The first cases of human illness due to the Zika virus (ZIKV) were reported from southern coastal Ecuador in February 2016. In this region, ZIKV is transmitted to people by the same mosquito vector (Aedes aegypti) as the dengue virus (DENV), one of the leading causes of febrile illness. The aim of this study was to measure the prevalence of Zika virus (ZIKV) and dengue virus (DENV) infections and co-infections in humans and Ae. aegypti mosquitoes in a cohort of households, in 4 sites (Machala, Huaquillas, Portovelo, Zaruma) with distinct climate regimes, in southern coastal Ecuador. This project expands the currently funded EEID project, “Nonlinear responses of vector-borne disease transmission to temperature (PI: E. Mordecai).  From July to December 2016, we enrolled 293 individuals from 226 households into the study. Over a four-month period, homes were visited every two weeks to collect adult mosquitoes inside and outside of the home. Mosquitoes were analyzed for the presence of ZIKV and DENV. Over 12,000 mosquitos of all species and sexes were collected and classified, including over 1,000 Ae. aegypti mosquitos. Blood samples were collected from study volunteers once per month to determine whether they had been infected with ZIKV or DENV. We monitored the microclimate (temperature, relative humidity) inside cohort homes to determine the effects of climate on disease transmission. Household social-ecological risk factors were measured through household surveys conducted in the EEID study. Training and outreach efforts included a GIS training workshop for the public health sector in Ecuador (15 participants) and 18 community meetings, trainings and symposiums/presentations that reached 840 persons across the four sites in Ecuador. Although no students were directly funded on this project, the project provided training opportunities for 18 students in a wide array of field methods, lab techniques, survey methods, and entomological research. Preliminary results indicate that 12 pools of Ae. aegypti (10 specimens or less per pool) were positive for DENV, and 21 pools were positive for ZIKV. Diagnostic analyses of human samples are ongoing. These results will be used to understand the effects of climate and local social-ecological risk factors on the spatiotemporal dynamics of DENV and ZIKV through multilevel hierarchical modeling. This RAPID study has generated spatially and temporally explicit data on an emerging and unfolding epidemic of ZIKV. These findings will elucidate key factors in the spread, and thus control efforts, needed for ZIKV, and will provide a large repository of basic scientific data on the virus and disease vector. 

Last Modified: 08/29/2017
Modified by: Anna Stewart