Insecticide resistance levels and associated mechanisms in three Aedes aegypti populations from Venezuela

BACKGROUND The massive use of insecticides in public health has exerted selective pressure resulting in the development of resistance in Aedes aegypti to different insecticides in Venezuela. Between 2010 and 2020, the only insecticides available for vector control were the organophosphates (Ops) fenitrothion and temephos which were focally applied. OBJECTIVES To determine the state of insecticide resistance and to identify the possible biochemical and molecular mechanisms involved in three populations of Ae. aegypti from Venezuela. METHODS CDC bottle bioassays were conducted on Ae. aegypti collected between October 2019 and February 2020 in two hyperendemic localities for dengue in Aragua State and in a malaria endemic area in Bolívar State. Insecticide resistance mechanisms were studied using biochemical assays and polymerase chain reaction (PCR) to detect kdr mutations. FINDINGS Bioassays showed contrasting results among populations; Las Brisas was resistant to malathion, permethrin and deltamethrin, Urbanización 19 de Abril was resistant to permethrin and Nacupay to malathion. All populations showed significantly higher activity of mixed function oxidases and glutathione-S-transferases (GSTs) in comparison with the susceptible strain. The kdr mutations V410L, F1534C, and V1016I were detected in all populations, with F1534C at higher frequencies. MAIN CONCLUSION Insecticide resistance persists in three Ae. aegypti populations from Venezuela even in the relative absence of insecticide application.

Reasons for absenteeism in rural primary schools in two Colombian municipalities / Razones de ausentismo en escuelas primarias rurales de dos municipios colombianos / Razões do não comparecimento nas escolas primarias rurais nos municípios colombianos

Background: School absenteeism is a considerable problem generally related to higher dropout rates, poor academic achievement and school lag. This study determined the frequency and causes of overall and illness-related absenteeism of students in rural schools from two Colombian municipalities. Methods: A prospective and descriptive study was conducted in a population of 948 school children from 34 rural schools. Absenteeism data were collected for 2013 academic year consisted of the number of students registered and absent by grade, school, day and reason for absence. Absence rates (overall and illness-related absenteeism) were recorded, based on full or partial days absence, measured both as episodes, and accumulating the number of days. Results: From the students included in the study, 55.1% were male and 71.6% were between 5 and 9 years old. The overall absence rate was 5.7 episodes per child-year (95% confidence interval 5.5 to 5.8) and 8.6 days per child-year (8.4 to 8.9). The main reasons for non-attendance were illness (24.4%), medical or dental check-up (12.9%), travel (12.3%), lack of motivation to attend school (10.0%) and bad weather (9.3%). The illness- related absence rate was 1.4 episodes per child-year (95% confidence interval 1.3 to 1.5) and 2.5 days per child-year (2.4 to 2.6). The main reasons for illness-related absence were cold (37.0%), nonspecific fever (10.9%) and stomach pain or vomiting (8.4%). Conclusions: In this study, the most common reasons for non-attendance were illness-related. The importance of respiratory and gastrointestinal infections in absenteeism was evident, showing rates similar to other urban school studies. Then, the results of this study provide knowledge on the magnitude and reasons for absenteeism in rural schoolchildren.

Antecedentes. El ausentismo escolar es un problema importante relacionado con altas tasas de abandono escolar, bajo rendimiento académico y rezago escolar. Este estudio determinó la frecuencia y las causas del ausentismo general y el ausentismo relacionado con la enfermedad en estudiantes de escuelas rurales de dos municipios de Colombia. Métodos. Se realizó un estudio descriptivo en una población de 948 escolares de 34 escuelas rurales. Los datos de ausentismo recopilados para el año 2013 consistieron en el número de episodios y días de ausentismo por grado y motivo de ausencia general y por enfermedad. Se calcularon las tasas de ausentismo general y por enfermedad. Resultados. El 55,1% de la población participante eran hombres y el 71,6% tenían entre 5 y 9 años. La tasa de ausentismo general fue 5,7 episodios por niño-año, IC 95% (5,5-5,8) y 8,6 días por niño-año, IC 95% (8,4-8,9). Las principales razones del ausentismo fueron enfermedades (24,4%), chequeo médico u odontológico (12,9%), viajes (12,3%), falta de motivación para asistir a la escuela (10,0%) y mal clima (9,3%). La tasa de ausentismo por enfermedad fue 1,4 episodios por niño-año IC 95% (1,3-1,5) y 2,5 días por niño-año IC 95% (2,4-2,6). Las principales razones del ausentismo por enfermedad fueron el resfriado común (37,0%), la fiebre inespecífica (10,9%) y el dolor de estómago o vómito (8,4%). Conclusiones. Las razones más comunes para la no asistencia estuvieron relacionadas con la enfermedad. La importancia de las infecciones respiratorias y gastrointestinales en el absentismo fue evidente, mostrando tasas similares a las de otros estudios en escuelas urbanas. Los resultados de este estudio proporcionan conocimiento sobre la magnitud y las razones del absentismo en la población escolar rural.

Antecedentes. O absentismo escolar é um grande problema relacionado às altas taxas de evasão escolar, baixo desempenho acadêmico e atraso escolar. Este estudo determinou a frequência e causas do não comparecimento geral e por doenças em estudantes de escolas rurais de dois municípios da Colômbia. Métodos. Estudo descritivo, realizado em uma população de 948 escolares de 34 escolas rurais. Os dados de absentismo coletados para 2013 consistiram no número de episódios e dias de não comparecimento por grau e motivo da ausência geral e por doença, foram calculadas as taxas de cada evento. Resultados. 55,1% da população participante eram crianças masculinas do primeiro grau, 71,6% entre 5 e 9 anos de idade. A taxa geral de absentismo foi de 5,7 episódios por criança-ano, IC95% (5,5-5,8) e 8,6 dias por criança-ano, IC95% (8,4-8,9). Os principais motivos do não comparecimento foram doenças (24,4%), check-up médico ou odontológico (12,9%), viagens (12,3%), falta de motivação para frequentar a escola (10,0%) e mau tempo (9,3%). A taxa de absentismo da doença foi de 1,4 episódios por IC95% criança-ano (1,3-1,5) e 2,5 dias por IC95% criança-ano (2,4-2,6). Os principais motivos da ausência de doença foram resfriado comum (37,0%), febre inespecífica (10,9%) e dor de estômago ou vômito (8,4%). Conclusões. Os motivos mais comuns de não comparecimento foram relacionados à doença. A importância das infecções respiratórias e gastrointestinais no absenteísmo foi evidente, mostrando taxas semelhantes às de outros estudos em escolas urbanas. Os resultados deste estudo fornecem informações sobre a magnitude e as razões para evasão escolar na população escolar rural.

Knowledge, attitudes and practices about dengue among pupils from rural schools in Colombia / Conocimientos, actitudes y prácticas sobre dengue en estudiantes de escuelas rurales en Colombia

Abstract Introduction: Dengue is a public health problem in tropical and subtropical regions of the world. Studies on dengue in rural areas are scarce since the disease is considered mainly urban. Objective: To determine the knowledge (K), attitudes (A) and practices (P) of dengue in an endemic area in Colombia. Materials and methods: We conducted a cross-sectional study with 515 pupils (7-16 years old) in 34 rural schools in Anapoima and La Mesa municipalities during 2011. Each KAP category was evaluated independently by a scoring system and then categorized into high, medium or low. Results: Pupils recognized knowledge variables such as the symptoms (fever, bone pain), transmission route (mosquito bites), and mosquito breeding sites (uncovered wáter tanks, solid waste). Average scores on attitude were high in both municipalities indicating a well-developed perception of disease severity. Seeking treatment in medical centers and self-medication for fever management and the use of mosquito net and space-spraying of insecticides were the most frequently identified practices. Discussion: This is the first KAP dengue study performed in a rural area in Colombia and as such it contributes to the understanding of dengue perceptions by the inhabitants of these areas. It showed a medium level of knowledge about dengue and a lower level of preventive practices in pupils from rural schools. It also showed that pupils considered space-spraying as crucial for vector control. The presence of the vector in rural areas of the country underlines the need to improve surveillance and education to more effectively control the vector and promote prevention methods including community participation.

Resumen Introducción. El dengue es un problema de salud pública en las regiones tropicales y subtropicales del mundo. Los estudios sobre la enfermedad en áreas rurales son escasos debido a que se presenta principalmente en los núcleos urbanos. Objetivo. Determinar los conocimientos, las actitudes y las prácticas sobre el dengue en un área rural endémica en Colombia. Materiales y métodos. Se hizo un estudio transversal con 515 estudiantes, entre los 7 y los 16 años de edad en 34 escuelas rurales de los municipios de Anapoima y La Mesa en el 2011. Cada categoría se evaluó por separado con un puntaje clasificado como alto, medio o bajo. Resultados. Los estudiantes reconocieron los síntomas (fiebre, dolor de huesos), la ruta de transmisión (picadura de mosquitos) y los criaderos (depósitos de agua destapados, residuos sólidos). El promedio de los puntajes de actitudes fue alto en ambos municipios, lo que indica que percibían la gravedad del dengue. Las prácticas más frecuentes de tratamiento de la fiebre fueron la consulta médica y la automedicación, en tanto que los métodos de control más frecuentes fueron el uso de mosquiteros y el rociamiento con insecticidas. Discusión. Este es el primer estudio de conocimientos, actitudes y prácticas sobre el dengue en un área rural de Colombia. Los resultados contribuyen a entender las percepciones de la enfermedad en sus habitantes y evidenciaron niveles medios de conocimiento y puntuaciones bajas en cuanto a las prácticas entre los estudiantes de las escuelas rurales. Los estudiantes consideraron que la fumigación es importante para el control del vector. La presencia del mosquito en áreas rurales del país resalta la necesidad de mejorar la vigilancia y la educación para lograr un control efectivo del vector y promover métodos de prevención que incluyan la participación comunitaria.

Control de diarrea y dengue en escuelas primarias rurales de Colombia: protocolo de estudio para un ensayo aleatorio y controlado por conglomerados / Diarrhea and dengue control in rural primary schools in Colombia: study protocol for a randomized controlled trial

Antecedentes. Las enfermedades diarreicas y el dengue son graves problemas de salud pública a nivel global. Cuando el suministro de agua potable es inadecuado, el almacenamiento de agua es crucial. La contaminación fecal del agua almacenada es una fuente común de las enfermedades diarreicas y, al mismo tiempo, el agua almacenada proporciona criaderos para los mosquitos vectores del dengue. Un manejo deficiente del agua doméstica y del saneamiento son, por lo tanto, determinantes potenciales de ambas enfermedades. Poco se sabe de la importancia del agua almacenada para el riesgo combinado de la diarrea y el dengue, sin embargo, una intervención compartida podría ser importante para el desarrollo de esfuerzos en gestión y control integrado. Aun menos conocidos son los efectos de un control integrado de estas enfermedades en los entornos escolares. El objetivo de este estudio fue investigar si las intervenciones contra la diarrea y el dengue reducían significativamente las enfermedades diarreicas y los factores de riesgo entomológico de dengue, en las escuelas primarias rurales de dos municipios de Cundinamarca. Metodología y diseño. Se trata de un ensayo por conglomerados, factorial de 2 x 2, controlado y de asignación aleatoria. Las instituciones elegibles fueron las escuelas rurales de los municipios de La Mesa y Anapoima en el departamento de Cundinamarca. Los estudiantes elegibles fueron los niños de las escuelas de los grados 0 a 5. Las escuelas fueron asignadas aleatoriamente a uno de los cuatro grupos del estudio: intervenciones de diarrea, intervenciones de dengue, las dos intervenciones, diarrea y dengue, y control. Las escuelas fueron estratificadas por municipio y asignadas mediante un acto público al inicio del ensayo. La variable de respuesta primaria para la diarrea fue la tasa de incidencia de diarrea en los niños de las escuelas, y para dengue, la densidad de adultos hembra de Aedes aegypti por escuela. Aproximadamente...

Background: Diarrheal diseases and dengue fever are major global health problems. Where provision of clean water is inadequate, water storage is crucial. Fecal contamination of stored water is a common source of diarrheal illness, but stored water also provides breeding sites for dengue vector mosquitoes. Poor household water management and sanitation are therefore potential determinants of both diseases. Little is known of the role of stored water for the combined risk of diarrhea and dengue, yet a joint role would be important for developing integrated control and management efforts. Even less is known of the effect of integrating control of these diseases in school settings. The objective of this trial was to investigate whether interventions against diarrhea and dengue will significantly reduce diarrheal disease and dengue entomological risk factors in rural primary schools. Methods/design: This is a 2×2 factorial cluster randomized controlled trial. Eligible schools were rural primary schools in La Mesa and Anapoima municipalities, Cundinamarca, Colombia. Eligible pupils were school children in grades 0 to 5. Schools were randomized to one of four study arms: diarrhea interventions (DIA); dengue interventions (DEN); combined diarrea and dengue interventions (DIADEN); and control (C). Schools were allocated publicly in each municipality (strata) at the start of the trial, obviating the need for allocation concealment. The primary outcome for diarrea is incidence rate of diarrhea in school children and for dengue it is density of adult female Aedes aegypti per school. Approximately 800 pupils from 34 schools were enrolled in the trial with eight schools in the DIA arm, nine in the DEN, eight in the DIADEN, and nine in the control arms. The trial was funded by the Research Council of Norway and the Lazos de Calandaima Foundation. Discussion: This is the first trial investigating...