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1.
N Engl J Med ; 386(24): 2283-2294, 2022 06 16.
Artículo en Inglés | MEDLINE | ID: mdl-35704480

RESUMEN

BACKGROUND: In June 2019, the Bolivian Ministry of Health reported a cluster of cases of hemorrhagic fever that started in the municipality of Caranavi and expanded to La Paz. The cause of these cases was unknown. METHODS: We obtained samples for next-generation sequencing and virus isolation. Human and rodent specimens were tested by means of virus-specific real-time quantitative reverse-transcriptase-polymerase-chain-reaction assays, next-generation sequencing, and virus isolation. RESULTS: Nine cases of hemorrhagic fever were identified; four of the patients with this illness died. The etiologic agent was identified as Mammarenavirus Chapare mammarenavirus, or Chapare virus (CHAPV), which causes Chapare hemorrhagic fever (CHHF). Probable nosocomial transmission among health care workers was identified. Some patients with CHHF had neurologic manifestations, and those who survived had a prolonged recovery period. CHAPV RNA was detected in a variety of human body fluids (including blood; urine; nasopharyngeal, oropharyngeal, and bronchoalveolar-lavage fluid; conjunctiva; and semen) and in specimens obtained from captured small-eared pygmy rice rats (Oligoryzomys microtis). In survivors of CHHF, viral RNA was detected up to 170 days after symptom onset; CHAPV was isolated from a semen sample obtained 86 days after symptom onset. CONCLUSIONS: M. Chapare mammarenavirus was identified as the etiologic agent of CHHF. Both spillover from a zoonotic reservoir and possible person-to-person transmission were identified. This virus was detected in a rodent species, O. microtis. (Funded by the Bolivian Ministry of Health and others.).


Asunto(s)
Arenavirus del Nuevo Mundo , Fiebre Hemorrágica Americana , ARN Viral , Roedores , Animales , Arenavirus del Nuevo Mundo/genética , Arenavirus del Nuevo Mundo/aislamiento & purificación , Bolivia/epidemiología , Infección Hospitalaria/transmisión , Infección Hospitalaria/virología , Transmisión de Enfermedad Infecciosa , Fiebre Hemorrágica Americana/complicaciones , Fiebre Hemorrágica Americana/genética , Fiebre Hemorrágica Americana/transmisión , Fiebre Hemorrágica Americana/virología , Fiebres Hemorrágicas Virales/genética , Fiebres Hemorrágicas Virales/transmisión , Fiebres Hemorrágicas Virales/virología , Secuenciación de Nucleótidos de Alto Rendimiento , Humanos , Reacción en Cadena de la Polimerasa , ARN Viral/genética , ARN Viral/aislamiento & purificación , Ratas/virología , Roedores/virología , Zoonosis Virales/transmisión , Zoonosis Virales/virología
2.
J Infect Dis ; 221(5): 707-714, 2020 02 18.
Artículo en Inglés | MEDLINE | ID: mdl-31858125

RESUMEN

BACKGROUND: Identifying risk factors for household transmission of Ebola virus (EBOV) is important to guide preventive measures during Ebola outbreaks. METHODS: We enrolled all confirmed persons with EBOV disease who were the first case patient in a household from December 2014 to April 2015 in Freetown, Sierra Leone, and their household contacts. Index patients and contacts were interviewed, and contacts were followed up for 21 days to identify secondary cases. Epidemiologic data were linked to EBOV real-time reverse-transcription polymerase chain reaction cycle threshold (Ct) data from initial diagnostic specimens obtained from enrolled index case patients. RESULTS: Ct data were available for 106 (71%) of 150 enrolled index patients. Of the Ct results, 85 (80%) were from blood specimens from live patients and 21 (20%) from oral swab specimens from deceased patients. The median Ct values for blood and swab specimens were 21.0 and 24.0, respectively (P = .007). In multivariable analysis, a Ct value from blood specimens in the lowest quintile was an independent predictor of both increased risk of household transmission (P = .009) and higher secondary attack rate among household contacts (P = .03), after adjustment for epidemiologic factors. CONCLUSIONS: Our findings suggest the potential to use Ct values from acute EBOV diagnostic specimens for index patients as an early predictor of high-risk households and high-risk groups of contacts to help prioritize EBOV disease investigation and control efforts.


Asunto(s)
Brotes de Enfermedades/prevención & control , Ebolavirus/genética , Composición Familiar , Fiebre Hemorrágica Ebola/epidemiología , Fiebre Hemorrágica Ebola/transmisión , Adolescente , Adulto , Niño , Preescolar , Femenino , Estudios de Seguimiento , Fiebre Hemorrágica Ebola/prevención & control , Fiebre Hemorrágica Ebola/virología , Humanos , Masculino , Persona de Mediana Edad , Estudios Prospectivos , Reacción en Cadena en Tiempo Real de la Polimerasa , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Factores de Riesgo , Sierra Leona/epidemiología , Adulto Joven
3.
Clin Infect Dis ; 62(12): 1552-1555, 2016 06 15.
Artículo en Inglés | MEDLINE | ID: mdl-27045122

RESUMEN

We investigated the duration of Ebola virus (EBOV) RNA and infectious EBOV in semen specimens of 5 Ebola virus disease (EVD) survivors. EBOV RNA and infectious EBOV was detected by real-time RT-PCR and virus culture out to 290 days and 70 days, respectively, after EVD onset.


Asunto(s)
Ebolavirus/aislamiento & purificación , Fiebre Hemorrágica Ebola/virología , Semen/virología , Adulto , Estudios de Cohortes , Ebolavirus/patogenicidad , Humanos , Masculino , Sobrevivientes
4.
Emerg Infect Dis ; 22(2): 217-23, 2016 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-26812579

RESUMEN

To determine whether 2 readily available indicators predicted survival among patients with Ebola virus disease in Sierra Leone, we evaluated information for 216 of the 227 patients in Bo District during a 4-month period. The indicators were time from symptom onset to healthcare facility admission and quantitative real-time reverse transcription PCR cycle threshold (Ct), a surrogate for viral load, in first Ebola virus-positive blood sample tested. Of these patients, 151 were alive when detected and had reported healthcare facility admission dates and Ct values available. Time from symptom onset to healthcare facility admission was not associated with survival, but viral load in the first Ebola virus-positive blood sample was inversely associated with survival: 52 (87%) of 60 patients with a Ct of >24 survived and 20 (22%) of 91 with a Ct of <24 survived. Ct values may be useful for clinicians making treatment decisions or managing patient or family expectations.


Asunto(s)
Ebolavirus , Fiebre Hemorrágica Ebola/mortalidad , Fiebre Hemorrágica Ebola/virología , Adolescente , Adulto , Femenino , Fiebre Hemorrágica Ebola/epidemiología , Hospitalización , Humanos , Masculino , Persona de Mediana Edad , Mortalidad , Vigilancia de la Población , Pronóstico , Sierra Leona/epidemiología , Adulto Joven
5.
PLoS Pathog ; 8(10): e1002877, 2012.
Artículo en Inglés | MEDLINE | ID: mdl-23055920

RESUMEN

Marburg virus (family Filoviridae) causes sporadic outbreaks of severe hemorrhagic disease in sub-Saharan Africa. Bats have been implicated as likely natural reservoir hosts based most recently on an investigation of cases among miners infected in 2007 at the Kitaka mine, Uganda, which contained a large population of Marburg virus-infected Rousettus aegyptiacus fruit bats. Described here is an ecologic investigation of Python Cave, Uganda, where an American and a Dutch tourist acquired Marburg virus infection in December 2007 and July 2008. More than 40,000 R. aegyptiacus were found in the cave and were the sole bat species present. Between August 2008 and November 2009, 1,622 bats were captured and tested for Marburg virus. Q-RT-PCR analysis of bat liver/spleen tissues indicated ~2.5% of the bats were actively infected, seven of which yielded Marburg virus isolates. Moreover, Q-RT-PCR-positive lung, kidney, colon and reproductive tissues were found, consistent with potential for oral, urine, fecal or sexual transmission. The combined data for R. aegyptiacus tested from Python Cave and Kitaka mine indicate low level horizontal transmission throughout the year. However, Q-RT-PCR data show distinct pulses of virus infection in older juvenile bats (~six months of age) that temporarily coincide with the peak twice-yearly birthing seasons. Retrospective analysis of historical human infections suspected to have been the result of discrete spillover events directly from nature found 83% (54/65) events occurred during these seasonal pulses in virus circulation, perhaps demonstrating periods of increased risk of human infection. The discovery of two tags at Python Cave from bats marked at Kitaka mine, together with the close genetic linkages evident between viruses detected in geographically distant locations, are consistent with R. aegyptiacus bats existing as a large meta-population with associated virus circulation over broad geographic ranges. These findings provide a basis for developing Marburg hemorrhagic fever risk reduction strategies.


Asunto(s)
Quirópteros/virología , Enfermedad del Virus de Marburg/epidemiología , Enfermedad del Virus de Marburg/transmisión , Marburgvirus/aislamiento & purificación , Animales , Secuencia de Bases , Cuevas , Quirópteros/clasificación , Reservorios de Enfermedades , Femenino , Humanos , Masculino , Marburgvirus/genética , Proteínas Nucleares/genética , Filogenia , ARN Viral/análisis , Estudios Retrospectivos , Estaciones del Año , Análisis de Secuencia de ARN , Uganda/epidemiología , Proteínas Reguladoras y Accesorias Virales/genética
6.
Emerg Infect Dis ; 18(4): 643-5, 2012 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-22469505

RESUMEN

We evaluated Crimean-Congo hemorrhagic fever (CCHF) surveillance data from southern Kazakhstan during 2009-2010 and found both spatial and temporal association between reported tick bites and CCHF cases. Public health measures should center on preventing tick bites, increasing awareness of CCHF signs and symptoms, and adopting hospital infection control practices.


Asunto(s)
Enfermedades Endémicas , Fiebre Hemorrágica de Crimea/epidemiología , Mordeduras y Picaduras de Insectos/epidemiología , Garrapatas , Adolescente , Adulto , Anciano , Animales , Niño , Preescolar , Vectores de Enfermedades , Virus de la Fiebre Hemorrágica de Crimea-Congo , Fiebre Hemorrágica de Crimea/etiología , Fiebre Hemorrágica de Crimea/transmisión , Humanos , Incidencia , Lactante , Mordeduras y Picaduras de Insectos/complicaciones , Kazajstán/epidemiología , Persona de Mediana Edad , Vigilancia de la Población , Adulto Joven
7.
J Virol ; 85(8): 4020-4, 2011 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-21307206

RESUMEN

Lassa virus (LASV), is a significant cause of severe, often fatal, hemorrhagic fever in humans throughout western Africa, with an estimated 100,000 infections each year. No vaccines are commercially available. We report the development of an efficient reverse genetics system to rescue recombinant LASV and to investigate the contributions of the long 5' and 3' noncoding regions (NCRs) of the S genomic segment to in vitro growth and in vivo virulence. This work demonstrates that deletions of large portions of these NCRs confer an attenuated phenotype and are a first step toward further insights into the high virulence of LASV.


Asunto(s)
Virus Lassa/genética , Virus Lassa/patogenicidad , ARN Viral/genética , Replicación Viral , Regiones no Traducidas 3' , Regiones no Traducidas 5' , Animales , Línea Celular , Datos de Secuencia Molecular , Análisis de Secuencia de ADN , Eliminación de Secuencia , Virulencia
8.
Emerg Infect Dis ; 16(10): 1598-600, 2010 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-20875288

RESUMEN

We report a case of Lassa fever in a US traveler who visited rural Liberia, became ill while in country, sought medical care upon return to the United States, and subsequently had his illness laboratory confirmed. The patient recovered with supportive therapy. No secondary cases occurred.


Asunto(s)
Fiebre de Lassa/diagnóstico , Fiebre de Lassa/virología , Virus Lassa/aislamiento & purificación , Viaje , Humanos , Virus Lassa/clasificación , Virus Lassa/genética , Liberia , Masculino , Persona de Mediana Edad , Pennsylvania , Reacción en Cadena de la Polimerasa/métodos
9.
J Virol ; 83(11): 5606-14, 2009 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-19321606

RESUMEN

The New World arenaviruses, Junin, Machupo, Guanarito, Sabia, and Chapare, are associated with rapidly progressing severe hemorrhagic fever with a high rate of case fatality in various regions of South America. The threat of natural or deliberate outbreaks associated with these viruses makes the development of preventive or therapeutic measures important. Here we describe a Junin virus functional minigenome system and a reverse genetics system for production of infectious Junin virus. This robust, highly efficient system involves transfection of cells with only two plasmids which transcribe the virus S and L antigenomic RNAs. The utility of the system is demonstrated by generating Junin viruses which encode a glycoprotein precursor (GPC) containing the following: (i) the wild-type (SKI-1/S1P peptidase) cleavage site, (ii) no cleavage site, or (iii) a cleavage site where the SKI-1/S1P motif (RSLK) is replaced by a furin cleavage site (RRKR). In contrast to the wild-type virus, Junin virus lacking a GPC cleavage site replicated within successfully transfected cells but failed to yield infectious virus particles. This confirms observations with other arenaviruses suggesting that GPC cleavage is essential for arenavirus infectivity. In contrast, infectious Junin virus which encoded GPC cleaved by furin-like proteases was easily generated. The two-plasmid, high efficiency aspects of this Junin virus reverse genetics system show great promise for addressing important questions regarding arenavirus hemorrhagic fever disease and for development of precisely attenuated live arenavirus vaccines.


Asunto(s)
Glicoproteínas/metabolismo , Virus Junin/metabolismo , Animales , Secuencia de Bases , Línea Celular , Genoma Viral/genética , Glicoproteínas/genética , Virus Junin/genética , Mutación/genética , Proproteína Convertasas/genética , Proproteína Convertasas/metabolismo , Ingeniería de Proteínas , ARN Viral/genética , Serina Endopeptidasas/genética , Serina Endopeptidasas/metabolismo , Replicación Viral
10.
J Virol ; 82(6): 2681-91, 2008 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-18199647

RESUMEN

Rift Valley fever (RVF) virus is a mosquito-borne human and veterinary pathogen associated with large outbreaks of severe disease throughout Africa and more recently the Arabian peninsula. Infection of livestock can result in sweeping "abortion storms" and high mortality among young animals. Human infection results in self-limiting febrile disease that in approximately 1 to 2% of patients progresses to more serious complications including hepatitis, encephalitis, and retinitis or a hemorrhagic syndrome with high fatality. The virus S segment-encoded NSs and the M segment-encoded NSm proteins are important virulence factors. The development of safe, effective vaccines and tools to screen and evaluate antiviral compounds is critical for future control strategies. Here, we report the successful reverse genetics generation of multiple recombinant enhanced green fluorescent protein-tagged RVF viruses containing either the full-length, complete virus genome or precise deletions of the NSs gene alone or the NSs/NSm genes in combination, thus creating attenuating deletions on multiple virus genome segments. These viruses were highly attenuated, with no detectable viremia or clinical illness observed with high challenge dosages (1.0 x 10(4) PFU) in the rat lethal disease model. A single-dose immunization regimen induced robust anti-RVF virus immunoglobulin G antibodies (titer, approximately 1:6,400) by day 26 postvaccination. All vaccinated animals that were subsequently challenged with a high dose of virulent RVF virus survived infection and could be serologically differentiated from naïve, experimentally infected animals by the lack of NSs antibodies. These rationally designed marker RVF vaccine viruses will be useful tools for in vitro screening of therapeutic compounds and will provide a basis for further development of RVF virus marker vaccines for use in endemic regions or following the natural or intentional introduction of the virus into previously unaffected areas.


Asunto(s)
Virus de la Fiebre del Valle del Rift/genética , Proteínas no Estructurales Virales/genética , Vacunas Virales/inmunología , Animales , Anticuerpos Antivirales/biosíntesis , Ensayo de Inmunoadsorción Enzimática , Genes Virales , Proteínas Fluorescentes Verdes/genética , Plásmidos , Ratas , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Virus de la Fiebre del Valle del Rift/inmunología , Virus de la Fiebre del Valle del Rift/patogenicidad , Virulencia
12.
PLoS Negl Trop Dis ; 8(2): e2670, 2014 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-24551252

RESUMEN

BACKGROUND: Previously, we investigated the role of the Rift Valley fever virus (RVFV) virulence genes NSs and NSm in mosquitoes and demonstrated that deletion of NSm significantly reduced the infection, dissemination, and transmission rates of RVFV in Aedes aegypti mosquitoes. The specific aim of this study was to further characterize midgut infection and escape barriers of RVFV in Ae. aegypti infected with reverse genetics-generated wild type RVFV (rRVF-wt) or RVFV lacking the NSm virulence gene (rRVF-ΔNSm) by examining sagittal sections of infected mosquitoes for viral antigen at various time points post-infection. METHODOLOGY AND PRINCIPAL FINDINGS: Ae. aegypti mosquitoes were fed an infectious blood meal containing either rRVF-wt or rRVF-ΔNSm. On days 0, 1, 2, 3, 4, 6, 8, 10, 12, and 14 post-infection, mosquitoes from each experimental group were fixed in 4% paraformaldehyde, paraffin-embedded, sectioned, and examined for RVFV antigen by immunofluorescence assay. Remaining mosquitoes at day 14 were assayed for infection, dissemination, and transmission. Disseminated infections were observed in mosquitoes as early as three days post infection for both virus strains. However, infection rates for rRVF-ΔNSm were statistically significantly less than for rRVF-wt. Posterior midgut infections in mosquitoes infected with rRVF-wt were extensive, whereas midgut infections of mosquitoes infected with rRVF-ΔNSm were confined to one or a few small foci. CONCLUSIONS/SIGNIFICANCE: Deletion of NSm resulted in the reduced ability of RVFV to enter, replicate, and disseminate from the midgut epithelial cells. NSm appears to have a functional role in the vector competence of mosquitoes for RVFV at the level of the midgut barrier.


Asunto(s)
Aedes/virología , Tracto Gastrointestinal/virología , Virus de la Fiebre del Valle del Rift/genética , Virus de la Fiebre del Valle del Rift/patogenicidad , Replicación Viral/genética , Animales , Femenino , Eliminación de Gen , Interacciones Huésped-Patógeno/genética
13.
PLoS Negl Trop Dis ; 6(5): e1639, 2012.
Artículo en Inglés | MEDLINE | ID: mdl-22563517

RESUMEN

BACKGROUND: Rift Valley fever virus is an arthropod-borne human and animal pathogen responsible for large outbreaks of acute and febrile illness throughout Africa and the Arabian Peninsula. Reverse genetics technology has been used to develop deletion mutants of the virus that lack the NSs and/or NSm virulence genes and have been shown to be stable, immunogenic and protective against Rift Valley fever virus infection in animals. We assessed the potential for these deletion mutant viruses to infect and be transmitted by Aedes mosquitoes, which are the principal vectors for maintenance of the virus in nature and emergence of virus initiating disease outbreaks, and by Culex mosquitoes which are important amplification vectors. METHODOLOGY AND PRINCIPAL FINDINGS: Aedes aegypti and Culex quinquefasciatus mosquitoes were fed bloodmeals containing the deletion mutant viruses. Two weeks post-exposure mosquitoes were assayed for infection, dissemination, and transmission. In Ae. aegypti, infection and transmission rates of the NSs deletion virus were similar to wild type virus while dissemination rates were significantly reduced. Infection and dissemination rates for the NSm deletion virus were lower compared to wild type. Virus lacking both NSs and NSm failed to infect Ae. aegypti. In Cx. quinquefasciatus, infection rates for viruses lacking NSm or both NSs and NSm were lower than for wild type virus. CONCLUSIONS/SIGNIFICANCE: In both species, deletion of NSm or both NSs and NSm reduced the infection and transmission potential of the virus. Deletion of both NSs and NSm resulted in the highest level of attenuation of virus replication. Deletion of NSm alone was sufficient to nearly abolish infection in Aedes aegypti mosquitoes, indicating an important role for this protein. The double deleted viruses represent an ideal vaccine profile in terms of environmental containment due to lack of ability to efficiently infect and be transmitted by mosquitoes.


Asunto(s)
Aedes/virología , Culex/virología , Fiebre del Valle del Rift/transmisión , Fiebre del Valle del Rift/virología , Virus de la Fiebre del Valle del Rift/genética , Proteínas no Estructurales Virales/genética , Factores de Virulencia/genética , África , Animales , Eliminación de Gen , Humanos , Virus de la Fiebre del Valle del Rift/aislamiento & purificación , Proteínas no Estructurales Virales/metabolismo , Factores de Virulencia/metabolismo
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