| 51881. |
- Massad, E., et al.
(author)
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On the origin and timing of Zika virus introduction in Brazil
- 2017
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In: Epidemiology and Infection. - : Cambridge University Press. - 0950-2688 .- 1469-4409. ; 145:11, s. 2303-2312
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Journal article (peer-reviewed)abstract
- The timing and origin of Zika virus (ZIKV) introduction in Brazil has been the subject of controversy. Initially, it was assumed that the virus was introduced during the FIFA World Cup in June-July 2014. Then, it was speculated that ZIKV may have been introduced by athletes from French Polynesia (FP) who competed in a canoe race in Rio de Janeiro in August 2014. We attempted to apply mathematical models to determine the most likely time window of ZIKV introduction in Brazil. Given that the timing and origin of ZIKV introduction in Brazil may be a politically sensitive issue, its determination (or the provision of a plausible hypothesis) may help to prevent undeserved blame. We used a simple mathematical model to estimate the force of infection and the corresponding individual probability of being infected with ZIKV in FP. Taking into account the air travel volume from FP to Brazil between October 2013 and March 2014, we estimated the expected number of infected travellers arriving at Brazilian airports during that period. During the period between December 2013 and February 2014, 51 individuals travelled from FP airports to 11 Brazilian cities. Basing on the calculated force of ZIKV infection (the per capita rate of new infections per time unit) and risk of infection (probability of at least one new infection), we estimated that 18 (95% CI 12-22) individuals who arrived in seven of the evaluated cities were infected. When basic ZIKV reproduction numbers greater than one were assumed in the seven evaluated cities, ZIKV could have been introduced in any one of the cities. Based on the force of infection in FP, basic reproduction ZIKV number in selected Brazilian cities, and estimated travel volume, we concluded that ZIKV was most likely introduced and established in Brazil by infected travellers arriving from FP in the period between October 2013 and March 2014, which was prior to the two aforementioned sporting events.
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| 51882. |
- Massad, Eduardo, et al.
(author)
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Risk of symptomatic dengue for foreign visitors to the 2014 FIFA World Cup in Brazil
- 2014
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In: Memórias do instituto Oswaldo Cruz. - : FapUNIFESP (SciELO). - 0074-0276 .- 1678-8060. ; 109:3, s. 394-397
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Journal article (peer-reviewed)abstract
- Brazil will host the FIFA World Cup™, the biggest single-event competition in the world, from June 12-July 13 2014 in 12 cities. This event will draw an estimated 600,000 international visitors. Brazil is endemic for dengue. Hence, attendees of the 2014 event are theoretically at risk for dengue. We calculated the risk of dengue acquisition to non-immune international travellers to Brazil, depending on the football match schedules, considering locations and dates of such matches for June and July 2014. We estimated the average per-capita risk and expected number of dengue cases for each host-city and each game schedule chosen based on reported dengue cases to the Brazilian Ministry of Health for the period between 2010-2013. On the average, the expected number of cases among the 600,000 foreigner tourists during the World Cup is 33, varying from 3-59. Such risk estimates will not only benefit individual travellers for adequate pre-travel preparations, but also provide valuable information for public health professionals and policy makers worldwide. Furthermore, estimates of dengue cases in international travellers during the World Cup can help to anticipate the theoretical risk for exportation of dengue into currently non-infected areas.
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| 51883. |
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| 51884. |
- Massad, E, et al.
(author)
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The risk of infectious diseases introduction into non-infected countries by travelers visiting endemic countries
- 2015
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In: Tropical medicine & international health. - : Wiley-Blackwell. - 1360-2276 .- 1365-3156. ; 20:Suppl. 1, s. 340-340
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Journal article (other academic/artistic)abstract
- This work is an attempt to estimate the risk of infections importation and exportation by travelers. In it we propose a model that takes into account the force of infection of the disease in the endemic country, which can either be a visited country (source of infection importation) or a country from where local residents export the infection when travel in the latent condition for disease-free countries. The model is deterministic but a preliminary stochastic formulation is presented in the appendix. It considers two countries: one is the host home-country and the other is the source country (with an endemic infectious disease). Susceptible individuals travel from their home-country to the endemic country and eventually return infected. The input of the model is the force of infection at the visited/source country which is assumed to be known and we assume that, in the case of disease importation, travelers are subject to the same risk of infection as local residents but do not contribute to it. In the case of disease exportation, the model calculates the probability that a latent individual travels from an endemic (or epidemic) country to a disease-free country. We exemplify the model with two distinct situation, namely, the risk of dengue importation from Thailand to Europe and the risk of Ebola exportation from Liberia to the USA.Disclosure: Nothing to disclose.
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| 51885. |
- Massad, Eduardo, et al.
(author)
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Theoretical impact of insecticide-impregnated school uniforms on dengue incidence in Thai children
- 2013
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In: Global Health Action. - : Co-Action Publishing. - 1654-9716 .- 1654-9880. ; 6, s. 1-6
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Journal article (peer-reviewed)abstract
- Background: Children carry the main burden of morbidity and mortality caused by dengue. Children spend a considerable amount of their day at school; hence strategies that reduce human-mosquito contact to protect against the day-biting habits of Aedes mosquitoes at schools, such as insecticide-impregnated uniforms, could be an effective prevention strategy.Methodology: We used mathematical models to calculate the risk of dengue infection based on force of infection taking into account the estimated proportion of mosquito bites that occur in school and the proportion of school time that children wear the impregnated uniforms. Principal findings: The use of insecticide-impregnated uniforms has efficacy varying from around 6% in the most pessimistic estimations, to 55% in the most optimistic scenarios simulated.Conclusions: Reducing contact between mosquito bites and human hosts via insecticide-treated uniforms during school time is theoretically effective in reducing dengue incidence and may be a valuable additional tool for dengue control in school-aged children. The efficacy of this strategy, however, is dependent on the compliance of the target population in terms of proper and consistent wearing of uniforms and, perhaps more importantly, the proportion of bites inflicted by the Aedes population during school time.
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| 51886. |
- Massad, Eduardo, et al.
(author)
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Two complementary model-based methods for calculating the risk of international spreading of a novel virus from the outbreak epicentre. The case of COVID-19
- 2020
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In: Epidemiology and Infection. - : Cambridge University Press. - 0950-2688 .- 1469-4409. ; 148
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Journal article (peer-reviewed)abstract
- We present two complementary model-based methods for calculating the risk of international spread of the novel coronavirus SARS-CoV-2 from the outbreak epicentre. One model aims to calculate the number of cases that would be exported from an endemic country to disease-free regions by travellers. The second model calculates the probability that an infected traveller will generate at least one secondary autochthonous case in the visited country. Although this paper focuses on the data from China, our methods can be adapted to calculate the risk of importation and subsequent outbreaks. We found an averageR(0)= 5.31 (ranging from 4.08 to 7.91) and a risk of spreading of 0.75 latent individuals per 1000 travellers. In addition, one infective traveller would be able to generate at least one secondary autochthonous case in the visited country with a probability of 23%.
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| 51887. |
- Massai, Francesco, et al.
(author)
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Development, Optimization, and Validation of a High Throughput Screening Assay for Identification of Tat and Type II Secretion Inhibitors of Pseudomonas aeruginosa
- 2019
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In: Frontiers in Cellular and Infection Microbiology. - : Frontiers Media S.A.. - 2235-2988. ; 9
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Journal article (peer-reviewed)abstract
- Antibiotics are becoming less effective in treatment of infections caused by multidrug-resistant Pseudomonas aeruginosa. Antimicrobial therapies based on the inhibition of specific virulence-related traits, as opposed to growth inhibitors, constitute an innovative and appealing approach to tackle the threat of P. aeruginosa infections. The twin-arginine translocation (Tat) pathway plays an important role in the pathogenesis of P. aeruginosa, and constitutes a promising target for the development of anti-pseudomonal drugs. In this study we developed and optimized a whole-cell, one-well assay, based on native phospholipase C activity, to identify compounds active against the Tat system. Statistical robustness, sensitivity and consequently suitability for high-throughput screening (HTS) were confirmed by a dry run/pre-screening test scoring a Z' of 0.82 and a signal-to-noise ratio of 49. Using this assay, we evaluated ca. 40,000 molecules and identified 59 initial hits as possible Tat inhibitors. Since phospholipase C is exported into the periplasm by Tat, and subsequently translocated across the outer membrane by the type II secretion system (T2SS), our assay could also identify T2SS inhibitors. To validate our hits and discriminate between compounds that inhibited either Tat or T2SS, two separate counter assays were developed and optimized. Finally, three Tat inhibitors and one T2SS inhibitor were confirmed by means of dose-response analysis and additional counter and confirming assays. Although none of the identified inhibitors was suitable as a lead compound for drug development, this study validates our assay as a simple, efficient, and HTS compatible method for the identification of Tat and T2SS inhibitors.
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| 51888. |
- Massei, Riccardo, et al.
(author)
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Toxicity and neurotoxicity profiling of contaminated sediments from Gulf of Bothnia (Sweden) : a multi-endpoint assay with Zebrafish embryos
- 2019
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In: Environmental Sciences Europe. - : Springer. - 2190-4707 .- 2190-4715. ; 31
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Journal article (peer-reviewed)abstract
- The toxicological characterization of sediments is an essential task to monitor the quality of aquatic environments. Many hazardous pollutants may accumulate in sediments and pose a risk to the aquatic community. The present study provides an attempt to integrate a diagnostic whole mixture assessment workflow based on a slightly modified Danio rerio embryo acute toxicity test with chemical characterization. Danio rerio embryos were directly exposed to sieved sediment (≤ 63 μm) for 96 h. Sediment samples were collected from three polluted sites (Kramfors, Sundsvall and Örnsköldsvik) in the Gulf of Bothnia (Sweden) which are characterized by a long history of pulp and paper industry impact. Effect data were supported by chemical analyses of 237 organic pollutants and 30 trace elements.
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| 51889. |
- Masselot, Pierre, et al.
(author)
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Differential mortality risks associated with PM2.5 components : a multi-country, multi-city study
- 2022
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In: Epidemiology. - : Wolters Kluwer. - 1044-3983 .- 1531-5487. ; 33:2, s. 167-175
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Journal article (peer-reviewed)abstract
- BACKGROUND: The association between fine particulate matter (PM2.5) and mortality widely differs between as well as within countries. Differences in PM2.5 composition can play a role in modifying the effect estimates, but there is little evidence about which components have higher impacts on mortality.METHODS: We applied a two-stage analysis on data collected from 210 locations in 16 countries. In the first stage, we estimated location-specific relative risks (RR) for mortality associated with daily total PM2.5 through time series regression analysis. We then pooled these estimates in a meta-regression model that included city-specific logratio-transformed proportions of seven PM2.5 components as well as meta-predictors derived from city-specific socio-economic and environmental indicators.RESULTS: We found associations between RR and several PM2.5 components. Increasing the ammonium (NH4+) proportion from 1% to 22%, while keeping a relative average proportion of other components, increased the RR from 1.0063 (95%CI: 1.0030-1.0097) to 1.0102 (95%CI:1.0070-1.0135). Conversely, an increase in nitrate (NO3-) from 1% to 71% resulted in a reduced RR, from 1.0100 (95%CI: 1.0067-1.0133) to 1.0037 (95%CI: 0.9998- 1.0077). Differences in composition explained a substantial part of the heterogeneity in PM2.5 risk.CONCLUSIONS: These findings contribute to the identification of more hazardous emission sources. Further work is needed to understand the health impacts of PM2.5 components and sources given the overlapping sources and correlations among many components.
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| 51890. |
- Massing, André, 1977-
(author)
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A Cut Discontinuous Galerkin Method for Coupled Bulk-Surface Problems
- 2017
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In: Geometrically Unfitted Finite Element Methods and Applications. - Cham : Springer. - 9783319714318 - 9783319714301 ; , s. 259-279
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Conference paper (peer-reviewed)abstract
- We develop a cut Discontinuous Galerkin method (cutDGM) for a diffusion-reaction equation in a bulk domain which is coupled to a corresponding equation on the boundary of the bulk domain. The bulk domain is embedded into a structured, unfitted background mesh. By adding certain stabilization terms to the discrete variational formulation of the coupled bulk-surface problem, the resulting cutDGM is provably stable and exhibits optimal convergence properties as demonstrated by numerical experiments. We also show both theoretically and numerically that the system matrix is well-conditioned, irrespective of the relative position of the bulk domain in the background mesh.
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