The effects of weather and climate change on dengue

There is much uncertainty about the future impact of climate change on vector-borne diseases. Such uncertainty reflects the difficulties in modelling the complex interactions between disease, climatic and socioeconomic determinants. We used a comprehensive panel dataset from Mexico covering 23 years of province-specific dengue reports across nine climatic regions to estimate the impact of weather on dengue, accounting for the effects of non-climatic factors

Social sciences research in neglected tropical diseases 2: A bibliographic analysis

The official published version of the article can be found at the link below.Background There are strong arguments for social science and interdisciplinary research in the neglected tropical diseases. These diseases represent a rich and dynamic interplay between vector, host, and pathogen which occurs within social, physical and biological contexts. The overwhelming sense, however, is that neglected tropical diseases research is a biomedical endeavour largely excluding the social sciences. The purpose of this review is to provide a baseline for discussing the quantum and nature of the science that is being conducted, and the extent to which the social sciences are a part of that. Methods A bibliographic analysis was conducted of neglected tropical diseases related research papers published over the past 10 years in biomedical and social sciences. The analysis had textual and bibliometric facets, and focussed on chikungunya, dengue, visceral leishmaniasis, and onchocerciasis. Results There is substantial variation in the number of publications associated with each disease. The proportion of the research that is social science based appears remarkably consistent (<4%). A textual analysis, however, reveals a degree of misclassification by the abstracting service where a surprising proportion of the "social sciences" research was pure clinical research. Much of the social sciences research also tends to be "hand maiden" research focused on the implementation of biomedical solutions. Conclusion There is little evidence that scientists pay any attention to the complex social, cultural, biological, and environmental dynamic involved in human pathogenesis. There is little investigator driven social science and a poor presence of interdisciplinary science. The research needs more sophisticated funders and priority setters who are not beguiled by uncritical biomedical promises

Climate change and the emergence of vector-borne diseases in Europe: Case study of dengue fever

Background: Dengue fever is the most prevalent mosquito-borne viral disease worldwide. Dengue transmission is critically dependent on climatic factors and there is much concern as to whether climate change would spread the disease to areas currently unaffected. The occurrence of autochthonous infections in Croatia and France in 2010 has raised concerns about a potential re-emergence of dengue in Europe. The objective of this study is to estimate dengue risk in Europe under climate change scenarios. Methods. We used a Generalized Additive Model (GAM) to estimate dengue fever risk as a function of climatic variables (maximum temperature, minimum temperature, precipitation, humidity) and socioeconomic factors (population density, urbanisation, GDP per capita and population size), under contemporary conditions (1985-2007) in Mexico. We then used our model estimates to project dengue incidence under baseline conditions (1961-1990) and three climate change scenarios: short-term 2011-2040, medium-term 2041-2070 and long-term 2071-2100 across Europe. The model was used to calculate average number of yearly dengue cases at a spatial resolution of 10 × 10 km grid covering all land surface of the currently 27 EU member states. To our knowledge, this is the first attempt to model dengue fever risk in Europe in terms of disease occurrence rather than mosquito presence. Results: The results were presented using Geographical Information System (GIS) and allowed identification of areas at high risk. Dengue fever hot spots were clustered around the coastal areas of the Mediterranean and Adriatic seas and the Po Valley in northern Italy. Conclusions: This risk assessment study is likely to be a valuable tool assisting effective and targeted adaptation responses to reduce the likely increased burden of dengue fever in a warmer world

Protective and Enhancing HLA Alleles, HLA-DRB1*0901 and HLA-A*24, for Severe Forms of Dengue Virus Infection, Dengue Hemorrhagic Fever and Dengue Shock Syndrome

Dengue has become one of the most common viral diseases transmitted by infected mosquitoes (with any of the four dengue virus serotypes: DEN-1, -2, -3, or -4). It may present as asymptomatic or illness, ranging from mild to severe disease. Recently, the severe forms, dengue hemorrhagic fever (DHF) and dengue shock syndrome (DSS), have become the leading cause of death among children in Southern Vietnam. The pathogenesis of DHF/DSS, however, is not yet completely understood. The immune response, virus virulence, and host genetic background are considered to be risk factors contributing to disease severity. Human leucocyte antigens (HLA) expressed on the cell surface function as antigen presenting molecules and those polymorphism can change individuals' immune response. We investigated the HLA-A, -B (class I), and -DRB1 (class II) polymorphism in Vietnamese children with different severity (DHF/DSS) by a hospital-based case-control study. The study showed persons carrying HLA-A*2402/03/10 are about 2 times more likely to have severe dengue infection than others. On the other hand, HLA-DRB1*0901 persons are less likely to develop DSS with DEN-2 virus infection. These results clearly demonstrated that HLA controlled the susceptibility to severe forms of DV infection

Destabilizing effect of the host immune status on the sequential transmission dynamic of the dengue virus infection

A mathematical model describing the sequential transmission dynamics of dengue virus infection in the presence of two serotypes of the virus is developed. Since a dengue infection can lead to an apparent (symptomatic) illness or an in-apparent (asymptomatic) illness, our model allows for a fraction (pi) of the population infected by virus 'i' to exhibit no symptoms of the illness. The model allows for cross-protection of an individual already immune to one virus against a new infection by the other virus. The conditions governing the stabilities of three equilibrium states; a disease free state, a state where only one serotype is present and another state where both serotypes coexist, are obtained. It is found that the conditions depend oil the values of the fractions of infected population who exhibit no symptoms. The existence of the last two equilibrium states also depends on degree of cross-protection bestowed by the infection by one serotype against an infection by the other serotype. Our analysis shows that the presence of an in-apparent class of infected individuals or of a degree of cross-protection, can affect the conditions required for the two serotypes to co-exist. It is also found two serotype equilibrium state can be destabilized by increasing the number of asymptomatic ill individuals in the infected population

Risk quantification of arthropod-borne disease in link with meteorological data

National audienc

Ordered microphase separation in thin films of PMMA-PBA synthesized by RAFT: effect of block polydispersity.

The microphase separation of diblock copolymers synthesized by reversible addition−fragmentation chain transfer (RAFT) polymerization, containing one monodisperse block (poly(methyl methacrylate), PMMA) and one polydisperse block (poly(butyl acrylate), PBA), was investigated in thin films (<100 nm). The formation of ordered microphase-separated domains was observed by atomic force microscopy (AFM) and resulted in four morphologies, depending on composition and film thickness: parallel lamellae, hexagonally packed perforated lamellae (PL), parallel cylinders (C∥), and hexagonally packed spheres, and in C∥-to-PL-to-C∥ transitions. Polydispersity of the PBA block shifts the phase boundaries toward higher PBA volume fraction values with respect to those expected for monodisperse block copolymers and stabilizes the perforated lamella morphology. Neutron reflectivity data confirmed that lamellae parallel to the substrate form at a very low PBA volume fraction, fPBA = 0.23. Polydispersity of the PBA block also has the effect of stabilizing each microphase domain over a film thickness regime larger than expected for monodisperse blocks. For the first time RAFT-polymerized block copolymers are shown to microphase separate with high reproducibility and with excellent degree of order, hence proving to be ideal systems to test the effect of polydispersity on microphase separation. © 2009, American Chemical Societ

Monthly district level risk of dengue occurrences in Sakon Nakhon Province, Thailand

International audienceThe paper deals with the incidence of the Dengue Virus Infection (DVI) in the 18 districts of Sakon Nakhon Province, Thailand, from January 2005 to December 2007. Using a statistical and autoregressive analysis to smooth incidence data, we have constructed yearly and monthly district level maps of the DVI distribution. It is found that the DVI incidence is very correlated with weather conditions and higher occurrences are observed in the three most populated districts Wanon Niwat, Sawang Daen Din and Mueang Sakon Nakhon, and the virus transmission period spans from mid-summer to mid-rainy seasons (from April to August). Employing a Generalized Linear Model (GLM), we found that the DVI incidences were related with current meteorological (monthly minimum temperature, past 2-month cumulated rainfall) and socio-economical (population of 0–4 years old, per capita number of public small water wells, and proportion of villages with primary schools) covariates. And using the GLM under the climate change conditions (A1B scenario of IPCC), we found that the higher risk of DVI spreads from the three most populated districts to less populated ones, and the period of virus transmission increases from 5 to 9 months to include part of winter, summer and rainy seasons (from March to November) during which 6%, 61% and 33% of districts will be at low, medium and high risk of DVI occurrences, respectively