Identifying hotspots of viral haemorrhagic fevers in the Eastern Mediterranean Region: perspectives for the Emerging and Dangerous Pathogens Laboratory Network.

BACKGROUND: The emergence and re-emergence of viral haemorrhagic fevers (VHFs) is a growing concern worldwide. They are associated with major epidemics with an estimated 51-101 million cases each year, of which around 67 000 are fatal. In 2007, 13 countries in the Eastern Mediterranean Region reported VHF cases. AIMS: The main purpose of the study was to review the epidemiological situation in the Region vis-à-vis VHFs to obtain baseline epidemiological information for the establishment of the Emerging Dangerous Pathogen Laboratory Network (EDPLN). METHODS: A literature search was performed using PubMed, ProMED-Mail and GIDEON databases. Reported data included disease burden (reported cases and deaths), human prevalence (general population, high-risk groups), vectors and reservoirs. A scoring method was employed to divide countries into 4 groups (very highly, highly, medium and low affected countries). RESULTS: Very highly affected countries were Afghanistan, Egypt, Islamic Republic of Iran, Saudi Arabia and Sudan. Highly affected countries were Djibouti, Morocco, Oman, Pakistan, Tunisia and Yemen. Medium affected countries were Iraq, Somalia and United Arab Emirates. Low affected countries were Bahrain, Jordan, Lebanon, Libya, Palestine, Qatar and Syrian Arab Republic. CONCLUSIONS: This study contributes in prioritizing countries to be part of EDPLN and in addressing specific needs related to outbreak investigations, surveillance and research.

The pathogenesis of severe fever with thrombocytopenia syndrome virus infection in alpha/beta interferon knockout mice: insights into the pathologic mechanisms of a new viral hemorrhagic fever.

Severe fever with thrombocytopenia syndrome virus (SFTSV) is a newly discovered Phlebovirus causing an emerging hemorrhagic fever in East Asia, with reported case fatality rates up to 30%. Despite the high case fatality rate and large number of persons at risk of infection, the pathobiology of the disease is unknown, and no effective animal model has been available for investigating its pathogenesis. We have studied mice and hamsters as potential small-animal models of SFTSV infection following subcutaneous, intraperitoneal, or intracerebral inoculation. Animal tissues were processed for viral load determination, histopathology, immunohistochemistry, and confocal microscopic studies. We found that immunocompetent adult mice and hamsters did not become ill after SFTSV infection. However, alpha/beta interferon receptor knockout (IFNAR(-/-)) mice were highly susceptible to SFTSV infection, and all mice died within 3 to 4 days after subcutaneous inoculation of 10(6) focus-forming units of SFTSV. Histologic examination of tissues of IFNAR(-/-) mice infected with SFTSV showed no detectable lesions. In contrast, by immunohistochemistry virus antigen was found in liver, intestine, kidney, spleen, lymphoid tissue, and brain, but not in the lungs. Mesenteric lymph nodes and spleen were the most heavily infected tissues. Quantitative reverse transcription-PCR (RT-PCR) confirmed the presence of virus in these tissues. Confocal microscopy showed that SFTSV colocalized with reticular cells but did not colocalize with dendritic cells, monocytes/macrophages, neutrophils, or endothelium. Our results indicate that SFTSV multiplied in all organs except for lungs and that mesenteric lymph nodes and spleen were the most heavily infected tissues. The major target cells of SFTSV appear to be reticular cells in lymphoid tissues of intestine and spleen.

Infection and pathogenesis of Huaiyangshan virus (a novel tick-borne bunyavirus) in laboratory rodents.

A novel tick-borne bunyavirus (Huaiyangshan virus, HYSV), which causes haemorrhagic fever-like disease, has recently been reported in China. So far no animal experiments have been performed to study its pathogenesis. Towards developing an animal model for HYSV fever, newborn and adult mice and rats and golden hamsters were inoculated intracerebrally or intraperitoneally with HYSV. Newborn rats and newborn mice, especially Kunming (KM) mice, appeared highly susceptible. Remarkably, the KM mice that died of the HYSV infection developed large necrotic areas in the liver, while no obvious pathological changes were observed within the other organs. PCR and immunohistochemical analyses of the post-mortem material detected both HYSV antigen and RNA in almost all organs, indicating a systemic infection. Our data demonstrate that HYSV can cause a lethal infection of both newborn mice and newborn rats with apparent pathological damage of the liver. This animal model may help to understand the pathogenesis of the HYSV infection in humans.

Hemorrhagic fever caused by a novel Bunyavirus in China: pathogenesis and correlates of fatal outcome.

BACKGROUND: Hemorrhagic fever-like illness caused by a novel Bunyavirus, Huaiyangshan virus (HYSV, also known as Severe Fever with Thrombocytopenia virus [SFTSV] and Fever, Thrombocytopenia and Leukopenia Syndrome [FTLS]), has recently been described in China. METHODS: Patients with laboratory-confirmed HYSV infection who were admitted to Union Hospital or Zhongnan Hospital between April 2010 and October 2010 were included in this study. Clinical and routine laboratory data were collected and blood, throat swab, urine, or feces were obtained when possible. Viral RNA was quantified by real-time reverse-transcriptase polymerase chain reaction. Blood levels of a range of cytokines, chemokines, and acute phase proteins were assayed. RESULTS: A total of 49 patients with hemorrhagic fever caused by HYSV were included; 8 (16.3%) patients died. A fatal outcome was associated with high viral RNA load in blood at admission, as well as higher serum liver transaminase levels, more pronounced coagulation disturbances (activated partial thromboplastin time, thrombin time), and higher levels of acute phase proteins (phospholipase A, fibrinogen, hepcidin), cytokines (interleukin [IL]-6, IL-10, interferon-γ), and chemokines (IL-8, monocyte chemotactic protein 1, macrophage inflammatory protein 1b). The levels of these host parameters correlated with viral RNA levels. Blood viral RNA levels gradually declined over 3-4 weeks after illness onset, accompanied by resolution of symptoms and laboratory abnormalities. Viral RNA was also detectable in throat, urine, and fecal specimens of a substantial proportion of patients, including all fatal cases assayed. CONCLUSIONS. Viral replication and host immune responses play an important role in determining the severity and clinical outcome in patients with infection by HYSV.

Non-pathogenic Sindbis virus causes hemorrhagic fever in the absence of alpha/beta and gamma interferons.

The role of interferon-gamma (IFNgamma) in antiviral innate immune responses during acute alphavirus infection is not well defined. We examined the contribution of IFNgamma to the protection of adult mice from Sindbis virus (SB)-induced disease by comparing subcutaneous infection of mice lacking receptors for either IFNalpha/beta (A129), IFNgamma (G129) or both (AG129) to normal mice (WT129). While neither G129 nor WT129 mice exhibited clinical signs of disease, infection of A129 or AG129 mice was fatal with AG129 mice succumbing more rapidly. Furthermore, AG129 mice developed signs of viral hemorrhagic fever (VHF), including extensive hepatocellular damage, inflammatory infiltrates in multiple organs and vascular leakage, which were significantly delayed and/or partially ameliorated during fatal A129 infections. We conclude that: (i) IFNalpha/beta is the primary mediator of innate immunity to SB infection, however; (ii) IFNgamma is directly antiviral in vivo, acting before the adaptive immune response appears and; (iii) development of VHF may involve viral suppression of both IFNalpha/beta and IFNgamma responses.

Hemorrhagic fever viruses.

This article reviews the epidemiology, pathophysiology, and clinical management of patients with suspected or confirmed viral hemorrhagic fever infection. The focus is on clinical management based on case series from naturally occuring outbreaks of viral hemorrhagic fever infection as well as imported cases of viral hemorrhagic fever encountered in industrialized nations. The potential risk of bioterrorism involving these agents is discussed as well as emergency department and critical care management of isolated cases or larger outbreaks. Important aspects of management, including recognition of infected patients, isolation and decontamination procedures, as well as available vaccines and therapies are emphasized.

Stampidine prevents mortality in an experimental mouse model of viral hemorrhagic fever caused by lassa virus.

BACKGROUND: The potential use of microorganisms as agents of biological warfare (BW) is a growing concern. Lassa virus, a member of the Arenavirus class of Hemorrhagic fever (HF) viruses has emerged as a worldwide concern among public health officials. The purpose of the present study was to further elucidate the antiviral activity spectrum of stampidine, a novel nucleoside analog with potent anti-viral activity against the immunodeficiency viruses HIV-1, HIV-2, and FIV, by examining its effects on survival of mice challenged with Lassa virus. METHODS: We examined the therapeutic effect of Stampidine in CBA mice inoculated with intracerebral injections of the Josiah strain of Lassa virus. Mice were treated either with vehicle or nontoxic doses of stampidine administered intraperitoneally 24 hours prior to, 1 hour prior to, and 24 hours, 48 hours, 72 hours, and 96 hours after virus inoculation. RESULTS: The probability of survival following the Lassa challenge was significantly improved for stampidine treated mice (Kaplan Meier, Chi-squared = 11.7, df = 2, Log-Rank p-value = 0.003). CONCLUSION: Therefore, stampidine shows clinical potential as a new agent for treatment of viral hemorrhagic fevers caused by Lassa virus.

Serum albumin level correlates with disease severity in patients with Hemorrhagic Fever with Renal Syndrome.

Hypoalbuminemia frequently occurs in Hemorrhagic Fever with Renal Syndrome (HFRS), but clinical significance of hypoalbuminemia is not well known. This study was designed to evaluate hypoalbuminemia as a marker of severity of disease in patients with HFRS. We evaluated the relationship between the level of serum albumin and clinical parameters representing the severity of disease in 144 patients with HFRS. The patients were divided into three groups based on the level of serum albumin; Group I (normal serum albumin), Group II (serum albumin <3.5 g/dL and >/=3.0 g/dL), and Group III (serum albumin <3.0 g/dL). Of the total of 144 patients, 42 patients (29.2%) were categorized as Group I, 39 patients (27.1%) as Group II, and 63 patients (43.8%) as Group III. Group III had a higher rate of incidence in episode of hypotension, pulmonary edema than did Group I and Group II. The lowest level of serum albumin was positively correlated with platelet count (r=0.505, p<0.001) and was negatively correlated with leukocyte count (r=-0.329, p<0.001), BUN (r=-0.484, p<0.001), serum creatinine (r=-0.394, p<0.001), and AST (r=-0.251, p=0.002). Our data suggest that hypoalbuminemia frequently occurs in the acute stage of HFRS, and level of serum albumin is associated with the disease severity of HFRS.

Role of the endothelium in viral hemorrhagic fevers.

OBJECTIVE: To describe endothelial participation in the pathogenesis of viral hemorrhagic fevers and certain other acute infectious diseases. DATA EXTRACTION AND SYNTHESIS: Survey of published literature on viral hemorrhagic fevers interpreted in light of observations in patients and research on those diseases. CONCLUSIONS: Endothelial involvement is an extremely important factor in the clinical syndrome termed viral hemorrhagic fever. Endothelial dysfunction is important in the genesis of bleeding, which is not universal and is commonly seen only in the presence of thrombocytopenia or severe platelet dysfunction. The pathogenesis of endothelial dysfunction varies in the different diseases. In some situations, direct endothelial infection is important in increased vascular permeability, changes in the procoagulant vs. anticoagulant balance, or cytokine production. In all the viral hemorrhagic fevers studied to date, cytokine induction is an important factor and also acts on the endothelium. Poor myocardial contractility is a very important issue in viral hemorrhagic fever and is not caused by direct viral infection of the heart; it is increasingly being recognized that these patients present with low cardiac output and high peripheral resistance and that they respond poorly to fluid infusion. The clinical findings in viral hemorrhagic fever differ from those in the sepsis syndrome and should be studied and interpreted separately; this approach will sharpen therapeutic approaches and could shed light on the problems of sepsis in general.

Isolation and partial characterisation of a new strain of Ebola virus.

We have isolated a new strain of Ebola virus from a non-fatal human case infected during the autopsy of a wild chimpanzee in the Côte-d'Ivoire. The wild troop to which this animal belonged has been decimated by outbreaks of haemorrhagic syndromes. This is the first time that a human infection has been connected to naturally-infected monkeys in Africa. Data from the long-term survey of this troop of chimpanzees could answer questions about the natural reservoir of the Ebola virus.

Outbreak of fatal illness among captive macaques in the Philippines caused by an Ebola-related filovirus.

Following the detection of an Ebola-like virus in cynomolgus macaques recently imported into the United States from The Philippines, studies were initiated to document transmission at export facilities located in the latter country. At one export facility, 52.8% of 161 monkeys that died over a 2.5-month period were shown to be infected with this virus using an enzyme-linked immunosorbent assay to detect antigen in liver homogenates. A case fatality rate of 82.4% was documented for the infected monkeys. The initial anti-viral antibody prevalence among the captive macaques at this facility was 25.9% (indirect fluorescent antibody titer greater than or equal to 1:16). Followup documented infection of 24.4% of initially seronegative animals and 8.7% of initially seropositive monkeys. Being held in a gang cage versus a single cage was found to be a significant risk factor for subsequent virus infection, and the presence of IFA antibody was shown to predict protection. This study documents unequivocally for the first time the presence of an Ebola-related filovirus in Asia.

Firsthand clinical observations of hemorrhagic manifestations in Ebola hemorrhagic fever in Zaire.

About 5 weeks after the beginning of the outbreak of Ebola virus fever in Yambuku, Zaire, several acute cases of the disease were observed. All of those affected had the following common signs and symptoms: sudden onset of high fever, with chills, headache, myalgia, anorexia, nausea, abdominal pain, sore throat, expressionless face, and profound prostration. In some cases, on around the fifth day of the acute phase, the appearance of an exanthematous rash on the trunk announced the hemorrhagic manifestations: hemorrhagic conjunctivitis, bleeding ulcerations in the mouth and on the lips, gingival bleeding, hematemesis, and melena; epistaxis, ear bleeding, hematuria, and postpartum hemorrhages were also reported. All these hemorrhagic cases had a fatal outcome within about a week. The hemorrhagic manifestations were less severe in the cases that occurred by the end of the outbreak than in the first reported cases. Hemorrhagic manifestations were less frequent and less severe, or even absent, in the nonfatal cases (convalescents, serologically confirmed). No biologic investigation of the hemostatic impairment could be performed under the emergency conditions of this field study.

The effects of gamma irradiation on the lymphoid organs of rainbow trout and subsequent susceptibility to fish pathogens.

Fish were irradiated with 60Co gamma rays at doses ranging from 10 to 50 Gy. Lethal doses were determined in fishes of different ages. For a given dose, fry and fingerlings were more susceptible than subadults. Whatever the irradiation dose was, the fish displayed a sharp decrease in blood leucocyte count. At the lowest doses, this acute leucopaenia was reversible. The cellular damage in the lymphoid organs was particularly obvious in the thymus. The depletion of lymphoid cells from immunocompetent organs decreased (viral hemorrhagic septicaemia, VHS) or increased (Y. ruckeri, A salmonicida) the susceptibility of trout to pathogens. The suppressive effect of radiation was age dependent. Irradiation appeared to be a reliable technique to detect asymptomatic carrier fish.

Simian hemorrhagic fever: Studies of coagulation and pathology.

Simian hemorrhagic fever (SHF) was induced in three species of monkeys (Macaca mulatta, M. radiata and M. fascicularis) using plasma from animals that died with SHF in the 1967 outbreak at the California Primate Research Center. The disease was uniformly fatal in all three species with death occurring by day 5 in M. radiata and M. fascicularis and by day 7 in M. mulatta. Serial studies of hemostasis were consistent with the occurrence of disseminated intravascular coagulation, particularly in the M. mulatta. Studies of pathology were typical of previously reported findings in SHF and support the possibility of intravascular coagulation. The role of intravascular coagulation in the pathogenesis and outcome of SHF remains uncertain but studies of the influence of heparin on the disease are in progress.