Crimean-Congo hemorrhagic fever in Turkey

Viral load as a predictor of outcome in Crimean-Congo hemorrhagic fever

Crimean-Congo hemorrhagic fever (CCHF) is a potentially fatal disease affecting multiple organ systems. To determine the association between viral load and severity of CCHF infection, quantitative measurement of CCHF virus was performed using 1-step reverse-transcriptase polymerase chain reaction for 36 patients with CCHF infection. Viral loads ranged from 1.1x10(3) copies/mL to > or = 9.9x10(9) copies/mL. Nine (25%) of 36 patients died. In 8 of the 9 patients with fatal outcomes, viral loads were detected that were > or = 1x10(9) copies/mL, whereas in 25 of the 26 patients with nonfatal outcomes, viral loads were detected that were < 1x10(9) copies/mL (P<.001). A viral load > or = 1x10(9) RNA copies/mL can be considered to predict a fatal outcome with a positive predictive value of 80%, with 88.9% sensitivity and 92.6% specificity. We suggest that viral load is a measure of the severity of CCHF.

Recent progress in molecular biology of Crimean-Congo hemorrhagic fever

Crimean-Congo hemorrhagic fever (CCHF) is a severe hemorrhagic fever in humans with a case fatality rate of up to 50%. A causative agent of CCHF is CCHF virus, which is a tick-borne virus in the family Bunyaviridae, genus Nairovirus. The virus is transmitted to humans through infected tick bites, squashed ticks or from direct contact with viremic animals or humans. Outbreaks of CCHF have been documented in Africa, the Middle East, Eastern Europe and Western Asia where the vector and/or reservoir ticks of Hyalomma spp. are distributed. Recent advances in molecular and biochemical analyses of CCHF virus revealed that the virus encodes larger proteins compared to other genus of Bunyavirus and the processing of viral proteins are complicated. Recent studies also showed that the CCHF viruses are relatively divergent in its genome sequence and the viruses are grouped in seven different clades. In general, these phylogenetic analyses based on sequences of S-RNA and L-RNA segment of CCHF viruses indicate that the seven clades correlate with their geographical location. The phylogenetic topology based on M-RNA segment sequences of CCHF viruses is different from those based on S-RNA and L-RNA segments. These analyses indicate that M-RNA segment reassortment events occur more frequently than those in S- and L-RNA segments.

Haemophagocytosis in a patient with Crimean–Congo haemorrhagic fever

Crimean–Congo haemorrhagic fever (CCHF) is a severe disease with a case fatality of 2.8 to 80 %. A patient dwelling in an endemic region for CCHF was admitted with fever preceding bleeding diathesis and pancytopenia. Despite no history of tick exposure, CCHF was highly suspected. With an oral ribavirin therapy, clinical and laboratory improvements were obtained. The diagnosis was confirmed by detection of IgM antibody to CCHF virus and positive RT-PCR. Although the main pathogenesis of CCHF infection is not elucidated yet, haemophagocytosis, a symptom rarely reported in viral haemorrhagic fevers, was observed in this case. Haemophagocytosis is suggested to have a role in the development of pancytopenia in CCHF, the mechanism of which still needs to be investigated, probably with cytokine studies. Together with clinical symptoms and patient history, haemophagocytosis may be an indicator for CCHF.

Imported Crimean-Congo hemorrhagic fever cases in Istanbul

We described a series of imported cases of Crimean-Congo Hemorrhagic Fever (CCHF) in Istanbul and investigated the genetic diversity of the virus. All the suspected cases of CCHF, who were applied to the health centers in Istanbul, were screened for CCHF virus (CCHFv) infection by using semi-nested Polymerase Chain Reaction (PCR) following RT-PCR. Simultaneous blood samples were also sent to the national reference laboratory in Ankara for serologic investigation. In 10 out of 91 patients, CCHFv was detected by PCR, and among 9 out of 10, anti-CCHFv IgM antibodies were also positive. Clinical features were characterized by fever, myalgia, and hemorrhage. The levels of liver enzymes, creatinine phosphokinase, and lactate dehydrogenase were elevated, and bleeding markers were prolonged. All the cases were treated with ribavirin. There was no fatal case. All the strains clustered within the same group as other Europe/Turkey isolates.

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.

Emerging zoonoses and vector-borne infections affecting humans in Europe

The purpose of this study was to assess and describe the current spectrum of emerging zoonoses between 2000 and 2006 in European countries. A computerized search of the Medline database from January 1966 to August 2006 for all zoonotic agents in European countries was performed using specific criteria for emergence. Fifteen pathogens were identified as emerging in Europe from 2000 to August 2006: Rickettsiae spp., Anaplasma phagocytophilum, Borrelia burgdorferi, Bartonella spp., Francisella tularensis, Crimean Congo Haemorrhagic Fever Virus, Hantavirus, Toscana virus, Tick-borne encephalitis virus group, West Nile virus, Sindbis virus, Highly Pathogenic Avian influenza, variant Creutzfeldt-Jakob disease, Trichinella spp., and Echinococus multilocularis. Main risk factors included climatic variations, certain human activities as well as movements of animals, people or goods. Multi-disciplinary preventive strategies addressing these pathogens are of public health importance. Uniform harmonized case definitions should be introduced throughout Europe as true prevalence and incidence estimates are otherwise impossible.

Plasma activity of thrombin activatable fibrinolysis inhibitor in Crimean-Congo hemorrhagic fever

OBJECTIVES

Crimean-Congo hemorrhagic fever (CCHF) is a potentially fatal viral infection. The exact mechanism for hemorrhage remains unknown. Thrombin activatable fibrinolysis inhibitor (TAFI) is a plasma procarboxypeptidase B-like proenzyme and synthesized in the liver, down-regulating fibrinolysis. In this study, we measured the TAFI activity in plasma of patients with CCHF to examine the relationship between hemorrhage and the pathogenesis of CCHF.

METHODS

Twenty-one patients and similar number of controls were included in the study. The diagnosis of CCHF was confirmed through detection of IgM by ELISA and/or PCR. TAFI activity was measured in plasma samples.

RESULTS

TAFI activity in CCHF patient group was mean 7.2+/-2.3 microg/ml (range: 0.95-10.31 microg/ml) and in the control group was mean 11.7+/-4.1 microg/ml (range: 3.07-23.9 microg/ml). There was a significant decrease of TAFI activity in CCHF patients when compared to controls. A positive correlation between CRP, PT, INR, serum albumin and TAFI activity levels were found. We suggest that the decrease of TAFI activity may be due to liver dysfunction during viral active disease state.

CONCLUSIONS

Low TAFI activity may be an attributable factor, leading to imbalance in fibrinolysis, resulting in bleeding complications in CCHF.

Crimean-Congo hemorrhagic fever virus: genetic analysis and tick survey in Turkey

Crimean-Congo hemorrhagic fever virus (CCHFV) is a tick-borne virus in the family Bunyaviridae, genus Nairovirus. The virus is transmitted to humans through infected tick bites or from direct contact with viremic animals or humans. In the present study, a total of 1,015 adult ticks were collected from cattle (603 specimens), sheep (17 specimens), and goats (395 specimens) in the Kelkit Valley in Turkey. Four tick species were recognized on the animals in the surveyed region. The most abundant species were Rhipicephalus bursa and Hyalomma marginatum marginatum, at 47.68% (484/1,015) and 46.40% (471/1,015), respectively. Reverse transcriptase PCR was used to recover partial sequences of the CCHFV small (S) genome segment. The presence of CCHFV was determined in 3 of 33 (9.09%) R. bursa pools and in 1 of 31 (3.22%) H. m. marginatum pools. Virus sequences from R. bursa were extremely different from those of the Greek CCHFV strain (U04958) isolated from an R. bursa tick. Phylogenetic analysis indicated that the CCHFV isolates obtained in this study clustered in group 5, whose range encompasses southwestern Russian and Kosovo. This is the first evidence of CCHFV in ticks from Turkey. Even though Hyalomma is the main vector for CCHFV, R. bursa may play a role in CCHFV transmission.

Crimean-Congo hemorrhagic fever virus genomics and global diversity

Crimean-Congo hemorrhagic fever (CCHF) is a severe illness with high case fatality that occurs in Africa, Europe, the Middle East, and Asia. The complete genomes of 13 geographically and temporally diverse virus strains were determined, and CCHF viruses were found to be highly variable with 20 and 8%, 31 and 27%, and 22 and 10% nucleotide and deduced amino acid differences detected among virus S (nucleocapsid), M (glycoprotein), and L (polymerase) genome segments, respectively. Distinct geographic lineages exist, but with multiple exceptions indicative of long-distance virus movement. Discrepancies among the virus S, M, and L phylogenetic tree topologies document multiple RNA segment reassortment events. An analysis of individual segment datasets suggests genetic recombination also occurs. For an arthropod-borne virus, the genomic plasticity of CCHF virus is surprisingly high.

Zoonotic infections among veterinarians in Turkey: Crimean-Congo hemorrhagic fever and beyond

OBJECTIVES

We aimed to determine the seroprevalence of Crimean-Congo hemorrhagic fever (CCHF) virus, Brucella spp, and Coxiella burnetii among veterinarians in a highly endemic and a non-endemic region for these infections in Turkey.

METHODS

The antibody levels against these three infections were surveyed. Eighty-three veterinarians were included from two distinct geographic regions.

RESULTS

CCHF IgG positivity (3% vs. 0%) and Brucella agglutination titer of > or =1/160 (33% vs. 5%) were more common in the endemic region, whereas the rates of Coxiella burnetii antibodies were similar (7% and 8%). A history of tick bite was significantly more common in the endemic region (35% vs. 12%, p=0.011). A multivariate analysis was performed among the veterinarians living in the endemic area, and percutaneous injuries were found to be associated with Brucella infection (OR 1.8, CI 1.09-3, p=0.022).

CONCLUSIONS

Veterinarians should protect themselves against tick bites, and should use masks to prevent transmission by inhalation of zoonotic infections in endemic countries.

Cytokine levels in Crimean-Congo hemorrhagic fever

BACKGROUND

Crimean-Congo hemorrhagic fever (CCHF) virus causes severe disease in humans with a mortality reaching 30%. A CCHF outbreak took place in Albania in 2003. As in other viral hemorrhagic fevers cytokines may be involved and play a role in the pathogenesis and outcome of the disease.

OBJECTIVES

To investigate the levels of TNF-alpha, sTNF-R, IL-6 and IL-10 in serum samples obtained from laboratory confirmed CCHF cases and relate them to the severity of the disease.

STUDY DESIGN

A study population of 51 was divided into three groups: group A, consisting of PCR-positive cases; group B, consisting of PCR-negative and serology-positive cases; group C, consisting of doubly negative cases. Concentrations of serum TNF-alpha, sTNF-R, IL-6 and IL-10 were measured during the illness.

RESULTS

High levels of all cytokines tested were present in one fatal case. Statistically significant differences between the groups were obtained for TNF-alpha and IL-6: TNF-alpha was detected in 3 cases in group A, and in none of the other groups, while IL-6 was elevated in 10/16 patients in group A, 4/9 in group B, and 4/26 in group C. sTNF-R was not significantly different for the three groups. High concentration of IL-10 was detected only in the fatal case.

CONCLUSIONS

TNF-alpha and IL-6 are the cytokines most often detected during a CCHF viral infection. TNF-alpha was associated with the severe form of CCHF, while IL-6 was elevated in both severe and mild cases.

Analysis of risk-factors among patients with Crimean-Congo haemorrhagic fever virus infection: severity criteria revisited

The aim of this study was to determine the predictors of mortality among patients infected with Crimean-Congo haemorrhagic fever (CCHF) virus. Among patients with acute febrile syndrome, characterised by malaise, bleeding, leukopenia and thrombocytopenia, who were admitted to hospital during the spring and summer of 2002-2004, 54 had positive IgM and/or PCR results for CCHF virus in blood or tissue. The overall case fatality rate was 7.4%. Among the fatalities, haematemesis (p 0.009), melaena (p 0.001) and somnolence (p 0.022) were more common, the median platelet count was significantly lower (10,600/mL vs. 20,000/mL; p 0.038), the mean prothrombin time (27 s vs. 16 s; p 0.002) and mean activated partial thromboplastin time (73 s vs. 44 s; p < 0.001) were longer, and the mean alanine transferase (ALT) level (1,125 vs. 331; p < 0.001), the mean aspartate transferase (AST) level (3,118 vs. 913; p 0.004) and the mean fibrinogen level (119 vs. 340; p 0.012) were higher. Serum IgM and IgG against CCHF virus was detected in 25% and 0%, respectively, of fatal cases, compared with 94% and 62%, respectively, of cases with favourable outcomes. Oral ribavirin was prescribed to 22 (41%) patients. Of the four fatal cases, it was the intention to prescribe ribavirin to three patients, but this was not possible because of haematemesis and melaena. Higher levels of AST (>or= 700 U/L) and ALT (>or= 900 U/L) are suggested for use as severity criteria. Oral ribavirin was not effective for patients with haematemesis, and intravenous ribavirin is necessary for treatment of CCHF.

Novel one-step real-time RT-PCR assay for rapid and specific diagnosis of Crimean-Congo hemorrhagic fever encountered in the Balkans

Early and accurate diagnosis of Crimean-Congo hemorrhagic fever (CCHF) is essential for the treatment and outcome of the disease and prevention of its further transmission. Molecular-based diagnostic assays now serve as the front-line tool in the diagnosis of CCHF. However, the development of real-time RT-PCR assay for the detection of Crimean-Congo hemorrhagic fever virus (CCHFV) has been hampered by a virus strain variation. The development of a one-step real-time RT-PCR assay for the detection of CCHFV is described herein. The technique is based on the fluorescence resonance energy transfer probe technology employing the endonuclease activity of Taq polymerase enzyme. The assay was designed to detect specifically the strains from a phylogenetic cluster of CCHFV which encompasses the known CCHFV strains circulating in the Balkan region. The detection system was tested using CCHFV strain Kosovo Hoti, clinical serum samples and ticks. The real-time assay described is rapid, specific and sensitive. Since the Balkan peninsula is also an endemic region for hemorrhagic fever with renal syndrome (HFRS), this method is suggested as convenient for early differential diagnosis of suspected viral hemorrhagic fever patients.

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.

Complete L segment coding-region sequences of Crimean Congo hemorrhagic fever virus strains from the Russian Federation and Tajikistan

The large (L) RNA segment of Crimean Congo hemorrhagic fever (CCHF) virus strain AST/TI30908, isolated from pooled Hyalomma marginatum ticks collected in 2002 from the Astrakhan region of European Russia, was amplified piecemeal using reverse-transcription/polymerase chain reaction, followed by direct sequencing of gel-purified amplicons. After removal of 5' and 3' primer-generated termini, the assembled AST/TI30908 L segment sequence is 12112 nucleotides long, with 41.3% G + C content, and is greater than 87% and 96% identical at the nucleotide and translated amino acid levels, respectively, to partial or full-length CCHF virus L segment sequences deposited in GenBank. A complete L segment coding-region sequence for CCHF virus strain TAJ/HU8966, isolated from a patient in Tajikistan in 1990, was determined in a similar fashion. This L segment (12133 nucleotides long, 41.1% G + C content) shares 88% nucleotide identity with the full-length strain Matin from Pakistan, and 97% nucleotide identity with a partial L segment sequence of strain Khodzha from Uzbekistan. Strain TAJ/HU8966 shares at least 96% identity at the translated amino acid level with all other CCHF virus L segment sequences. Although, for the most part, CCHF virus L polyprotein primary sequences are uniformly well conserved, a region of marked variability was identified in the N-terminal half of the RNA-dependent RNA polymerase. This region, approximately 50 amino acids in length, is flanked by previously-reported arenavirus and bunyavirus-conserved regions, and may prove useful in CCHF diagnosis and viral taxonomy.