Sensationalised accounts of wards of dying patients have fueled intense public fascination with filoviruses and highlighted the global threat of emerging and re-emerging infectious diseases. Filoviruses are the prototypical emerging pathogens: they cause a haemorrhagic disease of high case-fatality associated with explosive outbreaks due to person-to-person transmission, have no known treatment, occur unpredictably, and have an unknown reservoir. In truth, since their initial discovery in 1967, only a handful of filoviral outbreaks have occurred, mostly in remote locations. However, the documented occurrence of secondary cases in locations far from endemic areas validates the concern that filoviruses have the potential to cause unprecedented outbreaks in the future. (+info)
Ebola virus: a comparison, at ultrastructural level, of the behaviour of the Sudan and Zaire strains in monkeys.
Histopathological and electron microscopical examination of human liver specimens collected during the Ebola haemorrhagic fever outbreaks in Zaire and Sudan indicated that Zairean strains of the virus produced more extensive lesions. Experimental infection of rhesus monkeys wiht Zairean and Sudanese strains of Ebola virus produced similar changes to those found in man. In Zairean strain infections large numbers of virus particles were found in the liver, lung and spleen accompanied by extensive necrosis in the spleen. In Sudan strain infections particles were found only in the liver and in greatly reduced numbers. The main distinction lay in the high proportion of aberrant particles found with the Sudanese strain. The possibility of these being defective particles is discussed. (+info)
Clinical and epidemiological patterns of Argentine haemorrhagic fever.
The epidemiology of Argentine haemorrhagic fever (AHF) is closely related to cricetine rodents acting as natural hosts of Junin virus. The endemo-epidemic area, which has increased 5 times since the disease was first recognized 15-20 years ago, is located in a densely populated region of Argentina. It has been shown that the virus of LCM is active in humans and rodents of the AHF endemic area; this demonstrates the simultaneous presence of two arenaviruses pathogenic for man in a given geographic location.The disease is characterized by haematological, renal, neurological and cardiovascular changes. Electron microscopy and immunohistochemical studies have shown cytopathic changes, characteristic intracellular virus-like particles, and antigenic determinants of Junin virus in different organs from 9 cases of AHF. No deposits of immunoglobulins or C3 were found in the kidneys; in addition, an absence of fibrinogen and C3 in the hepatocytes and of immunoglobulins in the spleen was observed. These findings suggest a direct viral pathogenic action in the human disease.Ultrastructural and immunofluorescence studies in tissues of guinea-pigs inoculated with two strains of Junin virus revealed the presence of the same types of virus-like particles and antigenic determinants of Junin virus as were encountered in the human subjects with AHF. (+info)
Arenavirus chemotherapy--retrospect and prospect.
Two groups of compounds, identifiable by structural similarity, have been found to interfere with the in vitro replication of arenaviruses. All 4 members of the benzimidazole group contain dipolar fused benzene and 5-membered nitrogen-containing rings and share potential chelating ability through the different bidentate structures formed with their side-chains. The biological activity of one of these compounds, metisazone, has been shown to depend on the presence of divalent metals of the first transition series, Cu(++) being the most effective. Furthermore, whereas metisazone inactivates cell-free virus, two other members of the group, HBB and 1,2-bis(5-methoxy-1H-benzimidazol-2-yl)-1,2-ethanediol, act intracellularly. The site of action of the fourth member, SKF 30097, is not known. Using murine lymphocytic choriomeningitis infections as an in vivo model, the bisbenzimidazole derivative has been found to increase life-span without interfering with virus replication. Medication with SKF 30097 or metisazone and copper (2(+)) sulfate did not significantly or reproducibly change the expected day of death of the animals. The amantadine compounds of the second group have unusual symmetric structures with a 10-carbon cage. The parent compound acts intracellularly, while the site of action of an octachloro derivative is not known. Medication with the parent compound, but not the derivative, shortened the interval between LCM infection and death of the mouse. Tissue culture and animal screening of the many available derivatives in these two groups may uncover compounds more efficacious than those already examined. (+info)
Directions for future research on the pathogenesis of arenaviral infections.
The pathogenesis of arenavirus infection is considered separately for the haemorrhagic fever (HF) syndrome and for lymphocytic choriomeningitis (LCM) virus infection of rodents. Experimental models of HF have received only limited study, mainly because of the virulence of the causal agents. Two useful models (Junin virus in guinea-pigs and Machupo virus in rhesus monkeys) are now available and an attempt is made to delineate crucial questions for future studies, including the physiology of shock, disseminated intravascular coagulation, immune mediation of disease, efficacy of antibody in treatment, and relative utility of attenuated and inactivated vaccines. Immunobiologic problems currently under investigation in LCM virus infection include the mechanism of immune destruction of infected tissues, the H-2 restriction of in vitro T-cell-mediated lysis of infected target cells, the transient immunodepression that accompanies acute primary LCM virus infection, and the mechanism of T-cell-mediated clearance of virus from infected tissues following adoptive immunization of persistently infected carrier mice. (+info)
Viral hemorrhagic fever hazards for travelers in Africa.
This short review covers 6 viral hemorrhagic fevers (VHFs) that are known to occur in Africa: yellow fever, Rift Valley fever, Crimean-Congo hemorrhagic fever, Lassa fever, Marburg virus disease, and Ebola hemorrhagic fever. All of these have at one time or another affected travelers, often the adventurous kind who are "roughing it" in rural areas, who should therefore be made aware by their physicians or travel health clinics about their potential risk of exposure to any VHF along their travel route and how to minimize the risk. A significant proportion of VHF cases involving travelers have affected expatriate health care workers who were nosocomially exposed in African hospitals or clinics. The VHFs are associated with a high case-fatality rate but are readily prevented by well-known basic precautions. (+info)
Isolation of ribosome-like sturctures from Pichinde virus.
Three classes of mamalian ribosome-like structures were found to be associated with purified Pichinde virus preparations. These structures, possessing sedimentation coefficients of 80S, 60S and 40S, were sensitive to EDTA dissociation and possessed a buoyant density in caesium chloride of 1-61 g/ml, a value analogous to that displayed by BHK21 cell ribosomes. Analyses of RNA components associated with ribosomal particles of Pichinde virus established that 28S and 18S RNAs could be extracted from 80S monosomes. Similarly, 28S and 18S RNAs were derived, respectively, from 60S and 30S ribosomal subunits. Virus-specific 31S and 22S RNAs, as well as 28S and 18S RNAs, could be isolated from the heavy region of sucrose gradients. An additional 15S type of RNA, which was subsequently shown to be a component of intact virus particles, was also isolated from the heavy region. (+info)
Recognition of illness associated with the intentional release of a biologic agent.
On September 11, 2001, following the terrorist incidents in New York City and Washington, D.C., CDC recommended heightened surveillance for any unusual disease occurrence or increased numbers of illnesses that might be associated with the terrorist attacks. Subsequently, cases of anthrax in Florida and New York City have demonstrated the risks associated with intentional release of biologic agents. This report provides guidance for health-care providers and public health personnel about recognizing illnesses or patterns of illnessthat might be associated with intentional release of biologic agents. (+info)