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The Intergovernmental Panel on Climate Change (IPCC) released its latest report on March 31, 2014. This report was the second instalment of the Fifth Assessment Report, prepared by Working Group 2, on impacts, vulnerability, and adaptation to climate change. In this Comment, we, as contributors to the chapter on human health, explain how the IPCC report was prepared and highlight important findings.

Dengue viruses are endemic across most tropical and subtropical regions. Because no proven vaccines are available, dengue prevention is primarily accomplished through controlling the mosquito vector Aedes aegypti. While dispersal distance is generally believed to be approximately 100 m, patterns of dispersion may vary in urban areas due to landscape features acting as barriers or corridors to dispersal. Anthropogenic features ultimately affect the flow of genes affecting vector competence and insecticide resistance. Therefore, a thorough understanding of what parameters impact dispersal is essential for efficient implementation of any mosquito population suppression program. Population replacement and genetic control strategies currently under consideration are also dependent upon a thorough understanding of mosquito dispersal in urban settings. We examined the effect of a major highway on dispersal patterns over a 2 year period. A. aegypti larvae were collected on the east and west sides of Uriah Butler Highway (UBH) to examine any effect UBH may have on the observed population structure in the Charlieville neighborhood in Trinidad, West Indies. A panel of nine microsatellites, two SNPs and a 710 bp sequence of mtDNA cytochrome oxidase subunit 1 (CO1) were used for the molecular analyses of the samples. Three CO1 haplotypes were identified, one of which was only found on the east side of the road in 2006 and 2007. AMOVA using mtCO1 and nuclear markers revealed significant differentiation between the east- and west-side collections. Our results indicate that anthropogenic barriers to A. aegypti dispersal exist in urban environments and should be considered when implementing control programs during dengue outbreaks and population suppression or replacement programs.

Results will provide a benchmark for subsequent trials in which combinations of interventions are assessed.\\n Ignoring human movement during study design considerations would require an artificial increase in the expected effectiveness to achieve adequate power because every individual in a treatment cluster will be predicted to have the \"maximum\" effect. Insights from such trials will help guide the scaling up of effective dengue control strategies, whether vector control alone or in combination with vaccines, and will be applicable to other Ae. aegypti-borne viral infections of current public health concern, such as chikungunya and Zika viruses.

Given the continued successes of the world's lymphatic filariasis (LF) elimination programs and the growing successes of many malaria elimination efforts, the necessity of low cost tools and methodologies applicable to long-term disease surveillance is greater than ever before. As many countries reach the end of their LF mass drug administration programs and a growing number of countries realize unprecedented successes in their malaria intervention efforts, the need for practical molecular xenomonitoring (MX), capable of providing surveillance for disease recrudescence in settings of decreased parasite prevalence is increasingly clear. Current protocols, however, require testing of mosquitoes in pools of 25 or fewer, making high-throughput examination a challenge. The new method we present here screens the excreta/feces from hundreds of mosquitoes per pool and provides proof-of-concept for a practical alternative to traditional methodologies resulting in significant cost and labor savings. Excreta/feces of laboratory reared Aedes aegypti or Anopheles stephensi mosquitoes provided with a Brugia malayi microfilaria-positive or Plasmodium vivax-positive blood meal respectively were tested for the presence of parasite DNA using real-time PCR. A titration of samples containing various volumes of B. malayi-negative mosquito feces mixed with positive excreta/feces was also tested to determine sensitivity of detection. Real-time PCR amplification of B. malayi and P. vivax DNA from the excreta/feces of infected mosquitoes was demonstrated, and B. malayi DNA in excreta/feces from one to two mf-positive blood meal-receiving mosquitoes was detected when pooled with volumes of feces from as many as 500 uninfected mosquitoes. While the operationalizing of excreta/feces testing may require the development of new strategies for sample collection, the high-throughput nature of this new methodology has the potential to greatly reduce MX costs. This will prove particularly useful in post-transmission-interruption settings, where this inexpensive approach to long-term surveillance will help to stretch the budgets of LF and malaria elimination programs. Furthermore, as this methodology is adaptable to the detection of both single celled (P. vivax) and multicellular eukaryotic pathogens (B. malayi), exploration of its use for the detection of various other mosquito-borne diseases including viruses should be considered. Additionally, integration strategies utilizing excreta/feces testing for the simultaneous surveillance of multiple diseases should be explored.

Populations of Aedes aegypti naturally exhibit variable susceptibility to dengue viruses. This natural variation can be impacted by nutritional stress resulting from larval-stage crowding, indicating the influence of environment components on the adult mosquito immune response. In particular, larval crowding was previously shown to reduce the susceptibility of adult females of a Trinidad field isolate of A. aegypti to the dengue serotype 2 (JAM1409) virus. Here, we present the first whole transcriptome study to address the impact of environmental stress on A. aegypti response to dengue virus. We examined expression profiles of adult females resulting from crowded and optimum reared larvae from the same Trinidad isolate at two critical early time points-3 and 18 hours post dengue virus infected blood meal. We exposed specimens to either a dengue or naïve blood meal, and then characterized the response in ten gene co-expression modules based on their transcriptional associations with environmental stress and time. We further analyzed the top 30 hub or master regulatory genes in each of the modules, and validated our results via qRT-PCR. These hub genes reveal which functions are critical to the mechanisms that confer dengue virus refractoriness or susceptibility to stress conditioned A. aegypti, as well as the time points at which they are most important.

The epidemiology of dengue fever is characterized by highly seasonal, multi-annual fluctuations, and the irregular circulation of its four serotypes. It is believed that this behaviour arises from the interplay between environmental drivers and serotype interactions. The exact mechanism, however, is uncertain. Constraining mathematical models to patterns characteristic to dengue epidemiology offers a means for detecting such mechanisms. Here, we used a pattern-oriented modelling (POM) strategy to fit and assess a range of dengue models, driven by combinations of temporary cross protective-immunity, cross-enhancement, and seasonal forcing, on their ability to capture the main characteristics of dengue dynamics. We show that all proposed models reproduce the observed dengue patterns across some part of the parameter space. Which model best supports the dengue dynamics is determined by the level of seasonal forcing. Further, when tertiary and quaternary infections are allowed, the inclusion of temporary cross-immunity alone is strongly supported, but the addition of cross-enhancement markedly reduces the parameter range at which dengue dynamics are produced, irrespective of the strength of seasonal forcing. The implication of these structural uncertainties on predicted vulnerability to control is also discussed. With ever expanding spread of dengue, greater understanding of dengue dynamics and control efforts (e.g. a near-future vaccine introduction) has become critically important. This study highlights the capacity of multi-level pattern-matching modelling approaches to offer an analytic tool for deeper insights into dengue epidemiology and control.

Background Historically, Aedes aegypti (L.) mosquitoes were controlled/eradicated by fumigation, residual spraying and the elimination of breeding sites. However, the underlying mechanisms of how these vector populations were managed have never been evaluated. Most studies report that these programs failed due to the emergence of DDT resistance in the 1950s and early 1960s. Therefore, behavioural and physiological factors have never been examined to determine program success or failure. Methods A ten- week study collecting resting and flying mosquitoes from every room in houses using small hand nets and Propokock aspirators in St. Augustine, Trinidad, West Indies was conducted during the rainy season months of October to December 2010. During this period a laboratory study was also conducted to determine how soon after egg laying individual females took a blood-meal. Results The field study showed the major resting sites of Ae. aegypti were bed rooms (81.9%), living rooms (8.7%) and kitchen (6.9%). The laboratory study showed only 10% of females accepted a blood meal immediately after oviposition but the majority, 70% accepted a blood meal 12 hours post oviposition. Conclusions The results provide evidence for the efficacy of indoor residual spraying (IRS) and recommend its re-introduction by targeting the major resting sites of these mosquitoes, especially during dengue fever outbreaks.

BACKGROUND: Dengue is an acute arboviral disease responsible for most of the illness and death in tropical and subtropical regions. Over the last 25 years there has been increase epidemic activity of the disease in the Caribbean, with the co-circulation of multiple serotypes. An understanding of the space and time dynamics of dengue could provide health agencies with important clues for reducing its impact. METHODS: Dengue Haemorrhagic Fever (DHF) cases observed for the period 1998–2004 were georeferenced using Geographic Information System software. Spatial clustering was calculated for individual years and for the entire study period using the Nearest Neighbor Index. Space and time interaction between DHF cases was determined using the Knox Test while the Nearest Neighbor Hierarchical method was used to extract DHF hot spots. All space and time distances calculated were validated using the Pearson r significance test. RESULTS: Results shows that (1) a decrease in mean distance between DHF cases correlates with activity leading up to an outbreak, (2) a decrease in temporal distance between DHF cases leads to increased geographic spread of the disease, with an outbreak occurrence about every 2 years, and (3) a general pattern in the movement of dengue incidents from more rural to urban settings leading up to an outbreak with hotspot areas associated with transportation hubs in Trinidad. CONCLUSION: Considering only the spatial dimension of the disease, results suggest that DHF cases become more concentrated leading up to an outbreak. However, with the additional consideration of time, results suggest that when an outbreak occurs incidents occur more rapidly in time leading to a parallel increase in the rate of distribution of the disease across space. The results of this study can be used by public health officers to help visualize and understand the spatial and temporal patterns of dengue, and to prepare warnings for the public. Dengue space-time patterns and hotspot detection will provide useful information to support public health officers in their efforts to control and predict dengue spread over critical hotspots allowing better allocation of resources.

Summary of what was known * Few studies on road traffic collisions conducted in Latin American and the Caribbean region * Increasing car ownership within the region * Lack of seatbelt usage in Trinidad * Most accidents are associated with alcohol usage * High mortality among pedestrians Summary of what this study adds * Most collisions occur at night * Most collisions occur at weekends * Collisions are evenly distributed throughout the year * More males than females die in fatal collisions * The most productive age group (15-44) is affected the most * More drivers than pedestrians are affected * Reflects the pattern of developed rather than developing countries with respect to time of day for RTCs The purpose of the study is to determine the epidemiology of road traffic collisions (RTCs) in Trinidad and Tobago by characterizing RTCs in terms of number of collisions, fatalities, victim profiles, and locations for the purpose of informing accident prevention programs. Previous studies of RTCs in Trinidad and Tobago were primarily concerned with patterns of drivers use of seat belts, road collisions as a cause of mortality in young men, and the economic burden of road collisions. Attempts were made to model road fatalities, but limited epidemiological data meant that it was difficult to determine trends or develop models. This study determined the epidemiology of RTCs in Trinidad and Tobago over the period 2000-2011using data collected by the Trinidad and Tobago Road Traffic Branch of the Police Service and secondary data from the Central Statistical Office. Data were analyzed using Excel, SPSS, and R statistical packages. Fatalities were greater among men (80%) than among women (20%) and were highest on two major freeways in Trinidad [the Churchill-Roosevelt Highway and the Sir Solomon Hochoy Highway]. Most collisions occurred during the night among individuals between the ages of 15 and 44 years. Fatalities among drivers steadily increased over the study period and overtook fatalities among pedestrians, who were the group most affected in 2000. Most fatalities occurred at weekends. These patterns can inform (i) education programs and (ii) road and traffic control measures.

Efforts directed at genetic modification of mosquitoes for population control or replacement are highly dependent on the initial mating success of transgenic male mosquitoes following their release into natural populations. Adult mosquito phenotypes are influenced by the environmental conditions experienced as larvae. Semifield studies conducted to date have not taken that under consideration when testing male mating fitness, and have compared mating success of males reared under identical environmental conditions. We performed pairwise mating challenges between males from a genetically modified laboratory strain (BF2) versus males from a recent Trinidad field isolate of Aedes aegypti (L.), a major vector of multiple arboviruses. We utilized larval density and nutrition to simulate environmental stress experienced by the Trinidad males and females. Our results indicated that environmental stress during larval development negatively influenced the competitiveness and reproductive success of males from the Trinidad population when paired with optimum reared BF2 males. Small (0.027 m3) and large (0.216 m3) trials were conducted wherein stressed or optimum Trinidad males competed with optimum BF2 males for mating with stressed Trinidad females. When competing with stress reared Trinidad males, optimum reared BF2 males were predominant in matings with stress reared Trinidad females, and large proportions of these females mated with males of both strains. When competing with optimum reared Trinidad males, no difference in mating success was observed between them and BF2 males, and frequencies of multiple matings were low. Our results indicate that future mating competition studies should incorporate appropriate environmental conditions when designing mating fitness trials of genetically modified males.