Vector role and human biting activity of Anophelinae mosquitoes in different landscapes in the Brazilian Amazon.

BACKGROUND: Environmental disturbance, deforestation and socioeconomic factors all affect malaria incidence in tropical and subtropical endemic areas. Deforestation is the major driver of habitat loss and fragmentation, which frequently leads to shifts in the composition, abundance and spatial distribution of vector species. The goals of the present study were to: (i) identify anophelines found naturally infected with Plasmodium; (ii) measure the effects of landscape on the number of Nyssorhynchus darlingi, presence of Plasmodium-infected Anophelinae, human biting rate (HBR) and malaria cases; and (iii) determine the frequency and peak biting time of Plasmodium-infected mosquitoes and Ny. darlingi. METHODS: Anopheline mosquitoes were collected in peridomestic and forest edge habitats in seven municipalities in four Amazon Brazilian states. Females were identified to species and tested for Plasmodium by real-time PCR. Negative binomial regression was used to measure any association between deforestation and number of Ny. darlingi, number of Plasmodium-infected Anophelinae, HBR and malaria. Peak biting time of Ny. darlingi and Plasmodium-infected Anophelinae were determined in the 12-h collections. Binomial logistic regression measured the association between presence of Plasmodium-infected Anophelinae and landscape metrics and malaria cases. RESULTS: Ninety-one females of Ny. darlingi, Ny. rangeli, Ny. benarrochi B and Ny. konderi B were found to be infected with Plasmodium. Analysis showed that the number of malaria cases and the number of Plasmodium-infected Anophelinae were more prevalent in sites with higher edge density and intermediate forest cover (30-70%). The distance of the drainage network to a dwelling was inversely correlated to malaria risk. The peak biting time of Plasmodium-infected Anophelinae was 00:00-03:00 h. The presence of Plasmodium-infected mosquitoes was higher in landscapes with > 13 malaria cases. CONCLUSIONS: Nyssorhynchus darlingi, Ny. rangeli, Ny. benarrochi B and Ny. konderi B can be involved in malaria transmission in rural settlements. The highest fraction of Plasmodium-infected Anophelinae was caught from midnight to 03:00 h. In some Amazonian localities, the highest exposure to infectious bites occurs when residents are sleeping, but transmission can occur throughout the night. Forest fragmentation favors increases in both malaria and the occurrence of Plasmodium-infected mosquitoes in peridomestic habitat. The use of insecticide-impregnated mosquito nets can decrease human exposure to infectious Anophelinae and malaria transmission.

Anthropogenic landscape decreases mosquito biodiversity and drives malaria vector proliferation in the Amazon rainforest.

Inter-relationships among mosquito vectors, Plasmodium parasites, human ecology, and biotic and abiotic factors, drive malaria risk. Specifically, rural landscapes shaped by human activities have a great potential to increase the abundance of malaria vectors, putting many vulnerable people at risk. Understanding at which point the abundance of vectors increases in the landscape can help to design policies and interventions for effective and sustainable control. Using a dataset of adult female mosquitoes collected at 79 sites in malaria endemic areas in the Brazilian Amazon, this study aimed to (1) verify the association among forest cover percentage (PLAND), forest edge density (ED), and variation in mosquito diversity; and to (2) test the hypothesis of an association between landscape structure (i.e., PLAND and ED) and Nyssorhynchus darlingi (Root) dominance. Mosquito collections were performed employing human landing catch (HLC) (peridomestic habitat) and Shannon trap combined with HLC (forest fringe habitat). Nyssorhynchus darlingi abundance was used as the response variable in a generalized linear mixed model, and the Shannon diversity index (H') of the Culicidae community, PLAND, and the distance house-water drainage were used as predictors. Three ED categories were also used as random effects. A path analysis was used to understand comparative strengths of direct and indirect relationships among Amazon vegetation classes, Culicidae community, and Ny. darlingi abundance. Our results demonstrate that Ny. darlingi is negatively affected by H´ and PLAND of peridomestic habitat, and that increasing these variables (one-unit value at ß0 = 768) leads to a decrease of 226 (P < 0.001) and 533 (P = 0.003) individuals, respectively. At the forest fringe, a similar result was found for H' (ß1 = -218; P < 0.001) and PLAND (ß1 = -337; P = 0.04). Anthropogenic changes in the Amazon vegetation classes decreased mosquito biodiversity, leading to increased Ny. darlingi abundance. Changes in landscape structure, specifically decreases in PLAND and increases in ED, led to Ny. darlingi becoming the dominant species, increasing malaria risk. Ecological mechanisms involving changes in landscape and mosquito species composition can help to understand changes in the epidemiology of malaria.

The environmental footprint of health care: a global assessment.

BACKGROUND: Health-care services are necessary for sustaining and improving human wellbeing, yet they have an environmental footprint that contributes to environment-related threats to human health. Previous studies have quantified the carbon emissions resulting from health care at a global level. We aimed to provide a global assessment of the wide-ranging environmental impacts of this sector. METHODS: In this multiregional input-output analysis, we evaluated the contribution of health-care sectors in driving environmental damage that in turn puts human health at risk. Using a global supply-chain database containing detailed information on health-care sectors, we quantified the direct and indirect supply-chain environmental damage driven by the demand for health care. We focused on seven environmental stressors with known adverse feedback cycles: greenhouse gas emissions, particulate matter, air pollutants (nitrogen oxides and sulphur dioxide), malaria risk, reactive nitrogen in water, and scarce water use. FINDINGS: Health care causes global environmental impacts that, depending on which indicator is considered, range between 1% and 5% of total global impacts, and are more than 5% for some national impacts. INTERPRETATION: Enhancing health-care expenditure to mitigate negative health effects of environmental damage is often promoted by health-care practitioners. However, global supply chains that feed into the enhanced activity of health-care sectors in turn initiate adverse feedback cycles by increasing the environmental impact of health care, thus counteracting the mission of health care. FUNDING: Australian Research Council, National eResearch Collaboration Tools and Resources project.

Global consumption and international trade in deforestation-associated commodities could influence malaria risk.

Deforestation can increase the transmission of malaria. Here, we build upon the existing link between malaria risk and deforestation by investigating how the global demand for commodities that increase deforestation can also increase malaria risk. We use a database of trade relationships to link the consumption of deforestation-implicated commodities in developed countries to estimates of country-level malaria risk in developing countries. We estimate that about 20% of the malaria risk in deforestation hotspots is driven by the international trade of deforestation-implicated export commodities, such as timber, wood products, tobacco, cocoa, coffee and cotton. By linking malaria risk to final consumers of commodities, we contribute information to support demand-side policy measures to complement existing malaria control interventions, with co-benefits for reducing deforestation and forest disturbance.

A method for estimating the deforestation timeline in rural settlements in a scenario of malaria transmission in frontier expansion in the Amazon Region.

The Malaria Frontier Hypothesis (MFH) is the current model for predicting malaria emergence in the Brazilian Amazon. It has two important dimensions, 'settlement time' and 'malaria incidence', and its prediction are: malaria incidence peaks five years after the initiation of human settlement and declines towards zero after an estimated 10 years. Although MFH is currently accepted, it has been challenged recently. Herein, we described a novel method for estimating settlement timeline by using remote sensing technology integrated in an open-software geographic information system. Surprisingly, we found that of the majority of the rural settlements with high malaria incidence are more than 10 years old.

Abundance of impacted forest patches less than 5 km2 is a key driver of the incidence of malaria in Amazonian Brazil.

The precise role that deforestation for agricultural settlements and commercial forest products plays in promoting or inhibiting malaria incidence in Amazonian Brazil is controversial. Using publically available databases, we analyzed temporal malaria incidence (2009-2015) in municipalities of nine Amazonian states in relation to ecologically defined variables: (i) deforestation (rate of forest clearing over time); (ii) degraded forest (degree of human disturbance and openness of forest canopy for logging) and (iii) impacted forest (sum of deforested and degraded forest patches). We found that areas affected by one kilometer square of deforestation produced 27 new malaria cases (r² = 0.78; F1,10 = 35.81; P < 0.001). Unexpectedly, we found both a highly significant positive correlation between number of impacted forest patches less than 5 km2 and malaria cases, and that these patch sizes accounted for greater than ~95% of all patches in the study area. There was a significantly negative correlation between extraction forestry economic indices and malaria cases. Our results emphasize not only that deforestation promotes malaria incidence, but also that it directly or indirectly results in a low Human Development Index, and favors environmental conditions that promote malaria vector proliferation.

Sistema ecológico da malária / Ecological system of malaria

As alterações das paisagens promovidas pelo homem, em razão das atividades relacionadas ao uso e ocupação do solo, representam um desafio para as atividades de controle da malária na Amazônia brasileira. Desse modo, buscou-se avaliar o sistema ecológico da malária através da construção de três eixos: desmatamento, uso do solo e diversidade de Culicidae. Esses eixos tiveram a paisagem como centro de conexão, modulados por fatores de pressão (hospedeiro humano), de risco (o vetor) e de causa (o agente infeccioso). A transmissão de patógenos, incluindo espécies de Plasmodium, ocorre na intersecção entre os nichos do hospedeiro humano, dos vetores e dos parasitos, em ambiente que permite a interconexão dos mesmos. Nesse sentido, verificou-se que cada quilômetro quadrado de área impactada pelo desmatamento, entre 2009-2015, produziu 27 novos casos de malária (r² = 0,78; F1,10 = 35,81; P <0,001) na Amazônia Legal brasileira, com uma correlação positiva altamente significativa entre o número de áreas de florestas impactadas com menos de 5 km² e a incidência da doença. Em virtude das relações indiretas com o desmatamento, foi possível verificar que o aumento da produção de soja, madeira, gado e óleo de palma no mundo apresentou alta correlação positiva significativa com a incidência de malária em países tropicais. No cenário brasileiro, a abundância de Nyssorhynchus darlingi respondeu positivamente à perda da cobertura florestal de áreas endêmicas de malária. Ao contrário, a diversidade de Culicidae diminuiu, deixando os vetores como espécies dominantes, favorecendo a taxa de picada e a capacidade de transmissão do Plasmodium. Desse modo, foi possível concluir que a incidência da doença, em áreas rurais, está fortemente associada aos padrões de uso e ocupação do solo. A estrutura da paisagem pode ser indicador de risco para a doença, em virtude das dinâmicas ecológicas do Ny. darlingi.

Changes in the landscapes caused by humans, due to the activities related to the use and occupation of the soil, represent a challenge for malaria control activities in the Brazilian Amazon. Therefore, we evaluated the ecological system of malaria in relation to the construction of three drivers: deforestation, land use and Culicidae diversity. These drivers had in common the landscape, modulated by factors of pressure (human host), risk (the vector) and necessary cause (the infectious agent). The transmission of pathogens, including species of Plasmodium, occurs at the intersection among niches of the human host, the vectors and the parasites, in an environment that allows the interconnection of these organisms. The data analyzed herein verified that every square kilometer of area impacted by deforestation between 2009-2015 produced 27 new cases of malaria (r² = 0.78, F1.10 = 35.81, P <0.001) in the Brazilian Legal Amazon, with a highly significant positive correlation between the number of forest areas with impacted less than 5 km² and the incidence of the disease. Due to the indirect relationship with deforestation, it was possible to verify that the increase in the production of soybean, wood, cattle and palm oil worldwide showed a significant positive correlation with the incidence of malaria in tropical countries. In the Brazilian scenario, the abundance of Nyssorhynchus darlingi responded positively to the loss of forest cover of endemic areas of malaria. In opposite, the Culicidae diversity decreased, leaving vectors as dominant species, favoring the biting rate and the capacity to Plasmodium transmission. Thus, it was possible to conclude that the incidence of the disease in rural areas is strongly associated with the patterns of land use and occupation. The structure of the landscape can be an indicator of risk for the disease, due to the ecological dynamics of the Ny. darlingi.

A method for estimating the deforestation timeline in rural settlements in a scenario of malaria transmission in frontier expansion in the Amazon Region

The Malaria Frontier Hypothesis (MFH) is the current model for predicting malaria emergence in the Brazilian Amazon. It has two important dimensions, 'settlement time' and 'malaria incidence', and its prediction are: malaria incidence peaks five years after the initiation of human settlement and declines towards zero after an estimated 10 years. Although MFH is currently accepted, it has been challenged recently. Herein, we described a novel method for estimating settlement timeline by using remote sensing technology integrated in an open-software geographic information system. Surprisingly, we found that of the majority of the rural settlements with high malaria incidence are more than 10 years old.

Kerteszia Theobald (Diptera: Culicidae) mosquitoes and bromeliads: A landscape ecology approach regarding two species in the Atlantic rainforest.

On the ecological scale of an organism, a homogeneous geographical landscape can represent a mosaic of heterogeneous landscapes. The bionomy of Kerteszia mosquitoes can contribute to foundation landscape ecology by virtue of in the role of the configuration and composition of the habitat played in the distribution of mosquito species. Thus, this study aimed: to compare the abundance of Kerteszia in dense tropical rainforest, restinga and rural area, to assess the bioecological characteristics of the main bromeliads hosting Kerteszia, and to associate the bioecological arrangement of the bromeliads with Kerteszia distribution. Field collections were conducted in a monthly schedule from December of 2010 to November 2011. The vegetation of landscapes was characterized on the basis of a digital cartographic database, the manual of the Brazilian vegetation, environmental atlas information, satellite images and visits to the sites. Multivariate generalized linear models were employed using the R-project statistical program. The results were: Anopheles cruzii was the most frequent species in dense tropical rainforest (67.42%), with a positive association (deviance=25.8; P=0.002). Anopheles bellator was more abundant in the Restinga area (78.97%), with a positive association (deviance=10.4, P=0.018). There was a positive aggregation of Restinga with An. bellator (RR=2.42) but a lower level with An. cruzii (RR=0.31). Thus we can conclude that landscape characteristics influence the distribution of Kerteszia mosquitoes. An. bellator has a higher prevalence in Restinga areas, whereas An. cruzii was the most prevalent in the dense tropical rainforest.

[Public drinking water supply and egg laying by Aedes aegypti]. / Água de abastecimento público de consumo humano e oviposição de Aedes aegypti.

OBJECTIVE: To evaluate the effect of the quality of publicly supplied water in domestic water tanks on egg laying by female Aedes aegypti. METHODS: Laboratory study on immature Ae. aegypti, collected from water-tanks in the municipality of Potim, SP, Southeastern Brazil. Each cage contained three types of water in which eggs could be laid: Three choice per test were simultaneously used to deposit the eggs, ovipositor (A) with water collected from a water tank in Taubaté, ovipositor (B) with distilled water (control) and ovipositor (C) water collected from a water tank in the municipality of Potim. Physiochemical parameters were analyzed. The Kruskall-Wallis test was used to analyze the mean number of eggs in each water sample and the Dwass-Steel-Critchlow-Fligner test was used in making comparisons. To evaluate egg laying, an ovipositional activity index was adopted. RESULTS: A significant difference in the number of eggs was found between the liquid solutions tested (H = 45; p < 0.0001). The number of eggs found in water tank samples originating from deep wells (C), was statistically superior to water samples from water tanks originating from superficial wells (A) (p < 0.0001) and from the Control (C) p < 0.0001. There was no significant difference between the number of eggs in Control (B) and the surface water (A). In all three tests, the first position was the most productive in all tested solutions. Only water sample (C) produced a positive index (0.54), i.e., attractive to egg laying. CONCLUSIONS: Water quality influences egg laying by Aedes aegypti. The high concentrations of ammonium nitrate in public water supplies suggest that this chemical component was responsible for attracting pregnant female Aedes aegypti to lay eggs in these environments.

Água de abastecimento público de consumo humano e oviposição de Aedes aegypti / Agua de abastecimiento público de consumo humano y oviposición de Aedes aegypti / Public drinking water supply and egg laying by Aedes aegypti

OBJETIVO: Analisar o efeito da qualidade da água de reservatórios domésticos de abastecimento público na resposta oviposicional de fêmeas de Aedes aegypti. MÉTODOS: Estudo conduzido em laboratório a partir de imaturos de Ae. aegypti, coletados em caixas d'água do município de Potim, SP, 2009. Foram disponibilizados simultaneamente três tipos de água por gaiola para a deposição dos ovos: ovipositor (A) com água coletada em caixa d'água de Taubaté, SP; ovipositor (B) com água destilada (controle); e ovipositor (C) com água coletada em caixa d'água de Potim. Foram analisados parâmetros fisicoquímicos. O teste de Kruskall-Wallis foi utilizado para analisar a média de ovos nas diferentes amostras de água e nas comparações posteriores, o teste Dwass-Steel-Chritchlow-Flingner. O índice de atividade de oviposição foi adotado para avaliar a resposta oviposicional. RESULTADOS: Foi observada diferença significativa no número de ovos entre as soluções líquidas testadas (H = 45; p < 0,0001). O número de ovos na água de caixas d'água de abastecimento público de captação em poços profundos (C) foi estatisticamente superior a amostras de água de caixas d'água de abastecimento público de superfície (A) (p < 0,0001) e do Controle (B) (p < 0,0001). Não houve diferença significante entre o número de ovos do Controle (B) e água de superfície (A). A primeira postura foi a mais produtiva em todas as soluções testadas nas três gaiolas. A amostra de água (C) produziu índice positivo (0,54), i.e., atrativo para oviposição. CONCLUSÕES: A qualidade da água influiu na oviposição de Ae. aegypti. As elevadas concentrações de nitrogênio ...

OBJETIVO: Analizar el efecto de la calidad de agua de reservatorios domésticos de abastecimiento público en la respuesta de oviposición por hembras de Aedes aegypti. MÉTODOS: Estudio conducido en laboratorio a partir de inmaduros de Ae. aegypti, colectados en tanques de agua del municipio de Potim, SP, Brasil, 2009. Se disponibilizaron simultáneamente tres tipos de agua por jaula para la deposición de los huevos: ovipositor (A) con agua colectada en tanque de agua de Taubaté, SP (Brasil), ovipositor (B) agua destilada (control) y ovipositor (C) con agua colectada en el tanque de agua de Potim. Se analizaron parámetros fisicoquímicos. La prueba de Kruskall-Wallis fue usada para analizar el promedio de huevos en las diferentes muestras de agua y en las comparaciones posteriores, la prueba de Dwass-Steel-Chritchlow-Flingner. El índice de actividad de oviposición fue adoptado para evaluar la respuesta en las diferentes muestras. RESULTADOS: Se observó diferencia significativa en el número de huevos entre las soluciones líquidas evaluadas (H= 45; p˂0,0001). El número de huevos en el agua de los tanques para abastecimiento público, de captación en pozos profundos (C) fue estadísticamente superior a las muestras de tanques para abastecimiento público de superficie (A) (p˂0,0001) y del Control (B) (p˂0,0001). No hubo diferencia significativa entre el número de huevos del Control (B) y el agua de superficie (A). La primera postura fue la más productiva en todas las soluciones evaluadas en las tres jaulas. La muestra de agua (C) produjo índice positivo (0,54), es decir, atractivo para oviposición. CONCLUSIONES: La calidad de agua influyó en la oviposición de Ae. aegypti. Las elevadas concentraciones de nitrógeno amoniacal en el agua de abastecimiento público sugieren que dicho componente ...

OBJECTIVE: To evaluate the effect of the quality of publicly supplied water in domestic water tanks on egg laying by female Aedes aegypti. METHODS: Laboratory study on immature Ae. aegypti, collected from water-tanks in the municipality of Potim, SP, Southeastern Brazil. Each cage contained three types of water in which eggs could be laid: Three choice per test were simultaneously used to deposit the eggs, ovipositor (A) with water collected from a water tank in Taubaté, ovipositor (B) with distilled water (control) and ovipositor (C) water collected from a water tank in the municipality of Potim. Physiochemical parameters were analyzed. The Kruskall-Wallis test was used to analyze the mean number of eggs in each water sample and the Dwass-Steel-Critchlow-Fligner test was used in making comparisons. To evaluate egg laying, an ovipositional activity index was adopted. RESULTS: A significant difference in the number of eggs was found between the liquid solutions tested (H = 45; p < 0.0001). The number of eggs found in water tank samples originating from deep wells (C), was statistically superior to water samples from water tanks originating from superficial wells (A) (p < 0.0001) and from the Control (C) p < 0.0001. There was no significant difference between the number of eggs in Control (B) and the surface water (A). In all three tests, the first position was the most productive in all tested solutions. Only water sample (C) produced a positive index (0.54), i.e., attractive to egg laying. CONCLUSIONS: Water quality influences egg laying by Aedes aegypti. The high concentrations of ammonium nitrate in public water supplies suggest that this chemical component was responsible for attracting pregnant female Aedes aegypti to lay eggs in these environments. .

Eficácia de três tipos de armadilhas para captura de culicídeos em área de Mata Atlântica no sudeste do Brasil / Efficacy of three mosquitoes traps in area of Atlantic Forest in the southeastern of Brazil

Introdução: Armadilhas entomológicas são ferramentas importantes nas atividades de vigilância e controle. Poucos estudos foram realizados para avaliar a eficácia de armadilhas contendo Lurex3 como ferramenta na pesquisa entomológica de culicídeos no Vale do Ribeira. Objetivo: Comparar a eficácia das armadilhas, CDC luminosa, CDC com CO2 mais lurex® e Mosquito Magnet® (MM) Independence com lurex® para a captura de culicídeos. Métodos: foram definidos três pontos próximos da mata, onde foram instaladas as armadilhas, sempre às 15:00 hs e removidas às 21:00 hs com revezamento diário, por três dias consecutivos ao mês, por um ano. Resultados: A armadilha CDC-luz capturou o menor número de mosquitos (1.368), seguida da CDC+CO2+lurex (2.284) e da MM (5.477). O teste de Tukey mostrou diferença significativa, indicando a armadilha MM superior, quando comparada com a CDC-luminosa (p < 0,01) e CDC-CO2-lurex (p < 0,03). Não houve diferença significante entre o total de mosquitos coletados na CDC-luminosa e na CDC-CO2- lurex. O número de espécies capturadas na armadilha MM (63 espécies) foi maior do que na CDC-luminosa (p < 0,001) e CDC-CO2-lurex (p < 0,03). Houve uma associação positiva (OR > 1) para as espécies Ae. scapularis, An. bellator, An. cruzii e Ps. ferox quando utilizada a MM e a CDC-CO2-lurex, não houve associação (OR = 1) para a espécie Ae. serratus e Cx. nigripalpus . Conclusões: O poder de captura da MM mostrou ser significativamente maior em comparação às outras duas.