Dengue fever and Aedes aegypti risk in the Galapagos Islands, Ecuador

Nightingale, R.; Lippi, C. A.; Ryan, S. J.; Borbor-Cordova, M. J.; Cruz B, M.; Ortega, F.; Leon, R.; Waggoner, E.; Stewart Ibarra, A. M.

doi:10.1101/113829

bioRxiv · 10.1101/113829

Dengue fever and Aedes aegypti risk in the Galapagos Islands, Ecuador

Nightingale, R.·Lippi, C. A.·Ryan, S. J.·Borbor-Cordova, M. J.·Cruz B, M.·Ortega, F.·Leon, R.·Waggoner, E.·Stewart Ibarra, A. M.

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Abstract

IntroductionDengue fever is an emerging infectious disease in the Galapagos Islands of Ecuador, with the first cases reported in 2002 and periodic outbreaks since then. Here we report the results of a pilot study conducted in two cities in 2014: Puerto Ayora (PA) on Santa Cruz Island, and Puerto Baquerizo Moreno (PB) on Santa Cristobal Island. The aims of this study were to assess the social-ecological risk factors associated with dengue and mosquito presence at the household-level.\n\nMethodsIn 2014 we conducted 100 household surveys (50 on each island) in neighborhoods with prior reported dengue. Adult mosquitoes were collected inside and outside the home, larval indices were determined through container surveys, and heads of households were interviewed to determine demographics, prior dengue infections, housing conditions, and knowledge, attitudes and practices regarding dengue. Multimodel selection methods were used to derive best-fit generalized linear regression (GLM) models of prior dengue infection, and the presence of Ae. aegypti in the home.\n\nResultsWe found that 24% of PB and 14% of PA respondents self-reported a prior dengue infection, and more PB homes than PA homes had Ae. aegypti. The top-ranked model for prior dengue infection included human movement - travel between neighborhoods, between islands, and to the mainland; demographics including salary level and education of the head of household, and increase with more people per room in a house, house condition, access to water quality issues, and dengue awareness. The top-ranked model for the presence of Ae. aegypti included housing conditions, including the presence of window screens and air conditioners, mosquito control actions, and dengue risk perception.\n\nDiscussion/conclusionTo our knowledge, this is the first study of dengue risk and Aedes aegypti in the Galapagos Islands. The findings that human movement within and between islands, and to and from the mainland, were important to reported dengue cases confirms concerns of this route of introduction and repeated transmission.

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Nightingale, R., Lippi, C. A., Ryan, S. J., Borbor-Cordova, M. J., Cruz B, M., Ortega, F., Leon, R., Waggoner, E., Stewart Ibarra, A. M.. 2017-03-06. Dengue fever and Aedes aegypti risk in the Galapagos Islands, Ecuador. https://doi.org/10.1101/113829

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