Dynamic mapping of the probability of infestation by urban arbovirus vectors in the municipalities of Rio Grande do Sul state, Brazil, 2016-2017. / Mapeamento dinâmico da probabilidade de infestação por vetores urbanos de arbovírus nos municípios do Rio Grande do Sul, 2016-2017.

OBJECTIVE: To compare official mapping with probabilistic mapping of infestation by Aedes spp. in the municipalities of Rio Grande do Sul state, Brazil. METHODS: This was an ecological study using data from samples of mosquito breeding sites collected in 2016-2017; official classification was obtained from epidemiological reports, and infestation per municipality and week was estimated by fitting a dynamic site-occupancy model to data from municipal epidemiological surveillance. RESULTS: 187,245 samples collected in 473 municipalities returned 10,648 detections of Aedes aegypti, and 8,414 detections of Aedes albopictus; official mapping agrees with probabilistic mapping in municipalities in the northwestern and western regions of the state. The mappings are not in agreement in the eastern, central, northeastern and southern regions, revealing municipalities officially not infested but with high probability of infestation and notification of arbovirus infection. CONCLUSION: While official classification identified critically infested municipalities in the state's northwestern and western regions, it did not identify infestation in municipalities with possible false zero errors and where infestation varies over time.

Dynamic mapping of the probability of infestation by arbovirus urban vectors in the municipalities of Rio Grande do Sul state, Brazil, 2016-2017 / Mapeo dinámico de la probabilidad de infestación por vectores urbanos de arbovirus en los municipios de Rio Grande do Sul, Brasil, 2016-2017 / Mapeamento dinâmico da probabilidade de infestação por vetores urbanos de arbovírus nos municípios do Rio Grande do Sul, 2016-2017

Objective: To compare the official mapping with the probabilistic mapping of infestation by Aedes spp. in Rio Grande do Sul municipalities, Brazil. Methods: Ecological study analyzing samples of mosquito breeding sites collected in 2016-2017; official classification was obtained from epidemiological reports, and infestation per municipality and week was estimated by fitting a dynamic site-occupancy model to data from municipal epidemiological surveillance. Results: 187,245 samples collected in 473 municipalities returned 10,648 detections of Aedes aegypti, and 8,414 detections of Aedes albopictus.; official mapping agrees with the probabilistic mapping in municipalities from northwestern and western regions. These mappings disagree in eastern, center, northeastern and southern regions, revealing municipalities not officially infested with high infestation probability and notification of arbovirus. Conclusion: While official classification correctly identifies critically infested municipalities from northwestern and western regions, it did not identify infestation in municipalities with false negative errors and where infestation varies over time.

Objetivo: Comparar o mapeamento oficial com um mapeamento probabilístico da infestação por Aedes spp. nos municípios do Rio Grande do Sul, Brasil. Métodos: Estudo ecológico com dados de amostras de criadouros em 2016-2017; obteve-se a classificação oficial em boletins epidemiológicos e estimou-se a probabilidade de infestação por município e semana, ajustando-se um modelo dinâmico de ocupação de sítios aos dados da vigilância epidemiológica municipal. Resultados: 187.245 amostras coletadas em 473 municípios originaram 10.648 detecções de Aedes aegypti e 8.414 de Aedes albopictus; o mapeamento oficial concorda com o probabilístico em municípios da região noroeste e oeste do RS; os mapeamentos discordam nas regiões leste, centro, nordeste e sul, revelando municípios oficialmente não infestados com alta probabilidade de infestação e notificação de arboviroses. Conclusão: A classificação oficial identificou infestação nos municípios infestados do noroeste e oeste; e não identificou infestação em municípios com possíveis falsos zeros e onde ela varia temporalmente.

Lifecycle cost assessment of high strength carbon and stainless steel girder bridges.

This paper addresses the lifecycle cost assessment of a steel girder bridge considering the material costs and maintenance activities along the bridge's lifecycle. A reference highway bridge case study is chosen. It was initially designed using carbon steel S355. Two more steel grades are included in the comparison: high strength carbon steel S460 and duplex stainless steel EN 1.4162. For each design option, fatigue appears to be the driving design criterion for the following critical welded details: transversal stiffeners, cope holes and full penetration butt welds in the flanges. In addition to ultimate limit state verifications, specific attention is therefore given to fatigue through the use of different verification methods: the well-known nominal stress method and the hot spot stress method. It is concluded that the net present value of the lifecycle cost of the stainless steel option is attractive compared to painted the carbon steel options.

Mapeamento dinâmico da probabilidade de infestação por vetores urbanos de arbovírus nos municípios do Rio Grande do Sul, 2016-2017 / Mapeo dinámico de la probabilidad de infestación por vectores urbanos de arbovirus en los municipios de Rio Grande do Sul, Brasil, 2016-2017 / Dynamic mapping of the probability of infestation by urban arbovirus vectors in the municipalities of Rio Grande do Sul state, Brazil, 2016-2017

Objetivo: Comparar o mapeamento oficial com um mapeamento probabilístico da infestação por Aedes spp. nos municípios do Rio Grande do Sul, Brasil. Métodos: Estudo ecológico com dados de amostras de criadouros em 2016-2017; obteve-se a classificação oficial em boletins epidemiológicos e estimou-se a probabilidade de infestação por município e semana, ajustando-se um modelo dinâmico de ocupação de sítios aos dados da vigilância epidemiológica municipal. Resultados: 187.245 amostras coletadas em 473 municípios originaram 10.648 detecções de Aedes aegypti e 8.414 de Aedes albopictus; o mapeamento oficial concorda com o probabilístico em municípios da região noroeste e oeste do RS; os mapeamentos discordam nas regiões leste, centro, nordeste e sul, revelando municípios oficialmente não infestados com alta probabilidade de infestação e notificação de arboviroses. Conclusão: A classificação oficial identificou infestação nos municípios infestados do noroeste e oeste, e não identificou infestação em municípios com possíveis falsos zeros e onde ela varia temporalmente.

Objetivo: Comparar el mapeo oficial con un mapeo probabilístico de infestación por Aedes spp. en los municipios de Rio Grande do Sul, Brasil. Métodos: Estudio ecológico analizando muestras colectadas en criaderos en 2016-2017; se obtuvo la clasificación oficial en boletines epidemiológicos, y la probabilidad de infestación por municipio y semana ajustando un modelo dinámico de ocupación de sitios a los datos de la vigilancia epidemiológica municipal. Resultados: 187.245 muestras de 473 municipios generaron 10.648 detecciones de Aedes aegypti y 8.414 detecciones de Aedes albopictus. El mapeo oficial está de acuerdo con el probabilístico en municipios del noroeste y oeste de RS; los mapeos no concuerdan en el este, centro, nordeste y sur, revelando municipios oficialmente no infestados con alta probabilidad de infestación y notificación de arbovirus. Conclusión: Mientras la clasificación oficial identifica municipios del noroeste y oeste infestados críticamente, no identifica infestación en municipios con posiblemente falsos ceros y en donde la infestación varía temporalmente.

Objective: To compare official mapping with probabilistic mapping of infestation by Aedes spp. in the municipalities of Rio Grande do Sul state, Brazil. Methods: This was an ecological study using data from samples of mosquito breeding sites collected in 2016-2017; official classification was obtained from epidemiological reports, and infestation per municipality and week was estimated by fitting a dynamic site-occupancy model to data from municipal epidemiological surveillance. Results: 187,245 samples collected in 473 municipalities returned 10,648 detections of Aedes aegypti, and 8,414 detections of Aedes albopictus; official mapping agrees with probabilistic mapping in municipalities in the northwestern and western regions of the state. The mappings are not in agreement in the eastern, central, northeastern and southern regions, revealing municipalities officially not infested but with high probability of infestation and notification of arbovirus infection. Conclusion: While official classification identified critically infested municipalities in the state's northwestern and western regions, it did not identify infestation in municipalities with possible false zero errors and where infestation varies over time.

Site Occupancy by Aedes aegypti in a Subtropical City is Most Sensitive to Control during Autumn and Winter Months.

The Aedes aegypti mosquito inhabits most tropical and subtropical regions of the globe, where it transmits arboviral diseases of substantial public health relevance, such as dengue fever. In subtropical regions, Ae. aegypti often presents an annual abundance cycle driven by weather conditions. Because different population states may show varying responses to control, we are interested in studying what time of the year is most appropriate for control. To do so, we developed two dynamic site-occupancy models based on more than 200 weeks of mosquito trapping data from nearly 900 sites in a subtropical Brazilian city. Our phenomenological, Markovian models, fitted to data in a Bayesian framework, accounted for failure to detect mosquitoes in two alternative ways and for temporal variation in dynamic rates of local extinction and colonization of new sites. Infestation varied from nearly full cover of the city area in late summer, to between 10% and 67% of sites occupied in winter depending on the model. Sensitivity analysis reveals that changes in dynamic rates should have the greatest impact on site occupancy during autumn and early winter months, when the mosquito population is declining. We discuss the implications of this finding to the timing of mosquito control.

Culturable bacteria from two Portuguese salterns: diversity and bioactive potential.

Salterns are extreme environments, where the high salt concentration is the main limitation to microbial growth, along with solar radiation, temperature and pH. These selective pressures might lead to the acquisition of unique genetic adaptations that can manifest in the production of interesting natural products. The present study aimed at obtaining the culturable microbial diversity from two Portuguese salterns located in different geographic regions. A total of 190 isolates were retrieved and identified as belonging to 30 genera distributed among 4 phyla-Firmicutes, Proteobacteria, Actinobacteria and Bacteroidetes. Specifically, members of the genus Bacillus were the most frequently isolated from both salterns and all actinobacterial isolates belong to the rare members of this group. The molecular screening of NRPS and PKS-I genes allowed the detection of 38 isolates presenting PKS-I, 25 isolates presenting NRPS and 23 isolates presenting both types of biosynthetic genes. Sequencing of randomly selected amplicons revealed similarity with known PKS-I and NRPS genes or non-annotated hypothetical proteins. This study is the first contribution on the culturable bacterial diversity of Portuguese salterns and on their bioactive potential. Ultimately, these findings provide a novel contribution to improve the understanding on the microbial diversity of salterns.

Mosquito-disseminated pyriproxyfen yields high breeding-site coverage and boosts juvenile mosquito mortality at the neighborhood scale.

BACKGROUND: Mosquito-borne pathogens pose major public health challenges worldwide. With vaccines or effective drugs still unavailable for most such pathogens, disease prevention heavily relies on vector control. To date, however, mosquito control has proven difficult, with low breeding-site coverage during control campaigns identified as a major drawback. A novel tactic exploits the egg-laying behavior of mosquitoes to have them disseminate tiny particles of a potent larvicide, pyriproxyfen (PPF), from resting to breeding sites, thus improving coverage. This approach has yielded promising results at small spatial scales, but its wider applicability remains unclear. METHODOLOGY/PRINCIPAL FINDINGS: We conducted a four-month trial within a 20-month study to investigate mosquito-driven dissemination of PPF dust-particles from 100 'dissemination stations' (DSs) deployed in a 7-ha sub-area to surveillance dwellings and sentinel breeding sites (SBSs) distributed over an urban neighborhood of about 50 ha. We assessed the impact of the trial by measuring juvenile mosquito mortality and adult mosquito emergence in each SBS-month. Using data from 1,075 dwelling-months, 2,988 SBS-months, and 29,922 individual mosquitoes, we show that mosquito-disseminated PPF yielded high coverage of dwellings (up to 100%) and SBSs (up to 94.3%). Juvenile mosquito mortality in SBSs (about 4% at baseline) increased by over one order of magnitude during PPF dissemination (about 75%). This led to a >10-fold decrease of adult mosquito emergence from SBSs, from approximately 1,000-3,000 adults/month before to about 100 adults/month during PPF dissemination. CONCLUSIONS/SIGNIFICANCE: By expanding breeding-site coverage and boosting juvenile mosquito mortality, a strategy based on mosquito-disseminated PPF has potential to substantially enhance mosquito control. Sharp declines in adult mosquito emergence can lower vector/host ratios, reducing the risk of disease outbreaks. This approach is a very promising complement to current and novel mosquito control strategies; it will probably be especially relevant for the control of urban disease vectors, such as Aedes and Culex species, that often cause large epidemics.

Epidemiology of cutaneous leishmaniasis in central Amazonia: a comparison of sex-biased incidence among rural settlers and field biologists.

OBJECTIVE: Cutaneous leishmaniasis (CL) is more frequently reported in men than in women; this may be due to male-biased exposure to CL vectors, female-biased resistance against the disease or both. We sought to determine whether gender-specific exposure to vector habitats explains male-biased CL incidence in two human populations of central Amazonia. METHODS: We compared the CL incidence in one population of field researchers (N = 166), with similar exposure for males and females, and one population of rural settlers (N = 646), where exposure is overall male-biased. We used a combination of questionnaires and clinical data to quantify CL cases, and modelled disease incidence in a Bayesian framework. RESULTS: There was a moderately higher incidence of CL among men than among women in both populations, but male bias decreased as exposure time increased. Disease incidence was overall higher among field researchers, suggesting that they are an important but understudied CL risk group. CONCLUSION: Our comparison of two contrasting populations provided epidemiological evidence that CL incidence can be male-biased even when exposure is comparable in both sexes.

Modeling dengue vector dynamics under imperfect detection: three years of site-occupancy by Aedes aegypti and Aedes albopictus in urban Amazonia.

Aedes aegypti and Ae. albopictus are the vectors of dengue, the most important arboviral disease of humans. To date, Aedes ecology studies have assumed that the vectors are truly absent from sites where they are not detected; since no perfect detection method exists, this assumption is questionable. Imperfect detection may bias estimates of key vector surveillance/control parameters, including site-occupancy (infestation) rates and control intervention effects. We used a modeling approach that explicitly accounts for imperfect detection and a 38-month, 55-site detection/non-detection dataset to quantify the effects of municipality/state control interventions on Aedes site-occupancy dynamics, considering meteorological and dwelling-level covariates. Ae. aegypti site-occupancy estimates (mean 0.91; range 0.79-0.97) were much higher than reported by routine surveillance based on 'rapid larval surveys' (0.03; 0.02-0.11) and moderately higher than directly ascertained with oviposition traps (0.68; 0.50-0.91). Regular control campaigns based on breeding-site elimination had no measurable effects on the probabilities of dwelling infestation by dengue vectors. Site-occupancy fluctuated seasonally, mainly due to the negative effects of high maximum (Ae. aegypti) and minimum (Ae. albopictus) summer temperatures (June-September). Rainfall and dwelling-level covariates were poor predictors of occupancy. The marked contrast between our estimates of adult vector presence and the results from 'rapid larval surveys' suggests, together with the lack of effect of local control campaigns on infestation, that many Aedes breeding sites were overlooked by vector control agents in our study setting. Better sampling strategies are urgently needed, particularly for the reliable assessment of infestation rates in the context of control program management. The approach we present here, combining oviposition traps and site-occupancy models, could greatly contribute to that crucial aim.

A large-scale forest fragmentation experiment: the Stability of Altered Forest Ecosystems Project.

Opportunities to conduct large-scale field experiments are rare, but provide a unique opportunity to reveal the complex processes that operate within natural ecosystems. Here, we review the design of existing, large-scale forest fragmentation experiments. Based on this review, we develop a design for the Stability of Altered Forest Ecosystems (SAFE) Project, a new forest fragmentation experiment to be located in the lowland tropical forests of Borneo (Sabah, Malaysia). The SAFE Project represents an advance on existing experiments in that it: (i) allows discrimination of the effects of landscape-level forest cover from patch-level processes; (ii) is designed to facilitate the unification of a wide range of data types on ecological patterns and processes that operate over a wide range of spatial scales; (iii) has greater replication than existing experiments; (iv) incorporates an experimental manipulation of riparian corridors; and (v) embeds the experimentally fragmented landscape within a wider gradient of land-use intensity than do existing projects. The SAFE Project represents an opportunity for ecologists across disciplines to participate in a large initiative designed to generate a broad understanding of the ecological impacts of tropical forest modification.

Modeling disease vector occurrence when detection is imperfect: infestation of Amazonian palm trees by triatomine bugs at three spatial scales.

BACKGROUND: Failure to detect a disease agent or vector where it actually occurs constitutes a serious drawback in epidemiology. In the pervasive situation where no sampling technique is perfect, the explicit analytical treatment of detection failure becomes a key step in the estimation of epidemiological parameters. We illustrate this approach with a study of Attalea palm tree infestation by Rhodnius spp. (Triatominae), the most important vectors of Chagas disease (CD) in northern South America. METHODOLOGY/PRINCIPAL FINDINGS: The probability of detecting triatomines in infested palms is estimated by repeatedly sampling each palm. This knowledge is used to derive an unbiased estimate of the biologically relevant probability of palm infestation. We combine maximum-likelihood analysis and information-theoretic model selection to test the relationships between environmental covariates and infestation of 298 Amazonian palm trees over three spatial scales: region within Amazonia, landscape, and individual palm. Palm infestation estimates are high (40-60%) across regions, and well above the observed infestation rate (24%). Detection probability is higher ( approximately 0.55 on average) in the richest-soil region than elsewhere ( approximately 0.08). Infestation estimates are similar in forest and rural areas, but lower in urban landscapes. Finally, individual palm covariates (accumulated organic matter and stem height) explain most of infestation rate variation. CONCLUSIONS/SIGNIFICANCE: Individual palm attributes appear as key drivers of infestation, suggesting that CD surveillance must incorporate local-scale knowledge and that peridomestic palm tree management might help lower transmission risk. Vector populations are probably denser in rich-soil sub-regions, where CD prevalence tends to be higher; this suggests a target for research on broad-scale risk mapping. Landscape-scale effects indicate that palm triatomine populations can endure deforestation in rural areas, but become rarer in heavily disturbed urban settings. Our methodological approach has wide application in infectious disease research; by improving eco-epidemiological parameter estimation, it can also significantly strengthen vector surveillance-control strategies.

Perturbation analysis for patch occupancy dynamics.

Perturbation analysis is a powerful tool to study population and community dynamics. This article describes expressions for sensitivity metrics reflecting changes in equilibrium occupancy resulting from small changes in the vital rates of patch occupancy dynamics (i.e., probabilities of local patch colonization and extinction). We illustrate our approach with a case study of occupancy dynamics of Golden Eagle (Aquila chrysaetos) nesting territories. Examination of the hypothesis of system equilibrium suggests that the system satisfies equilibrium conditions. Estimates of vital rates obtained using patch occupancy models are used to estimate equilibrium patch occupancy of eagles. We then compute estimates of sensitivity metrics and discuss their implications for eagle population ecology and management. Finally, we discuss the intuition underlying our sensitivity metrics and then provide examples of ecological questions that can be addressed using perturbation analyses. For instance, the sensitivity metrics lead to predictions about the relative importance of local colonization and local extinction probabilities in influencing equilibrium occupancy for rare and common species.

A large-scale deforestation experiment: effects of patch area and isolation on Amazon birds.

As compared with extensive contiguous areas, small isolated habitat patches lack many species. Some species disappear after isolation; others are rarely found in any small patch, regardless of isolation. We used a 13-year data set of bird captures from a large landscape-manipulation experiment in a Brazilian Amazon forest to model the extinction-colonization dynamics of 55 species and tested basic predictions of island biogeography and metapopulation theory. From our models, we derived two metrics of species vulnerability to changes in isolation and patch area. We found a strong effect of area and a variable effect of isolation on the predicted patch occupancy by birds.

Rates of species loss from Amazonian forest fragments.

In the face of worldwide habitat fragmentation, managers need to devise a time frame for action. We ask how fast do understory bird species disappear from experimentally isolated plots in the Biological Dynamics of Forest Fragments Project, central Amazon, Brazil. Our data consist of mist-net records obtained over a period of 13 years in 11 sites of 1, 10, and 100 hectares. The numbers of captures per species per unit time, analyzed under different simplifying assumptions, reveal a set of species-loss curves. From those declining numbers, we derive a scaling rule for the time it takes to lose half the species in a fragment as a function of its area. A 10-fold decrease in the rate of species loss requires a 1,000-fold increase in area. Fragments of 100 hectares lose one half of their species in <15 years, too short a time for implementing conservation measures.