Crimean hemorrhagic fever-Congo (CHF-C) virus antibodies in man, and in domestic and small mammals, in Iran

Replicon particle vaccination induces non-neutralizing anti-nucleoprotein antibody-mediated control of Crimean-Congo hemorrhagic fever virus

Crimean-Congo hemorrhagic fever virus (CCHFV) can cause severe human disease and is considered a WHO priority pathogen due to the lack of efficacious vaccines and antivirals. A CCHF virus replicon particle (VRP) has previously shown protective efficacy in a lethal Ifnar-/- mouse model when administered as a single dose at least 3 days prior to challenge. Here, we determine that non-specific immune responses are not sufficient to confer short-term protection, since Lassa virus VRP vaccination 3 days prior to CCHFV challenge was not protective. We also investigate how CCHF VRP vaccination confers protective efficacy by examining viral kinetics, histopathology, clinical analytes and immunity early after challenge (3 and 6 days post infection) and compare to unvaccinated controls. We characterize how these effects differ based on vaccination period and correspond to previously reported CCHF VRP-mediated protection. Vaccinating Ifnar-/- mice with CCHF VRP 28, 14, 7, or 3 days prior to challenge, all known to confer complete protection, significantly reduced CCHFV viral load, mucosal shedding, and markers of clinical disease, with greater reductions associated with longer vaccination periods. Interestingly, there were no significant differences in innate immune responses, T cell activation, or antibody titers after challenge between groups of mice vaccinated a week or more before challenge, but higher anti-NP antibody avidity and effector function (ADCD) were positively associated with longer vaccination periods. These findings support the importance of antibody-mediated responses in VRP vaccine-mediated protection against CCHFV infection.

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.

Distribution pattern of Crimean-Congo Hemorrhagic Fever in Asia and the Middle East

Crimean-Congo Hemorrhagic Fever (CCHF) is one of the most important vector-borne diseases of zoonotic potential that can be acquired following the bite of the Hyalomma species of ticks. It is a highly prevalent disease in Asia and the Middle East. The risk factors of this disease are contact with infected tissue, blood, patient, or livestock in the acute viremic phase, infected tick bites, or the manual removal of ticks. The disease is clinically described as progressive hemorrhages, fever, and pain in musculature. Biochemical tests reveal elevated levels of creatinine phosphokinase, alanine transaminase, aspartate aminotransferase, and lactate dehydrogenase. Clotting time is prolonged in pro-thrombin tests, and pathogenesis is mostly related to the disruption of the epithelium during viral replication and indirectly by secreting cytotoxic molecules. These molecules cause endothelial activation and result in the loss of function. Supportive therapy is given through blood or plasma infusions to treat or manage the patients. According to the most advanced studies, CCHF can be treated by Ribavirin, which is an antiviral drug that shows excellent results in preventing the disease. Health-care staff are more prone to infection. The hemorrhagic phase represents a high risk for accidental exposures. This literature review presents a comprehensive overview of the viral epidemiology, zoonotic perspectives, and significant risk factors of CCHF in various Middle East and Asian countries. Furthermore, the pathophysiology and preventive strategies of CCHF have also been discussed as well as legislation and policies regarding public outreach programs, research, and development aimed at infection prevention and control that are required at a global level.

Molecular Epidemiology and Phylogeny of Crimean-Congo Haemorrhagic Fever (CCHF) Virus of Ixodid Ticks in Khorasan Razavi Province of Iran

Background:

Crimean–Congo hemorrhagic fever (CCHF) is a fatal disease caused by Nairovirus classified within the Bunyaviridae family. The virus is transmitted to humans through the bites of infected ticks or direct contact with viremic animals or humans. The current study aimed to detect the virus genome in ticks from Khorasan Razavi Province.

Methods:

One hundred hard ticks were collected randomly from 100 sheep in four different areas of the province. Collected ticks were kept alive and identified. All the ticks were analyzed for the presence of CCHF virus genome using reverse transcriptase polymerase chain reactions (RT-PCR).

Results:

The identified ticks were belonging to Hyalomma marginatum (16% female and 6% male), Rhipicephalus turanicus (52% female and 25% male), and Dermacentor raskemensis (1%). The CCHF virus genome was found in Hyalomma marginatum (5% male from Taibad and Sabzevar region and 1% female from Taibad). Genetic analysis of the virus genome isolated from two regions (Sabzevar and Taibad) showed 100% identity.

Conclusion:

This study indicated that CCHF should be regarded as a risk-borne infection in this province. Therefore, special health management is needed to control this disease.

Zoonotic implications of camel diseases in Iran

Approximately 60% of all human pathogens and 75% of emerging infectious diseases are zoonotic (of animal origin). Camel zoonotic diseases can be encountered in all camel-rearing countries. In this article, all studies carried out on camel zoonotic diseases in Iran are reviewed to show the importance of camels for public health in this country. More than 900 published documents were systematically searched to find relevant studies from 1,890 until late 2018. The collected articles were classified according to the aetiological agents. In this study, 19 important zoonotic diseases were reported among Iranian camels including listeriosis, leptospirosis, plague, Q fever, brucellosis, campylobacteriosis, tuberculosis, pasteurellosis, clostridiosis, salmonellosis, Escherichia coli infections, rabies, camelpox, Middle East respiratory syndrome coronavirus, Crimean-Congo haemorrhagic fever, echinococcosis, cryptosporidiosis, toxoplasmosis and dermatophytosis, most of which belong to bacterial, viral, parasitic and fungal pathogens, respectively. Results show that camels are one of the most important sources of infections and diseases in human; therefore, continuous monitoring and inspection programs are necessary to prevent the outbreak of zoonotic diseases caused by this animal in humans.

Diagnostic Testing for Crimean-Congo Hemorrhagic Fever

Crimean-Congo hemorrhagic fever is the most geographically widespread tick-borne virus, with infection resulting in mortality in up to 30% of cases. Clinical diagnosis alone is difficult due to the nonspecific nature of symptoms; therefore, laboratory diagnostics should be utilized for patients with residence in or travel to regions of endemicity in whom the disease is suspected. This minireview provides an overview of laboratory tests available for Crimean-Congo hemorrhagic fever (CCHF) and their utility in diagnosis with a focus on diagnosing CCHF in humans.

Epidemiological investigations of Crimean-Congo haemorrhagic fever virus infection in sheep and goats in Balochistan, Pakistan

Crimean-Congo haemorrhagic fever (CCHF) is a tick-borne zoonotic disease caused by the arbovirus Crimean-Congo haemorrhagic fever virus (CCHFV). Livestock serve as a transient reservoir for CCHFV, but do not show clinical signs. In this cross-sectional study, sheep and goats in Balochistan, Pakistan, were examined to determine the CCHFV seroprevalence, spatial distribution of seropositive sheep and goats, and to identify potential risk factors for seropositivity to CCHFV in these animals. To this end, farms and animals were selected by systematic sampling, blood samples from 800 sheep and 800 goats were collected and information regarding farm management and the kept animals were retrieved using a standard questionnaire. Sera were tested for antibodies against CCHFV in two independent ELISA formats and an immunofluorescence assay (IFA) following a hierarchical diagnostic decision tree. By these assays 149 (19 %, 95 %-CI: 16-21 %) out of 800 sheep serum samples and 37 (5 %, 95 %-CI: 3-6 %) out of 800 goat serum samples were positive for CCHFV-specific IgG antibodies. Interestingly, at least 8 (5 %, 95 %-CI: 2-10 %) out of 160 sera pools were from CCHFV viraemic sheep, as sera (in pools of 5) tested positive for CCHFV genome by real-time PCR (RT-qPCR). Risk factor analysis revealed that the open type of housing (OR = 3.76, 95 %-CI:1.57-9.56, p-value = 0.003), grazing (OR = 4.18, 95 %-CI:1.79-10.37, p-value = 0.001), presence of vegetation in or around the farm (OR = 3.13, 95 %-CI: 1.07-10.15, p-value = 0.043), lack of treatment against ticks (OR = 3.31, 95 %-CI: 1.16-10.21, p-value = 0.029), absence of rural poultry (OR = 2.93, 95 %-CI: 1.41-6.29, p-value = 0.004), animals with age ≥ 2 years (OR = 4.15, 95 %-CI: 2.84-6.19, p-value<0.001), animals infested with ticks (OR = 2.35, 95 %-CI: 1.59-3.52, p-value<0.001), and sheep species (OR = 4.72, 95 %-CI:3.24-6.86, p-value<0.001) represented statistically significant risk factors associated with seropositivity to CCHFV. Taken together this study confirms the circulation of CCHFV in livestock in Balochistan, Pakistan. The identification of risk factors might help to reduce the risk of infection in sheep and goats, which may also mitigate the risk for human infection. An interesting option for reducing the risk of CCHFV infection in small ruminants is keeping also chickens, since they pick ticks that transmit CCHFV.

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 (CCHF) seroprevalence: A systematic review and meta-analysis

Crimean-Congo haemorrhagic fever (CCHF) is the most widespread, tick-borne viral disease affecting humans and therefore this paper performed a meta-analysis to highlight seroprevalence features of CCHF in a global context. After a preliminary review of the 396 papers representing areas throughout the world, 206 were selected for detailed meta-analysis. In general the total means of CCHF seroprevalence were, respectively 4.7 and 24.6% for humans and animals; and 17.1, 18.9, 24.3, 29.3 and 27.1% for camels, cattle, goats, sheep and livestock. Statistical analysis revealed a significant difference in seroprevalence between humans and camels (P = 0.043), cattle (P = 0.010), goats (P = 0.015), sheep (P = 0.005) and livestock (P = 0.017). Regionally, there also was a difference between humans, and goats (P = 0.0001), sheep (P = 0.007) and livestock (P = 0.002). Globally, CCHF seroprevalence in at-risk professionals was 7.5 fold greater than in normal humans, while CCHF seroprevalence was 5 fold greater in animals, camels, cattle, goats, sheep and livestock than normal humans. Animal contact, animal husbandry, farming, tick bite history and secretion exposure were the most frequently reported CCHF seropositivity risk factors. This study serves as an important resource for epidemiological discussions related to CCHF and CCHF seroprevalence features, providing specific information in understanding human and animal mean and trend CCHF seroprevalence for different regions of the world and on an aggregate global scale; seroprevalence in at-risk professionals; and total mean and trend CCHF seropositivity involving risk factors.

Can Bats Serve as Reservoirs for Arboviruses?

Bats are known to harbor and transmit many emerging and re-emerging viruses, many of which are extremely pathogenic in humans but do not cause overt pathology in their bat reservoir hosts: henipaviruses (Nipah and Hendra), filoviruses (Ebola and Marburg), and coronaviruses (SARS-CoV and MERS-CoV). Direct transmission cycles are often implicated in these outbreaks, with virus shed in bat feces, urine, and saliva. An additional mode of virus transmission between bats and humans requiring further exploration is the spread of disease via arthropod vectors. Despite the shared ecological niches that bats fill with many hematophagous arthropods (e.g. mosquitoes, ticks, biting midges, etc.) known to play a role in the transmission of medically important arboviruses, knowledge surrounding the potential for bats to act as reservoirs for arboviruses is limited. To this end, a comprehensive literature review was undertaken examining the current understanding and potential for bats to act as reservoirs for viruses transmitted by blood-feeding arthropods. Serosurveillance and viral isolation from either free-ranging or captive bats are described in relation to four arboviral groups (Bunyavirales, Flaviviridae, Reoviridae, Togaviridae). Further, ecological associations between bats and hematophagous viral vectors are characterized (e.g. bat bloodmeals in mosquitoes, ingestion of mosquitoes by bats, etc). Lastly, knowledge gaps related to hematophagous ectoparasites (bat bugs and bed bugs (Cimicidae) and bat flies (Nycteribiidae and Streblidae)), in addition to future directions for characterization of bat-vector-virus relationships are described.

Rodent-borne diseases and their public health importance in Iran

Background

Rodents are reservoirs and hosts for several zoonotic diseases such as plague, leptospirosis, and leishmaniasis. Rapid development of industry and agriculture, as well as climate change throughout the globe, has led to change or increase in occurrence of rodent-borne diseases. Considering the distribution of rodents throughout Iran, the aim of this review is to assess the risk of rodent-borne diseases in Iran.

Methodology/Principal finding

We searched Google Scholar, PubMed, Science Direct, Scientific Information Database (SID), and Magiran databases up to September 2016 to obtain articles reporting occurrence of rodent-borne diseases in Iran and extract information from them. Out of 70 known rodent-borne diseases, 34 were reported in Iran: 17 (50%) parasitic diseases, 13 (38%) bacterial diseases, and 4 (12%) viral diseases. Twenty-one out of 34 diseases were reported from both humans and rodents. Among the diseases reported in the rodents of Iran, plague, leishmaniasis, and hymenolepiasis were the most frequent. The most infected rodents were Rattus norvegicus (16 diseases), Mus musculus (14 diseases), Rattus rattus (13 diseases), Meriones persicus (7 diseases), Apodemus spp. (5 diseases), Tatera indica (4 diseases), Meriones libycus (3 diseases), Rhombomys opimus (3 diseases), Cricetulus migratorius (3 diseases), and Nesokia indica (2 diseases).

Conclusions/Significance

The results of this review indicate the importance of rodent-borne diseases in Iran. Considering notable diversity of rodents and their extensive distribution throughout the country, it is crucial to pay more attention to their role in spreading infectious diseases for better control of the diseases.

This review showed that approximately half of the known rodent-borne diseases have been reported in Iran, half of which were reported both in humans and rodents. Most of the diseases were bacterial and parasitic. Plague, leishmaniasis, and hymenolepiasis were the most frequent diseases among rodent populations. Also, this review showed that among the rodent species, three commensal ones—R. norvegicus, M. musculus, and R. rattus—play an important role in the transmission of diseases to humans in Iran. Considering repeated reports of many of these diseases in humans and rodents, and the notable diversity and extensive distribution of rodents throughout Iran, it is crucial to pay adequate attention to rodents as a source of zoonotic infectious diseases in the country.

Co-circulation of Crimean-Congo Hemorrhagic Fever virus strains Asia 1 and 2 between the border of Iran and Pakistan

Crimean-Congo Hemorrhagic Fever (CCHF) is a tick-borne viral disease that is transmitted by numerous species of ticks, which serve both as a reservoir and vector of CCHF virus (CCHFV). Molecular and serological tests were undertaken on hard ticks (Ixodidae spp.) and samples from livestock were collected in 2015 from Chabahar County in Southeast Iran. Using RT-PCR, the ticks were tested for the presence of CCHFV. In addition, seven livestock were serologically tested for the presence of IgG antibodies using an ELISA test. IgG antibodies against CCHFV were detected in one of 7 of the livestock that were tested. In total, 49 ticks including five species: Rhipicephalus sanguineus, Hyalomma anatolicum, Hy. asiaticum, Hy. dromedarii and Hy. marginatum with a prevalence of 46.9%, 32.7%, 4.1%, 4.1% and 2.1% respectively were identified. CCHFV was detected in three ticks among 49 collected ticks. The ticks infected with CCHFV belonged to the genus Hyalomma and Rhipicephalus. Phylogenetic analysis demonstrated that two sequences clustered in clade IV (Asia-1) and one sequence was located within clade IV (Asia-2). Most of the animal and human CCHF cases of the country are reported from Sistan and Baluchistan provinces. Regular monitoring programs in the tick population and livestock are needed in the future.

Draft Genome Sequences of Eight Crimean-Congo Hemorrhagic Fever Virus Strains

Crimean-Congo hemorrhagic fever virus (CCHFV) is a geographically widespread RNA virus with a high degree of genomic diversity that complicates sequence-based diagnostics. Here, we sequenced eight CCHFV strains for improved assay design and deposition into FDA-ARGOS, the FDA’s pathogen database for development and verification of next generation sequencing assays.

Vector and Serologic Survey for Crimean-Congo Hemorrhagic Fever Virus in Poland

In contrast to animals, Crimean-Congo hemorrhagic fever (CCHF) causes a severe disease in humans with a high mortality rate. The etiological agent, CCHF virus (CCHFV), can be transmitted by argasid and ixodid ticks, but arachnids of the genus Hyalomma, followed by Rhipicephalus and Dermacentor serve as the major vectors of this virus. The goal of the study was to assess the epidemiological situation of CCHFV infection in cattle in south-east Poland, and survey for potential tick vector species. A total of 592 bovine blood samples from animals located in the southernmost region in Poland were tested by IgG sandwich enzyme-linked immunosorbent assay. Ticks (n = 993) from south-east Poland were collected from dogs, cats, cattle, and horses and tested by RT-PCR. All 592 serum samples were negative for IgG antibodies to CCHFV. Of the ticks collected, 125 were Dermacentor reticulatus and 868 represented Ixodes ricinus, both species are regarded as potential vectors of CCHFV. All tick samples were negative for the presence of CCHFV. Considering the zoonotic nature, public health importance, and the virus increasing spread, it was prudent to assess the seroprevalence of CCHFV in the south-east area of Poland, bordering with CCHFV endemic areas. It seems unlikely that CCHFV infection will suddenly spread in Poland, but considering the multiple possibilities of the virus introduction, serosurveys and vector biosurveillance should be conducted at regular intervals.

Current situation of Crimean-Congo hemorrhagic fever in Southeastern Europe and neighboring countries: a public health risk for the European Union?

Crimean-Congo hemorrhagic fever (CCHF) is the most widespread tick-borne viral infection of humans, occurring across western China through southern Asia, Middle East, and Southeastern Europe (SEE) and in the most of African countries. CCHF virus is maintained through vertical and horizontal transmission in several genera of ticks, mainly in Hyalomma, which spreads the virus to a variety of wild and domestic mammals, which develop a transient viremia without signs of illness. Human infections occur through tick bite or exposure to the blood or other body fluids of an infected animal or of a CCHF patient. In SEE the number of clinical cases of CCHF as well as the areal of the infected ticks continuously rapidly increased after 2000. The aim of this study was to present actual situation of CCHF in SEE. Sources of information include published literature and personal unpublished data.

CONCLUSIONS

Based on: 1. Hyaloma's presence in Western EU countries, 2. Changes in climatic conditions and 3. Absence of an active vaccination against CCHF, it can be expected that this disease will continue to present real threat for human health in SEE and Southwestern Europe (SWE).

Seroepidemiological Studies of Crimean-Congo Hemorrhagic Fever Virus in Domestic and Wild Animals

Crimean-Congo hemorrhagic fever (CCHF) is a widely distributed, tick-borne viral disease. Humans are the only species known to develop illness after CCHF virus (CCHFV) infection, characterized by a nonspecific febrile illness that can progress to severe, often fatal, hemorrhagic disease. A variety of animals may serve as asymptomatic reservoirs of CCHFV in an endemic cycle of transmission. Seroepidemiological studies have been instrumental in elucidating CCHFV reservoirs and in determining endemic foci of viral transmission. Herein, we review over 50 years of CCHFV seroepidemiological studies in domestic and wild animals. This review highlights the role of livestock in the maintenance and transmission of CCHFV, and provides a detailed summary of seroepidemiological studies of wild animal species, reflecting their relative roles in CCHFV ecology.

Crimean-Congo Hemorrhagic Fever Virus Clade IV (Asia 1) in Ticks of Western Iran

Crimean-Congo Hemorrhagic Fever virus (CCHFV) is transmitted through the bite of an infected tick, or by direct contact with CCHFV-infected patients' blood or the products of infected livestock. In 2012, ticks were collected in eight regions of Lorestan Province, Iran. In total, 434 ticks were collected. Reverse transcriptase polymerase chain reaction was used for the detection of CCHFV RNA. Of 434 ticks, 419 (96.6%) ticks were from the family Ixodidae (hard ticks) and 15 (3.5%) ticks were from the family Argasidae (soft ticks). The presence of CCHFV RNA was detected in 29 (6.7%) of 434 ticks. The infected tick species include Hyalomma asiaticum (n = 7, 7.4%), Hyalomma anatolicum (n = 12, 13.2%), Hyalomma marginatum (n = 1, 16.7%), and Rhipicephalus sanguineus (n = 9, 4.3%). These empirical data demonstrated that the majority of CCHFV-positive ticks belonged to the Ixodidae. None of the Argasidae and Haemaphysalis sulcata species was infected with CCHFV. The phylogenetic analyses of the tick-derived CCHFV strains revealed that all 29 viral strains fell in clade IV (Asia 1). The most abundant species of tick collected in this study was R. sanguineus followed by different species of Hyalomma. Given the infection rate among collected ticks, H. marginatum was the most abundant infected tick species (16.7%) followed by H. anatolicum (13.2%), H. asiaticum (7.4%), and R. sanguineus (4.3%).

First phylogenetic analysis of a Crimean-Congo hemorrhagic fever virus genome in naturally infected Rhipicephalus appendiculatus ticks (Acari: Ixodidae)

Crimean-Congo haemorrhagic fever (CCHF) is a potentially fatal systemic viral disease in many parts of the world, including Iran. The nationwide incidence of human CCHF in endemic areas was 870 confirmed cases with 126 deaths (case fatality rate, CFR = 17.6 %) in the decade leading to 2012. The detection of the CCHF virus (CCHFV) genome in tick vectors is of fundamental importance for identifying these ticks as potential reservoirs of CCHFV infection. From May to October 2013, following detection of four new clinical cases resulting in two deaths in the city of Mashhad (northeast Iran), hard ticks were recovered from infested livestock in 40 villages in Khorasan-Razavi province and examined by the microscopic method for species identification. About a quarter of the ticks were then subjected to reverse-transcription polymerase chain reaction (RT-PCR) to detect the CCHFV genome. The PCR products were then sequenced, and their phylogenetic lineages were determined. A total of 407 hard ticks were captured, representing seven different species in two distinct genera. Members of the genus Hyalomma were widely distributed in all but two of the villages studied, and this was also the most frequent (83.3 %) tick genus. Of 105 adult ticks subjected to RT-PCR, four (3.8 %) ticks were found positive for the CCHFV genome. One brown ear tick, Rhipicephalus appendiculatus, was found to be naturally infected for the first time anywhere in the world. Ticks of Hyalomma asiaticum, Hyalomma marginatum, and Rhipicephalus turanicus were also found to be naturally infected with CCHFV. CCHFV found in these four different tick species were clustered in the same lineage with the Matin and SR3 strains from Pakistan and some other strains from Iran, indicating that these tick species were naturally infected with genetically closely related CCHFV in the region. The presence of CCHFV infection in four different hard tick species was confirmed using RT-PCR in northeast Iran. Part of this infection was attributed to Rh. appendiculatus, which is thus a potential new natural vector of CCHFV in Iran. It is also confirmed by phylogenetic analysis that CCHFV in this region is genetically closely related, even in the different tick species.

Spatial analysis of Crimean Congo hemorrhagic fever in Iran

Crimean Congo hemorrhagic fever (CCHF) is a viral zoonotic disease. During 1999-2011, 871 human cases of CCHF were diagnosed in Iran. A history of serologic conversion for CCHF virus was seen in 58.7% of 2,447 sheep samples, 25.0% of 1,091 cattle samples and 24.8% of 987 goat samples from different parts of Iran. Spatial analysis showed that the main foci of this disease in humans during these years were in eastern Iran (P < 0.01) and the second most common foci were in northeastern and central Iran. Two livestock foci were detected in the northeastern northwestern Iran. On the basis of the results of this study, infection likely entered Iran from eastern and western neighboring countries.

A case report of crimean congo hemorrhagic Fever in ostriches in iran

Crimean Congo hemorrhagic fever (CCHF) is a viral zoonosis, which is usually transmitted via tick bites or close contact with infected blood or tissue. This disease can cause a case fatality rate of up to 25%-30% in humans. CCHF Infection in birds is less documented. An ostrich can reproduce viruses and can also play the role of a mechanical vector, by transporting infected ticks without becoming ill. In March 2007, three butchers and one worker in an ostrich farm were infected with CCHF in central part of Iran. Considering the role ostriches play in transmitting the disease, serum samples from five ostriches of that farm were taken and sent to the laboratory for CCHF ELISA tests. The result of the IgG test was positive for one (20%) of the ostriches. At the same time, serum samples of eight sheep from the same farm were sent for IgG testing, two (25%) of which were positive. This was the first report of CCHF infection of an ostrich in Iran and tracing CCHF IgG against this ostrich and the afore-mentioned sheep may have revealed that the disease in the worker was the cause of transmission of this disease from these animals or their ticks.

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.

Crimean-Congo hemorrhagic fever in Iran

The presence of Crimean-Congo hemorrhagic fever virus (CCHFV) in Iran was first identified in studies of livestock sera and ticks in the 1970s, but the first human infection was not diagnosed until 1999. Since that time, the number of cases of CCHF in Iran has markedly increased. Through January 2012, articles in the published literature have reported a total of 870 confirmed cases, with 126 deaths, for a case fatality rate (CFR) of 17.6%. The disease has been seen in 26 of the country's 31 provinces, with the greatest number of cases in Sistan and Baluchestan, Isfahan, Fars, Tehran, Khorasan, and Khuzestan provinces. The increase in CCHF in Iran has paralleled that in neighboring Turkey, though the number of cases in Turkey has been much larger, with an overall CFR of around 5%. In this article, we review the features of CCHF in Iran, including its history, epidemiology, animal and tick reservoirs, current surveillance and control programs, diagnostic methods, clinical features and experience with ribavirin therapy, and consider possible explanations for the difference in the CFR of CCHF between Iran and Turkey. The emergence of CCHF in Iran calls for countermeasures at many levels to protect the population, but also provides opportunities for studying the epidemiology, diagnosis and management of the disease.

Molecular detection of Crimean-Congo haemorrhagic fever (CCHF) virus in ticks from southeastern Iran

Crimean-Congo haemorrhagic fever (CCHF) virus is a tick-borne member of the genus Nairovirus, family Bunyaviridae. CCHF virus has been isolated from at least 31 different species of ticks. The virus is transmitted through the bite of an infected tick or by direct contact with CCHF virus-infected patients or the products of infected livestock. This study was conducted to determine the rate of CCHF virus infection in ticks in the district of Zahedan, in the province of Sistan and Baluchistan, southeastern Iran. A total of 140 ticks were collected from Sistan and Baluchistan. Reverse transcriptase-polymerase chain reaction (RT-PCR) was used for the detection of the CCHF virus genome in the tick population. This genome was detected in 4.3% of ticks collected from livestock of different regions of Zahedan. The infected tick genera belonged to Hyalomma and Haemaphysalis. Although in the epidemiology of CCHF virus Hyalomma ticks are considered to be the most important vectors and reservoirs, the virus has also been reported to occur in other genera of ticks, which conforms to the current data in our study from Sistan and Baluchistan. Given that animals are common hosts for Hyalomma and Haemaphysalis, regular monitoring programmes for livestock should be applied for CCHF virus control.

Serological evaluation of Crimean-Congo hemorrhagic fever in humans with high-risk professions living in enzootic regions of Isfahan province of Iran and genetic analysis of circulating strains

Crimean-Congo hemorrhagic fever (CCHF) is a zoonotic viral disease that is asymptomatic in infected livestock, but causes a serious threat to humans with a mortality rate up to 50%. Although the CCHF virus (CCHFV) is often transmitted by ticks, livestock-to-human and human-to-human transmission also occurs. In the current study, we focused on CCHF in the province of Isfahan, located in the center of Iran and deemed to be the second most infected province. Human and livestock sera and resident ticks in the livestock are collected from different regions of the province and analyzed with specific IgG ELISA and RT-PCR tests. Overall, 12% and 12.7% of studied human and livestock populations were IgG positive, respectively. The genome of CCHFV was detected in 9% of ticks resident in livestock involved in this survey. The CCHFV isolates from infected ticks were genetically examined. Nucleotide sequence of the S-segment revealed that the different isolates were closely related to each other, with nucleotide sequence identities higher than 98%. Phylogenetic analysis demonstrated that a variant isolate clustered with the Iraq strain. This high proportion of IgG-positive sera and nearly high proportion of infected ticks increases the risk of CCHF outbreaks in the province and probably posits a great danger to other provinces.

A serosurvey of Crimean-Congo haemorrhagic fever virus in dairy cattle in Iran

A seroepidemiological survey to determine the prevalence of Crimean-Congo haemorrhagic fever (CCHF) virus among dairy cattle in Iran was carried out during 2006 and 2008. Blood samples were collected from 876 animals in five different provinces of the country. Sera were tested by a sandwich enzyme-linked immunosorbent assay (ELISA) for quantitative determination of antibodies to CCHF virus. Serological evidence of infection was noted in 52 (5.9%) of 876 dairy cattle. Antibody prevalence increased with age; 78.8% seroprevalence in cattle older than 3 years versus 21.2% in animals less than 2 years old. There was a difference between provinces representing north-east (11.7%) and east (2%) of Iran.

Geographical distribution and surveillance of Crimean-Congo hemorrhagic fever in Iran

Crimean-Congo hemorrhagic fever (CCHF) is viral hemorrhagic fever caused by CCHF virus, which belongs to the family Bunyaviridae and the genus Nairovirus. The virus is transmitted to humans via contact with blood and tissue from infected livestock, a tick bite, or contact with an infected person. Since 2000, we have shown the disease to be prevalent in 23 out of 30 provinces of Iran. Among those, Sistan-va-Baluchistan, Isfahan, Fars, Tehran, Khorasan, and Khuzestan demonstrated the highest infection, respectively. Notably, Sistan-va-Baluchistan province, southeast of Iran, has the highest prevalence of CCHF, and has shown to be present since at least 2000. Phylogenetic study of the CCHF virus genome isolated from Iranian patients showed a close relationship with the CCHF Matin strain (Pakistan). Our epidemiological data in the last decade have implied that the severity and fatality rate of the disease has ranged variably in different provinces of Iran. More pathogenesis and phylogenetic studies should therefore be investigated to clarify these differences.

Crimean-Congo haemorrhagic fever cases in Turkey

Crimean-Congo haemorrhagic fever (CCHF) is an arbovirus infection, which is transmitted through ticks or via blood and secretions. Until recently, human cases of CCHF were unknown in Turkey; however, several acute disease cases were reported in 2002. We report on the investigation of a cluster of suspected CCHF cases in the middle part of the Black Sea from May 2002 to October 2003. The medical charts that we reviewed were obtained from all local physicians and our field investigations. 'Suspected case' was defined with regard to time, place, and both clinical and laboratory characteristics. A total of 108 patients were defined as suspected case. Among them 36 patients were reached and blood samples taken for examination for CCHF by using ELISA and RT-PCR. According to the laboratory analysis, 80.6% (29/36) were acute cases and 8.3% (3/36) were past CCHF infections. The overall mortality rate was 5.6%. There was no nosocomial infection; however, there were 2 family clusters. Tick exposure was the most prevalent risk factor (74.2%). A multidisciplinary collaboration should be developed in order to understand the magnitude of the disease and also to keep it under control.

Crimean-Congo hemorrhagic fever virus in high-risk population, Turkey

In the Tokat and Sivas provinces of Turkey, the overall Crimean-Congo hemorrhagic fever virus (CCHFV) seroprevalence was 12.8% among 782 members of a high-risk population. CCHFV seroprevalence was associated with history of tick bite or tick removal from animals, employment in animal husbandry or farming, and being >40 years of age.

Evaluation of a Crimean-Congo hemorrhagic fever virus recombinant antigen expressed by Semliki Forest suicide virus for IgM and IgG antibody detection in human and animal sera collected in Iran

Crimean-Congo hemorrhagic fever virus (CCHFV) is transmitted to humans by ticks or by direct contact with infected blood. It causes severe, often fatal, hemorrhagic diseases in humans but infection in animals is asymptomatic. CCHFV can spread from person to person and has caused many nosocomial outbreaks. Because the virus is very pathogenic for humans it must be manipulated in a biosafety level 4 (BSL4) laboratory, rendering the production of antigen for serological diagnosis difficult. To replace the native antigen, we produced a recombinant nucleoprotein expressed in mammalian cells via the recombinant Semliki Forest alphavirus replicon and developed an indirect immunofluorescence assay (IFA) as well as an enzyme-linked immunosorbent assay (ELISA) by immunocapture to detect IgM and IgG in human and animal serum. Using these methods, we analyzed clinical samples from human patients and sera from domestic animals collected in Iran and we show that this novel antigen provides a novel, sensitive and specific tool for CCHF diagnosis.

Crimean-Congo haemorrhagic fever outbreak in Middle Anatolia: a multicentre study of clinical features and outcome measures

A Crimean-Congo haemorrhagic fever (CCHF) outbreak emerged from 2001 to 2003 in the Middle Anatolia region of Turkey. This study describes the clinical characteristics and outcome features of CCHF patients admitted to four tertiary care hospitals in Turkey. Definitive diagnosis was based on the detection of CCHF virus-specific IgM by ELISA or of genomic segments of the CCHF virus by RT-PCR. Related data were collected by a retrospective chart review. Hospital costs were extracted from the final discharge bills. Univariate and multivariate analyses were conducted to determine the independent predictors of mortality. CCHF virus-specific antibodies or genomic segments were detected in the sera of 99 cases. Seven cases that were treated with ribavirin were excluded from the study. Cases were mostly farmers (83 cases, 90 %), and 60 % had a tick-bite history before the onset of fever. Impaired consciousness and splenomegaly were independent predictors of a fatal outcome.

Genetic analysis of Crimean-congo hemorrhagic fever virus in Iran

Crimean-Congo hemorrhagic fever (CCHF) is a potentially fatal disease caused by a tick-borne virus in the family Bunyavridae. The disease occurs in parts of Africa, Asia, Middle East, and Eastern Europe. During recent years, an increasing number of human CCHF cases have been diagnosed in Iran, but very little information is available on the prevalence and genetic diversity of CCHFV in Iran. In the present study, CCHF virus (CCHFV) isolates from nine Iranian patients infected during 2002 were examined genetically. Nucleotide sequencing of the S- and M-segments, encoding the nucleocapsid protein (NP) and the glycoproteins, respectively, revealed that the different isolates were related closely to each other with nucleotide sequence identities exceeding 98% for both S- and M-segments. Phylogenetic analysis of partial S-segment nucleotide sequences showed that the viruses clustered along with strains from Pakistan and Madagascar in one distinct lineage. Phylogenetic analysis also demonstrated that the Iranian isolates examined in this study and the previously published CCHFV strain ArTeh193-3 clustered into different genetic groups, indicating that at least two genetic lineages of CCHFV could be co-circulating in Iran.

Crimean-Congo hemorrhagic fever in Sistan and Baluchestan Province of Iran, a case-control study on epidemiological characteristics

OBJECTIVES

Several cases of Crimean-Congo hemorrhagic fever (CCHF), an arboviral disease, have been reported since summer 1999 in different areas of Iran. The main objectives of this research were to determine the most important means and patterns of transmission and the epidemiologic characteristics of this disease.

DESIGN

In this population-based case-control study, 24 patients from Zabol and Zahedan Districts in the Sistan and Baluchestan province, reported to the Center for Disease Control of Iran, were compared with 300 controls. The controls were sampled through the 'probability proportional to size cluster sampling' method from the general population of the same districts. The following variables were checked: age, sex, living environment (rural versus urban), education years, job, past history of tick bite, contact history with livestock, history of livestock slaughtering, presence of a designated place for animals at home, history of keeping livestock in the house.

RESULTS

Variables which increased the chance of disease include: history of slaughtering (OR = 7.57, CI: 2.21-25.91), high-risk occupations (OR = 4.97, CI: 0.97-25.43), history of tick bite (OR = 105.89, CI: 9.32-1202.44), age above 40 years (OR = 7.32, CI: 1.06-50.26).

CONCLUSION

The results of this study confirm that the scheme of risk factors and risk groups for Crimean-Congo hemorrhagic fever (CCHF) in Iran do not differ substantially from the other parts of the world. Even though tick bite is one of the most important risk factors for CCHF, it cannot explain all cases and there are other important risk factors such as high-risk occupations and having contact with livestock. Even taking care of livestock for a short period at home can increase the chance of contracting CCHF.

Detection of immunoglobulin G to Crimean-Congo hemorrhagic fever virus in sheep sera by recombinant nucleoprotein-based enzyme-linked immunosorbent and immunofluorescence assays

Crimean-Congo hemorrhagic fever virus is a tick-borne virus that causes severe hemorrhagic symptoms with an up to 50% mortality rate in humans. Wild and domestic animals, such as sheep, cattle and goats, are the reservoirs. The recombinant nucleoprotein-based Crimean-Congo hemorrhagic fever virus antibody detection systems for sheep sera were developed by enzyme-linked immunosorbent assay (ELISA) and an indirect immunofluorescence assay techniques. The samples used for evaluation were 80 sera collected from sheep in a Crimean-Congo hemorrhagic fever-endemic area (western part of the Xinjiang Uygur Autonomous Region) and 39 sera collected from sheep in a disease-free region (Shandong province, eastern China). The ELISA and indirect immunofluorescence assay using recombinant nucleoprotein of the virus proved to have high sensitivity and specificity for detecting the immunoglobulin G antibodies to the virus in sheep sera. Within this limited number of samples, the recombinant nucleoprotein-based ELISA and indirect immunofluorescence assay are considered to be useful tools for seroepidemiological study of virus infections in sheep sera.

Endemic infectious diseases of Afghanistan

The current crisis in Afghanistan has resulted in an influx of Western military personnel, peacekeepers, humanitarian workers, and journalists. At the same time, unprecedented numbers of internally displaced persons and refugees have overwhelmed much of the already fragile infrastructure, setting the stage for outbreaks of infectious diseases among both foreigners and local populations. This review surveys the literature concerning the infectious diseases of Afghanistan and south-central Asia, with particular emphasis on diseases not typically seen in the Western world.

Enzyme-linked immunosorbent assays for the detection of antibody to Crimean-Congo haemorrhagic fever virus in the sera of livestock and wild vertebrates

IgM antibody response to Crimean-Congo haemorrhagic fever (CCHF) virus was monitored in experimentally infected sheep and cattle by an IgM capture enzyme-linked immunoassay (ELISA). Specific binding of antigen was detected by a rabbit anti-CCHF horseradish peroxidase conjugate or a sandwich technique with hyperimmune mouse anti-CCHF ascitic fluid and commercially available anti-mouse immunoglobulin peroxidase conjugate. The persistence of IgM antibody activity was found to be of shorter duration than in humans, and this may be a function of the relative lack of susceptibility of these animals to infection with CCHF virus. IgG antibody responses in the sheep could be monitored by sandwich ELISA using commercially available anti-sheep immunoglobulin peroxidase conjugates. Total antibody activity in the sera of experimentally infected sheep, cattle and small mammals could be monitored in a competitive ELISA (CELISA) using rabbit anti-CCHF peroxidase conjugate. The CELISA was applied to the sera of 960 wild vertebrates from a nature reserve in South Africa, and the prevalence of antibody was found to be greatest in large mammals such as rhinoceros, giraffe and buffalo, which are known to be the preferred hosts of the adult tick (Hyalomma) vectors of the virus.

Preparation and use of monoclonal antibodies for identifying Crimean-Congo hemorrhagic fever virus

Seven monoclonal antibodies were prepared against a South African strain of Crimean-Congo hemorrhagic fever (CCHF) virus and were found to be directed against viral nucleocapsid protein. Five of the monoclonal antibodies reacted to high titer in indirect immunofluorescence (IF) tests and enzyme-linked immunosorbent assays (ELISA) with 22 strains of CCHF virus and failed to cross-react with the closest antigenic relative of CCHF, Hazara virus, or with 4 other nairoviruses which need to be distinguished from CCHF virus in Africa. These antibodies, used in the IF technique, readily detected antigens induced by all strains of CCHF virus included in the study in cell culture monolayers and mouse brain tissue, which represent the systems commonly used for isolation of CCHF virus. The IF technique with monoclonal antibodies constitutes a rapid and specific means of identifying newly isolated strains of CCHF virus.