Blood Meals With Active and Heat-Inactivated Serum Modifies the Gene Expression and Microbiome of Aedes albopictus.

The Asian "tiger mosquito" Aedes albopictus is currently the most widely distributed disease-transmitting mosquito in the world. Its geographical expansion has also allowed the expansion of multiple arboviruses like dengue, Zika, and chikungunya, to higher latitudes. Due to the enormous risk to global public health caused by mosquitoes species vectors of human disease, and the challenges in slowing their expansion, it is necessary to develop new and environmentally friendly vector control strategies. Among these, host-associated microbiome-based strategies have emerged as promising options. In this study, we performed an RNA-seq analysis on dissected abdomens of Ae. albopictus females from Manhattan, KS, United States fed with sugar and human blood containing either normal or heat-inactivated serum, to evaluate the effect of heat inactivation on gene expression, the bacteriome transcripts and the RNA virome of this mosquito species. Our results showed at least 600 genes with modified expression profile when mosquitoes were fed with normal vs. heat-inactivated-containing blood. These genes were mainly involved in immunity, oxidative stress, lipid metabolism, and oogenesis. Also, we observed bacteriome changes with an increase in transcripts of Actinobacteria, Rhodospirillaceae, and Anaplasmataceae at 6 h post-feeding. We also found that feeding with normal blood seems to particularly influence Wolbachia metabolism, demonstrated by a significant increase in transcripts of this bacteria in mosquitoes fed with blood containing normal serum. However, no differences were observed in the virome core of this mosquito population. These results suggest that heat and further inactivation of complement proteins in human serum may have profound effect on mosquito and microbiome metabolism, which could influence interpretation of the pathogen-host interaction findings when using this type of reagents specially when measuring the effect of Wolbachia in vector competence.

Transcriptome of the Aedes aegypti Mosquito in Response to Human Complement Proteins.

Aedes aegypti is the primary mosquito vector of several human arboviruses, including the dengue virus (DENV). Vector control is the principal intervention to decrease the transmission of these viruses. The characterization of molecules involved in the mosquito physiological responses to blood-feeding may help identify novel targets useful in designing effective control strategies. In this study, we evaluated the in vivo effect of feeding adult female mosquitoes with human red blood cells reconstituted with either heat-inactivated (IB) or normal plasma (NB). The RNA-seq based transcript expression of IB and NB mosquitoes was compared against sugar-fed (SF) mosquitoes. In in vitro experiments, we treated Aag2 cells with a recombinant version of complement proteins (hC3 or hC5a) and compared transcript expression to untreated control cells after 24 h. The transcript expression analysis revealed that human complement proteins modulate approximately 2300 transcripts involved in multiple biological functions, including immunity. We also found 161 upregulated and 168 downregulated transcripts differentially expressed when human complement protein C3 (hC3) and human complement protein C5a (hC5a) treated cells were compared to the control untreated cells. We conclude that active human complement induces significant changes to the transcriptome of Ae. aegypti mosquitoes, which may influence the physiology of these arthropods.

Barriers that limit the implementation of thermal fogging for the control of dengue in Colombia: a study of mixed methods.

BACKGROUND: Thermal fogging of Insecticides is a vector control strategy used by the Medellin Secretary of Health to combat dengue. This method is employed during outbreaks to curb populations of potentially infectious adult mosquitoes and interrupt transmission cycles. While this strategy has been used in Medellin since 2007, in some years it has not reduced dengue cases as expected. Difficulties in the implementation of fumigation strategies, such as lack of opportunity for treatment and public perception may be factors that limit its utility. The objective of this study was to identify barriers that hinder the implementation of thermal fogging, as well as attitudes and beliefs that prevent its acceptance. METHODS: We used a cross-sectional observational study of mixed methods carried out in neighborhoods prioritized for fumigation treatment in Medellin, Colombia. First, we assessed the timeliness of treatment by determining the latency period between reported dengue cases and the implementation of fumigation in response to those cases. Next, we administered structured questionnaires to residents in the area of fumigation treatments (n = 4455 homes) to quantify acceptance and rejection, as well as factors associated with rejection. RESULTS: The median time between notification and treatment was 25 days (IQR 20.0-36.5). Fumigators were only able to treat 53.7% of total households scheduled for treatment; 9.6% rejected treatment, and treatment teams were unable to fumigate the remaining 36.7% of homes due to absent residents, no adults being present, and other reasons. The most frequent causes for rejection were residents being busy at the time of treatment (33.1%) and no interest in the treatment (24.5%). Other reasons for rejection include the perceptions that fumigation does not control pests other than mosquitoes (4.3%), that no mosquitoes were present in the home (3.3%), and that fumigation affects human health (3.1%). CONCLUSIONS: The high percentage of houses where it was not possible to perform fumigation limits control of the vector. Future strategies should consider more flexible treatment schedules and incorporate informational messages to educate residents about the safety and importance of treatment.

Knowledge, practices and entomological aspects of dengue in Medellín, Colombia: A comparative study of neighborhoods with high and low incidence

Introduction: Dengue, mainly transmitted by Aedes aegypti, is a very important viral disease in terms of public health. Colombia is an endemoepidemic country for dengue and, in cities like Medellín, there are neighborhoods with high and low incidence. The disease dynamics in the neighborhoods might be determined by differences in the knowledge, practices and entomological aspects of the vector among the communities. Objective: To identify the knowledge and practices of residents of neighborhoods with high and low incidence of dengue, and to explore the entomological aspects related to the presence of the vector. Materials and methods: We conducted a cross-sectional study comparing two neighborhoods with high incidence and two with low incidence during the triennium of 2013-2015. A random sample of 100 houses per neighborhood was selected in order to evaluate the knowledge, practices and entomological aspects related to dengue. In addition, descriptive, bivariate and multivariate analyses (logistic regression) were performed. Results: In neighborhoods with high incidence, participants had not attended school or had only a primary school level of education (OR=1.69; 95% CI: 1.09-2.63). Additionally, they did not have health coverage or belonged to the subsidized regime (OR=2.16; 95% CI: 1.41-3.32). In contrast, they had a greater knowledge of the vector (OR=1.53; 95% CI: 1.00-2.35). In terms of practices, there was a greater chance of finding houses where water was stored (OR=1.69; 95% CI: 1.11-2.57) and regarding the entomological aspects, more houses with adult mosquitoes were found (OR=2.13 95% CI: 1.29-3.50). Conclusions: We found important differences among the neighborhoods regarding knowledge, practices, and the presence of adult stages of the vector, which helps to explain the epidemiology of dengue in these sites.

Monitoring and Predicting Net Longevity by Measuring Surface Levels of Insecticide: Implementing a Faster, Cost Effective, Nondestructive, and Field-Ready Alternative to the World Health Organization Cone Test Bioassay.

An important component of malaria control programs is the ability to assess the effectiveness of the insecticide in insecticide-treated nets (ITNs) during normal usage. The standard technique to measure insecticidal activity is the World Health Organization (WHO) cone test, which in many circumstances, may be difficult to implement. We have evaluated an alternative technique, the colorimetric field test (CFT) on a group of 24-month-old Permanet® 2.0 (Vestergaard-Frandsen, Denmark) nets collected in Colombia. The CFT, which measures surface levels (SL) of deltamethrin is compared with standard high-performance liquid chromatography (HPLC) and the WHO cone test. Effective concentrations of deltamethrin for 80% mortality (EC80) were determined from the CFT and HPLC results. Distribution of insecticide SL after 24 months of use reveal that sampling of the midsection best represents the condition of the entire net. We conclude that the CFT is a practical alternative to the WHO cone test for assessing ITN efficacy.

Conocimientos, prácticas y aspectos entomológicos del dengue en Medellín, Colombia: un estudio comparativo entre barrios con alta y baja incidencia / Knowledge, practices and entomological aspects of dengue in Medellín, Colombia: A comparative study of neighborhoods with high and low incidence

Introducción. El dengue, transmitido principalmente por Aedes aegypti, es una enfermedad viral de gran importancia en salud pública. Colombia es un país endemoepidémico para el dengue y, en ciudades como Medellín, hay barrios con alta y baja incidencia. Las diferencias en cuanto a los conocimientos, las prácticas y los aspectos entomológicos podrían estar determinando la dinámica de la enfermedad en los barrios. Objetivo. Determinar los conocimientos y prácticas en torno al dengue de los habitantes de barrios con alta y baja incidencia y explorar los aspectos entomológicos relacionados con la presencia del vector. Materiales y métodos. Se hizo un estudio transversal y se compararon dos barrios con alta incidencia y dos con baja incidencia durante el trienio de 2013 a 2015. Se seleccionó una muestra aleatoria de 100 viviendas por barrio para evaluar los conocimientos, las prácticas y los aspectos entomológicos. Se hicieron el análisis descriptivo, el bivariado y el multivariado (regresión logística). Resultados. En los barrios con alta incidencia, los participantes se caracterizaron por no haber realizado estudios o haber cursado únicamente primaria (odds ratio, OR=1,69; IC95%=1,09-2,63), así como por pertenecer al régimen subsidiado del sistema de seguridad social en salud o no estar afiliado (OR=2,16; IC95% 1,41-3,32) y, además, presentaron un mayor conocimiento del vector (OR=1,53; IC95% 1,00-2,35). En cuanto a las prácticas, la posibilidad de encontrar viviendas en donde se almacenaba el agua fue mayor (OR=1,69; IC95% 1,11-2,57) y, en lo relacionado con los aspectos entomológicos, se encontraron más viviendas con mosquitos adultos (OR=2,13; IC95% 1,29-3,50). Conclusiones. En este estudio se encontraron diferencias importantes entre los barrios en cuanto a los conocimientos, las prácticas y la presencia de estados adultos del vector, lo cual contribuye a explicar la epidemiología del dengue en estos lugares.

Introduction: Dengue, mainly transmitted by Aedes aegypti, is a very important viral disease in terms of public health. Colombia is an endemoepidemic country for dengue and, in cities like Medellín, there are neighborhoods with high and low incidence. The disease dynamics in the neighborhoods might be determined by differences in the knowledge, practices and entomological aspects of the vector among the communities. Objective: To identify the knowledge and practices of residents of neighborhoods with high and low incidence of dengue, and to explore the entomological aspects related to the presence of the vector. Materials and methods: We conducted a cross-sectional study comparing two neighborhoods with high incidence and two with low incidence during the triennium of 2013-2015. A random sample of 100 houses per neighborhood was selected in order to evaluate the knowledge, practices and entomological aspects related to dengue. In addition, descriptive, bivariate and multivariate analyses (logistic regression) were performed. Results: In neighborhoods with high incidence, participants had not attended school or had only a primary school level of education (OR=1.69; 95% CI: 1.09-2.63). Additionally, they did not have health coverage or belonged to the subsidized regime (OR=2.16; 95% CI: 1.41-3.32). In contrast, they had a greater knowledge of the vector (OR=1.53; 95% CI: 1.00-2.35). In terms of practices, there was a greater chance of finding houses where water was stored (OR=1.69; 95% CI: 1.11-2.57) and regarding the entomological aspects, more houses with adult mosquitoes were found (OR=2.13 95% CI: 1.29-3.50). Conclusions: We found important differences among the neighborhoods regarding knowledge, practices, and the presence of adult stages of the vector, which helps to explain the epidemiology of dengue in these sites.

Virological surveillance of Aedes (Stegomyia) aegypti and Aedes (Stegomyia) albopictus as support for decision making for dengue control in Medellín.

INTRODUCTION: Dengue represents an important public health problem in Colombia. No treatment is available and the vaccine has not been approved in all countries, hence, actions should be strengthened to mitigate its impact through the control of Aedes aegypti, the vector mosquito. In Colombia, surveillance is done using entomological indexes and case notification, which is usually informed late, leading to untimely interventions. Viral detection in urban mosquitoes using molecular techniques provides more accurate entomological information for decision-making. OBJECTIVE: To report results of virological surveillance in Aedes specimens collected during routine entomological activities of the Secretaría de Salud de Medellín. MATERIALS AND METHODS: Specimens were collected during two periods in each of which we selected 18 dwellings around each one of the 250 larva traps arranged for mosquitoe surveillance, as well as 70 educational institutions and 30 health centers. Specimens were identified morphologically, and divided in pools for viral detection using reverse transcription polymerase chain reaction (RT-PCR). We calculated the minimum infection rate and the adult infestation index for each group. RESULTS: We collected 1,507 adult mosquitoes, 10 of which were identified as A. albopictus. Out of the 407 pools, 132 (one of them Ae. albopictus) were positive, and 14.39% were A. aegypti males. The minimum infection rates for Ae. aegypti were 120.07 and 69,50 for the first and second periods, respectively, and the adult infestation index was higher in educational institutions (23.57%). CONCLUSIONS: Using RT-PCR we identified natural infectivity and vertical transmission of dengue virus in A. aegypti and A. albopictus. We suggest the use of molecular techniques in arbovirosis surveillance and control programs in Colombia.

Vigilancia virológica de Aedes (Stegomyia) aegypti y Aedes (Stegomyia) albopictus como apoyo para la adopción de decisiones en el control del dengue en Medellín / Virological surveillance of Aedes (Stegomyia) aegypti and Aedes (Stegomyia) albopictus as support for decision making for dengue control in Medellín

Resumen Introducción. El dengue en Colombia representa un grave problema de salud y, dado que no existe un tratamiento efectivo para la enfermedad y la vacuna no se ha aprobado en todos los países, se deben fortalecer acciones para mitigar su impacto mediante el control de Aedes aegypti, el mosquito vector. La vigilancia en el país se hace con base en los índices entomológicos y en la notificación de casos, la cual es frecuentemente tardía y por ello conduce a falta de oportunidad en las intervenciones. La detección viral en mosquitos urbanos mediante técnicas moleculares proporciona información entomológica más precisa para la adopción de decisiones. Objetivo. Reportar los resultados de la vigilancia virológica de especímenes de Aedes spp. recolectados durante actividades entomológicas rutinarias de la Secretaría de Salud de Medellín. Materiales y métodos. Los ejemplares se recolectaron durante dos periodos, en cada uno de los cuales se seleccionaron 18 viviendas alrededor de cada una de las 250 trampas para larvas dispuestas para la vigilancia entomológica, así como 70 instituciones educativas y 30 centros de salud. Los ejemplares se identificaron y se conformaron grupos para la detección viral mediante reacción en cadena de la polimerasa con transcripción inversa (Reverse Transcription Polymerase Chain Reaction, RT-PCR). Se calculó la tasa mínima de infección y el índice de infestación en adultos. Resultados. Se recolectaron 1.507 mosquitos, 10 de los cuales eran Ae. albopictus. De los 407 grupos conformados, 132 (uno de ellos de Ae. albopictus) fueron positivos, y 14,39 % correspondió a machos de Ae. aegypti. La tasa mínima de infección para Ae. aegypti fue de 120,07 y 69,50 en el primer y segundo períodos, respectivamente, y el índice de infestación en adultos fue mayor en las instituciones educativas (23,57 %). Conclusión. Mediante la RT-PCR se detectaron la infección natural y la transmisión vertical del virus del dengue en Ae. aegypti y en Ae. albopictus. Se propone considerar la incorporación de estas técnicas moleculares en los programas de vigilancia y control de las arbovirosis en el país.

Abstract Introduction: Dengue represents an important public health problem in Colombia. No treatment is available and the vaccine has not been approved in all countries, hence, actions should be strengthened to mitigate its impact through the control of Aedes aegypti, the vector mosquito. In Colombia, surveillance is done using entomological indexes and case notification, which is usually informed late, leading to untimely interventions. Viral detection in urban mosquitoes using molecular techniques provides more accurate entomological information for decision-making. Objective: To report results of virological surveillance in Aedes specimens collected during routine entomological activities of the Secretaría de Salud de Medellín. Materials and methods: Specimens were collected during two periods in each of which we selected 18 dwellings around each one of the 250 larva traps arranged for mosquitoe surveillance, as well as 70 educational institutions and 30 health centers. Specimens were identified morphologically, and divided in pools for viral detection using reverse transcription polymerase chain reaction (RT-PCR). We calculated the minimum infection rate and the adult infestation index for each group. Results: We collected 1,507 adult mosquitoes, 10 of which were identified as A. albopictus. Out of the 407 pools, 132 (one of them Ae. albopictus) were positive, and 14.39% were A. aegypti males. The minimum infection rates for Ae. aegypti were 120.07 and 69,50 for the first and second periods, respectively, and the adult infestation index was higher in educational institutions (23.57%). Conclusions: Using RT-PCR we identified natural infectivity and vertical transmission of dengue virus in A. aegypti and A. albopictus. We suggest the use of molecular techniques in arbovirosis surveillance and control programs in Colombia.

Modelado del efecto de la variabilidad climática local sobre la transmisión de dengue en Medellín (Colombia) mediante análisis de series temporales / Modelling the effect of local climatic variability on dengue transmission in Medellin (Colombia) by means temporary series analysis

ntroducción. El dengue es una enfermedad de transmisión vectorial de gran impacto en la salud pública. La transmisión del dengue es afectada por factores entomológicos, socioculturales y económicos. Además, la variabilidad climática juega un importante papel en la dinámica de transmisión. Un amplio consenso científico ha indicado que la fuerte asociación entre la enfermedad y las variables climáticas podría ser empleada para desarrollar modelos que expliquen la incidencia de la enfermedad. Objetivo. Desarrollar un modelo que permita comprender la dinámica de transmisión del dengue en Medellín y predecir incrementos en la incidencia de la enfermedad. Materiales y métodos. Se empleó la incidencia de dengue como variable dependiente y como variables independientes, los factores climáticos (temperatura máxima, media y mínima, humedad relativa y precipitación) registrados a escala semanal. Se utilizó el programa Expert Modeler para desarrollar un modelo que explique mejor el comportamiento de la enfermedad. Mediante modelos ARIMA, se seleccionaron las variables climáticas que tuvieron una relación significativa con la variable dependiente. Resultados. El 34 % de la variabilidad observada se explicó por el modelo. La precipitación fue la variable climática que mostró una asociación estadísticamente significativa con la incidencia del dengue, pero con un rezago de 20 semanas. Conclusiones. La transmisión del dengue en Medellín se vio afectada por la variabilidad climática, en particular, por la precipitación. La fuerte asociación entre el dengue y la precipitación permitió construir un modelo que ayuda a comprender la dinámica de transmisión, información que será de gran utilidad para el desarrollo de adecuadas y oportunas estrategias de control.

Introduction: Dengue fever is a major impact on public health vector-borne disease, and its transmission is influenced by entomological, sociocultural and economic factors. Additionally, climate variability plays an important role in the transmission dynamics. A large scientific consensus has indicated that the strong association between climatic variables and disease could be used to develop models to explain the incidence of the disease. Objective: To develop a model that provides a better understanding of dengue transmission dynamics in Medellin and predicts increases in the incidence of the disease. Materials and methods: The incidence of dengue fever was used as dependent variable, and weekly climatic factors (maximum, mean and minimum temperature, relative humidity and precipitation) as independent variables. Expert Modeler was used to develop a model to better explain the behavior of the disease. Climatic variables with significant association to the dependent variable were selected through ARIMA models. Results: The model explains 34% of observed variability. Precipitation was the climatic variable showing statistically significant association with the incidence of dengue fever, but with a 20 weeks delay. Conclusions: In Medellin, the transmission of dengue fever was influenced by climate variability, especially precipitation. The strong association dengue fever/precipitation allowed the construction of a model to help understand dengue transmission dynamics. This information will be useful to develop appropriate and timely strategies for dengue control.

[Modelling the effect of local climatic variability on dengue transmission in Medellin (Colombia) by means of time series analysis]. / Modelado del efecto de la variabilidad climática local sobre la transmisión de dengue en Medellín (Colombia) mediante análisis de series temporales.

INTRODUCTION: Dengue fever is a major impact on public health vector-borne disease, and its transmission is influenced by entomological, sociocultural and economic factors. Additionally, climate variability plays an important role in the transmission dynamics. A large scientific consensus has indicated that the strong association between climatic variables and disease could be used to develop models to explain the incidence of the disease. OBJECTIVE: To develop a model that provides a better understanding of dengue transmission dynamics in Medellin and predicts increases in the incidence of the disease. MATERIALS AND METHODS: The incidence of dengue fever was used as dependent variable, and weekly climatic factors (maximum, mean and minimum temperature, relative humidity and precipitation) as independent variables. Expert Modeler was used to develop a model to better explain the behavior of the disease. Climatic variables with significant association to the dependent variable were selected through ARIMA models. RESULTS: The model explains 34% of observed variability. Precipitation was the climatic variable showing statistically significant association with the incidence of dengue fever, but with a 20 weeks delay. CONCLUSIONS: In Medellin, the transmission of dengue fever was influenced by climate variability, especially precipitation. The strong association dengue fever/precipitation allowed the construction of a model to help understand dengue transmission dynamics. This information will be useful to develop appropriate and timely strategies for dengue control.

Implicaciones epidemiológicas de Aedes albopictus (Skuse) en Colombia / Epidemiological implications of Aedes albopictus (Skuse) in Colombia

El Aedes albopictus es originario del sureste asiático y se lo considera como un importante vector de dengue en algunos países de ese continente, así como de otros virus o parásitos causantes de enfermedades como fiebre amarilla, encefalitis y filariosis. La presencia de este mosquito en diferentes ciudades del país plantea retos para el control de enfermedades como el dengue. OBJETIVOS: analizar aspectos relevantes de la biología del vector y su importancia en la salud humana y presentar sugerencias para el control vectorial. METODOLOGIA: se realizó una revisión bibliográfica en las bases de datos PubMed y Medline a través de una estrategia de búsqueda pertinente, de donde se seleccionó un total de 83 documentos. RESULTADOS: el Ae. albopictus ha mostrado una rápida distribución en el país desde su primer registro en Amazonas en 1998; actualmente se encuentra en varias ciudades del país. Sumado a esto, las características biológicas del vector favorecen el establecimiento de esta especie en sitios con condiciones ecoepidemiológicas aptas para la transmisión del dengue y la fiebre amarilla urbana. CONCLUSIONES: la presencia del Ae. albopictus en Colombia plantea nuevos retos en salud pública, dado que esta especie se ha identificado como competente vector en la transmisión experimental de una amplia variedad de arbovirus, además, de que se ha encontrado naturalmente infectado con virus del dengue (serotipos 1 y 2) en nuestro país.

Aedes albopictus, a mosquito species from Southeast Asia, is considered an important vector of dengue in some countries of that continent. It is also a vector of viruses and parasites causing diseases such as yellow fever, encephalitis, and filariasis. The presence of this mosquito in different cities of our country poses challenges for the control of diseases such as dengue.OBJEECTIVE: to analyze the relevant aspects of this vector's biology along with its importance in human health while providing suggestions for vector control. METHODOLOGY: a literature review was performed using the PUBMED and MEDLINE databases and an appropriate search strategy. As a result of this, 83 documents were selected.RESULTS: Aedes albopictus has shown rapid distribution in Colombia since it was first recorded in the Amazon in 1998, and is now present in several cities. Additionally, the biology of the vector favors the establishment of this species in sites whose eco-epidemiological conditions are suitable for the transmission of dengue and urban yellow fever. CONCLUSIONS: The presence of Ae. Albopictus in Colombia poses new challenges in public health because this species has been suggested as a competent vector in the experimental transmission of a wide variety of arboviruses. Moreover, it has also been found naturally infected with the dengue virus (serotypes 1 and 2) in our country.