An improved ovitrap-based surveillance framework: facilitating cost-efficient monitoring and efficacy assessment of integrated vector management strategies for dengue outbreak control.

Background: Dengue fever, transmitted primarily by Aedes aegypti and Ae. albopictus, remains one of the most pervasive mosquito-borne diseases worldwide. In China, the mosquito oviposition trap (MOT) - based Aedes monitoring system has become a cornerstone for dengue prevention and control. However, during outbreaks, this system faces operational challenges because of its labour-intensive nature and time requirements, limiting its efficiency for rapid vector control assessment.

Methods: Based on the oviposition behavior of Ae. albopictus, a novel Improved Ovitrap (IMT) was designed, featuring a bucket-shaped body and a thermoplastic elastomer (TPE) oviposition band. Two field investigations were conducted in Guangzhou, Guangdong Province, China. Field Investigation 1 focused on continuous mosquito surveillance to evaluate the effectiveness of the IMT. Distance-incremental spatial autocorrelation analysis was performed to determine the monitoring radius of the IMTs, and suitable sampling fractions were estimated to identify the optimal sampling density. Field Investigation 2 aimed to compare the monitoring effectiveness of the IMT and the standard MOT for Ae. albopictus. Finally, an IMT-based surveillance strategy was proposed for local dengue epidemic control and was preliminarily implemented within case-area targeted intervention (CATI) practices.

Results: Our research established a significant positive correlation between the newly developed new Ovitrap Index (NOI) and the existing mosquito or oviposition positive index (MOI), which facilitated the creation of a IMT based surveillance strategy for dengue outbreak response. This optimized system recommends deploying six IMTs per standard 120,000 m2 CATI zone, maintaining continuous 24-hour monitoring cycles until official outbreak resolution, and implementing NOI threshold categories (0, 0-10, 10-20, 20-40, and ≥40) analogous to established MOI standards. Following successful implementation during three 2024 Guangdong CATI initiatives, this strategy has proven adaptable to complex urban environments while providing daily surveillance capabilities superior to those of conventional MOI-based systems.

Conclusions: In the present study, the IMT was developed and evaluated for field surveillance of Ae. albopictus mosquitoes. The core usage parameters of the IMT-based surveillance system, including the working radius and area deployment density, have been determined using systematic field investigations combined with mathematical modelling assessments. Furthermore, a novel strategy utilizing the IMT for evaluating the efficacy of integrated mosquito vector management in CATI during dengue outbreaks has been proposed. Preliminary results have confirmed the feasibility of using the IMT at outbreak sites, providing valuable support for CATI-based implementation. This innovative monitoring system offers an alternative solution and implementation strategy for conducting cost-effective surveillance of the dengue vector Ae. albopictus, as well as for evaluating the efficacy of integrated vector management during outbreaks.