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1.
EMBO Rep ; 23(7): e53600, 2022 07 05.
Artículo en Inglés | MEDLINE | ID: mdl-35607830

RESUMEN

The dengue virus nonstructural protein 1 (NS1) is a secreted virulence factor that modulates complement, activates immune cells and alters endothelial barriers. The molecular basis of these events remains incompletely understood. Here we describe a functional high affinity complex formed between NS1 and human high-density lipoproteins (HDL). Collapse of the soluble NS1 hexamer upon binding to the lipoprotein particle leads to the anchoring of amphipathic NS1 dimeric subunits into the HDL outer layer. The stable complex can be visualized by electron microscopy as a spherical HDL with rod-shaped NS1 dimers protruding from the surface. We further show that the assembly of NS1-HDL complexes triggers the production of pro-inflammatory cytokines in human primary macrophages while NS1 or HDL alone do not. Finally, we detect NS1 in complex with HDL and low-density lipoprotein (LDL) particles in the plasma of hospitalized dengue patients and observe NS1-apolipoprotein E-positive complexes accumulating overtime. The functional reprogramming of endogenous lipoprotein particles by NS1 as a means to exacerbate systemic inflammation during viral infection provides a new paradigm in dengue pathogenesis.


Asunto(s)
Virus del Dengue , Dengue , Dengue/metabolismo , Virus del Dengue/fisiología , Humanos , Lipoproteínas HDL/metabolismo , Fagocitosis , Proteínas no Estructurales Virales/metabolismo
2.
J Gen Virol ; 104(11)2023 11.
Artículo en Inglés | MEDLINE | ID: mdl-37909282

RESUMEN

Enterovirus 71 (EV-A71) is a major public health problem, causing a range of illnesses from hand-foot-and-mouth disease to severe neurological manifestations. EV-A71 strains have been phylogenetically classified into eight genogroups (A to H), based on their capsid-coding genomic region. Genogroups B and C have caused large outbreaks worldwide and represent the two canonical circulating EV-A71 subtypes. Little is known about the antigenic diversity of new genogroups as compared to the canonical ones. Here, we compared the antigenic features of EV-A71 strains that belong to the canonical B and C genogroups and to genogroups E and F, which circulate in Africa. Analysis of the peptide sequences of EV-A71 strains belonging to different genogroups revealed a high level of conservation of the capsid residues involved in known linear and conformational neutralization antigenic sites. Using a published crystal structure of the EV-A71 capsid as a model, we found that most of the residues that are seemingly specific to some genogroups were mapped outside known antigenic sites or external loops. These observations suggest a cross-neutralization activity of anti-genogroup B or C antibodies against strains of genogroups E and F. Neutralization assays were performed with diverse rabbit and mouse anti-EV-A71 sera, anti-EV-A71 human standards and a monoclonal neutralizing antibody. All the batches of antibodies that were tested successfully neutralized all available isolates, indicating an overall broad cross-neutralization between the canonical genogroups B and C and genogroups E and F. A panel constituted of more than 80 individual human serum samples from Cambodia with neutralizing antibodies against EV-A71 subgenogroup C4 showed quite similar cross-neutralization activities between isolates of genogroups C4, E and F. Our results thus indicate that the genetic drift underlying the separation of EV-A71 strains into genogroups A, B, C, E and F does not correlate with the emergence of antigenically distinct variants.


Asunto(s)
Enterovirus Humano A , Infecciones por Enterovirus , Enterovirus , Enfermedad de Boca, Mano y Pie , Humanos , Ratones , Animales , Conejos , Enterovirus Humano A/genética , Antígenos Virales/genética , Proteínas de la Cápside/genética , Genotipo , Anticuerpos Monoclonales
3.
PLoS Pathog ; 16(1): e1008191, 2020 01.
Artículo en Inglés | MEDLINE | ID: mdl-31951644

RESUMEN

Avian influenza viruses (AIVs) periodically cross species barriers and infect humans. The likelihood that an AIV will evolve mammalian transmissibility depends on acquiring and selecting mutations during spillover, but data from natural infection is limited. We analyze deep sequencing data from infected humans and domestic ducks in Cambodia to examine how H5N1 viruses evolve during spillover. Overall, viral populations in both species are predominated by low-frequency (<10%) variation shaped by purifying selection and genetic drift, and half of the variants detected within-host are never detected on the H5N1 virus phylogeny. However, we do detect a subset of mutations linked to human receptor binding and replication (PB2 E627K, HA A150V, and HA Q238L) that arose in multiple, independent humans. PB2 E627K and HA A150V were also enriched along phylogenetic branches leading to human infections, suggesting that they are likely human-adaptive. Our data show that H5N1 viruses generate putative human-adapting mutations during natural spillover infection, many of which are detected at >5% frequency within-host. However, short infection times, genetic drift, and purifying selection likely restrict their ability to evolve extensively during a single infection. Applying evolutionary methods to sequence data, we reveal a detailed view of H5N1 virus adaptive potential, and develop a foundation for studying host-adaptation in other zoonotic viruses.


Asunto(s)
Subtipo H5N1 del Virus de la Influenza A/aislamiento & purificación , Gripe Aviar/virología , Gripe Humana/virología , Animales , Cambodia , Patos/virología , Evolución Molecular , Humanos , Subtipo H5N1 del Virus de la Influenza A/clasificación , Subtipo H5N1 del Virus de la Influenza A/genética , Mutación , Filogenia , Proteínas Virales/genética
4.
Malar J ; 20(1): 366, 2021 Sep 09.
Artículo en Inglés | MEDLINE | ID: mdl-34503519

RESUMEN

BACKGROUND: In many endemic areas, Plasmodium vivax malaria is predominantly a disease of young adults and children. International recommendations for radical cure recommend fixed target doses of 0.25 or 0.5 mg/kg/day of primaquine for 14 days in glucose-6-phosphate dehydrogenase normal patients of all ages. However, for many anti-malarial drugs, including primaquine, there is evidence that children have lower exposures than adults for the same weight-adjusted dose. The aim of the study was to develop 14-day weight-based and age-based primaquine regimens against high-frequency relapsing tropical P. vivax. METHODS: The recommended adult target dose of 0.5 mg/kg/day (30 mg in a 60 kg patient) is highly efficacious against tropical P. vivax and was assumed to produce optimal drug exposure. Primaquine doses were calculated using allometric scaling to derive a weight-based primaquine regimen over a weight range from 5 to 100 kg. Growth curves were constructed from an anthropometric database of 53,467 individuals from the Greater Mekong Subregion (GMS) to define weight-for-age relationships. The median age associated with each weight was used to derive an age-based dosing regimen from the weight-based regimen. RESULTS: The proposed weight-based regimen has 5 dosing bands: (i) 5-7 kg, 5 mg, resulting in 0.71-1.0 mg/kg/day; (ii) 8-16 kg, 7.5 mg, 0.47-0.94 mg/kg/day; (iii) 17-40 kg, 15 mg, 0.38-0.88 mg/kg/day; (iv) 41-80 kg, 30 mg, 0.37-0.73 mg/kg/day; and (v) 81-100 kg, 45 mg, 0.45-0.56 mg/kg/day. The corresponding age-based regimen had 4 dosing bands: 6-11 months, 5 mg, 0.43-1.0 mg/kg/day; (ii) 1-5 years, 7.5 mg, 0.35-1.25 mg/kg/day; (iii) 6-14 years, 15 mg, 0.30-1.36 mg/kg/day; and (iv) ≥ 15 years, 30 mg, 0.35-1.07 mg/kg/day. CONCLUSION: The proposed weight-based regimen showed less variability around the primaquine dose within each dosing band compared to the age-based regimen and is preferred. Increased dose accuracy could be achieved by additional dosing bands for both regimens. The age-based regimen might not be applicable to regions outside the GMS, which must be based on local anthropometric data. Pharmacokinetic data in small children are needed urgently to inform the proposed regimens.


Asunto(s)
Antimaláricos/administración & dosificación , Esquema de Medicación , Malaria Vivax/prevención & control , Plasmodium vivax/efectos de los fármacos , Primaquina/administración & dosificación , Adolescente , Adulto , Factores de Edad , Anciano , Anciano de 80 o más Años , Peso Corporal , Niño , Preescolar , Femenino , Humanos , Lactante , Masculino , Persona de Mediana Edad , Adulto Joven
5.
PLoS Pathog ; 14(5): e1006965, 2018 05.
Artículo en Inglés | MEDLINE | ID: mdl-29723307

RESUMEN

Despite estimates that, each year, as many as 300 million dengue virus (DENV) infections result in either no perceptible symptoms (asymptomatic) or symptoms that are sufficiently mild to go undetected by surveillance systems (inapparent), it has been assumed that these infections contribute little to onward transmission. However, recent blood-feeding experiments with Aedes aegypti mosquitoes showed that people with asymptomatic and pre-symptomatic DENV infections are capable of infecting mosquitoes. To place those findings into context, we used models of within-host viral dynamics and human demographic projections to (1) quantify the net infectiousness of individuals across the spectrum of DENV infection severity and (2) estimate the fraction of transmission attributable to people with different severities of disease. Our results indicate that net infectiousness of people with asymptomatic infections is 80% (median) that of people with apparent or inapparent symptomatic infections (95% credible interval (CI): 0-146%). Due to their numerical prominence in the infectious reservoir, clinically inapparent infections in total could account for 84% (CI: 82-86%) of DENV transmission. Of infections that ultimately result in any level of symptoms, we estimate that 24% (95% CI: 0-79%) of onward transmission results from mosquitoes biting individuals during the pre-symptomatic phase of their infection. Only 1% (95% CI: 0.8-1.1%) of DENV transmission is attributable to people with clinically detected infections after they have developed symptoms. These findings emphasize the need to (1) reorient current practices for outbreak response to adoption of pre-emptive strategies that account for contributions of undetected infections and (2) apply methodologies that account for undetected infections in surveillance programs, when assessing intervention impact, and when modeling mosquito-borne virus transmission.


Asunto(s)
Dengue/transmisión , Aedes/virología , Animales , Dengue/diagnóstico , Dengue/virología , Virus del Dengue/patogenicidad , Reservorios de Enfermedades/virología , Interacciones Huésped-Patógeno , Humanos , Modelos Biológicos , Mosquitos Vectores/virología , Viremia/diagnóstico , Viremia/transmisión , Viremia/virología
6.
Bull World Health Organ ; 98(8): 539-547, 2020 Aug 01.
Artículo en Inglés | MEDLINE | ID: mdl-32773899

RESUMEN

OBJECTIVE: To better understand the potential risks of Nipah virus emergence in Cambodia by studying different components of the interface between humans and bats. METHODS: From 2012 to 2016, we conducted a study at two sites in Kandal and Battambang provinces where fruit bats (Pteropus lylei) roost. We combined research on: bat ecology (reproductive phenology, population dynamics and diet); human practices and perceptions (ethnographic research and a knowledge, attitude and practice study); and Nipah virus circulation in bat and human populations (virus monitoring in bat urine and anti-Nipah-virus antibody detection in human serum). FINDINGS: Our results confirmed circulation of Nipah virus in fruit bats (28 of 3930 urine samples positive by polymerase chain reaction testing). We identified clear potential routes for virus transmission to humans through local practices, including fruit consumed by bats and harvested by humans when Nipah virus is circulating, and palm juice production. Nevertheless, in the serological survey of 418 potentially exposed people, none of them were seropositive to Nipah virus. Differences in agricultural practices among the regions where Nipah virus has emerged may explain the situation in Cambodia and point to actions to limit the risks of virus transmission to humans. CONCLUSION: Human practices are key to understanding transmission risks associated with emerging infectious diseases. Social science disciplines such as anthropology need to be integrated in health programmes targeting emerging infectious diseases. As bats are hosts of major zoonotic pathogens, such integrated studies would likely also help to reduce the risk of emergence of other bat-borne diseases.


Asunto(s)
Quirópteros/virología , Infecciones por Henipavirus/psicología , Infecciones por Henipavirus/transmisión , Virus Nipah/aislamiento & purificación , Animales , Antropología Cultural , Anticuerpos Antivirales , Cambodia/epidemiología , Femenino , Frutas , Conocimientos, Actitudes y Práctica en Salud , Infecciones por Henipavirus/epidemiología , Infecciones por Henipavirus/orina , Humanos , Masculino , Virus Nipah/inmunología , Factores de Riesgo , Zoonosis/virología
7.
Arch Virol ; 165(8): 1869-1875, 2020 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-32488616

RESUMEN

Coronaviruses can become zoonotic, as in the case of COVID-19, and hunting, sale, and consumption of wild animals in Southeast Asia increases the risk for such incidents. We sampled and tested rodents (851) and other mammals and found betacoronavirus RNA in 12 rodents. The sequences belong to two separate genetic clusters and are closely related to those of known rodent coronaviruses detected in the region and distantly related to those of human coronaviruses OC43 and HKU1. Considering the close human-wildlife contact with many species in and beyond the region, a better understanding of virus diversity is urgently needed for the mitigation of future risks.


Asunto(s)
Animales Salvajes/virología , Betacoronavirus/genética , Infecciones por Coronavirus/veterinaria , Pandemias/veterinaria , Neumonía Viral/veterinaria , ARN Viral/genética , Roedores/virología , Animales , Betacoronavirus/aislamiento & purificación , COVID-19 , Quirópteros/virología , Coronavirus Humano OC43/genética , Humanos , Laos/epidemiología , ARN Viral/aislamiento & purificación , SARS-CoV-2
8.
Emerg Infect Dis ; 25(7): 1354-1362, 2019 07.
Artículo en Inglés | MEDLINE | ID: mdl-31211672

RESUMEN

We investigated dengue virus (DENV) and asymptomatic DENV infections in rural villages of Kampong Cham Province, Cambodia, during 2012 and 2013. We conducted perifocal investigations in and around households for 149 DENV index cases identified through hospital and village surveillance. We tested participants 0.5-30 years of age by using nonstructural 1 rapid tests and confirmed DENV infections using quantitative reverse transcription PCR or nonstructural 1-capture ELISA. We used multivariable Poisson regressions to explore links between participants' DENV infection status and household characteristics. Of 7,960 study participants, 346 (4.4%) were infected with DENV, among whom 302 (87.3%) were <15 years of age and 225 (65.0%) were <9 years of age. We identified 26 (7.5%) participants with strictly asymptomatic DENV infection at diagnosis and during follow-up. We linked symptomatic DENV infection status to familial relationships with index cases. During the 2-year study, we saw fewer asymptomatic DENV infections than expected based on the literature.


Asunto(s)
Enfermedades Asintomáticas/epidemiología , Virus del Dengue , Dengue/epidemiología , Dengue/virología , Adolescente , Adulto , Factores de Edad , Cambodia/epidemiología , Niño , Preescolar , Dengue/diagnóstico , Dengue/historia , Brotes de Enfermedades , Femenino , Historia del Siglo XXI , Humanos , Masculino , Tamizaje Masivo , Vigilancia en Salud Pública , Vigilancia de Guardia , Adulto Joven
9.
Ecol Appl ; 29(4): e01886, 2019 06.
Artículo en Inglés | MEDLINE | ID: mdl-30986339

RESUMEN

The reduction in biodiversity from land use change due to urbanization and agricultural intensification appears to be linked to major epidemiological changes in many human diseases. Increasing disease risks and the emergence of novel pathogens result from increased contact among wildlife, domesticated animals, and humans. We investigated the relationship between human alteration of the environment and the occurrence of generalist and synanthropic rodent species in relation to the diversity and prevalence of rodent-borne pathogens in Southeast Asia, a hotspot of threatened and endangered species, and a foci of emerging infectious diseases. We used data from an extensive pathogen survey of rodents from seven sites in mainland Southeast Asia in conjunction with past and present land cover analyses. At low spatial resolutions, we found that rodent-borne pathogen richness is negatively associated with increasing urbanization, characterized by increased habitat fragmentation, agriculture cover and deforestation. However, at a finer spatial resolution, we found that some major pathogens are favored by environmental characteristics associated with human alteration including irrigation, habitat fragmentation, and increased agricultural land cover. In addition, synanthropic rodents, many of which are important pathogen reservoirs, were associated with fragmented and human-dominated landscapes, which may ultimately enhance the opportunities for zoonotic transmission and human infection by some pathogens.


Asunto(s)
Enfermedades de los Roedores , Animales , Asia Sudoriental , Biodiversidad , Ecosistema , Humanos , Roedores
10.
J Infect Dis ; 217(11): 1690-1698, 2018 05 05.
Artículo en Inglés | MEDLINE | ID: mdl-29490079

RESUMEN

Background: Early detection of severe dengue can improve patient care and survival. To date, no reliable single-gene biomarker exists. We hypothesized that robust multigene signatures exist. Methods: We performed a prospective study on Cambodian dengue patients aged 4 to 22 years. Peripheral blood mononuclear cells (PBMCs) were obtained at hospital admission. We analyzed 42 transcriptomic profiles of patients with secondary dengue infected with dengue serotype 1. Our novel signature discovery approach controls the number of included genes and captures nonlinear relationships between transcript concentrations and severity. We evaluated the signature on secondary cases infected with different serotypes using 2 datasets: 22 PBMC samples from additional patients in our cohort and 32 whole blood samples from an independent cohort. Results: We identified an 18-gene signature for detecting severe dengue in patients with secondary infection upon hospital admission with a sensitivity of 0.93 (95% confidence interval [CI], .82-.98), specificity of 0.67 (95% CI, .53-.80), and area under the receiver operating characteristic curve (AUC) of 0.86 (95% CI, .75-.97). At validation, the signature had empirical AUCs of 0.85 (95% CI, .69-1.00) and 0.83 (95% CI, .68-.98) for the PBMCs and whole blood datasets, respectively. Conclusions: The signature could detect severe dengue in secondary-infected patients upon hospital admission. Its genes offer new insights into the pathogenesis of severe dengue.


Asunto(s)
ARN/sangre , Dengue Grave/sangre , Dengue Grave/diagnóstico , Adolescente , Adulto , Niño , Preescolar , Coinfección/sangre , Coinfección/diagnóstico , Coinfección/virología , Virus del Dengue/genética , Femenino , Marcadores Genéticos/genética , Hospitalización , Hospitales , Humanos , Leucocitos Mononucleares/virología , Masculino , Estudios Prospectivos , Curva ROC , Sensibilidad y Especificidad , Serogrupo , Transcriptoma/genética , Adulto Joven
11.
Am J Epidemiol ; 187(2): 306-315, 2018 02 01.
Artículo en Inglés | MEDLINE | ID: mdl-29020186

RESUMEN

Postexposure prophylaxis (PEP) prevents human rabies and is accessible in Cambodia principally in Phnom Penh, the capital. Timely, affordable access to PEP is a challenge for the mainly rural population. We aimed to identify districts independently associated with PEP noncompletion to position frontline vaccination centers. We analyzed the 2009-2013 database at the Rabies Prevention Center at the Institut Pasteur du Cambodge, Phnom Penh. Logistic regressions identified nongeographic determinants of PEP noncompletion as well as the districts that were independently associated with noncompletion after adjustment for these determinants. The influence of distance by road was estimated using a boosted regression-trees model. We computed a population attributable fraction (rabies index (RI)) for each district and developed a map of this RI distribution. A cartographic analysis based on the statistic developed by Getis and Ord identified clusters of high-RI districts. Factors independently associated with noncompletion were patients' district of residence, male sex, age 15-49 years, initial visit during rice harvest, the dog's status (culled or disappeared), and a prescribed PEP protocol requiring more than 3 PEP sessions (4 or 5). Four clusters of high-RI districts were identified using this analytical strategy, which is applicable to many vaccination or other health services. Positioning frontline PEP centers in these districts could significantly widen access to timely and adequate PEP.


Asunto(s)
Mordeduras y Picaduras/epidemiología , Perros , Pacientes Desistentes del Tratamiento/estadística & datos numéricos , Profilaxis Posexposición/estadística & datos numéricos , Rabia/prevención & control , Adolescente , Adulto , Animales , Mordeduras y Picaduras/virología , Cambodia/epidemiología , Femenino , Accesibilidad a los Servicios de Salud/estadística & datos numéricos , Humanos , Masculino , Área sin Atención Médica , Persona de Mediana Edad , Rabia/virología , Virus de la Rabia , Población Rural/estadística & datos numéricos , Adulto Joven
12.
Lancet ; 390(10098): 946-958, 2017 Sep 02.
Artículo en Inglés | MEDLINE | ID: mdl-28689664

RESUMEN

BACKGROUND: We have previously estimated that respiratory syncytial virus (RSV) was associated with 22% of all episodes of (severe) acute lower respiratory infection (ALRI) resulting in 55 000 to 199 000 deaths in children younger than 5 years in 2005. In the past 5 years, major research activity on RSV has yielded substantial new data from developing countries. With a considerably expanded dataset from a large international collaboration, we aimed to estimate the global incidence, hospital admission rate, and mortality from RSV-ALRI episodes in young children in 2015. METHODS: We estimated the incidence and hospital admission rate of RSV-associated ALRI (RSV-ALRI) in children younger than 5 years stratified by age and World Bank income regions from a systematic review of studies published between Jan 1, 1995, and Dec 31, 2016, and unpublished data from 76 high quality population-based studies. We estimated the RSV-ALRI incidence for 132 developing countries using a risk factor-based model and 2015 population estimates. We estimated the in-hospital RSV-ALRI mortality by combining in-hospital case fatality ratios with hospital admission estimates from hospital-based (published and unpublished) studies. We also estimated overall RSV-ALRI mortality by identifying studies reporting monthly data for ALRI mortality in the community and RSV activity. FINDINGS: We estimated that globally in 2015, 33·1 million (uncertainty range [UR] 21·6-50·3) episodes of RSV-ALRI, resulted in about 3·2 million (2·7-3·8) hospital admissions, and 59 600 (48 000-74 500) in-hospital deaths in children younger than 5 years. In children younger than 6 months, 1·4 million (UR 1·2-1·7) hospital admissions, and 27 300 (UR 20 700-36 200) in-hospital deaths were due to RSV-ALRI. We also estimated that the overall RSV-ALRI mortality could be as high as 118 200 (UR 94 600-149 400). Incidence and mortality varied substantially from year to year in any given population. INTERPRETATION: Globally, RSV is a common cause of childhood ALRI and a major cause of hospital admissions in young children, resulting in a substantial burden on health-care services. About 45% of hospital admissions and in-hospital deaths due to RSV-ALRI occur in children younger than 6 months. An effective maternal RSV vaccine or monoclonal antibody could have a substantial effect on disease burden in this age group. FUNDING: The Bill & Melinda Gates Foundation.


Asunto(s)
Hospitalización/estadística & datos numéricos , Modelos Estadísticos , Virus Sincitiales Respiratorios/aislamiento & purificación , Infecciones del Sistema Respiratorio/epidemiología , Preescolar , Países en Desarrollo , Salud Global , Mortalidad Hospitalaria , Humanos , Incidencia , Lactante , Recién Nacido , Factores de Riesgo
13.
Proc Natl Acad Sci U S A ; 112(47): 14688-93, 2015 Nov 24.
Artículo en Inglés | MEDLINE | ID: mdl-26553981

RESUMEN

Three-quarters of the estimated 390 million dengue virus (DENV) infections each year are clinically inapparent. People with inapparent dengue virus infections are generally considered dead-end hosts for transmission because they do not reach sufficiently high viremia levels to infect mosquitoes. Here, we show that, despite their lower average level of viremia, asymptomatic people can be infectious to mosquitoes. Moreover, at a given level of viremia, DENV-infected people with no detectable symptoms or before the onset of symptoms are significantly more infectious to mosquitoes than people with symptomatic infections. Because DENV viremic people without clinical symptoms may be exposed to more mosquitoes through their undisrupted daily routines than sick people and represent the bulk of DENV infections, our data indicate that they have the potential to contribute significantly more to virus transmission to mosquitoes than previously recognized.


Asunto(s)
Virus del Dengue/fisiología , Dengue/transmisión , Dengue/virología , Adolescente , Aedes/virología , Animales , Niño , Dengue/sangre , Relación Dosis-Respuesta Inmunológica , Femenino , Humanos , Masculino , Análisis Multivariante , Análisis de Regresión , Viremia/sangre , Viremia/virología
14.
Emerg Infect Dis ; 23(2): 296-299, 2017 02.
Artículo en Inglés | MEDLINE | ID: mdl-27875110

RESUMEN

We describe a retrospective study on circulation of Zika virus in Cambodia during 2007-2016 among patients with dengue-like symptoms and Aedes aegypti mosquitoes. Our findings suggest that Zika virus in Cambodia belongs to the Asia genotype, is endemic, has low prevalence, and has had low-level impact on public health.


Asunto(s)
Infección por el Virus Zika/epidemiología , Infección por el Virus Zika/virología , Virus Zika , Aedes/virología , Animales , Cambodia/epidemiología , Genotipo , Geografía Médica , Humanos , Insectos Vectores/virología , Filogenia , Vigilancia de la Población , Prevalencia , Estudios Retrospectivos , Proteínas no Estructurales Virales/genética , Virus Zika/clasificación , Virus Zika/genética , Infección por el Virus Zika/transmisión
15.
Emerg Infect Dis ; 23(2): 300-303, 2017 02.
Artículo en Inglés | MEDLINE | ID: mdl-28098551

RESUMEN

Thirty-five human influenza A(H5N1) cases were reported in Cambodia during 2013-2014 after emergence of a clade 1.1.2 reassortant virus. We tested 881 villagers and found 2 cases of pauci- or asymptomatic infection. Seroprevalence after emergence of the reassortant strain (0.2%) was lower than the aggregate seroprevalence of 1.3% reported in earlier studies.


Asunto(s)
Subtipo H5N1 del Virus de la Influenza A/clasificación , Subtipo H5N1 del Virus de la Influenza A/genética , Gripe Humana/transmisión , Gripe Humana/virología , Virus Reordenados , Animales , Cambodia/epidemiología , Geografía Médica , Historia del Siglo XXI , Humanos , Gripe Aviar/epidemiología , Gripe Aviar/virología , Gripe Humana/epidemiología , Gripe Humana/historia , Aves de Corral , Estudios Seroepidemiológicos
16.
J Gen Virol ; 98(9): 2287-2296, 2017 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-28840803

RESUMEN

Japanese encephalitis remains the most important cause of viral encephalitis in humans in several southeast Asian countries, including Cambodia, causing at least 65 000 cases of encephalitis per year. This vector-borne viral zoonosis - caused by Japanese encephalitis virus (JEV) - is considered to be a rural disease and is transmitted by mosquitoes, with birds and pigs being the natural reservoirs, while humans are accidental hosts. In this study we report the first two JEV isolations in Cambodia from human encephalitis cases from two studies on the aetiology of central nervous system disease, conducted at the two major paediatric hospitals in the country. We also report JEV isolation from Culextritaeniorhynchus mosquitoes and from pig samples collected in two farms, located in peri-urban and rural areas. Out of 11 reverse-transcription polymerase chain reaction-positive original samples, we generated full-genome sequences from 5 JEV isolates. Five additional partial sequences of the JEV NS3 gene from viruses detected in five pigs and one complete coding sequence of the envelope gene of a strain identified in a pig were generated. Phylogenetic analyses revealed that JEV detected in Cambodia belonged to genotype I and clustered in two clades: genotype I-a, mainly comprising strains from Thailand, and genotype I-b, comprising strains from Vietnam that dispersed northwards to China. Finally, in this study, we provide proof that the sequenced JEV strains circulate between pigs, Culex tritaeniorhynchus and humans in the Phnom Penh vicinity.


Asunto(s)
Culicidae/virología , Virus de la Encefalitis Japonesa (Especie)/aislamiento & purificación , Encefalitis Japonesa/veterinaria , Encefalitis Japonesa/virología , Genoma Viral , Enfermedades de los Porcinos/virología , Animales , Cambodia , Niño , Preescolar , Estudios de Cohortes , Virus de la Encefalitis Japonesa (Especie)/clasificación , Virus de la Encefalitis Japonesa (Especie)/genética , Femenino , Genotipo , Humanos , Lactante , Masculino , Filogenia , Porcinos
17.
BMC Pulm Med ; 17(1): 79, 2017 May 03.
Artículo en Inglés | MEDLINE | ID: mdl-28468650

RESUMEN

BACKGROUND: Influenza is a frequent cause of exacerbations of chronic obstructive pulmonary disease (COPD). Exacerbations are associated with worsening of the airflow obstruction, hospitalisation, reduced quality of life, disease progression, death, and ultimately, substantial healthcare-related costs. Despite longstanding recommendations to vaccinate vulnerable high-risk groups against seasonal influenza, including patients with COPD, vaccination rates remain sub-optimal in this population. METHODS: We conducted a systematic review to summarise current evidence from randomised controlled trials (RCTs) and observational studies on the immunogenicity, safety, efficacy, and effectiveness of seasonal influenza vaccination in patients with COPD. The selection of relevant articles was based on a three-step selection procedure according to predefined inclusion and exclusion criteria. The search yielded 650 unique hits of which 48 eligible articles were screened in full-text. RESULTS: Seventeen articles describing 13 different studies were found to be pertinent to this review. Results of four RCTs and one observational study demonstrate that seasonal influenza vaccination is immunogenic in patients with COPD. Two studies assessed the occurrence of COPD exacerbations 14 days after influenza vaccination and found no evidence of an increased risk of exacerbation. Three RCTs showed no significant difference in the occurrence of systemic effects between groups receiving influenza vaccine or placebo. Six out of seven studies on vaccine efficacy or effectiveness indicated long-term benefits of seasonal influenza vaccination, such as reduced number of exacerbations, reduced hospitalisations and outpatient visits, and decreased all-cause and respiratory mortality. CONCLUSIONS: Additional large and well-designed observational studies would contribute to understanding the impact of disease severity and patient characteristics on the response to influenza vaccination. Overall, the evidence supports a positive benefit-risk ratio for seasonal influenza vaccination in patients with COPD, and supports current vaccination recommendations in this population.


Asunto(s)
Progresión de la Enfermedad , Vacunas contra la Influenza/administración & dosificación , Gripe Humana/prevención & control , Enfermedad Pulmonar Obstructiva Crónica/complicaciones , Hospitalización/estadística & datos numéricos , Humanos , Gripe Humana/complicaciones , Gripe Humana/epidemiología , Calidad de Vida , Ensayos Clínicos Controlados Aleatorios como Asunto , Índice de Severidad de la Enfermedad , Vacunación/estadística & datos numéricos
18.
Emerg Infect Dis ; 22(1): 92-5, 2016 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-26690000

RESUMEN

Enterovirus 71 is reported to have emerged in Cambodia in 2012; at least 54 children with severe encephalitis died during that outbreak. We used serum samples collected during 2000-2011 to show that the virus had been widespread in the country for at least a decade before the 2012 outbreak.


Asunto(s)
Encefalitis/epidemiología , Enterovirus Humano A/genética , Infecciones por Enterovirus/epidemiología , Adolescente , Cambodia/epidemiología , Niño , Preescolar , Brotes de Enfermedades , Encefalitis/virología , Infecciones por Enterovirus/virología , Femenino , Humanos , Masculino , Estudios Seroepidemiológicos
19.
BMC Med ; 14(1): 171, 2016 10 27.
Artículo en Inglés | MEDLINE | ID: mdl-27784313

RESUMEN

BACKGROUND: In 2012, the World Health Organization recommended the addition of single low-dose primaquine (SLDPQ, 0.25 mg base/kg body weight) to artemisinin combination therapies to block the transmission of Plasmodium falciparum without testing for glucose-6-phosphate dehydrogenase deficiency. The targeted group was non-pregnant patients aged ≥ 1 year (later changed to ≥ 6 months) with acute uncomplicated falciparum malaria, primarily in countries with artemisinin-resistant P. falciparum (ARPf). No dosing regimen was suggested, leaving malaria control programmes and clinicians in limbo. Therefore, we designed a user-friendly, age-based SLDPQ regimen for Cambodia, the country most affected by ARPf. METHODS: By reviewing primaquine's pharmacology, we defined a therapeutic dose range of 0.15-0.38 mg base/kg (9-22.5 mg in a 60-kg adult) for a therapeutic index of 2.5. Primaquine doses (1-20 mg) were tested using a modelled, anthropometric database of 28,138 Cambodian individuals (22,772 healthy, 4119 with malaria and 1247 with other infections); age distributions were: 0.5-4 years (20.0 %, n = 5640), 5-12 years (9.1 %, n = 2559), 13-17 years (9.1 %, n = 2550), and ≥ 18 years (61.8 %, n = 17,389). Optimal age-dosing groups were selected according to calculated mg base/kg doses and proportions of individuals receiving a therapeutic dose. RESULTS: Four age-dosing bands were defined: (1) 0.5-4 years, (2) 5-9 years, (3) 10-14 years, and (4) ≥15 years to receive 2.5, 5, 7.5, and 15 mg of primaquine base, resulting in therapeutic doses in 97.4 % (5494/5640), 90.5 % (1511/1669), 97.7 % (1473/1508), and 95.7 % (18,489/19,321) of individuals, respectively. Corresponding median (1st-99th centiles) mg base/kg doses of primaquine were (1) 0.23 (0.15-0.38), (2) 0.29 (0.18-0.45), (3) 0.27 (0.15-0.39), and (4) 0.29 (0.20-0.42). CONCLUSIONS: This age-based SLDPQ regimen could contribute substantially to malaria elimination and requires urgent evaluation in Cambodia and other countries with similar anthropometric characteristics. It guides primaquine manufacturers on suitable tablet strengths and doses for paediatric-friendly formulations. Development of similar age-based dosing recommendations for Africa is needed.


Asunto(s)
Antimaláricos/administración & dosificación , Malaria Falciparum/tratamiento farmacológico , Primaquina/administración & dosificación , Adolescente , Adulto , Factores de Edad , Cambodia , Transmisión de Enfermedad Infecciosa/prevención & control , Quimioterapia Combinada , Femenino , Deficiencia de Glucosafosfato Deshidrogenasa/metabolismo , Deficiencia de Glucosafosfato Deshidrogenasa/parasitología , Humanos , Malaria Falciparum/enzimología , Malaria Falciparum/prevención & control , Malaria Falciparum/terapia , Masculino , Persona de Mediana Edad , Adulto Joven
20.
Trop Med Int Health ; 21(4): 564-7, 2016 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-26806229

RESUMEN

Although limited publications address clinical management of symptomatic patients with rabies in intensive care units, the overwhelming majority of human rabies cases occur in the rural setting of developing countries where healthcare workers are few, lack training and drugs. Based on our experience, we suggest how clinicians in resource-limited settings can make best use of essential drugs to provide assistance to patients with rabies and their families, at no risk to themselves. Comprehensive and compassionate patient management of furious rabies should aim to alleviate thirst, anxiety and epileptic fits using infusions, diazepam or midazolam and antipyretic drugs via intravenous or intrarectal routes. Although the patient is dying, respiratory failure must be avoided especially if the family, after being informed, wish to take the patient home alive for funereal rites to be observed. Healthcare staff should be trained and clinical guidelines should be updated to include palliative care for rabies in endemic countries.


Asunto(s)
Países en Desarrollo , Medicamentos Esenciales/uso terapéutico , Cuidados Paliativos , Rabia/complicaciones , Ansiedad/tratamiento farmacológico , Ansiedad/etiología , Humanos , Insuficiencia Respiratoria/etiología , Insuficiencia Respiratoria/prevención & control , Población Rural , Convulsiones/tratamiento farmacológico , Convulsiones/etiología , Sed
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