Estimating Risks of Inapparent Avian Exposure for Human Infection: Avian Influenza Virus A (H7N9) in Zhejiang Province, China

Eco-engineering controls vegetation trends in southwest China karst

The karst area in Yunnan-Guangxi-Guizhou region in southwest China is known for widespread rocky desertification but several studies report a greening trend since the year 2000. While the start of the greening trend seems to match with the implementation of ecological conservation projects, no statistical evidence on a relationship between vegetation greening and eco-engineering exists. Moreover, dominant factors influencing the spatial patterns of vegetation trends have rarely been investigated. Here we use six comprehensive factors representing the natural conditions and human activities of the study area, and several statistical models consistently show that eco-engineering explains large parts of the positive vegetation trends in the karst areas, while negative vegetation trends in non-karst areas of Yunnan were related with a decrease in rainfall. We further show that the interaction of eco-engineering with other factors leads to a heterogeneous pattern of different vegetation trends. Knowing and understanding these patterns is crucial when planning ecological restoration, especially in diverse landscapes like China karst and the methods can be reused in other restoration areas.

Segment-Based Spatial Analysis for Assessing Road Infrastructure Performance Using Monitoring Observations and Remote Sensing Data

Road infrastructure is important to the well-being and economic health of all nations. The performance of road pavement infrastructure is sophisticated and affected by numerous factors and varies greatly across different roads. Large scale spatial analysis for assessing road infrastructure performance is increasingly required for road management, therefore multi-source factors, including satellite remotely sensed climate and environmental data, and ground-monitored vehicles observations, are collected as explanatory variables. Different from the traditional point or area based geospatial attributes, the performance of pavement infrastructure is the line segment based spatial data. Thus, a segment-based spatial stratified heterogeneity method is utilized to explore the comprehensive impacts of vehicles, climate, properties of road and socioeconomic conditions on pavement infrastructure performance. Segment-based optimal discretization is applied on discretizing segment-based pavement data, and a segment-based geographical detector is utilized to assess the spatial impacts of variables and their interactions. Results show that the segment-based methods can more reasonably and accurately describe the characteristics of line segment based spatial data and assess the spatial associations. The two major categories of factors associated with pavement damage are the variables of traffic vehicles and heavy vehicles in particular, and climate and environmental conditions. Meanwhile, the interactions between the explanatory variables in these two categories have much more influence than the single explanatory variables, and the interactions can explain more than half of the pavement damage. This study highlights the great potential of remote sensing based large scale spatial analysis of road infrastructures. The approach in this study provides new ideas for spatial analysis for segmented geographical data. The findings indicate that the quantified comprehensive impacts of variables are practical for wise decision-making for road design, construction and maintenance.

Contact reductions from live poultry market closures limit the epidemic of human infections with H7N9 influenza

An early steep increase in the number of humans infected with avian influenza A(H7N9) virus was observed in China, raising great public concern domestically and internationally. Little is known about the dynamics of the transmission contacts between poultry and human populations, although such understanding is essential for developing effective strategies to control this zoonosis. In this study, we evaluated the effects of contact reductions from live poultry markets (LPMs) closures on the transmission of H7N9 virus during epidemics in Guangdong Province, China. A mathematical model of the poultry-to-person transmission dynamics of H7N9 virus was constructed. The parameters in the model were estimated from publicly available data on confirmed cases of human infection and information on LPMs closure during 2013-2017. By fitting the model, we measured the time-dependent contact quantity of the susceptible population to LPMs. The results showed that periodic intervention strategies can greatly reduce the magnitude of outbreaks, and the earlier interventions for policy are implemented, the smaller is the outbreak. The control efforts for LPMs to decrease the contact quantity are critical in preventing epidemics in the long term. This model should provide important insights for the development of a national intervention strategy for the long-term control of avian influenza virus epidemics.

Tackling a novel lethal virus: a focus on H7N9 vaccine development

INTRODUCTION

Avian-origin H7N9 influenza viruses first detected in humans in China in 2013 continue to cause severe human infections with a mortality rate close to 40%. These viruses are acknowledged as the subtype most likely to cause the next influenza pandemic. Areas covered: Here we review published data on the development of H7N9 influenza vaccine candidates and their evaluation in preclinical and clinical trials identified on PubMed database with the term 'H7N9 influenza vaccine'. In addition, a search with the same term was done on ClinicalTrials.gov to find ongoing clinical trials with H7N9 vaccines. Expert commentary: Influenza vaccines are the most powerful tool for protecting the human population from influenza infections, both seasonal and pandemic. During the past four years, a large number of promising H7N9 influenza vaccine candidates have been generated using traditional and advanced gene engineering techniques. In addition, with the support of WHO's GAP program, influenza vaccine production capacities have been established in a number of vulnerable low- and middle-income countries with a high population density, allowing the countries to be independent of vaccine supply from high-income countries. Overall, it is believed that the world is now well prepared for a possible H7N9 influenza pandemic.