A Cluster-Randomized Controlled Trial to Reduce Diarrheal Disease and Dengue Entomological Risk Factors in Rural Primary Schools in Colombia.
BACKGROUND
As many neglected tropical diseases are co-endemic and have common risk factors, integrated 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 interventions targeting diarrhea and dengue risk factors would significantly reduce absence due to diarrheal disease and dengue entomological risk factors in schools.


RESULTS
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 interventions (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
Integrated control of dengue and diarrhea has never been conducted before. This trial presents 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 outside the school area and mosquitoes flying in from nearby uncontrolled breeding sites. Integrated interventions targeting these diseases in a school context remain promising because of the reduced mosquito breeding and improved water quality, as well as educational benefits. However, to improve outcomes in future integrated approaches, simultaneous interventions in communities, in addition to schools, should be considered; using appropriate combinations of site-specific, effective, acceptable, and affordable interventions.


BACKGROUND
ClinicalTrials.gov no. ISRCTN40195031.
Department of Mathematical Sciences and Technology, Norwegian University of Life Sciences, Norway.|Institut de Recherche pour le Développement, Maladies Infectieuses et Vecteurs, Ecologie, Génétique, Evolution et Contrôle, Montpellier, France.|Department of Entomology, Faculty of Agriculture, Kasetsart University, Bangkok, Thailand.
Hans J
HJ
Overgaard
MRC Tropical Epidemiology Group, London School of Hygiene and Tropical Medicine, London.
Neal
N
Alexander
Instituto de Salud y Ambiente, Universidad El Bosque, Bogota, Colombia.
Maria Ines
MI
Matiz
Instituto de Salud y Ambiente, Universidad El Bosque, Bogota, Colombia.
Juan Felipe
JF
Jaramillo
Instituto de Salud y Ambiente, Universidad El Bosque, Bogota, Colombia.
Victor Alberto
VA
Olano
Instituto de Salud y Ambiente, Universidad El Bosque, Bogota, Colombia.
Sandra
S
Vargas
Instituto de Salud y Ambiente, Universidad El Bosque, Bogota, Colombia.
Diana
D
Sarmiento
Liverpool School of Tropical Medicine, Liverpool, United Kingdom.|U.S. Centers for Disease Control and Prevention, Atlanta, United States of America.
Audrey
A
Lenhart
SARChI Chair, Institute for Water and Waste Water Technology, Durban University of Technology, Durban, South Africa.
Thor Axel
TA
Stenström
D000328:Adult; D000330:Aedes / Q000821:virology*; D000818:Animals; D002648:Child; D003105:Colombia / Q000453:epidemiology; D003715:Dengue / Q000453:epidemiology / Q000517:prevention & control* / Q000635:transmission / Q000821:virology; D003967:Diarrhea / Q000453:epidemiology / Q000382:microbiology / Q000517:prevention & control*; D004926:Escherichia coli / Q000302:isolation & purification; D005260:Female; D006801:Humans; D008018:Life Cycle Stages; D009032:Mosquito Control; D000072138:Mosquito Vectors / Q000821:virology*; D012307:Risk Factors; D012424:Rural Population / Q000706:statistics & numerical data; D012574:Schools; D013334:Students / Q000706:statistics & numerical data; D014881:Water Supply / Q000592:standards