33%). In positive tick pools, the highest prevalence of CCHFV antigen was found in H. antolicum (39.6%) followed by H. marginatum (30.18%), H. rufipes (13.2%), H. impressum (3.77%), H. dromedarii (1.88%), R. microplus (5.66%) and R. sanguineus (5.66%). The current study confirms the presence of CCHFV in the ticks population of Punjab. The CCHF virus present in Punjab belongs to Asia-1 genotype. It is important to control the tick infestation of the animals present in these areas. So that the transmission cycle of CCHF can be inhibited.

Seroprevalence of Crimean-Congo haemorrhagic fever among three selected risk human groups in disease-endemic region of Pakistan

The occurrence of Crimean-Congo haemorrhagic fever (CCHF) in humans is linked with animals living in close vicinity, and information on the incidence of CCHF at the human-animal interface is scarce. Therefore, the current study was designed to identify the high-risk groups of individuals linked with animals in the Chakwal district of Pakistan having a history of CCHF cases in humans. In subject matter, coupled with risk factor analysis, we performed a sero-based CCHF surveillance in three selected risk groups of humans including abattoir workers (n = 137), milkmen (n = 169) and animal handlers (n = 147). Sera samples and questionnaire-based data were collected from each of the participants and screened for anti-CCHFV IgG antibodies using enzyme-linked immunosorbent assay. The highest seroprevalence was observed in animal handlers (n = 14, 9.52%, 95% CI: 4.68-13.99) followed by abattoir workers (n = 9, 6.57%, 95% CI: 2.42-10.72) and milkmen (n = 3, 1.78%, 95% CI: 0.24-4.24). The risk of seropositivity was significantly associated with humans linked with tick-infested animals (OR: 11.0, 95% CI: 1.5-83.0, p = .002), old age >40 years (OR: 6.6, 95% CI: 2.7-16.0, p < .0001), illiteracy (OR: 4.3, 95% CI: 1.5-13.0, p = .004) and humans without knowledge about CCHF (OR: 7.6, 95% CI: 1.8-33.0, p = .0009). The findings of the current study highlighted the seroprevalence of CCHF in high-risk groups of humans living in a disease-endemic area of Pakistan and highlight the need for well-integrated disease surveillance in the future to better comprehend disease control interventions.

New aspects about Crimean-Congo hemorrhagic fever (CCHF) cases and associated fatality trends: A global systematic review and meta-analysis

Crimean-Congo hemorrhagic fever (CCHF) is the most popular tick-borne disease causing by Crimean-Congo hemorrhagic fever virus (CCHFV). There are several valuable reviews considering some fields of the CCHF aspects. While there is no a systematic review about means and trends of CCHF cases and fatality rate, means and trends of CCHF cases and fatality rates of human occupations involved in CCHF. Therefore, this meta-analysis review performed to highlight and provide a global detailed of the above CCHF aspects. Among 398 collected papers, 173 papers were become this meta-analysis review. The study results confirm that an apparent increasing CCHF cases occurred through the past decades. The trends of annually and periodically CCHF cases and fatality rates were also increased. The means of annually and periodically CCHF cases and fatality rates were 57 and 432 cases, and 10 cases and 32.2 % and 49 cases and 28.8 %, respectively. The means of annually and periodically CCHF fatality rates are about one-tenth of CCHF human cases. The mean of CCHF fatality rates in Africa (22.0 %) is lower than Asia (33.5 %) and Europe (33.8 %). Among occupations involved in CCHF, agricultural (28.9 %), health-care (19.2 %) and slaughterhouse (16.7 %) workers, and farmers (13.9 %) had the maximum CCHF fatality rates in order. Based on literature review of CCHFV S-segment aspects, several clades and genotypes are reported to distribute in Africa, Asia and Europe regions. There are very wide fields to investigate the epidemiology characteristics of CCHFV clades, genotypes and their distribution in the future.

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.

An Emerging Biothreat: Crimean-Congo Hemorrhagic Fever Virus in Southern and Western Asia

Tick-borne Crimean-Congo hemorrhagic fever virus (CCHFV) is endemic in numerous countries, but the epidemiology and epizoology of Crimean-Congo hemorrhagic fever (CCHF) remain to be defined for most regions of the world. Using a broad database search approach, we reviewed the literature on CCHF and CCHFV in Southern and Western Asia to better define the disease burden in these areas. We used a One Health approach, moving beyond a focus solely on human disease burden to more comprehensively define this burden by reviewing CCHF case reports, human and animal CCHFV seroprevalence studies, and human and animal CCHFV isolations. In addition, we used published literature to estimate the distribution of Hyalomma ticks and infection of these ticks by CCHFV. Using these data, we propose a new classification scheme for organizing the evaluated countries into five categories by level of evidence for CCHF endemicity. Twelve countries have reported CCHF cases, five from Southern Asia and seven from Western Asia. These were assigned to level 1 or 2. Eleven countries that have evidence of vector circulation but did not report confirmed CCHF cases were assigned to level 3 or 4. This classification scheme was developed to inform policy toward strengthening CCHF disease surveillance in the Southern and Western Asia regions. In particular, the goal of this review was to inform international organizations, local governments, and health-care professionals about current shortcomings in CCHFV surveillance in these two high-prevalence regions.

Crimean-Congo hemorrhagic fever: An update

Crimean-Congo hemorrhagic fever (CCHF) is a severe form of hemorrhagic fever caused by a virus of the genus Nairovirus. The amplifying hosts are various mammal species that remain asymptomatic. Humans are infected by tick bites or contact with animal blood. CCHF has a broad geographic distribution and is endemic in Africa, Asia (in particular the Middle East) and South East Europe. This area has expanded in recent years with two indigenous cases reported in Spain in 2016 and 2018. The incubation period is short with the onset of symptoms in generally less than a week. The initial symptoms are common to other infectious syndromes with fever, headache, myalgia and gastrointestinal symptoms. The hemorrhagic syndrome occurs during a second phase with sometimes major bleeding in and from the mucous membranes and the skin. Strict barrier precautionary measures are required to prevent secondary and nosocomial spread. CCHF may be documented by PCR detection of the virus genome during the first days after the onset of illness, and then by serological testing for IgM antibodies as from the 2nd week after infection. Patient management is mainly based on supportive care. Despite a few encouraging retrospective reports, there is no confirmed evidence that supports the use of ribavirin for curative treatment. Nevertheless, the World Health Organization continues to recommend the use of ribavirin to treat CCHF, considering the limited medical risk related to short-term treatment. The prescription of ribavirin should however be encouraged post-exposure for medical professionals, to prevent secondary infection.

Outbreak of Crimean-Congo haemorrhagic fever with atypical clinical presentation in the Karak District of Khyber Pakhtunkhwa, Pakistan

Background

Crimean-Congo haemorrhagic fever (CCHF) is a potentially fatal disease endemic in Pakistan. The causative virus is transmitted by the bite of Hyalomma ticks or by contact with infected blood or tissue. First cases of the disease were reported in Pakistan in 1976 but regular outbreaks have been observed since the year 2000. A huge agricultural base with more than 175 million livestock, the concomitant presence of Hyalomma ticks and a lack of precautionary measures to prevent transmission lead to a considerable risk for exposed populations to contract CCHF in Pakistan. At the same time, secondary cases contracted by nosocomial transmission are reported from hospitals.

Case presentation

Here we present an outbreak of CCHF with four of six patients succumbing to the disease before the suspicion for CCHF was raised. Importantly, the main clinical features of these cases were gastrointestinal symptoms without any clinical signs of bleeding. Only the last two patients in this outbreak presented with typical signs of bleeding disorder and were then confirmed being infected by CCHF. Confirmation of diagnosis was done at the National Institute of Health by real-time RT-PCR.

Conclusions

This case series highlights the importance of early clinical suspicion for CCHF in exposed individuals and the need for improved precautionary measures against the spread of CCHF within the Pakistani population and hospitals.

Electronic supplementary material

The online version of this article (10.1186/s40249-018-0499-z) contains supplementary material, which is available to authorized users.

Ribavirin for treating Crimean Congo haemorrhagic fever

BACKGROUND

Crimean Congo haemorrhagic fever (CCHF) is a tick-borne disease that occurs in parts of Asia, Europe and Africa. Since 2000 the infection has caused epidemics in Turkey, Iran, Russia, Uganda and Pakistan. Good-quality general supportive medical care helps reduce mortality. There is uncertainty and controversy about treating CCHF with the antiviral drug ribavirin.

OBJECTIVES

To assess the effects of ribavirin for treating people with Crimean Congo haemorrhagic fever.

SEARCH METHODS

We searched the Cochrane Infectious Diseases Group Specialized Register; the Central Register of Controlled Trials (CENTRAL); MEDLINE (PubMed); Embase (OVID); Science Citation Index-Expanded, Social Sciences Citation index, conference proceedings (Web of Science); and CINAHL (EBSCOHost). We also searched the WHO International Clinical Trials Registry Platform (ICTRP) and ClinicalTrials.gov for trials in progress. We conducted all searches up to 16 October 2017. We also contacted experts in the field and obtained further studies from these sources.

SELECTION CRITERIA

We evaluated studies assessing the use of ribavirin in people with suspected or confirmed Crimean Congo haemorrhagic fever. We included randomised control trials (RCTs); non-randomised studies (NRSs) that included more than 10 participants designed as cohort studies with comparators; and case-control studies.

DATA COLLECTION AND ANALYSIS

Two review authors assessed eligibility, risk of bias, and extracted data. For non-randomized studies we used the ROBINS-I tool to assess risk of bias. The main effects analysis included all studies where we judged the risk of bias to be low, moderate or high. We summarized dichotomous outcomes using risk ratios (RRs) and continuous outcomes using mean differences (MDs), and used meta-analyses where appropriate. We carried out a subsidiary appraisal and analysis of studies with critical risk of bias for the primary outcome, as these are often cited to support using ribavirin.

MAIN RESULTS

For the main effects analysis, five studies met our inclusion criteria: one RCT with 136 participants and four non-randomized studies with 612 participants. We excluded 18 non-randomized studies with critical risk of bias, where none had attempted to control for confounding.We do not know if ribavirin reduces mortality (1 RCT; RR 1.13, 95% confidence interval (CI) 0.29 to 4.32; 136 participants; very low-certainty evidence; 3 non-randomized studies; RR 0.72, 95% CI 0.41 to 1.28; 549 participants; very low-certainty evidence). We do not know if ribavirin reduces the length of stay in hospital (1 RCT: mean difference (MD) 0.70 days, 95% CI -0.39 to 1.79; 136 participants; and 1 non-randomized study: MD -0.80, 95% CI -2.70 to 1.10; 50 participants; very low-certainty evidence). We do not know if it reduces the risk of patients needing platelet transfusions (1 RCT: RR 1.23, 95% CI 0.77 to 1.96; 136 participants; very low-certainty evidence). For adverse effects (including haemolytic anaemia and a need to discontinue treatment), we do not know whether there is an increased risk with ribavirin in people with CCHF as data are insufficient.We do not know if adding ribavirin to early supportive care improves outcomes. One non-randomized study assessed mortality in people receiving ribavirin and supportive care within four days or less from symptom onset compared to after four days since symptom onset: mortality was lower in the group receiving early supportive care and ribavirin, but it is not possible to distinguish between the effects of ribavirin and early supportive medical care alone.In the subsidiary analysis, 18 studies compared people receiving ribavirin with those not receiving ribavirin. All had a critical risk of bias due to confounding, reflected in the mortality point estimates favouring ribavirin.

AUTHORS' CONCLUSIONS

We do not know if ribavirin is effective for treating Crimean Congo haemorrhagic fever. Non-randomized studies are often cited as evidence of an effect, but the risk of bias in these studies is high.

A DNA vaccine for Crimean-Congo hemorrhagic fever protects against disease and death in two lethal mouse models

Crimean-Congo hemorrhagic fever virus (CCHFV) is a tick-borne virus capable of causing a severe hemorrhagic fever disease in humans. There are currently no licensed vaccines to prevent CCHFV-associated disease. We developed a DNA vaccine expressing the M-segment glycoprotein precursor gene of CCHFV and assessed its immunogenicity and protective efficacy in two lethal mouse models of disease: type I interferon receptor knockout (IFNAR^-/-) mice; and a novel transiently immune suppressed (IS) mouse model. Vaccination of mice by muscle electroporation of the M-segment DNA vaccine elicited strong antigen-specific humoral immune responses with neutralizing titers after three vaccinations in both IFNAR^-/- and IS mouse models. To compare the protective efficacy of the vaccine in the two models, groups of vaccinated mice (7–10 per group) were intraperitoneally (IP) challenged with a lethal dose of CCHFV strain IbAr 10200. Weight loss was markedly reduced in CCHFV DNA-vaccinated mice as compared to controls. Furthermore, whereas all vector-control vaccinated mice succumbed to disease by day 5, the DNA vaccine protected >60% of the animals from lethal disease. Mice from both models developed comparable levels of antibodies, but the IS mice had a more balanced Th1/Th2 response to vaccination. There were no statistical differences in the protective efficacies of the vaccine in the two models. Our results provide the first comparison of these two mouse models for assessing a vaccine against CCHFV and offer supportive data indicating that a DNA vaccine expressing the glycoprotein genes of CCHFV elicits protective immunity against CCHFV.

Crimean-Congo hemorrhagic Fever Virus (CCHFV) is a tick-borne virus capable of causing lethal human disease against which there are currently no approved vaccines. In this study, we compared the immunogenicity and protective efficacy of a candidate DNA vaccine expressing the glycoprotein precursor gene of CCHFV in two mouse models. In addition to the recently established IFNAR^-/- mouse pathogenesis model, we also tested the vaccine in a novel murine system in which the interferon (IFN) α/β signaling response of immunocompetent mice is transiently suppressed. We found that the DNA vaccine elicited high humoral immune responses and provided significant protection against challenge with CCHFV in both mouse models. These findings further our understanding of the requirements for a CCHFV vaccine and provide a new mouse model for the development of CCHFV countermeasures.

Infection prevention and control in health facilities in post-Ebola Liberia: don't forget the private sector!

Setting: Recognising the importance of infection prevention and control (IPC), a minimum standards tool (MST) was developed in Liberia to guide the safe (re-) opening and provision of care in health facilities. Objectives: To analyse the implementation of specific IPC measures after the 2014 Ebola virus outbreak between June 2015 and May 2016, and to compare the relative improvements in IPC between the public and private sectors. Design: A retrospective comparative cohort study. Results: We evaluated 723 (94%) of the 769 health facilities in Liberia. Of these, 437 (60%) were public and 286 (40%) were private. There was an overall improvement in the MST scores from a median of 13 to 14 out of a maximum possible score of 16. While improvements were observed in all aspects of IPC in both public and private health facilities, IPC implementation was systematically higher in public facilities. Conclusions: We demonstrate the feasibility of monitoring IPC implementation using the MST checklist in post-Ebola Liberia. Our study shows that improvements were made in key aspects of IPC after 1 year of evaluations and tailored recommendations. We also highlight the need to increase the focus on the private sector to achieve further improvements in IPC.

The reasons why Pakistan might be at high risk of Crimean Congo haemorrhagic fever epidemic; a scoping review of the literature

Pakistan has faced a number of significant healthcare challenges over the past decade. In 2000, one of these events - a deadly epidemic of Crimean Congo Haemorrhagic Fever (CCHF) - struck Pakistan. The people of Pakistan are at a very high risk of acquiring CCHF, due to a number of factors which emerge from a scoping review of the literature. First, the underdeveloped healthcare system of the country is currently not prepared to cope with challenges of this nature. Healthcare professionals and medical institutes are not sufficiently equipped to properly diagnose, manage and prevent CCHF. Second, a large percentage of the general public is unaware of the spread and control of the vector. The agricultural sector of Pakistan is vast and thus many people are involved in animal husbandry and the handling of livestock which can lead to the transmission of the CCHF virus. Even in urban areas the risk of transmission is significantly higher around the time of Eid-ul-Azha, when Muslims slaughter animals. Finally, the political upheavals faced by the country have also increased Pakistan's vulnerability because a large number of refugees from Afghanistan, a CCHF endemic country, have migrated to Pakistan as a result of the Afghan war. Most of the refugees and their animals settle in Baluchistan and Khyber Pakhtunkhwa provinces, which consequently have a higher prevalence of CCHF. This scoping review of the literature highlights the potential causes of high risk CCHF and draws conclusions and makes recommendations that policy-makers in Pakistan may wish to consider in-order to improve on the current situation.

[The "Black Death" : Crimean-Congo hemorrhagic fever]

The Crimean-Congo hemorrhagic fever (CCHF) is a tick-borne viral disease that has been known for centuries. In the last years more frequent cases reflect the effects of climate change, globalization and the increasing encroachment of humans into previously unexploited areas. Humans acquire the infection by tick bites or through the slaughtering and processing of infected animals. The course of the disease can be severe and the average mortality reaches up to 30 %. It is transmissible from human to human and there is no causal treatment. Thus, CCHF meets the criteria for a highly contagious life-threatening disease. In the following current data on the virus, its vector, the distribution and transmission will be presented, as well as information on the diagnosis, the disease, the underlying pathophysiology and consequences in dealing with patients and deceased.

Crimean-Congo hemorrhagic fever: Risk factors and control measures for the infection abatement

Crimean-Congo hemorrhagic fever (CCHF) is a vector-borne viral disease, widely distributed in different regions of the world. The fever is caused by the CCHF virus (CCHFV), which belongs to the Nairovirus genus and Bunyaviridae family. The virus is clustered in seven genotypes, which are Africa-1, Africa-2, Africa-3, Europe-1, Europe-2, Asia-1 and Asia-2. The virus is highly pathogenic in nature, easily transmissible and has a high case fatality rate of 10-40%. The reservoir and vector of CCHFV are the ticks of the Hyalomma genus. Therefore, the circulation of this virus depends upon the distribution of the ticks. The virus can be transmitted from tick to animal, animal to human and human to human. The major symptoms include headache, high fever, abdominal pain, myalgia, hypotension and flushed face. As the disease progresses, severe symptoms start appearing, which include petechiae, ecchymosis, epistaxis, bleeding gums and emesis. Enzyme-linked immunosorbent assay, quantitative polymerase chain reaction, antigen detection, serum neutralization and isolation of the virus by cell culture are the diagnostic techniques used for this viral infection. There is no specific antiviral therapy available thus far. However, ribavirin has been approved by the World Health Organization for the treatment of CCHFV infection. Awareness campaigns regarding the risk factors and control measures can aid in reducing the spread of this disease to a greater extent, particularly in developing countries.

Investigation of Crimean-Congo hemorrhagic fever virus transmission from patients to relatives: a prospective contact tracing study

We investigated the possibility of transmission of Crimean-Congo hemorrhagic fever (CCHF) virus through respiratory and physical contact. In this prospective study, we traced 116 close relatives of confirmed CCHF cases who were in close contact with the patients during the acute phase of the infection and evaluated the type of contact between patients and their relatives. These relatives were followed for clinical signs or symptoms indicative of CCHF disease, blood samples of those with and without clinical signs were analyzed for CCHF virus immunoglobulin M and G (IgM and IgG, respectively) by enzyme-linked immunosorbent assay. No close relatives developed any signs or symptoms of CCHF and were negative for CCHF virus IgM and IgG. The results suggest that CCHF virus is not easily transmitted from person to person through respiratory or physical contact.

Crimean-Congo hemorrhagic fever: history, epidemiology, pathogenesis, clinical syndrome and genetic diversity

Crimean-Congo hemorrhagic fever (CCHF) is the most important tick-borne viral disease of humans, causing sporadic cases or outbreaks of severe illness across a huge geographic area, from western China to the Middle East and southeastern Europe and throughout most of Africa. CCHFV is maintained in vertical and horizontal transmission cycles involving ixodid ticks and a variety of wild and domestic vertebrates, which do not show signs of illness. The virus circulates in a number of tick genera, but Hyalomma ticks are the principal source of human infection, probably because both immature and adult forms actively seek hosts for the blood meals required at each stage of maturation. CCHF occurs most frequently among agricultural workers following the bite of an infected tick, and to a lesser extent among slaughterhouse workers exposed to the blood and tissues of infected livestock and medical personnel through contact with the body fluids of infected patients. CCHFV is the most genetically diverse of the arboviruses, with nucleotide sequence differences among isolates ranging from 20% for the viral S segment to 31% for the M segment. Viruses with diverse sequences can be found within the same geographic area, while closely related viruses have been isolated in far distant regions, suggesting that widespread dispersion of CCHFV has occurred at times in the past, possibly by ticks carried on migratory birds or through the international livestock trade. Reassortment among genome segments during co-infection of ticks or vertebrates appears to have played an important role in generating diversity, and represents a potential future source of novel viruses. In this article, we first review current knowledge of CCHFV, summarizing its molecular biology, maintenance and transmission, epidemiology and geographic range. We also include an extensive discussion of CCHFV genetic diversity, including maps of the range of the virus with superimposed phylogenetic trees. We then review the features of CCHF, including the clinical syndrome, diagnosis, treatment, pathogenesis, vaccine development and laboratory animal models of CCHF. The paper ends with a discussion of the possible future geographic range of the virus. For the benefit of researchers, we include a Supplementary Table listing all published reports of CCHF cases and outbreaks in the English-language literature, plus some principal articles in other languages, with total case numbers, case fatality rates and all CCHFV strains on GenBank.

Recommended precaution procedures protect healthcare workers from Crimean-Congo hemorrhagic fever virus

OBJECTIVES

The Crimean-Congo hemorrhagic fever (CCHF) virus can spread from person to person and may cause nosocomial outbreaks among healthcare workers (HCWs). The US Centers for Disease Control and Prevention have recommended the use of personal protective equipment (PPE). We investigated the compliance of HCWs with PPE usage during the follow-up of patients, and also the number of risky contacts that occurred between patients and HCWs. We also aimed to determine the seroprevalence of CCHF virus in HCWs.

METHODS

This study was conducted at Cumhuriyet University Education and Research Hospital, a medical center located in a highly endemic area for CCHF where a total of 1284 confirmed CCHF patients were followed-up between 2002 and 2012. All HCWs who were at risk of CCHF virus contact and infection were included in the study. The compliance of the HCWs with PPE usage and the number of contacts that had occurred were recorded. HCW serum samples were analyzed for CCHF virus IgM and IgG by ELISA.

RESULTS

The total rates of PPE usage were 93.7% for gowns, 77.4% for gloves, and 38.9% for masks; the highest compliance was detected in the infectious diseases ward: 100%, 88.6%, and 82.9%, respectively. A total of four HCWs had a history of high-risk contact with contaminated material (two percutaneous exposure and two mucosal contacts), but the number of low-risk contacts was quite high. The total seroprevalence rate was only 0.53%.

CONCLUSIONS

Although the HCWs at our medical center have dealt with an extremely high number of CCHF patients during the last decade, the total seropositivity for CCHFV IgG was only 0.53%. This low rate may be a result of high compliance with PPE usage and also regular education programs.

Genetic analysis and epidemiology of Crimean Congo Hemorrhagic fever viruses in Baluchistan province of Pakistan

Background

Pakistan is considered as an endemic country for Crimean-Congo Hemorrhagic fever with numerous outbreaks and sporadic cases reported during the past two decades. Majority of cases are reported from Baluchistan province with subsequent transmissions to non-endemic regions mainly through infected animals directly or via infested ticks. We hereby describe the molecular investigations of CCHF cases reported during 2008 in Quetta city of Baluchistan province.

Methods

Serum Samples from 44 patients, with clinical signs of hemorrhagic fever attending a tertiary care hospital in Quetta city, were collected and tested for CCHF virus antigen and genomic RNA, using capture IgM EIA kit and standard RT-PCR assay, respectively. The partial S-gene fragments were directly sequenced to get information related to the prevailing CCHFV genotypes and their molecular epidemiology in Pakistan.

Results

Out of the total forty four, sixteen (36%) samples were found positive for CCHF IgM. Similarly, viral RNA was detected in six (16%) samples. Phylogenetic analysis revealed that all study viruses belong to genotype Asia-1 with closest similarity (99-100%) to the previously reported strains from Pakistan, Afghanistan and Iran.

Conclusion

We conclude that CCHF virus remains endemic within Baluchistan and its neighboring regions of Afghanistan warranting a need of incessant surveillance activities.

Viral haemorrhagic fevers in healthcare settings

Viral haemorrhagic fevers (VHFs) typically manifest as rapidly progressing acute febrile syndromes with profound haemorrhagic manifestations and very high fatality rates. VHFs that have the potential for human-to-human transmission and onset of large nosocomial outbreaks include Crimean-Congo haemorrhagic fever, Ebola haemorrhagic fever, Marburg haemorrhagic fever and Lassa fever. Nosocomial outbreaks of VHFs are increasingly reported nowadays, which likely reflects the dynamics of emergence of VHFs. Such outbreaks are associated with an enormous impact in terms of human lives and costs for the management of cases, contact tracing and containment. Surveillance, diagnostic capacity, infection control and the overall preparedness level for management of a hospital-based VHF event are very limited in most endemic countries. Diagnostic capacities for VHFs should increase in the field and become affordable. Availability of appropriate protective equipment and education of healthcare workers about safe clinical practices and infection control is the mainstay for the prevention of nosocomial spread of VHFs.

The emergence and maintenance of vector-borne diseases in the khyber pakhtunkhwa province, and the federally administered tribal areas of pakistan

Human populations throughout much of the world are experiencing unprecedented changes in their relationship to the environment and their interactions with the animals with which so many humans are intimately dependent upon. These changes result not only from human induced changes in the climate, but also from population demographic changes due to wars, social unrest, behavioral changes resulting from cultural mixing, and large changes in land-use practices. Each of these social shifts can affect the maintenance and emergence of arthropod vectors disease or the pathogenic organisms themselves. A good example is the country of Pakistan, with a large rural population and developing urban economy, it also maintains a wide diversity of entomological disease vectors, including biting flies, mosquitoes, and ticks. Pathogens endemic to the region include the agents of piroplasmosis, rickettsiosis, spirochetosis, and viral hemorrhagic fevers and encephalitis. The northwestern region of the country, including the Khyber Pakhtunkhwa Province (KPK), formerly the North-West Frontier Provence (NWFP), and the Federally Administered Tribal Areas (FATA) are mountainous regions with a high degree of habitat diversity that has recently undergone a massive increase in human population density due to an immigrating refugee population from neighboring war-torn Afghanistan. Vector-borne diseases in people and livestock are common in KPK and FATA regions due to the limited use of vector control measures and access to livestock vaccines. The vast majority of people in this region live in abject poverty with >70% of the population living directly from production gained in animal husbandry. In many instances whole families live directly alongside their animal counterparts. In addition, there is little to no awareness of the threat posed by ticks and transmission of either zoonotic or veterinary pathogens. Recent emergence of Crimean–Congo hemorrhagic fever virus in rural populations, outbreaks of Dengue hemorrhagic fever have been reported in the region, and high prevalence of cattle infected and co-infected with multiple species of hemoparasites (Theileria, Babesia, Anaplasma). The emergence of which has followed the increased density of the rural population due to an influx of refugees from violent conflicts in Afghanistan and is exacerbated by an already impoverished society and wide diversity of potential arthropod vectors. These human outbreaks may be exacerbated by episodes of social upheaval but are also tied to the historically close association of people in the region with their livestock and subsequent zoonosis that result from spillover from co-habitation with infected domestic animals.

Person-to-person transmission of severe fever with thrombocytopenia syndrome bunyavirus through blood contact

Severe fever with thrombocytopenia syndrome bunyavirus is a newly discovered bunyavirus with high pathogenicity to human. The transmission model has been largely uncharacterized. Investigation on a cluster of severe fever with thrombocytopenia syndrome cases provided evidence of person-to-person transmission through blood contact to the index patient with high serum virus load.

An update on crimean congo hemorrhagic Fever

Crimean Congo hemorrhagic fever (CCHF) is one of the deadly hemorrhagic fevers that are endemic in Africa, Asia, Eastern Europe, and the Middle East. It is a tick-borne zoonotic viral disease caused by CCHF virus of genus Nairovirus (family Bunyaviridae). CCHF not only forms an important public health threat but has a significant effect on the healthcare personnel, especially in resource-poor countries. India was always a potentially endemic area until an outbreak hit parts of Gujarat, taking four lives including the treating medical team. The current review is an attempt to summarize the updated knowledge on the disease particularly in modern era, with special emphasis on nosocomial infections. The knowledge about the disease may help answer certain questions regarding entry of virus in India and future threat to community.

Determination of serum adenosine deaminase and xanthine oxidase levels in patients with crimean-congo hemorrhagic fever

OBJECTIVE

Crimean-Congo hemorrhagic fever is an acute viral hemorrhagic fever with a high mortality rate. Despite increasing knowledge about hemorrhagic fever viruses, little is known about the pathogenesis of Crimean-Congo hemorrhagic fever. In this study, we measured serum adenosine deaminase and xanthine oxidase levels in Crimean-Congo hemorrhagic fever patients.

METHODS

Serum adenosine deaminase levels were measured with a sensitive colorimetric method described by Giusti and xanthine oxidase levels by the method of Worthington in 30 consecutive hospitalized patients (mean age 42.6 +/- 21.0). Laboratory tests confirmed their diagnoses of Crimean-Congo hemorrhagic fever. Thirty-five subjects (mean age 42.9 +/- 19.1) served as the control group.

RESULTS

There was a significant difference in adenosine deaminase and xanthine oxidase levels between cases and controls (p<0.05). However, neither adenosine deaminase nor xanthine oxidase levels varied with the severity of disease in the cases assessed (p>0.05).

CONCLUSION

Adenosine deaminase and xanthine oxidase levels were increased in patients with Crimean-Congo hemorrhagic fever. Elevated serum xanthine oxidase activity in patients with Crimean-Congo hemorrhagic fever may be associated with reactive oxygen species generated by the xanthine/xanthine oxidase system during inflammatory responses. In addition, elevated lipid peroxidation may contribute to cell damage and hemorrhage. The association of cell damage and hemorrhage with xanthine oxidase activity should be further investigated in large-scale studies.

Contact tracing and serosurvey among healthcare workers exposed to Crimean-Congo haemorrhagic fever in Greece

We investigated the probability of nosocomial transmission of Crimean-Congo haemorrhagic fever (CCHF) virus among healthcare workers (HCWs) who cared for the first CCHF case in Greece. Specific IgM and/or IgG antibodies against CCHF virus were not detected in the 21 HCWs studied. Although person-to-person transmission did not take place, education of HCWs about the modes of CCHF virus transmission and appropriate infection control measures is needed in order to avoid future nosocomial cases.

Knowledge, beliefs, and practices regarding tick bites in the Turkish population in a rural area of the Middle Anatolian Region

The aim of this study is to determine the knowledge, beliefs, and practices of a population living in a rural area in regards to tick bites and Crimean-Congo hemorrhagic fever (CCHF). The study was conducted in a rural area located in Central Anatolia in the region of Eskişehir. A total of 1,500 individuals aged 20 years and older chosen by a stratified random sample were enrolled. A questionnaire was administered in person. In 264 (17.4%) participants, there was a history of being bitten by a tick. This rate was higher in older persons, males, married persons, and farmers. The most commonly reported protective behavior was wearing long sleeves and long pants when wandering in rural areas (65.1% of participants). The least commonly reported behavior was using insect repellent on skin or clothes (3.3% of participants). Only 799 participants (54%) had heard about CCHF as a disease associated with ticks. Females, those with primary school education, housewives, and male farmers had a high frequency of having heard about CCHF. Tick bites and CCHF are important public health problems, yet the current knowledge of these problems is not sufficient in populations living in rural areas of the Middle Anatolian Region of Turkey.

Crimean Congo haemorrhagic fever, precautions and ribavirin prophylaxis: a case report

Crimean Congo haemorrhagic fever (CCHF) is a viral haemorrhagic disease, mostly transmitted by tick bites. It is clear that ignorance of the necessary precautions results in nosocomial infections in health care settings. Post exposure ribavirin prophylaxis is not well described. We report 2 cases of nosocomial CCHF infections.

Crimean-Congo hemorrhagic fever: a first case from Abbottabad, Pakistan

Crimean-Congo hemorrhagic fever (CCHF) is a deadly viral disease that is endemic in some parts of Pakistan. We report here the first ever case of CCHF from Abbottabad. The patient presented with abdominal pain, hematemesis and low platelets, and died within 24hours of admission. The diagnosis was confirmed by PCR for the CCHF virus. Because of the aggressive infection-control measures adopted, secondary and nosocomial spread was prevented.

Knowledge and attitude toward Crimean-Congo haemorrhagic fever in occupationally at-risk Iranian healthcare workers

We assessed the knowledge and attitude (K&A) toward Crimean-Congo haemorrhagic fever (CCHF) of occupationally at-risk healthcare workers (HCWs). A cross-sectional survey was performed in three referral hospitals in the Systan-Baluchestan and Isfahan provinces of Iran where CCHF is highly endemic. In all, 191/209 eligible HCWs were enrolled (response rate: 93%). All but 11 (5.8%) had heard of CCHF. The mean K&A scores of the respondents were 50.34% and 79.25%, respectively. The correlation between K&A was significant (correlation coefficient: 0.542; P<0.001). Being a physician, working in Isfahan (versus the relatively deprived Systan-Baluchestan) and relying on academic material rather than local media were independent factors significantly associated with more knowledge; higher education and laboratory staff with better attitude were also significant factors. Although HCWs showed the best K&A for preventive measures, only 44% wore gloves and masks for contact with CCHF patients and 22% failed to observe any safety measure. Those with a history of percutaneous contact (6.3%) had significantly lower knowledge scores (P=0.047). There is a need to establish professional education campaigns in highly endemic deprived areas in order to improve physicians' attitudes, encourage nurses' use of academic materials and increase the knowledge of less-educated HCWs.

Crimean congo hemorrhagic fever infection simulating thrombotic thrombocytopenic purpura

Crimean-Congo hemorrhagic fever (CCHF) is a tick-borne disease that may also be transmitted through person-to-person transmission by exposure to infected body fluids. Despite its wide geographic distribution in animals, CCHF virus is rarely associated with recognized human diseases. We report the first case of CCHF in Kermanshah province, Iran. Clinical presentation was characterized by fever, myalgia, and hemorrhage. The levels of liver enzymes, creatinine phosphokinase, and lactate dehydrogenase were elevated, and bleeding markers were prolonged.

Crimean-Congo hemorrhagic fever

PURPOSE OF REVIEW

Crimean-Congo hemorrhagic fever is a tick-borne viral zoonosis with the potential of human-to-human transmission, affecting wide areas in Asia, Southeastern Europe, and Africa. Hemorrhagic manifestations constitute a prominent symptom of late stage disease with case fatality rates from 10% to 50%. The purpose of this article is to review recent literature on Crimean-Congo hemorrhagic fever with emphasis on its epidemiology and management.

RECENT FINDINGS

Climate and environmental changes may affect Crimean-Congo hemorrhagic fever epidemiology and trigger community outbreaks. Risk factors for acquisition of infection have been well studied. In the hospital, high-risk activities include interventions for gastrointestinal bleeding and needle stick injuries. Reverse transcription-polymerase chain reaction may rapidly diagnose Crimean-Congo hemorrhagic fever with high sensitivity and specificity. Ribavirin is the only promising therapeutic agent currently available but case-control studies have not been conducted. Recently, the Mx proteins have been found to act against Crimean-Congo hemorrhagic fever virus and deserve further research.

SUMMARY

Clinicians should be aware of the potential of importation of Crimean-Congo hemorrhagic fever cases from endemic areas and nosocomial transmission. Studies on the efficacy of ribavirin are needed.

The lack of Crimean-Congo hemorrhagic fever virus antibodies in healthcare workers in an endemic region

We aimed to detect antibodies against Crimean-Congo hemorrhagic fever virus (CCHFV) in healthcare workers (HCWs) in an endemic region. The study was conducted in a tertiary care hospital that had cared for CCHFV infected patients in the period 2002-2003. The sera from the HCWs were collected one month after the last admitted hospital case (October 2003), and sent to the Pasteur Institute, Lyon, France to be studied for CCHF IgM and IgG by ELISA. The total number of HCWs included in the study was 75; the median age was 30, 68% of the subjects were female, and 83% of the HCWs were at risk of exposure to the body fluids of patients. Only one HCW from the group without risk of exposure was CCHF IgG positive. The adherence rate to universal precautions was high. In conclusion, a lack of CCHFV transmission from patients to HCWs was observed. This result could be related to the high rate of compliance to the universal precautions, which are sufficient to protect against CCHFV infection.

Crimean-Congo haemorrhagic fever

Crimean-Congo haemorrhagic fever (CCHF) is an often fatal viral infection described in about 30 countries, and it has the most extensive geographic distribution of the medically important tickborne viral diseases, closely approximating the known global distribution of Hyalomma spp ticks. Human beings become infected through tick bites, by crushing infected ticks, after contact with a patient with CCHF during the acute phase of infection, or by contact with blood or tissues from viraemic livestock. Clinical features commonly show a dramatic progression characterised by haemorrhage, myalgia, and fever. The levels of liver enzymes, creatinine phosphokinase, and lactate dehydrogenase are raised, and bleeding markers are prolonged. Infection of the endothelium has a major pathogenic role. Besides direct infection of the endothelium, indirect damage by viral factors or virus-mediated host-derived soluble factors that cause endothelial activations and dysfunction are thought to occur. In diagnosis, enzyme-linked immunoassay and real-time reverse transcriptase PCR are used. Early diagnosis is critical for patient therapy and prevention of potential nosocomial infections. Supportive therapy is the most essential part of case management. Recent studies suggest that ribavirin is effective against CCHF, although definitive studies are not available. Health-care workers have a serious risk of infection, particularly during care of patients with haemorrhages from the nose, mouth, gums, vagina, and injection sites. Simple barrier precautions have been reported to be effective.

Imported Crimean-Congo hemorrhagic Fever

Crimean-Congo hemorrhagic fever (CCHF) is a tick-borne disease that may also be transmitted through person-to-person transmission by exposure to infected body fluids. Despite its wide geographic distribution in animals, CCHF virus is rarely associated with recognized human diseases. We report the first case of imported CCHF in France.