Evaluating the effectiveness of dengue surveillance in the tropical and sub-tropical Asian nations through dengue case data from travelers returning to the five Western Pacific countries and territories

Introduction: Dengue, affecting over 3.9 billion people, is a significant health threat globally. Despite a tenfold increase in reported cases from 2000 to 2020, underreporting remains an issue. Our study utilized traveler data from the five Western Pacific countries and territories as sentinel sites, to examine dengue surveillance in in Southeast and South Asia.

Methods: We reported dengue cases among returning travelers (2010-2018) and computed dengue incidence per 100,000 travelers for each destination country. We compared officially reported dengue incidence per 100,000 inhabitants of the destination country with estimated incidence per 100,000 travelers, using Pearson's correlation coefficient.

Results: Key findings revealed eight Southeast and South Asia countries as popular destinations for our sentinel sites, with Australia exhibiting the highest incidence (40.7 per 100,000 travelers). Dengue incidence variations were evident, with Malaysia showing a sharp increase over time. Correlation analysis showed strong links in Malaysia (r = 0.66-0.92) and weaker connections in India (r = -0.54-0.76) between dengue incidence among inhabitants and travelers.

Conclusion: Systematically collected dengue surveillance data from returning travelers can serve as a proxy for dengue incidence in the destination country and can be used to assess the robustness of the country's dengue surveillance.