Mosquitoes in Paradise: An Interdisciplinary Approach To Explore the Adoption of Community-Based Mosquito Control Strategies for Aedes aegypti in Peñuelas, Puerto Rico

Abstract

Background: Aedes (Ae.) aegypti, predominantly found in urban environments, oviposit in human-made containers in and around households, and is the primary vector of dengue, Zika, and chikungunya viruses in tropical and subtropical areas of the world. While the continental United States has had only sporadic outbreaks, dengue transmission has been intractable in Puerto Rico, where seasonal outbreaks have been recorded since 1915. Recent emergence of chikungunya and Zika further worsened health outcomes from mosquito-borne diseases in Puerto Rico. Prevention and reduction of arboviral diseases continue to depend on controlling mosquito populations. Vector control efforts have shown a minimal degree of success over the last 50 years in Puerto Rico. Evidence suggests that community mobilization is an essential component of successful and sustainable mosquito control efforts. Before implementing these interventions, it is imperative to obtain community-level information and input. The objectives of this interdisciplinary dissertation were to characterize the human and environmental factors associated with immature Ae. aegypti habitats in Peñuelas, Puerto Rico, explore the application of stated preferences methodologies in vector control research, and measure preferences for an Ae. aegypti mosquito control program in Peñuelas, Puerto Rico using a best-worst choice (BWC) approach. Methods: Outdoor house inspections were performed in the 69 selected houses from 10 neighborhoods of Peñuelas, and all containers were searched and inspected for water and mosquito immatures. Descriptive statistics were used to summarize demographics and human factors (i.e., knowledge about mosquito breeding sites) among the surveyed sample and to characterize containers, water-holding containers, and containers producing immature mosquitoes. Principal container analyses were used to quantify immature mosquito abundance in proportion to water-holding containers. Multiple regression models were used to examine the relationship between demographic and human factors (i.e., age, education) and containers, water-holding containers, and mosquito immature abundance. A PRISMA-guided scoping literature review was performed in August 2021 to synthesize and summarize the current use of stated preferences tools and vector control and provide recommendations to improve the application of these tools in the development and evaluation of vector control programming. A total of three databases (PubMed, Embase, PsycInfo) were searched for eligible studies, and data were extracted from studies meeting the eligibility criteria. Recommendations for improving the application of stated preferences tools to vector control programming were made. Finally, a total of 175 participants from Peñuelas were selected and surveyed face-to-face in July 2021 using a two-stage cluster design. Stated preferences toward various components of mosquito control programs were identified by implementing BWC in the participants from Peñuelas. Furthermore, willingness/unwillingness to participate in and willingness to pay for a mosquito control program was explored. A conditional logit analysis was used to estimate preferences and random effects logit was used to measure willingness to participate and willingness to pay. Results: A total of 4090 containers were identified and inspected during the outdoor inspections of 69 homes, from which 7.0% held water, 1.5% were larvae-positive, and 0.5% pupae-positive. Bromeliads were the most common water-holding container and were found to be responsible for 37.8% of the production of mosquito immatures in the surveyed houses. Higher education level was significantly negatively associated with container abundance and with lower odds of having mosquito immatures in their houses. Also, knowing at least one specific container that serves a breeding site was significantly associated with higher odds of mosquito immature infestation. In the scoping review, only 17 studies were included from the 686 articles screened. Most of the studies were conducted in sub-Saharan African countries (72.2%), focused on insecticide-treated nets (ITNs) for malaria prevention (52.9%), and used contingent valuation methods (82.4%). Studies were classified into reducing human-vector contact (64.7%), reducing mosquito abundance (29.4%), or both (5.9%). While demand exists for vector control programs, there were no consistent associations between demand and explanatory factors (i.e., demographics, etc.) in either human-vector studies or mosquito abundance studies. The BWC assessment indicates that the most important features of a mosquito control program were that it was applied at the neighborhood level, implemented by the local government, and focused specifically on reducing disease transmission instead of mosquito abundance (i.e., dengue). Programs targeting the reduction of disease transmission had a positive effect on willingness to participate in the program. Education was positively correlated with expressing willingness to participate in a mosquito control program. Our study results revealed that participants were willing to pay up to $72.00 to have a program targeting the reduction of diseases, such as dengue. Conclusion: The results of this dissertation provide evidence that bromeliads, the most common water-holding container and disproportionately productive, must be targeted in future mosquito control efforts. Conversely, having mosquito control strategies targeting large water storage containers might not be efficient at reducing mosquito indices in Peñuelas. The current literature on stated preferences and vector control is limited in the scope of vector control methods being investigated, the countries being studied, and the determinants of demand measured. Future research is needed to expand the application of stated preferences to measure demand and preferences for various vector control strategies, including newly developed and community-based methods. This dissertation demonstrated that reducing disease transmission is the highest priority and influences the likelihood of participation for the residents in Peñuelas. Individuals were willing to pay a considerable amount of money for a program with this focus. This finding suggests that a mosquito control program can specifically target Ae. aegypti mosquitoes, which transmit dengue, chikungunya, and Zika in the study area. The results of this dissertation can improve stakeholders’ decisions regarding mosquito control strategies implemented in Peñuelas, Puerto Rico. There is strong potential to incorporate community-based efforts with government-led efforts to decrease Ae. aegypti mosquito abundance and reduce the transmission of dengue in Peñuelas, Puerto Rico.