A network analysis framework to improve the delivery of mosquito abatement services in Machala, Ecuador

Abstract

Background: Vector-borne disease places a high health and economic burden in the American tropics. Comprehensive vector control programs remain the primary method of containing local outbreaks. With limited resources, many vector control operations struggle to serve all affected communities within their districts. In the coastal city of Machala, Ecuador, vector control services, such as application of larvicides and truck-mounted fogging, are delivered through two deployment facilities managed by the Ecuadorian Ministry of Health. Public health professionals in Machala face several logistical issues when delivering mosquito abatement services, namely applying limited resources in ways that will most effectively suppress vectors of malaria, dengue, and encephalitis viruses.Methods: Using a transportation network analysis framework, we built models of service areas and optimized delivery routes based on distance costs associated with accessing neighborhoods throughout the city. Optimized routes were used to estimate the relative cost of accessing neighborhoods for mosquito control services in Machala, creating a visual tool to guide decision makers and maximize mosquito control program efficiency. Location-allocation analyses were performed to evaluate efficiency gains of moving service deployment to other available locations with respect to distance to service hub, neighborhood population, dengue incidence, and housing condition.Results: Using this framework, we identified different locations for targeting mosquito control efforts, dependent upon management goals and specified risk factors of interest, including human population, housing condition, and reported dengue incidence. Our models indicate that neighborhoods on the periphery of Machala with the poorest housing conditions are the most costly to access. Optimal locations of facilities for deployment of control services change depending on pre-determined management priorities, increasing the population served via inexpensive routes up to 34.9%, and reducing overall cost of accessing neighborhoods up to 12.7%. Conclusions:Our transportation network models indicate that current locations of mosquito control facilities in Machala are not ideal for minimizing driving distances or maximizing populations served. Services may be optimized by moving vector control operations to other existing public health facilities in Machala. This work represents a first step in creating a spatial tool for planning and critically evaluating the systematic delivery of mosquito control services in Machala and elsewhere.

Exploring the utility of social-ecological and entomological risk factors for dengue infection as surveillance indicators in the dengue hyper-endemic city of Machala, Ecuador

“…Houses made of cane were a risk factor for dengue, which is consistent with typical housing found in low income areas with active dengue transmission in Ecuador [52]. Generally found in the urban periphery of Machala, housing constructed from cane does not exclude potentially infectious mosquitoes from entering households [12]. Adjacency to abandoned properties and presence of shaded patios were identified as risk factors in this study, and have also been linked to transmission risk in other studies in the region, promoting favorable habitat and oviposition sites for container-breeding mosquitoes [14,48].…”

“…While there are many established protocols for designing and conducting public health vector control activities, these are subject to logistical constraints, resource availability, and fluctuating funding streams [6][7][8][9][10][11]. Development of targeted vector control strategies that focus on surveillance indicators or known risk factors for transmission offer a possible solution for implementing effective control measures in resourcelimited communities (e.g., Lippi et al 2020) [12]. Yet, social and ecological risk of exposure to arboviral infections is often understudied at fine spatial scales at which most vector control interventions operate, where household-level features and behaviors can vary greatly within the built environment [13][14][15], leading to varying risk of exposure to vectors, and thus, transmission.…”

“…Several previous studies conducted in Machala have assessed risk factors for dengue fever outbreaks at the mesoscale (e.g. neighborhoods or census blocks), including vector densities, environmental drivers, sociodemographic characteristics, community perceptions, and service accessibility [12,14,25,30,[32][33][34]. The findings of these studies are useful in a public health advisory capacity, providing information that guides decision-making and research.…”

Exploring the utility of social-ecological and entomological risk factors for dengue infection as surveillance indicators in the dengue hyper-endemic city of Machala, Ecuador

“…While there are many established protocols for designing and conducting public health vector control activities, these are subject to logistical constraints, resource availability, and fluctuating funding streams [6][7][8][9][10][11]. Development of targeted vector control strategies that focus on surveillance indicators, or known risk factors for transmission, offer a possible solution for implementing effective control measures in resource-limited communities (e.g., Lippi et al 2020) [12]. Yet, social and ecological risk of exposure to arboviral infections is often understudied at fine spatial scales, such as individual households, at which many vector control interventions operate.…”

“…Several previous studies conducted in Machala have assessed risk factors for dengue fever outbreaks at the mesoscale (e.g. neighborhoods or census blocks), including larval vector densities, environmental drivers, sociodemographic characteristics, community perceptions, and service accessibility [12,14,25,30,[32][33][34]. The findings of these studies are useful in a public health advisory capacity, providing information that guides decision-making and research.…”