Research Publications (Academic Support)
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Item A cluster-randomized controlled trial to reduce Diarrheal disease and dengue entomological risk factors in rural primary schools in Colombia(National Centre for Biotechnology Information, 2016-11-07) Overgaard, Hans J.; Alexander, Neal; Matiz, María Inés; Jaramillo, Juan Felipe; Olano, Victor Alberto; Vargas, Sandra Lucía; Sarmiento, Diana; Lenhart, Audrey; Stenström, Thor-AxelBackground As many neglected tropical diseases are co-endemic and have common risk factors, inte-grated control can efficiently reduce disease burden and relieve resource-strained public health budgets. Diarrheal diseases and dengue fever are major global health problems sharing common risk factors in water storage containers. 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. Integrating improved water management and educational strategies for both diseases in the school environment can potentially improve the health situation for students and the larger community. The objective of this trial was to investigate whether interven-tions targeting diarrhea and dengue risk factors would significantly reduce absence due to diarrheal disease and dengue entomological risk factors in schools. Methodology/Principal Findings A factorial cluster randomized controlled trial was carried out in 34 rural primary schools (1,301 pupils) in La Mesa and Anapoima municipalities, Cundinamarca, Colombia. Schools were randomized to one of four study arms: diarrhea interventions (DIA), dengue interven-tions (DEN), combined diarrhea and dengue interventions (DIADEN), and control (CON). Interventions had no apparent effect on pupil school absence due to diarrheal disease (p = 0.45) or on adult female Aedes aegypti density (p = 0.32) (primary outcomes). However, the dengue interventions reduced the Breteau Index on average by 78% (p = 0.029), with Breteau indices of 10.8 and 6.2 in the DEN and DIADEN arms, respectively compared to 37.5 and 46.9 in the DIA and CON arms, respectively. The diarrhea interventions improved water quality as assessed by the amount of Escherichia coli colony forming units (CFU); the ratio of Williams mean E. coli CFU being 0.22, or 78% reduction (p = 0.008). Conclusions/Significance Integrated control of dengue and diarrhea has never been conducted before. This trial pres-ents an example for application of control strategies that may affect both diseases and the first study to apply such an approach in school settings. The interventions were well received and highly appreciated by students and teachers. An apparent absence of effect in primary outcome indicators could be the result of pupils being exposed to risk factors out-side the school area and mosquitoes flying in from nearby uncontrolled breeding sites. Inte-grated interventions targeting these diseases in a school context remain promising because of the reduced mosquito breeding and improved water quality, as well as educa-tional benefits. However, to improve outcomes in future integrated approaches, simulta-neous interventions in communities, in addition to schools, should be considered; using appropriate combinations of site-specific, effective, acceptable, and affordable interventions.Item Detection of all four dengue serotypes in Aedes aegypti female mosquitoes collected in a rural area in Colombia(Instituto Oswaldo Cruz, Ministério da Saúde, 2016-04) Pérez-Castro, Rosalía; Castellanos, Jaime E.; Olano, Victor Alberto; Matiz, María Inés; Jaramillo, Juan Felipe; Vargas, Sandra Lucía; Sarmiento, Diana; Stenström, Thor-Axel; Overgaard, Hans J.The Aedes aegypti vector for dengue virus (DENV) has been reported in urban and periurban areas. The in-formation about DENV circulation in mosquitoes in Colombian rural areas is limited, so we aimed to evaluate the presence of DENV in Ae. aegypti females caught in rural locations of two Colombian municipalities, Anapoima and La Mesa. Mosquitoes from 497 rural households in 44 different rural settlements were collected. Pools of about 20 Ae. aegypti females were processed for DENV serotype detection. DENV in mosquitoes was detected in 74% of the analysed settlements with a pool positivity rate of 62%. The estimated individual mosquito infection rate was 4.12% and the minimum infection rate was 33.3/1,000 mosquitoes. All four serotypes were detected; the most frequent being DENV-2 (50%) and DENV-1 (35%). Two-three serotypes were detected simultaneously in separate pools. This is the first report on the co-occurrence of natural DENV infection of mosquitoes in Colombian rural areas. The findings are important for understanding dengue transmission and planning control strategies. A potential latent virus res-ervoir in rural areas could spill over to urban areas during population movements. Detecting DENV in wild-caught adult mosquitoes should be included in the development of dengue epidemic forecasting models.Item Schools as potential risk sites for Vector-Borne disease transmission: mosquito vectors in rural schools in two municipalities in Colombia(The American Mosquito Control Association, Inc., 2015) Olano, Victor Alberto; Matiz, María Inés; Lenhart, Audrey; Cabezas, Laura; Vargas, Sandra Lucía; Jaramillo, Juan Felipe; Sarmiento, Diana; Alexander, Neil; Stenström, Thor-Axel; Overgaard, Hans J.Dengue and other vector-borne diseases are of great public health importance in Colombia. Vector surveillance and control activities are often focused at the household level. Little is known about the importance of nonhousehold sites, including schools, in maintaining vector-borne disease transmission. The objectives of this paper were to determine the mosquito species composition in rural schools in 2 municipalities in Colombia and to assess the potential risk of vector-borne disease transmission in school settings. Entomological surveys were carried out in rural schools during the dry and rainy seasons of 2011. A total of 12 mosquito species were found: Aedes aegypti, Anopheles pseudopunctipennis, Culex coronator, Cx. quinquefasciatus, and Limatus durhamii in both immature and adult forms; Ae. fluviatilis, Cx. nigripalpus, Cx. corniger, and Psorophora ferox in immature forms only; and Ae. angustivittatus, Haemagogus equinus, and Trichoprosopon lampropus in adult forms only. The most common mosquito species was Cx. quinquefasciatus. Classrooms contained the greatest abundance of adult female Ae. aegypti and Cx. quinquefasciatus. The most common Ae. aegypti breeding sites were containers classified as “others” (e.g., cans), followed by containers used for water storage. A high level of Ae. aegypti infestation was found during the wet season. Our results suggest that rural schools are potentially important foci for the transmission of dengue and other mosquito-borne diseases. We propose that public health programs should be implemented in rural schools to prevent vector-borne diseases.