Impaired fibrinolysis in the pathogenesis of dengue hemorrhagic fever

The mechanisms contributing to bleeding complications in dengue hemorrhagic fever were studied by investigating the pattern of activation of the coagulation and fibrinolytic systems in 50 children with severe dengue hemorrhagic fever. Thirteen patients (26%) died, and activation of coagulation was most pronounced in the deceased group. Fibrinolysis was also activated, but this activation was relatively weak compared with that of coagulation as a result of persistently high plasminogen activator inhibitor levels. Plasminogen activator inhibitor also prevented a switch from the procoagulant to the profibrinolytic state in lethal dengue hemorrhagic fever, which was further enhanced by an acquired protein C deficiency. The present study is the first to demonstrate such a mechanism in a viral infection. This imbalance between coagulation and fibrinolysis may be used as a prognostic marker, but it may also be a target for future therapeutic intervention.     

TNF-alpha-308A allele, a possible severity risk factor of hemorrhagic manifestation in dengue fever patients

Among the several hypothesis postulated to explain the pathogenesis of severe dengue disease, the model of immunopathogenesis is the most supported one with a likely important role played by the cascade of cytokines. This work describes single-nucleotide polymorphism of tumor necrosis factor (TNF)-alpha, interferon-gamma, interleukin (IL)-6, transforming growth factor-beta1, and IL-10 in patients with dengue virus infections and analyzes their relation with clinical manifestations of the disease. Because cytokine gene polymorphisms affect cytokine production, the significant increase of the TNF-308A allele we have observed among patients with dengue fever (DF) with hemorrhagic manifestations compared to patients with DF only indicates that the former patients are genetically predisposed to express higher levels of TNF-alpha. This finding supports studies reporting a possible association between elevated levels of circulating TNF, vascular permeability, and hemorrhage in patients with dengue hemorrhagic fever.     

Profile of transforming growth factor-beta 1 in patients with dengue haemorrhagic fever

The pathogenesis of dengue haemorrhagic fever (DHF) is incompletely understood but it has been suggested that various cytokines may have a role in the process. In this study the profile of the cytokine Transforming Growth Factor-beta 1 (TGF-beta1) was investigated in the sera of 79 patients with various grades of dengue illness and in 21 normal healthy controls. Also, TGF-beta1-specific mRNA was examined in their peripheral blood mononuclear cells (PBMC). The results showed that neither TGF-beta1 protein nor its mRNA were detected in healthy controls. In dengue patients, the TGF-beta1 protein and its mRNA were detected in 96%. However, among the patient groups, the levels of TGF-beta1 were lowest in patients with dengue fever (DF; mean value 315 +/- 95 pg/ml) and were highest in patients with DHF grade IV (mean value 1350 +/- 280 pg/ml; P = < 0. 001). The cytokine appeared during the first four days of illness (304 +/- 90 pg/ml) and gradually increased, reaching peak levels (1050 +/- 215 pg/ml) after the 9th day of the illness. Thus TGF-beta1 in the sera and TGF-beta1-mRNA in the PBMC were present in most of the patients with dengue (96%) but the cytokine levels were highest during the later periods of illness and in patients with DHF grade IV, suggesting a possible role of TGF-beta1 in the pathogenesis of DHF.     

The pathology of dengue hemorrhagic fever

An estimated 2.5 billion people are at risk of dengue infection, and of the 100 million cases of dengue fever per year, up to 500,000 develop dengue hemorrhagic fever (DHF) or dengue shock syndrome (DSS), the life-threatening forms of the infection. The large majority of DHF/DSS occurs as the result of a secondary infection with a different serotype of the virus. While not completely understood, there is evidence that the target cells include dendritic reticulum cells, monocytes, lymphocytes, hepatocytes, and vascular endothelial cells. Viral replication appears to occur in dendritic cells, monocytes, and possibly circulating lymphoid cells, and damage to these and other target cells occurs through immune-mediated mechanisms related to cross-reacting antibodies and cytokines released by dendritic cells, monocytes, and vascular endothelium. There is evidence of a concomitant cellular activation as well as immune suppression during the infection. The activation of memory T cells results in cascades of inflammatory cytokines, including tumor necrosis factor-alpha, interleukins (IL-2, IL-6, and IL-8), and other chemical mediators that increase vascular endothelial permeability or trigger death of target cells through apoptosis. Pathological studies in humans are uncommon, and a suitable animal model of DHF/DSS does not exist. The current treatment of DHF/DSS is symptomatic, and prevention is through vector control. As such, there is a great impetus for the development of vaccines and novel therapeutic molecules to impede viral replication in infected cells or counteract the effects of specific inflammatory mediators on target cells. The role of genetics in relation to resistance to DHF/DSS also requires clarification.     

Elevated plasma levels of the long pentraxin, pentraxin 3, in severe dengue virus infections

C-reactive protein is one of the most widely used indicators of the response of acute-phase proteins. The measurement of C-reactive protein in dengue, however, is clinically not useful, because of marginally elevated levels and absent association with disease severity. The prototypic long pentraxin, pentraxin 3, is an acute phase protein that is structurally related but distinct from C-reactive protein which has proven to correlate with the severity of bacterial infection in critically ill patients. The potential involvement of pentraxin 3 in dengue and its aptitude to predict more severe disease or poor clinical outcome has not been studied previously. We therefore measured pentraxin 3 plasma levels in 44 dengue virus infected patients. Pentraxin 3 levels were strikingly higher when compared to C-reactive protein levels, with highest pentraxin 3 values observed in the first 7 days after the onset of symptoms. Median pentraxin 3 levels at admission and peak levels during follow up were higher in patients suffering from dengue shock syndrome (at admission: 119.3 ng/ml [interquartile range 61.8--188.7], peak values during follow up: 147.9 ng/ml [interquartile range 85.7--204.3]) compared to levels found in patients with dengue fever and dengue hemorrhagic fever (at admission: 59.0 ng/ml [interquartile range 28.6--100.3], P=0.040; peak values during follow up: 80.8 ng/ml [interquartile range 36.1--168.1], P=0.020). Our results indicate that pentraxin 3 seems to be a marker of infection better than C-reactive protein in dengue. The role of pentraxin 3 in the pathogenesis of dengue and its potential as an early prognostic indicator of disease severity needs further assessment.     

Elevation of soluble VCAM-1 plasma levels in children with acute dengue virus infection of varying severity

Approximately 1,000 million infections with dengue viruses are estimated to occur annually. The majority of the cases develop mild disease, whereas only small proportion of the infected individuals develop severe hemorrhagic manifestations at the end of the acute phase of illness. In this study, the value of plasma levels of vascular cell adhesion molecule 1 (VCAM-1) in the pathogenesis and prognosis of dengue illness was investigated in children with dengue infections of varying severity. The plasma levels of soluble VCAM-1 (sVCAM-1) were measured in serial plasma samples obtained from 168 children aged between 7 months and 14 years with confirmed dengue infection. Of those children, 71 were suffering from dengue fever, 30 were suffering from dengue hemorrhagic fever, and 67 were suffering from dengue shock syndrome. Plasma samples obtained from 21 patients with febrile illness other than dengue served as controls. A commercially available kit (R&D Systems, Oxon, UK) was used to measure the levels of sVCAM-1 in plasma samples. sVCAM-1 was elevated during acute dengue infection, and significantly elevated among dengue shock syndrome patients as compared to dengue fever or dengue hemorrhagic fever patients (P < 0.05). Statistical analysis revealed that sVCAM-1 was associated with dengue disease severity and the time post infection (acute vs. convalescent phase) and not with age, sex, or previous exposure of the patients to dengue infection. A significant difference was found in the plasma levels of sVCAM-1 between dengue shock syndrome and dengue fever patients, however, the prognostic value of this marker in the acute stage of dengue illness proved to be limited. These data also favor to study the further elucidation of the role of sVCAM-1 in the pathogenesis of dengue infections.     

Evaluation of patients with Crimean-Congo hemorrhagic fever in Bolu,Turkey

Background

Crimean-Congo hemorrhagic fever (CCHF), which is associated with a high mortality rate in the Black Sea region of Turkey, has received increasing attention.

Objective

In this study, the epidemiological features, clinical and laboratory findings, treatments, and outcomes of patients diagnosed with CCHF between 2006 and 2012 based on data obtained from the Bolu Provincial Directorate of Health (BPDH) were evaluated.

Methods

BPDH data were reviewed for the period between 1 January 2006 and 31 July 2012. The locations where the tick had attached to the patient, the site of the tick bite on the patient''s body, the dates of tick bite and removal, and the demographic characteristics of each patient were recorded. BPDH data on the total number of tick bites, patients with confirmed CCHF, and deaths due to CCHF in Bolu Province during the study period were also evaluated.

Results

A total of 46 patients with CCHF and 38 patients without CCHF but who had been bitten by ticks were admitted to the BPDH. Of the patients with CCHF, 54.3% were female. The mean age of the patients was 46.88 ± 2.05 years (range, 1–79 years). The mortality rate was 8.82%. Patients were predominantly observed in June and July. When the patients were distributed according to their occupations, the majority was houswife (48.6%), followed by animal husbandry worker (27.0%), farmer (10.8%), health worker (5.4%), and other (8.1%). The symptoms of the patients with CCHF included fatigue (60.9%), fever (60.9%), and myalgia (60.9%). Of those patients with CCHF, 41.3% were determined to have a high fever.

Conclusions

The probability of developing CCHF decreased as the duration of tick attachment increased. Moreover, although the clinical presentation is important, it is not diagnostic. Physical examination and laboratory findings become more specific in later stages.     

Serum cytokine/chemokine profiles in patients with dengue fever (DF) and dengue hemorrhagic fever (FHD) by using protein array

BackgroundDENV infection can induce different clinical manifestations varying from mild forms to dengue fever (DF) or the severe hemorrhagic fever (DHF). Several factors are involved in the progression from DF to DHF. No marker is available to predict this progression. Such biomarker could allow a suitable medical care at the beginning of the infection, improving patient prognosis.ObjectivesThe aim of this study was to compare the serum expression levels of acute phase proteins in a well-established cohort of dengue fever (DF) and dengue hemorrhagic fever (DHF) patients, in order to individuate a prognostic marker of diseases severity.Study designThe serum levels of 36 cytokines, chemokines and acute phase proteins were determined in DF and DHF patients and compared to healthy volunteers using a multiplex protein array and near-infrared (NIR) fluorescence detection. Serum levels of IL-1ra, IL-23, MIF, sCD40 ligand, IP-10 and GRO-α were also determined by ELISA.ResultsAt the early stages of infection, GRO-α and IP-10 expression levels were different in DF compared to DHF patients. Besides, GRO-α was positively correlated with platelet counts and IP-10 was negatively correlated with total protein levels.ConclusionsThese findings suggest that high levels of GRO-α during acute DENV infection may be associated with a good prognosis, while high levels of IP-10 may be a warning sign of infection severity.     

Sequence determination of the Crimean-Congo hemorrhagic fever virus L segment

Crimean-Congo hemorrhagic fever (CCHF) virus is highly pathogenic for humans and remains the only Category A virus for which full sequence information is currently unavailable. In this study we completed CCHF genome characterization by determining the L segment sequence using Dugbe and CCHF virus-specific oligonucleotides. Sequence alignments revealed the presence of four previously described conserved regions in all Bunyaviridae polymerases. Interestingly, additional regions containing putative Ovarian Tumor (OTU)-like cysteine protease and helicase domains were identified in the L segments of CCHF and Dugbe viruses, suggesting an autoproteolytic cleavage process for nairovirus L proteins.     

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: An emerging threat for the intensivist

We present the case of a 55-year-old female, who presented with 15 days of fever with rash, pancytopenia, and altered behavior. She was investigated for routine causes of fever with rash and multi organ dysfunction and treated for the same. As she tested negative for all routine causes of such an illness and did not show improvement to therapy, she was investigated for Crimean-Congo hemorrhagic fever and tested positive for the same. She was started on ribavirin, but eventually succumbed to her illness. This disease has rarely been reported from the Northern India and we need to have high clinical suspicion for this deadly disease so that appropriate therapy can be started in time for the patient and prophylaxis given to all inadvertently exposed.     

Rhabdomyolysis and severe muscular weakness in a traveler diagnosed with Alkhurma hemorrhagic fever virus infection

Alkhurma hemorrhagic fever virus (AHFV) is a tick-borne flavivirus with high case fatality rates, endemic in the Arabian Peninsula. Recently AHFV was detected in travelers returning from Egypt suggesting geographical spreading. We also report AHFV infection in a traveler ex Egypt, representing atypical symptoms of rhabdomyolysis and severe muscular weakness.     

广州市2001-2010年登革热流行病学分析

目的分析广州市近年来登革热疫情特点及流行规律,为制定预防控制措施提供依据。方法收集广州市2001-2010年登革热疫情资料,用描述性流行病学方法分析其流行特征和流行因素。结果 2001-2010年广州市共报告登革热病例2458例,每年均有本地感染病例和输入病例的报告,其中本地感染病例2366例,输入性病例92例。年发病率在0/10万～20.14/10万之间。疫情涉及12个区县,主要集中在荔湾区（26.24%）、越秀区（25.65%）、天河区（14.41）、白云区（12.00%）和番禺区（8.77%）。4-12月均有病例报告,其中5月份前为输入性为主的散发病例,6-12月为流行期,8-10月病例数占总病例数的88.12%,为发病高峰期。男女性别比为1.06∶1。各年龄组均有发病,但发病率以中壮年和老年人群居高。职业分布以家务及待业、工人和学生为主。病例输入地主要以印尼、越南、泰国等东南亚地区为主。暴发的疫情主要由登革病毒Ⅰ型引起。结论广州市登革热仍为输入或输入引起本地传播的传染病,至今仍无证据表明已成为地方性疾病。