Overview of latest articles and publications on ebola in PubMed. PubMed is a service of the US National Library of Medicine that includes over 18 million citations from MEDLINE and other life science journals.
- Accuracy of Zika virus disease case definition during simultaneous Dengue and Chikungunya epidemics.
Accuracy of Zika virus disease case definition during simultaneous Dengue and Chikungunya epidemics. [Journal Article]PLoS One 2017; 12(6):e0179725.PlosBraga JU, Bressan C, Dalvi APR, et al. Our derived score prediction model had the best performance because it demonstrated the highest sensitivity and specificity, 86·6% and 78·3%, respectively. This Zika case definition also had the highes...Publisher Full TextZika is a new disease in the American continent and its surveillance is of utmost importance, especially because of its ability to cause neurological manifestations as Guillain-Barré syndrome and serious congenital malformations through vertical transmission. The detection of suspected cases by the surveillance system depends on the case definition adopted. As the laboratory diagnosis of Zika infection still relies on the use of expensive and complex molecular techniques with low sensitivity due to a narrow window of detection, most suspected cases are not confirmed by laboratory tests, mainly reserved for pregnant women and newborns. In this context, an accurate definition of a suspected Zika case is crucial in order for the surveillance system to gauge the magnitude of an epidemic.We evaluated the accuracy of various Zika case definitions in a scenario where Dengue and Chikungunya viruses co-circulate. Signs and symptoms that best discriminated PCR confirmed Zika from other laboratory confirmed febrile or exanthematic diseases were identified to propose and test predictive models for Zika infection based on these clinical features.Our derived score prediction model had the best performance because it demonstrated the highest sensitivity and specificity, 86·6% and 78·3%, respectively. This Zika case definition also had the highest values for auROC (0·903) and R2 (0·417), and the lowest Brier score 0·096.In areas where multiple arboviruses circulate, the presence of rash with pruritus or conjunctival hyperemia, without any other general clinical manifestations such as fever, petechia or anorexia is the best Zika case definition.
- Peridomestic Aedes malayensis and Aedes albopictus are capable vectors of arboviruses in cities.
Peridomestic Aedes malayensis and Aedes albopictus are capable vectors of arboviruses in cities. [Journal Article]PLoS Negl Trop Dis 2017 Jun 26; 11(6):e0005667.PNMendenhall IH, Manuel M, Moorthy M, et al. Our study reveals the prevalence of competent vectors in peri-domestic areas, including Ae. malayensis for which we established the vector status. Epidemics can be driven by infection foci, which are e...Publisher Full TextDengue and chikungunya are global re-emerging mosquito-borne diseases. In Singapore, sustained vector control coupled with household improvements reduced domestic mosquito populations for the past 45 years, particularly the primary vector Aedes aegypti. However, while disease incidence was low for the first 30 years following vector control implementation, outbreaks have re-emerged in the past 15 years. Epidemiological observations point to the importance of peridomestic infection in areas not targeted by control programs. We investigated the role of vectors in peri-domestic areas.We carried out entomological surveys to identify the Aedes species present in vegetated sites in highly populated areas and determine whether mosquitoes were present in open-air areas frequented by people. We compared vector competence of Aedes albopictus and Aedes malayensis with Ae. aegypti after oral infection with sympatric dengue serotype 2 and chikungunya viruses. Mosquito saliva was tested for the presence of infectious virus particles as a surrogate for transmission following oral infection.We identified Aedes albopictus and Aedes malayensis throughout Singapore and quantified their presence in forested and opened grassy areas. Both Ae. albopictus and Ae. malayensis can occupy sylvatic niches and were highly susceptible to both arboviruses. A majority of saliva of infected Ae. malayensis contained infectious particles for both viruses.Our study reveals the prevalence of competent vectors in peri-domestic areas, including Ae. malayensis for which we established the vector status. Epidemics can be driven by infection foci, which are epidemiologically enhanced in the context of low herd immunity, selective pressure on arbovirus transmission and the presence of infectious asymptomatic persons, all these conditions being present in Singapore. Learning from Singapore's vector control success that reduced domestic vector populations, but has not sustainably reduced arboviral incidence, we suggest including peri-domestic vectors in the scope of vector management.
- Genetic Polymorphisms of Tumor Necrosis Factor Alpha and Susceptibility to Dengue Virus Infection in a Mexican Population.
Genetic Polymorphisms of Tumor Necrosis Factor Alpha and Susceptibility to Dengue Virus Infection in a Mexican Population. [Journal Article]Viral Immunol 2017 Jun 26.VISánchez-Leyva M, Sánchez-Zazueta JG, Osuna-Ramos JF, et al. To evaluate the association of the -308 and -238 tumor necrosis factor alpha (TNF-α) gene polymorphisms with clinical manifestations of dengue and TNF-α serum levels in a northwestern Mexican populatio...Publisher Full TextPublisher Full TextTo evaluate the association of the -308 and -238 tumor necrosis factor alpha (TNF-α) gene polymorphisms with clinical manifestations of dengue and TNF-α serum levels in a northwestern Mexican population. The study populations included dengue fever (DF) and dengue hemorrhagic fever (DHF) patients, and a group of healthy controls (HCs) without history of dengue. Polymerase chain reaction-restriction fragment length polymorphism and Enzyme-Linked Immunosorbent Assay were performed to determine genotypes and serum concentration of TNF-α, respectively. There were no significant differences in alleles, genotypes, and haplotype frequencies between patients and HCs. However, when patients were separated into DF and DHF, there was an increased prevalence of the -308 GA genotype in HCs compared to DHF (odds ratio [OR] = 0.129, 95% confidence interval [CI] = 0.018-0.945, p = 0.025), as well as the GG haplotype (OR = 0.49, 95% CI = 0.273-0.880, p = 0.01757) in DF. The genotypes of both polymorphisms were not associated with hematologic manifestations. Serum TNF-α levels were significantly higher in patients than in HCs (p = 0.004). Our results suggest a minimal effect of the -308 and -238 TNF-α gene polymorphisms in dengue patients and that their increased serum levels of TNF-α are independent of genotypes.
- An Approach for a Synthetic CTL Vaccine Design against Zika Flavivirus Using Class I and Class II Epitopes Identified by Computer Modeling.
An Approach for a Synthetic CTL Vaccine Design against Zika Flavivirus Using Class I and Class II Epitopes Identified by Computer Modeling. [Journal Article]Front Immunol 2017.:640.FICunha-Neto E, Rosa DS, Harris PE, et al. The threat posed by severe congenital abnormalities related to Zika virus (ZKV) infection during pregnancy has turned development of a ZKV vaccine into an emergency. Recent work suggests that the cytot...Publisher Full TextThe threat posed by severe congenital abnormalities related to Zika virus (ZKV) infection during pregnancy has turned development of a ZKV vaccine into an emergency. Recent work suggests that the cytotoxic T lymphocyte (CTL) response to infection is an important defense mechanism in response to ZKV. Here, we develop the rationale and strategy for a new approach to developing cytotoxic T lymphocyte (CTL) vaccines for ZKV flavivirus infection. The proposed approach is based on recent studies using a protein structure computer model for HIV epitope selection designed to select epitopes for CTL attack optimized for viruses that exhibit antigenic drift. Because naturally processed and presented human ZKV T cell epitopes have not yet been described, we identified predicted class I peptide sequences on ZKV matching previously identified DNV (Dengue) class I epitopes and by using a Major Histocompatibility Complex (MHC) binding prediction tool. A subset of those met the criteria for optimal CD8+ attack based on physical chemistry parameters determined by analysis of the ZKV protein structure encoded in open source Protein Data File (PDB) format files. We also identified candidate ZKV epitopes predicted to bind promiscuously to multiple HLA class II molecules that could provide help to the CTL responses. This work suggests that a CTL vaccine for ZKV may be possible even if ZKV exhibits significant antigenic drift. We have previously described a microsphere-based CTL vaccine platform capable of eliciting an immune response for class I epitopes in mice and are currently working toward in vivo testing of class I and class II epitope delivery directed against ZKV epitopes using the same microsphere-based vaccine.
- Preparing clinicians for (re-) emerging arbovirus infectious diseases in Europe.
Preparing clinicians for (re-) emerging arbovirus infectious diseases in Europe. [Journal Article, Review]Clin Microbiol Infect 2017 Jun 22.CMSigfrid L, Reusken C, Eckerle I, et al. There are a range of arboviruses of clinical significance to Europe. There has been an increase in notifications of endemic and travel-imported arbovirus cases in recent years and an increased geograph...Publisher Full TextArthropod-borne virus (Arbovirus) infections are considered an emerging threat for Europe, with an increase in cases in recent decades. The increase in global travel and trade has contributed to the introduction of vectors and viruses into new geographical areas. Tropical arboviruses such as dengue and chikungunya have re-emerged causing local, sporadic outbreaks ignited by travel-imported cases. The recent Zika virus outbreak in the Americas highlighted a need to strengthen preparedness to (re-)emerging arbovirus infections globally.To strengthen preparedness for the early identification of (re-)emerging arbovirus outbreaks in Europe and highlight areas for research.An evidence review of published and grey literature together with consultations with European arbovirus experts.This paper presents an overview of endemic and travel-imported arboviruses of clinical significance in Europe. The overview includes syndromic presentation, risk factors for infection and risk of transmission. Moreover, an update on treatments and vaccinations and surveillance notifications and reporting. The paper also presents predictive modelled risks of further geographical expansion of vectors and viruses.There are a range of arboviruses of clinical significance to Europe. There has been an increase in notifications of endemic and travel-imported arbovirus cases in recent years and an increased geographical range of vectors and viruses. The heterogeneity in surveillance reporting indicates a risk for the early identification of (re-)emerging outbreaks. The data presented shows a need to strengthen preparedness to (re-)emerging arbovirus infections and a need for research into neglected arboviruses, risks of non-vector transmission and effective therapeutics and vaccinations.
- Complete genome analysis of Dengue virus type 3 isolated from the 2013 Dengue outbreak in Yunnan, China.
Complete genome analysis of Dengue virus type 3 isolated from the 2013 Dengue outbreak in Yunnan, China. [Journal Article]Virus Res 2017 Jun 22.VRWang X, Ma D, Huang X, et al. In the past few decades, dengue has spread rapidly and is an emerging disease in China. An unexpected dengue outbreak occurred in Xishuangbanna, Yunnan, China, resulting in 1331 patients in 2013. In or...Publisher Full TextIn the past few decades, dengue has spread rapidly and is an emerging disease in China. An unexpected dengue outbreak occurred in Xishuangbanna, Yunnan, China, resulting in 1331 patients in 2013. In order to obtain the complete genome information and perform mutation and evolutionary analysis of causative agent related to this largest outbreak of dengue fever. The viruses were isolated by cell culture and evaluated by genome sequence analysis. Phylogenetic trees were then constructed by Neighbor-Joining methods (MEGA6.0), followed by analysis of nucleotide mutation and amino acid substitution. The analysis of the diversity of secondary structure for E and NS1 protein were also performed. Then selection pressures acting on the coding sequences were estimated by PAML software. The complete genome sequences of two isolated strains (YNSW1, YNSW2) were 10,710 and 10,702 nucleotides in length, respectively. Phylogenetic analysis revealed both strain were classified as genotype II of DENV-3. The results indicated that both isolated strains of Xishuangbanna in 2013 and Laos 2013 stains (KF816161.1, KF816158.1, LC147061.1, LC147059.1, KF816162.1) were most similar to Bangladesh (AY496873.2) in 2002. After comparing with the DENV-3SS (H87) 62 amino acid substitutions were identified in translated regions, and 38 amino acid substitutions were identified in translated regions compared with DENV-3 genotype II stains Bangladesh (AY496873.2). 27(YNSW1) or 28(YNSW2) single nucleotide changes were observed in structural protein sequences with 7(YNSW1) or 8(YNSW2) non-synonymous mutations compared with AY496873.2. Of them, 4 non-synonymous mutations were identified in E protein sequences with (2 in the β-sheet, 2 in the coil). Meanwhile, 117(YNSW1) or 115 (YNSW2) single nucleotide changes were observed in non-structural protein sequences with 31(YNSW1) or 30 (YNSW2) non-synonymous mutations. Particularly, 14 single nucleotide changes were observed in NS1 sequences with 4/14 non-synonymous substitutions (4 in the coil). Selection pressure analysis revealed no positive selection in the amino acid sites of the genes encoding for structural and non-structural proteins. This study may help understand the intrinsic geographical relatedness of dengue virus 3 and contributes further to research on their infectivity, pathogenicity and vaccine development.
- Larval stress alters dengue virus susceptibility in Aedes aegypti (L.) adult females.
Larval stress alters dengue virus susceptibility in Aedes aegypti (L.) adult females. [Journal Article]Acta Trop 2017 Jun 22.ATKang DS, Alcalay Y, Lovin DD, et al. In addition to genetic history, environmental conditions during larval stages are critical to the development, success and phenotypic fate of the Aedes aegypti mosquito. In particular, previous studies...Publisher Full TextIn addition to genetic history, environmental conditions during larval stages are critical to the development, success and phenotypic fate of the Aedes aegypti mosquito. In particular, previous studies have shown a strong genotype-by-environment component to adult mosquito body size in response to optimal vs stressed larval conditions. Here, we expand upon those results by investigating the effects of larval-stage crowding and nutritional limitation on the susceptibility of a recent field isolate of Aedes aegypti to dengue virus serotype-2. Interestingly, female mosquitoes from larvae subjected to a stressed regime exhibited significantly reduced susceptibility to disseminated dengue infection 14days post infection compared to those subjected to optimal regimes. Short term survivorship post-infected blood feeding was not significantly different. As with body size, dengue virus susceptibility of a mosquito population is determined by a combination of genetic and environmental factors and is likely maintained by balancing selection. Here, we provide evidence that under different environmental conditions, the innate immune response of field-reared mosquitoes exhibits a large range of phenotypic variability with regard to dengue virus susceptibility. Further, as with body size, our results suggest that mosquitoes reared under optimal laboratory conditions, as employed in all mosquito-pathogen studies to date, may not always be realistic proxies for natural populations.
- Infection-related microcephaly after the 2015 and 2016 Zika virus outbreaks in Brazil: a surveillance-based analysis.
Infection-related microcephaly after the 2015 and 2016 Zika virus outbreaks in Brazil: a surveillance-based analysis. [Journal Article]Lancet 2017 Jun 21.Lctde Oliveira WK, de França GVA, Carmo EH, et al. The distribution of infection-related microcephaly after Zika virus outbreaks has varied across time and Brazilian regions. Reasons for these apparent differences remain to be elucidated.Publisher Full TextOn Nov 11, 2015, the Brazilian Ministry of Health declared a Public Health Emergency of National Concern in response to an increased number of microcephaly cases, possibly related to previous Zika virus outbreaks. We describe the course of the dual epidemics of the Zika virus infection during pregnancy and microcephaly in Brazil up to Nov 12, 2016, the first anniversary of this declaration.We used secondary data for Zika virus and microcephaly cases obtained through the Brazilian Ministry of Health's surveillance systems from Jan 1, 2015, to Nov 12, 2016. We deemed possible Zika virus infections during pregnancy as all suspected cases of Zika virus disease and all initially suspected, but later discarded, cases of dengue and chikungunya fever. We defined confirmed infection-related microcephaly in liveborn infants as the presence of a head circumference of at least 2 SDs below the mean for their age and sex, accompanied by diagnostic imaging consistent with an infectious cause, or laboratory, clinical, or epidemiological results positive for Zika virus or STORCH (infectious agents known to cause congenital infection, mainly syphilis, toxoplasmosis, cytomegalovirus, and herpes simplex virus). We excluded cases of congenital anomalies or death without microcephaly. We analyse the spatial clustering of these diseases in Brazil to obtain the kernel density estimation.Two distinct waves of possible Zika virus infection extended across all Brazilian regions in 2015 and 2016. 1 673 272 notified cases were reported, of which 41 473 (2·5%) were in pregnant women. During this period, 1950 cases of infection-related microcephaly were confirmed. Most cases (1373 [70·4%]) occurred in the northeast region after the first wave of Zika virus infection, with peak monthly occurrence estimated at 49·9 cases per 10 000 livebirths. After a major, well documented second wave of Zika virus infection in all regions of Brazil from September, 2015, to September, 2016, occurrence of microcephaly was much lower than that following the first wave of Zika virus infection, reaching epidemic levels in all but the south of Brazil, with estimated monthly peaks varying from 3·2 cases to 15 cases per 10 000 livebirths.The distribution of infection-related microcephaly after Zika virus outbreaks has varied across time and Brazilian regions. Reasons for these apparent differences remain to be elucidated.None.
- Whither vaccines?
Whither vaccines? [Journal Article]J Infect 2017 Jun.:S2-S9.JIRodrigues CMC, Pinto MV, Sadarangani M, et al. Currently used vaccines have had major effects on eliminating common infections, largely by duplicating the immune responses induced by natural infections. Now vaccinology faces more complex problems, ...Publisher Full TextCurrently used vaccines have had major effects on eliminating common infections, largely by duplicating the immune responses induced by natural infections. Now vaccinology faces more complex problems, such as waning antibody, immunosenescence, evasion of immunity by the pathogen, deviation of immunity by the microbiome, induction of inhibitory responses, and complexity of the antigens required for protection. Fortunately, vaccine development is now incorporating knowledge from immunology, structural biology, systems biology and synthetic chemistry to meet these challenges. In addition, international organisations are developing new funding and licensing pathways for vaccines aimed at pathogens with epidemic potential that emerge from tropical areas.
- Discovery of a single male Aedes aegypti (L.) in Merseyside, England.
Discovery of a single male Aedes aegypti (L.) in Merseyside, England. [Journal Article]Parasit Vectors 2017 Jun 24; 10(1):309.PVDallimore T, Hunter T, Medlock JM, et al. The finding of the single male Ae. aegypti, while significant, presents no apparent disease risk to public health, and the follow-up survey suggests that there was no established population. However, t...Publisher Full TextThe mosquito Aedes aegypti (L.) is found in tropical and sub-tropical regions where it is the major vector of dengue fever, yellow fever, chikungunya and more recently Zika virus. Given its importance as a vector of arboviruses and its propensity to be transported to new regions, the European Centre for Disease Prevention and Control (ECDC) has placed Ae. aegypti on a list of potentially invasive mosquito species. It was previously reported in the United Kingdom (UK) in 1865 and 1919 but did not establish on either occasion. It is now beginning to reappear in European countries and has been recorded in the Netherlands (not established) and Madeira (Portugal), as well as southern Russia, Georgia and Turkey.During summer 2014, a single male Ae. aegypti was captured during mosquito collections in north-western England using a sweep net. Morphological identification complimented by sequencing of the ITS2 rDNA, and cox1 mtDNA regions, confirmed the species. Following confirmation, a programme of targeted surveillance was implemented around the collection site by first identifying potential larval habitats in greenhouses, a cemetery, a farm and industrial units. Despite intensive surveillance around the location, no other Ae. aegypti specimens were collected using a combination of sweep netting, larval dipping, mosquito magnets, BG sentinel traps and ovitraps. All species collected were native to the UK.The finding of the single male Ae. aegypti, while significant, presents no apparent disease risk to public health, and the follow-up survey suggests that there was no established population. However, this report does highlight the need for vigilance and robust surveillance, and the requirement for procedures to be in place to investigate such findings.