Multiple independent transmission cycles of a tick-borne pathogen within a local host community

Many pathogens are maintained by multiple host species and involve multiple strains with potentially different phenotypic characteristics. Disentangling transmission patterns in such systems is often challenging, yet investigating how different host species contribute to transmission is crucial to properly assess and manage disease risk. We aim to reveal transmission cycles of bacteria within the Borrelia burgdorferi species complex, which include Lyme disease agents. We characterized Borrelia genotypes found in 488 infected Ixodes ricinus nymphs collected in the Sénart Forest located near Paris (France). These genotypes were compared to those observed in three sympatric species of small mammals and network analyses reveal four independent transmission cycles. Statistical modelling shows that two cycles involving chipmunks, an introduced species, and non-sampled host species such as birds, are responsible for the majority of tick infections. In contrast, the cycle involving native bank voles only accounts for a small proportion of infected ticks. Genotypes associated with the two primary transmission cycles were isolated from Lyme disease patients, confirming the epidemiological threat posed by these strains. Our work demonstrates that combining high-throughput sequence typing with networks tools and statistical modeling is a promising approach for characterizing transmission cycles of multi-host pathogens in complex ecological settings

Layer-by-layer assembled composite films of side-functionalized poly(3-hexylthiophene) and CdSe nanocrystals: electrochemical, spectroelectrochemical and photovoltaic properties

Regioregular poly(3-hexylthiophene) containing one diaminopyrimidine side group per ten repeat units (P3HT-co-P3(ODAP)HT) can form molecular composites with 1-(6-mercaptohexyl)thymine capped CdSe nanocrystals (CdSe(MHT)) via hydrogen bonds directed molecular recognition. Here we report complementary spectroscopic, electrochemical and spectroelectrochemical investigations of both the functionalized poly(thiophene) and its composite with the nanocrystals, the latter being fabricated using the layer-by-layer (LbL) deposition technique. UV-Vis-NIR and Raman spectroelectrochemical investigations unequivocally show that the onset of the first anodic peak in the cyclic voltammogram of the copolymer can be attributed to the oxidation of the pi-conjugated backbone in the polymer chains. For this reason, it is possible to determine the width and the position of its band gap (corresponding to the pi-pi* transition) by UV-Vis spectroscopy combined with cyclic voltammetry. These studies show that the polymer exhibits a slightly larger band gap with the HOMO level insignificantly lower in energy (by 0.03 eV) as compared to the case of regioregular poly(3-hexylthiophene) of comparable degree of polymerization. Hydrogen bond interactions of the polymer with CdSe(MHT) in the molecular composite result in a hypsochromic shift of the band corresponding to the pi-pi* transition from 504 nm to 488 nm. This can be taken as a spectroscopic manifestation of the conformational changes induced by shortening of the conjugation length. The observed spectral modifications are consistent with electrochemically determined lowering of the polymer HOMO level (from -4.91 eV in the pure polymer to -4.99 eV in the composite). Cyclic voltammetry studies supported by spectroelectrochemistry also show that the redox stability of CdSe(MHT) in the molecular composite with P3HT-co-P3(ODAP)HT is lower than that determined for stearate-capped nanocrystals. Their irreversible oxidation starts at E = +0.7 V vs. Ag/0.1 M Ag(+)i.e. at potentials by ca. 0.3 V lower than the oxidation of stearate stabilized CdSe nanocrystals of the same size. We show that-despite these modifications-the alignment of the HOMO and LUMO levels of the composite components remains appropriate for its use in hybrid solar cells, which is demonstrated by the photovoltaic effect observed for the LbL-processed composite sandwiched between two electrode

Assessing the burden of arboviral diseases using a multiplexed serological survey in French Guiana

ObjectiveTo assess the level of circulation of DENV, CHIKV, ZIKV, MAYV in French Guiana.IntroductionArboviral infections have become a significant public health problem with the emergence and re-emergence of arboviral diseases worldwide in recent decades [1-6]. Given the increasing number of cases, geographic spread, but also health, social and economic impact of arboviral outbreaks, estimating their true burden represents a crucial issue but remains a difficult task [7-10].In French Guiana, the epidemiology of arboviral diseases has been marked by the occurrence several major dengue fever (DENV) outbreaks over the past few decades, recent emergences of Chikungunya (CHKV) and Zika virus (ZIKV) and the circulation of Mayaro virus (MAYV) [11-14].MethodsTo assess antibody seroprevalence against DENV, CHIKV, ZIKV, MAYV a random 2-stage household cross-sectional survey was conducted among the general population. We enrolled 2,697 individuals aged 1-87 years from June 1 to 12 October 2017. We performed detection of DENV, CHIKV, ZIKV, MAYV IgG antibodies on collected blood samples using a microsphere immunoassay (MIA). Socio-economic data, environmental variables and exposure to mosquitoes, perceptions of the illness and risk of contracting arboviral infections were collected using a standardized questionnaire administrated to all individuals included in the survey. Cross-reactivity between same families of viruses was taking into account using seroneutralisation and modeling approaches.ResultsOverall seroprevalence rates for antibodes against DENV were 69.5% [66.4%-72.5%] and differed significantly according to age and geographical area. Seroprevalence rates of CHIKV, ZIKV and MAYV antibodies were respectively 19.3% [16.5%-22.5%], 23.1% [19.5%-27.2%] and 9.6% [8.1%-11.3%] and did not differed significantly according to gender or age.The distribution of seroprevalence rates for CHIKV, ZIKV antibodies differed from extrapolations obtained from routine surveillance systems and brings valuable information to assess the epidemic risk of future outbreaks. MAYV has been circulating in the southern part of FG, at levels that appear to be substantially higher than those estimated from epidemiological and virological surveillance.ConclusionsSerological surveys provide the most direct measurement for defining the immunity landscape for infectious diseases, but the methodology remains difficult to implement particularly in the context of high cross-reactivity between flaviviruses or alphaviruses [15]. The development of reliable, rapid and affordable diagnosis tools and the use of innovative modeling approaches represent a significant issue concerning the ability of seroprevalence surveys to differentiate infections when multiple viruses co-circulate.References1. Bhatt S, Gething PW, Brady OJ, Messina JP, Farlow AW, Moyes CL, et al. The global distribution and burden of dengue. Nature. 2013;496: 504–507. pmid:235632662. Stanaway JD, Shepard DS, Undurraga EA, Halasa YA, Coffeng LE, Brady OJ, et al. The global burden of dengue: an analysis from the Global Burden of Disease Study 2013. Lancet Infect Dis. 2016;16: 712–723. pmid:268746193. Brathwaite Dick O, San Martín JL, Montoya RH, del Diego J, Zambrano B, Dayan GH. The history of dengue outbreaks in the Americas. Am J Trop Med Hyg. 2012;87: 584–593. pmid:230428464. Petersen LR, Jamieson DJ, Powers AM, Honein MA. Zika Virus. N Engl J Med. 2016;374: 1552–1563. pmid:270285615. Staples JE, Breiman RF, Powers AM. Chikungunya fever: an epidemiological review of a re-emerging infectious disease. Clin Infect Dis Off Publ Infect Dis Soc Am. 2009;49: 942–948. pmid:196636046. Duffy MR, Chen T-H, Hancock WT, Powers AM, Kool JL, Lanciotti RS, et al. Zika Virus Outbreak on Yap Island, Federated States of Micronesia. N Engl J Med. 2009;360: 2536–2543. pmid:195160347. Donoso Mantke O, Lemmer K, Biel SS, Groen J, Schmitz H, Durand JP, et al. Quality control assessment for the serological diagnosis of dengue virus infections. J Clin Virol. 2004;29: 105–112. pmid:147470298. Noden BH, Musuuo M, Aku-Akai L, van der Colf B, Chipare I, Wilkinson R. Risk assessment of flavivirus transmission in Namibia. Acta Trop. 2014;137: 123–129. pmid:248657929. Martins AC, Pereira TM, Oliart-Guzmán H, Delfino BM, Mantovani SAS, et al. Seroprevalence and Seroconversion of Dengue and Implications for Clinical Diagnosis in Amazonian Children, Seroprevalence and Seroconversion of Dengue and Implications for Clinical Diagnosis in Amazonian Children. Interdiscip Perspect Infect Dis Interdiscip Perspect Infect Dis. 2014;2014: e703875. pmid:2554855810. Conlan JV, Vongxay K, Khamlome B, Jarman RG, Gibbons RV, Fenwick SG, et al. Patterns of Flavivirus Seroprevalence in the Human Population of Northern Laos. Am J Trop Med Hyg. 2015;93: 1010–1013. pmid:2630492511. Flamand C, Quenel P, Ardillon V, Carvalho L, Bringay S, Teisseire M. The epidemiologic surveillance of dengue-fever in French Guiana: when achievements trigger higher goals. Stud Health Technol Inform. 2011;169: 629–633. pmid:2189382412. Adde A, Roucou P, Mangeas M, Ardillon V, Desenclos J-C, Rousset D, et al. Predicting Dengue Fever Outbreaks in French Guiana Using Climate Indicators. PLOS Negl Trop Dis. 2016;10: e0004681. pmid:2712831213. Fritzell C, Raude J, Adde A, Dusfour I, Quenel P, Flamand C. Knowledge, Attitude and Practices of Vector-Borne Disease Prevention during the Emergence of a New Arbovirus: Implications for the Control of Chikungunya Virus in French Guiana. PLOS Negl Trop Dis. 2016;10: e0005081. pmid:2780227514. Flamand C, Fritzell C, Matheus S, Dueymes M, Carles G, Favre A, et al. The proportion of asymptomatic infections and spectrum of disease among pregnant women infected by Zika virus: systematic monitoring in French Guiana, 2016. Eurosurveillance. 2017;22.15. Fritzell C, Rousset D, Adde A, Kazanji M, Van Kerkhove MD, Flamand C (2018) Current challenges and implications for dengue, chikungunya and Zika seroprevalence studies worldwide: A scoping review. PLoS Negl Trop Dis 12(7): e0006533

Early Hepatocellular Carcinoma Detection Using Magnetic Resonance Imaging Is Cost-Effective in High-Risk Patients with Cirrhosis

International audienc